微信小程序 | 人脸识别的最终解决方案

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干货内容推荐

🥇入门和进阶小程序开发，不可错误的精彩内容🥇 ：

• 《吐血整理的几十款小程序登陆界面【附完整代码】》

• 《你真的会做小程序按钮吗？看了字节35K前端的样式设计，悟了》

• 《来接私活吧？玩转小程序开发之丝滑拆红包【附完整代码】》

• 《来接私活吧？小程序接私活必备功能-婚恋交友【附完整代码】》

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一、人脸识别功能现状

1.1 微信原生接口篇

微信原生的人脸识别接口可以完美的结合小程序所采集到的图像，可以达到实时帧级别的识别，是高效开发人脸识别功能的首选！

但是，由于人脸数据是个人的敏感数据，微信在开放该接口出来时，就是为了方便各行各业的业务开展。所以，我们要用它，就必须具备相应的资质。后续才能通过审核并发布上线。

资质说明链接：微信开放能力文档

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1.2 百度接口篇

百度人脸识别SDK的服务模式是用户在平台开通好相应的权限以及获取到appId等一系列操作之后，再到我们开发端是采用对百度人脸验证平台的相应接口进行发送验证请求才能实现服务的调用。

也就是说：百度已经人脸验证服务帮你全部搭建好了，你只需要发起请求进行调即可。

百度人脸识别服务地址

可以按量收费，目前根据你的业务量的QPS进行计费统计。

如果您的业务并发支持要求较高，免费测试 QPS 不能满足，您可以随时购买扩充 QPS ，QPS 可包月购买，也可按天购买，灵活多样，适应多场景需求。

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1.3 虹软接口篇

平台链接地址：虹软接口平台

虹软 和 百度 这两者之间的区别在于：

• 百度直接替你部署好了识别用的服务，你只需要按照文档指引向其特定的 接口发送数据即可获得你的结果，在某些主前端开发轻后端服务的应用来说还是很有优势的。
• 虹软所走的模式是不管你是离线还是在线都能让你运行，他把搭建服务端的工作留给你自己去做。在这样的模式下，你可以实时把控用户的人脸数据，对其进行自定义操作，从而构造更为灵活的人脸设别方式，对业务场景的开发也可以有更多操作的空间！

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二、人脸识别功能流程

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三、微信接口解析

3.1 微信摄像头组件的使用

• 小程序中要使用到摄像头的功能在于使用标签：

<camera v-if='isAuthCamera' device-position="front" class="camera" flash="off" resolution='high' />
1

对于标签核心的参数如下：

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3.2 微信小程序实时视频帧获取

对如何调用和开启微信小程序中的摄像头摄像和拍照功能进行学习：微信小程序–摄像头接口详解

• 首先需要调用CameraContext wx.createCameraContext()方法创建camera操作对象。
• 然后在camera对象之后调用onCameraFrame(function callback),该方法用于实时获取摄像头所捕捉的相片帧，从而用于与后端人脸识别引擎进行交互。

const context = wx.createCameraContext()
const listener = context.onCameraFrame((frame) => {
 	 console.log(frame.data instanceof ArrayBuffer, frame.width, frame.height)
})
listener.start()
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四、工具包的准备

4.1 将帧数据转为Base64

• 针对onCameraFrame()方法，获取到的是相机所捕捉的图片帧数据，这个时候我们需要将其转为Base64格式的图片数据，这是为了让其传输到后端能够被人脸识别引擎所使用！
• 在微信所开放的用于将帧数据转化为base 64接口中wx.arrayBufferToBase64（已弃用），项目中需要用摄像头获取人脸并将获取的ArrayBuffer数据转化为base64,就需要经过一下流程：
  
  代码如下：

	let pngData = ToPNG.encode([frame.data], frame.width, frame.height),  
			base64 = Base64Util.arrayBufferToBase64(pngData)
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• 所以先准备ArrayBuffer数据转化为PNG数据的工具包ToPNG.js

import pako from 'pako'
var UPNG = {};



UPNG.toRGBA8 = function (out) {
    var w = out.width,
        h = out.height;
    if (out.tabs.acTL == null) return [UPNG.toRGBA8.decodeImage(out.data, w, h, out).buffer];

    var frms = [];
    if (out.frames[0].data == null) out.frames[0].data = out.data;

    var len = w * h * 4,
        img = new Uint8Array(len),
        empty = new Uint8Array(len),
        prev = new Uint8Array(len);
    for (var i = 0; i < out.frames.length; i++) {
        var frm = out.frames[i];
        var fx = frm.rect.x,
            fy = frm.rect.y,
            fw = frm.rect.width,
            fh = frm.rect.height;
        var fdata = UPNG.toRGBA8.decodeImage(frm.data, fw, fh, out);

        if (i != 0)
            for (var j = 0; j < len; j++) prev[j] = img[j];

        if (frm.blend == 0) UPNG._copyTile(fdata, fw, fh, img, w, h, fx, fy, 0);
        else if (frm.blend == 1) UPNG._copyTile(fdata, fw, fh, img, w, h, fx, fy, 1);

        frms.push(img.buffer.slice(0));

        if (frm.dispose == 0) {} else if (frm.dispose == 1) UPNG._copyTile(empty, fw, fh, img, w, h, fx, fy, 0);
        else if (frm.dispose == 2)
            for (var j = 0; j < len; j++) img[j] = prev[j];
    }
    return frms;
}
UPNG.toRGBA8.decodeImage = function (data, w, h, out) {
    var area = w * h,
        bpp = UPNG.decode._getBPP(out);
    var bpl = Math.ceil(w * bpp / 8); // bytes per line

    var bf = new Uint8Array(area * 4),
        bf32 = new Uint32Array(bf.buffer);
    var ctype = out.ctype,
        depth = out.depth;
    var rs = UPNG._bin.readUshort;

    //console.log(ctype, depth);
    var time = Date.now();

    if (ctype == 6) { // RGB + alpha
        var qarea = area << 2;
        if (depth == 8)
            for (var i = 0; i < qarea; i += 4) {
                bf[i] = data[i];
                bf[i + 1] = data[i + 1];
                bf[i + 2] = data[i + 2];
                bf[i + 3] = data[i + 3];
            }
        if (depth == 16)
            for (var i = 0; i < qarea; i++) {
                bf[i] = data[i << 1];
            }
    } else if (ctype == 2) { // RGB
        var ts = out.tabs["tRNS"];
        if (ts == null) {
            if (depth == 8)
                for (var i = 0; i < area; i++) {
                    var ti = i * 3;
                    bf32[i] = (255 << 24) | (data[ti + 2] << 16) | (data[ti + 1] << 8) | data[ti];
                }
            if (depth == 16)
                for (var i = 0; i < area; i++) {
                    var ti = i * 6;
                    bf32[i] = (255 << 24) | (data[ti + 4] << 16) | (data[ti + 2] << 8) | data[ti];
                }
        } else {
            var tr = ts[0],
                tg = ts[1],
                tb = ts[2];
            if (depth == 8)
                for (var i = 0; i < area; i++) {
                    var qi = i << 2,
                        ti = i * 3;
                    bf32[i] = (255 << 24) | (data[ti + 2] << 16) | (data[ti + 1] << 8) | data[ti];
                    if (data[ti] == tr && data[ti + 1] == tg && data[ti + 2] == tb) bf[qi + 3] = 0;
                }
            if (depth == 16)
                for (var i = 0; i < area; i++) {
                    var qi = i << 2,
                        ti = i * 6;
                    bf32[i] = (255 << 24) | (data[ti + 4] << 16) | (data[ti + 2] << 8) | data[ti];
                    if (rs(data, ti) == tr && rs(data, ti + 2) == tg && rs(data, ti + 4) == tb) bf[qi + 3] = 0;
                }
        }
    } else if (ctype == 3) { // palette
        var p = out.tabs["PLTE"],
            ap = out.tabs["tRNS"],
            tl = ap ? ap.length : 0;
        //console.log(p, ap);
        if (depth == 1)
            for (var y = 0; y < h; y++) {
                var s0 = y * bpl,
                    t0 = y * w;
                for (var i = 0; i < w; i++) {
                    var qi = (t0 + i) << 2,
                        j = ((data[s0 + (i >> 3)] >> (7 - ((i & 7) << 0))) & 1),
                        cj = 3 * j;
                    bf[qi] = p[cj];
                    bf[qi + 1] = p[cj + 1];
                    bf[qi + 2] = p[cj + 2];
                    bf[qi + 3] = (j < tl) ? ap[j] : 255;
                }
            }
        if (depth == 2)
            for (var y = 0; y < h; y++) {
                var s0 = y * bpl,
                    t0 = y * w;
                for (var i = 0; i < w; i++) {
                    var qi = (t0 + i) << 2,
                        j = ((data[s0 + (i >> 2)] >> (6 - ((i & 3) << 1))) & 3),
                        cj = 3 * j;
                    bf[qi] = p[cj];
                    bf[qi + 1] = p[cj + 1];
                    bf[qi + 2] = p[cj + 2];
                    bf[qi + 3] = (j < tl) ? ap[j] : 255;
                }
            }
        if (depth == 4)
            for (var y = 0; y < h; y++) {
                var s0 = y * bpl,
                    t0 = y * w;
                for (var i = 0; i < w; i++) {
                    var qi = (t0 + i) << 2,
                        j = ((data[s0 + (i >> 1)] >> (4 - ((i & 1) << 2))) & 15),
                        cj = 3 * j;
                    bf[qi] = p[cj];
                    bf[qi + 1] = p[cj + 1];
                    bf[qi + 2] = p[cj + 2];
                    bf[qi + 3] = (j < tl) ? ap[j] : 255;
                }
            }
        if (depth == 8)
            for (var i = 0; i < area; i++) {
                var qi = i << 2,
                    j = data[i],
                    cj = 3 * j;
                bf[qi] = p[cj];
                bf[qi + 1] = p[cj + 1];
                bf[qi + 2] = p[cj + 2];
                bf[qi + 3] = (j < tl) ? ap[j] : 255;
            }
    } else if (ctype == 4) { // gray + alpha
        if (depth == 8)
            for (var i = 0; i < area; i++) {
                var qi = i << 2,
                    di = i << 1,
                    gr = data[di];
                bf[qi] = gr;
                bf[qi + 1] = gr;
                bf[qi + 2] = gr;
                bf[qi + 3] = data[di + 1];
            }
        if (depth == 16)
            for (var i = 0; i < area; i++) {
                var qi = i << 2,
                    di = i << 2,
                    gr = data[di];
                bf[qi] = gr;
                bf[qi + 1] = gr;
                bf[qi + 2] = gr;
                bf[qi + 3] = data[di + 2];
            }
    } else if (ctype == 0) { // gray
        var tr = out.tabs["tRNS"] ? out.tabs["tRNS"] : -1;
        for (var y = 0; y < h; y++) {
            var off = y * bpl,
                to = y * w;
            if (depth == 1)
                for (var x = 0; x < w; x++) {
                    var gr = 255 * ((data[off + (x >>> 3)] >>> (7 - ((x & 7)))) & 1),
                        al = (gr == tr * 255) ? 0 : 255;
                    bf32[to + x] = (al << 24) | (gr << 16) | (gr << 8) | gr;
                }
            else if (depth == 2)
                for (var x = 0; x < w; x++) {
                    var gr = 85 * ((data[off + (x >>> 2)] >>> (6 - ((x & 3) << 1))) & 3),
                        al = (gr == tr * 85) ? 0 : 255;
                    bf32[to + x] = (al << 24) | (gr << 16) | (gr << 8) | gr;
                }
            else if (depth == 4)
                for (var x = 0; x < w; x++) {
                    var gr = 17 * ((data[off + (x >>> 1)] >>> (4 - ((x & 1) << 2))) & 15),
                        al = (gr == tr * 17) ? 0 : 255;
                    bf32[to + x] = (al << 24) | (gr << 16) | (gr << 8) | gr;
                }
            else if (depth == 8)
                for (var x = 0; x < w; x++) {
                    var gr = data[off + x],
                        al = (gr == tr) ? 0 : 255;
                    bf32[to + x] = (al << 24) | (gr << 16) | (gr << 8) | gr;
                }
            else if (depth == 16)
                for (var x = 0; x < w; x++) {
                    var gr = data[off + (x << 1)],
                        al = (rs(data, off + (x << 1)) == tr) ? 0 : 255;
                    bf32[to + x] = (al << 24) | (gr << 16) | (gr << 8) | gr;
                }
        }
    }
    //console.log(Date.now()-time);
    return bf;
}



UPNG.decode = function (buff) {
    var data = new Uint8Array(buff),
        offset = 8,
        bin = UPNG._bin,
        rUs = bin.readUshort,
        rUi = bin.readUint;
    var out = {
        tabs: {},
        frames: []
    };
    var dd = new Uint8Array(data.length),
        doff = 0; // put all IDAT data into it
    var fd, foff = 0; // frames

    var mgck = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
    for (var i = 0; i < 8; i++)
        if (data[i] != mgck[i]) throw "The input is not a PNG file!";

    while (offset < data.length) {
        var len = bin.readUint(data, offset);
        offset += 4;
        var type = bin.readASCII(data, offset, 4);
        offset += 4;
        //console.log(type,len);

        if (type == "IHDR") {
            UPNG.decode._IHDR(data, offset, out);
        } else if (type == "CgBI") {
            out.tabs[type] = data.slice(offset, offset + 4);
        } else if (type == "IDAT") {
            for (var i = 0; i < len; i++) dd[doff + i] = data[offset + i];
            doff += len;
        } else if (type == "acTL") {
            out.tabs[type] = {
                num_frames: rUi(data, offset),
                num_plays: rUi(data, offset + 4)
            };
            fd = new Uint8Array(data.length);
        } else if (type == "fcTL") {
            if (foff != 0) {
                var fr = out.frames[out.frames.length - 1];
                fr.data = UPNG.decode._decompress(out, fd.slice(0, foff), fr.rect.width, fr.rect.height);
                foff = 0;
            }
            var rct = {
                x: rUi(data, offset + 12),
                y: rUi(data, offset + 16),
                width: rUi(data, offset + 4),
                height: rUi(data, offset + 8)
            };
            var del = rUs(data, offset + 22);
            del = rUs(data, offset + 20) / (del == 0 ? 100 : del);
            var frm = {
                rect: rct,
                delay: Math.round(del * 1000),
                dispose: data[offset + 24],
                blend: data[offset + 25]
            };
            //console.log(frm);
            out.frames.push(frm);
        } else if (type == "fdAT") {
            for (var i = 0; i < len - 4; i++) fd[foff + i] = data[offset + i + 4];
            foff += len - 4;
        } else if (type == "pHYs") {
            out.tabs[type] = [bin.readUint(data, offset), bin.readUint(data, offset + 4), data[offset + 8]];
        } else if (type == "cHRM") {
            out.tabs[type] = [];
            for (var i = 0; i < 8; i++) out.tabs[type].push(bin.readUint(data, offset + i * 4));
        } else if (type == "tEXt" || type == "zTXt") {
            if (out.tabs[type] == null) out.tabs[type] = {};
            var nz = bin.nextZero(data, offset);
            var keyw = bin.readASCII(data, offset, nz - offset);
            var text, tl = offset + len - nz - 1;
            if (type == "tEXt") text = bin.readASCII(data, nz + 1, tl);
            else {
                var bfr = UPNG.decode._inflate(data.slice(nz + 2, nz + 2 + tl));
                text = bin.readUTF8(bfr, 0, bfr.length);
            }
            out.tabs[type][keyw] = text;
        } else if (type == "iTXt") {
            if (out.tabs[type] == null) out.tabs[type] = {};
            var nz = 0,
                off = offset;
            nz = bin.nextZero(data, off);
            var keyw = bin.readASCII(data, off, nz - off);
            off = nz + 1;
            var cflag = data[off],
                cmeth = data[off + 1];
            off += 2;
            nz = bin.nextZero(data, off);
            var ltag = bin.readASCII(data, off, nz - off);
            off = nz + 1;
            nz = bin.nextZero(data, off);
            var tkeyw = bin.readUTF8(data, off, nz - off);
            off = nz + 1;
            var text, tl = len - (off - offset);
            if (cflag == 0) text = bin.readUTF8(data, off, tl);
            else {
                var bfr = UPNG.decode._inflate(data.slice(off, off + tl));
                text = bin.readUTF8(bfr, 0, bfr.length);
            }
            out.tabs[type][keyw] = text;
        } else if (type == "PLTE") {
            out.tabs[type] = bin.readBytes(data, offset, len);
        } else if (type == "hIST") {
            var pl = out.tabs["PLTE"].length / 3;
            out.tabs[type] = [];
            for (var i = 0; i < pl; i++) out.tabs[type].push(rUs(data, offset + i * 2));
        } else if (type == "tRNS") {
            if (out.ctype == 3) out.tabs[type] = bin.readBytes(data, offset, len);
            else if (out.ctype == 0) out.tabs[type] = rUs(data, offset);
            else if (out.ctype == 2) out.tabs[type] = [rUs(data, offset), rUs(data, offset + 2), rUs(data, offset + 4)];
            //else console.log("tRNS for unsupported color type",out.ctype, len);
        } else if (type == "gAMA") out.tabs[type] = bin.readUint(data, offset) / 100000;
        else if (type == "sRGB") out.tabs[type] = data[offset];
        else if (type == "bKGD") {
            if (out.ctype == 0 || out.ctype == 4) out.tabs[type] = [rUs(data, offset)];
            else if (out.ctype == 2 || out.ctype == 6) out.tabs[type] = [rUs(data, offset), rUs(data, offset + 2), rUs(data, offset + 4)];
            else if (out.ctype == 3) out.tabs[type] = data[offset];
        } else if (type == "IEND") {
            break;
        }
        //else {  console.log("unknown chunk type", type, len);  out.tabs[type]=data.slice(offset,offset+len);  }
        offset += len;
        var crc = bin.readUint(data, offset);
        offset += 4;
    }
    if (foff != 0) {
        var fr = out.frames[out.frames.length - 1];
        fr.data = UPNG.decode._decompress(out, fd.slice(0, foff), fr.rect.width, fr.rect.height);
    }
    out.data = UPNG.decode._decompress(out, dd, out.width, out.height);

    delete out.compress;
    delete out.interlace;
    delete out.filter;
    return out;
}

UPNG.decode._decompress = function (out, dd, w, h) {
    var time = Date.now();
    var bpp = UPNG.decode._getBPP(out),
        bpl = Math.ceil(w * bpp / 8),
        buff = new Uint8Array((bpl + 1 + out.interlace) * h);
    if (out.tabs["CgBI"]) dd = UPNG.inflateRaw(dd, buff);
    else dd = UPNG.decode._inflate(dd, buff);
    //console.log(dd.length, buff.length);
    //console.log(Date.now()-time);

    var time = Date.now();
    if (out.interlace == 0) dd = UPNG.decode._filterZero(dd, out, 0, w, h);
    else if (out.interlace == 1) dd = UPNG.decode._readInterlace(dd, out);
    //console.log(Date.now()-time);
    return dd;
}

UPNG.decode._inflate = function (data, buff) {
    var out = UPNG["inflateRaw"](new Uint8Array(data.buffer, 2, data.length - 6), buff);
    return out;
}
UPNG.inflateRaw = function () {
    var H = {};
    H.H = {};
    H.H.N = function (N, W) {
        var R = Uint8Array,
            i = 0,
            m = 0,
            J = 0,
            h = 0,
            Q = 0,
            X = 0,
            u = 0,
            w = 0,
            d = 0,
            v, C;
        if (N[0] == 3 && N[1] == 0) return W ? W : new R(0);
        var V = H.H,
            n = V.b,
            A = V.e,
            l = V.R,
            M = V.n,
            I = V.A,
            e = V.Z,
            b = V.m,
            Z = W == null;
        if (Z) W = new R(N.length >>> 2 << 5);
        while (i == 0) {
            i = n(N, d, 1);
            m = n(N, d + 1, 2);
            d += 3;
            if (m == 0) {
                if ((d & 7) != 0) d += 8 - (d & 7);
                var D = (d >>> 3) + 4,
                    q = N[D - 4] | N[D - 3] << 8;
                if (Z) W = H.H.W(W, w + q);
                W.set(new R(N.buffer, N.byteOffset + D, q), w);
                d = D + q << 3;
                w += q;
                continue
            }
            if (Z) W = H.H.W(W, w + (1 << 17));
            if (m == 1) {
                v = b.J;
                C = b.h;
                X = (1 << 9) - 1;
                u = (1 << 5) - 1
            }
            if (m == 2) {
                J = A(N, d, 5) + 257;
                h = A(N, d + 5, 5) + 1;
                Q = A(N, d + 10, 4) + 4;
                d += 14;
                var E = d,
                    j = 1;
                for (var c = 0; c < 38; c += 2) {
                    b.Q[c] = 0;
                    b.Q[c + 1] = 0
                }
                for (var c = 0; c < Q; c++) {
                    var K = A(N, d + c * 3, 3);
                    b.Q[(b.X[c] << 1) + 1] = K;
                    if (K > j) j = K
                }
                d += 3 * Q;
                M(b.Q, j);
                I(b.Q, j, b.u);
                v = b.w;
                C = b.d;
                d = l(b.u, (1 << j) - 1, J + h, N, d, b.v);
                var r = V.V(b.v, 0, J, b.C);
                X = (1 << r) - 1;
                var S = V.V(b.v, J, h, b.D);
                u = (1 << S) - 1;
                M(b.C, r);
                I(b.C, r, v);
                M(b.D, S);
                I(b.D, S, C)
            }
            while (!0) {
                var T = v[e(N, d) & X];
                d += T & 15;
                var p = T >>> 4;
                if (p >>> 8 == 0) {
                    W[w++] = p
                } else if (p == 256) {
                    break
                } else {
                    var z = w + p - 254;
                    if (p > 264) {
                        var _ = b.q[p - 257];
                        z = w + (_ >>> 3) + A(N, d, _ & 7);
                        d += _ & 7
                    }
                    var $ = C[e(N, d) & u];
                    d += $ & 15;
                    var s = $ >>> 4,
                        Y = b.c[s],
                        a = (Y >>> 4) + n(N, d, Y & 15);
                    d += Y & 15;
                    while (w < z) {
                        W[w] = W[w++ - a];
                        W[w] = W[w++ - a];
                        W[w] = W[w++ - a];
                        W[w] = W[w++ - a]
                    }
                    w = z
                }
            }
        }
        return W.length == w ? W : W.slice(0, w)
    };
    H.H.W = function (N, W) {
        var R = N.length;
        if (W <= R) return N;
        var V = new Uint8Array(R << 1);
        V.set(N, 0);
        return V
    };
    H.H.R = function (N, W, R, V, n, A) {
        var l = H.H.e,
            M = H.H.Z,
            I = 0;
        while (I < R) {
            var e = N[M(V, n) & W];
            n += e & 15;
            var b = e >>> 4;
            if (b <= 15) {
                A[I] = b;
                I++
            } else {
                var Z = 0,
                    m = 0;
                if (b == 16) {
                    m = 3 + l(V, n, 2);
                    n += 2;
                    Z = A[I - 1]
                } else if (b == 17) {
                    m = 3 + l(V, n, 3);
                    n += 3
                } else if (b == 18) {
                    m = 11 + l(V, n, 7);
                    n += 7
                }
                var J = I + m;
                while (I < J) {
                    A[I] = Z;
                    I++
                }
            }
        }
        return n
    };
    H.H.V = function (N, W, R, V) {
        var n = 0,
            A = 0,
            l = V.length >>> 1;
        while (A < R) {
            var M = N[A + W];
            V[A << 1] = 0;
            V[(A << 1) + 1] = M;
            if (M > n) n = M;
            A++
        }
        while (A < l) {
            V[A << 1] = 0;
            V[(A << 1) + 1] = 0;
            A++
        }
        return n
    };
    H.H.n = function (N, W) {
        var R = H.H.m,
            V = N.length,
            n, A, l, M, I, e = R.j;
        for (var M = 0; M <= W; M++) e[M] = 0;
        for (M = 1; M < V; M += 2) e[N[M]]++;
        var b = R.K;
        n = 0;
        e[0] = 0;
        for (A = 1; A <= W; A++) {
            n = n + e[A - 1] << 1;
            b[A] = n
        }
        for (l = 0; l < V; l += 2) {
            I = N[l + 1];
            if (I != 0) {
                N[l] = b[I];
                b[I]++
            }
        }
    };
    H.H.A = function (N, W, R) {
        var V = N.length,
            n = H.H.m,
            A = n.r;
        for (var l = 0; l < V; l += 2)
            if (N[l + 1] != 0) {
                var M = l >> 1,
                    I = N[l + 1],
                    e = M << 4 | I,
                    b = W - I,
                    Z = N[l] << b,
                    m = Z + (1 << b);
                while (Z != m) {
                    var J = A[Z] >>> 15 - W;
                    R[J] = e;
                    Z++
                }
            }
    };
    H.H.l = function (N, W) {
        var R = H.H.m.r,
            V = 15 - W;
        for (var n = 0; n < N.length; n += 2) {
            var A = N[n] << W - N[n + 1];
            N[n] = R[A] >>> V
        }
    };
    H.H.M = function (N, W, R) {
        R = R << (W & 7);
        var V = W >>> 3;
        N[V] |= R;
        N[V + 1] |= R >>> 8
    };
    H.H.I = function (N, W, R) {
        R = R << (W & 7);
        var V = W >>> 3;
        N[V] |= R;
        N[V + 1] |= R >>> 8;
        N[V + 2] |= R >>> 16
    };
    H.H.e = function (N, W, R) {
        return (N[W >>> 3] | N[(W >>> 3) + 1] << 8) >>> (W & 7) & (1 << R) - 1
    };
    H.H.b = function (N, W, R) {
        return (N[W >>> 3] | N[(W >>> 3) + 1] << 8 | N[(W >>> 3) + 2] << 16) >>> (W & 7) & (1 << R) - 1
    };
    H.H.Z = function (N, W) {
        return (N[W >>> 3] | N[(W >>> 3) + 1] << 8 | N[(W >>> 3) + 2] << 16) >>> (W & 7)
    };
    H.H.i = function (N, W) {
        return (N[W >>> 3] | N[(W >>> 3) + 1] << 8 | N[(W >>> 3) + 2] << 16 | N[(W >>> 3) + 3] << 24) >>> (W & 7)
    };
    H.H.m = function () {
        var N = Uint16Array,
            W = Uint32Array;
        return {
            K: new N(16),
            j: new N(16),
            X: [16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15],
            S: [3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 999, 999, 999],
            T: [0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 0, 0, 0],
            q: new N(32),
            p: [1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577, 65535, 65535],
            z: [0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 0, 0],
            c: new W(32),
            J: new N(512),
            _: [],
            h: new N(32),
            $: [],
            w: new N(32768),
            C: [],
            v: [],
            d: new N(32768),
            D: [],
            u: new N(512),
            Q: [],
            r: new N(1 << 15),
            s: new W(286),
            Y: new W(30),
            a: new W(19),
            t: new W(15e3),
            k: new N(1 << 16),
            g: new N(1 << 15)
        }
    }();
    (function () {
        var N = H.H.m,
            W = 1 << 15;
        for (var R = 0; R < W; R++) {
            var V = R;
            V = (V & 2863311530) >>> 1 | (V & 1431655765) << 1;
            V = (V & 3435973836) >>> 2 | (V & 858993459) << 2;
            V = (V & 4042322160) >>> 4 | (V & 252645135) << 4;
            V = (V & 4278255360) >>> 8 | (V & 16711935) << 8;
            N.r[R] = (V >>> 16 | V << 16) >>> 17
        }

        function n(A, l, M) {
            while (l-- != 0) A.push(0, M)
        }
        for (var R = 0; R < 32; R++) {
            N.q[R] = N.S[R] << 3 | N.T[R];
            N.c[R] = N.p[R] << 4 | N.z[R]
        }
        n(N._, 144, 8);
        n(N._, 255 - 143, 9);
        n(N._, 279 - 255, 7);
        n(N._, 287 - 279, 8);
        H.H.n(N._, 9);
        H.H.A(N._, 9, N.J);
        H.H.l(N._, 9);
        n(N.$, 32, 5);
        H.H.n(N.$, 5);
        H.H.A(N.$, 5, N.h);
        H.H.l(N.$, 5);
        n(N.Q, 19, 0);
        n(N.C, 286, 0);
        n(N.D, 30, 0);
        n(N.v, 320, 0)
    }());
    return H.H.N
}()


UPNG.decode._readInterlace = function (data, out) {
    var w = out.width,
        h = out.height;
    var bpp = UPNG.decode._getBPP(out),
        cbpp = bpp >> 3,
        bpl = Math.ceil(w * bpp / 8);
    var img = new Uint8Array(h * bpl);
    var di = 0;

    var starting_row = [0, 0, 4, 0, 2, 0, 1];
    var starting_col = [0, 4, 0, 2, 0, 1, 0];
    var row_increment = [8, 8, 8, 4, 4, 2, 2];
    var col_increment = [8, 8, 4, 4, 2, 2, 1];

    var pass = 0;
    while (pass < 7) {
        var ri = row_increment[pass],
            ci = col_increment[pass];
        var sw = 0,
            sh = 0;
        var cr = starting_row[pass];
        while (cr < h) {
            cr += ri;
            sh++;
        }
        var cc = starting_col[pass];
        while (cc < w) {
            cc += ci;
            sw++;
        }
        var bpll = Math.ceil(sw * bpp / 8);
        UPNG.decode._filterZero(data, out, di, sw, sh);

        var y = 0,
            row = starting_row[pass];
        while (row < h) {
            var col = starting_col[pass];
            var cdi = (di + y * bpll) << 3;

            while (col < w) {
                if (bpp == 1) {
                    var val = data[cdi >> 3];
                    val = (val >> (7 - (cdi & 7))) & 1;
                    img[row * bpl + (col >> 3)] |= (val << (7 - ((col & 7) << 0)));
                }
                if (bpp == 2) {
                    var val = data[cdi >> 3];
                    val = (val >> (6 - (cdi & 7))) & 3;
                    img[row * bpl + (col >> 2)] |= (val << (6 - ((col & 3) << 1)));
                }
                if (bpp == 4) {
                    var val = data[cdi >> 3];
                    val = (val >> (4 - (cdi & 7))) & 15;
                    img[row * bpl + (col >> 1)] |= (val << (4 - ((col & 1) << 2)));
                }
                if (bpp >= 8) {
                    var ii = row * bpl + col * cbpp;
                    for (var j = 0; j < cbpp; j++) img[ii + j] = data[(cdi >> 3) + j];
                }
                cdi += bpp;
                col += ci;
            }
            y++;
            row += ri;
        }
        if (sw * sh != 0) di += sh * (1 + bpll);
        pass = pass + 1;
    }
    return img;
}

UPNG.decode._getBPP = function (out) {
    var noc = [1, null, 3, 1, 2, null, 4][out.ctype];
    return noc * out.depth;
}

UPNG.decode._filterZero = function (data, out, off, w, h) {
    var bpp = UPNG.decode._getBPP(out),
        bpl = Math.ceil(w * bpp / 8),
        paeth = UPNG.decode._paeth;
    bpp = Math.ceil(bpp / 8);

    var i, di, type = data[off],
        x = 0;

    if (type > 1) data[off] = [0, 0, 1][type - 2];
    if (type == 3)
        for (x = bpp; x < bpl; x++) data[x + 1] = (data[x + 1] + (data[x + 1 - bpp] >>> 1)) & 255;

    for (var y = 0; y < h; y++) {
        i = off + y * bpl;
        di = i + y + 1;
        type = data[di - 1];
        x = 0;

        if (type == 0)
            for (; x < bpl; x++) data[i + x] = data[di + x];
        else if (type == 1) {
            for (; x < bpp; x++) data[i + x] = data[di + x];
            for (; x < bpl; x++) data[i + x] = (data[di + x] + data[i + x - bpp]);
        } else if (type == 2) {
            for (; x < bpl; x++) data[i + x] = (data[di + x] + data[i + x - bpl]);
        } else if (type == 3) {
            for (; x < bpp; x++) data[i + x] = (data[di + x] + (data[i + x - bpl] >>> 1));
            for (; x < bpl; x++) data[i + x] = (data[di + x] + ((data[i + x - bpl] + data[i + x - bpp]) >>> 1));
        } else {
            for (; x < bpp; x++) data[i + x] = (data[di + x] + paeth(0, data[i + x - bpl], 0));
            for (; x < bpl; x++) data[i + x] = (data[di + x] + paeth(data[i + x - bpp], data[i + x - bpl], data[i + x - bpp - bpl]));
        }
    }
    return data;
}

UPNG.decode._paeth = function (a, b, c) {
    var p = a + b - c,
        pa = (p - a),
        pb = (p - b),
        pc = (p - c);
    if (pa * pa <= pb * pb && pa * pa <= pc * pc) return a;
    else if (pb * pb <= pc * pc) return b;
    return c;
}

UPNG.decode._IHDR = function (data, offset, out) {
    var bin = UPNG._bin;
    out.width = bin.readUint(data, offset);
    offset += 4;
    out.height = bin.readUint(data, offset);
    offset += 4;
    out.depth = data[offset];
    offset++;
    out.ctype = data[offset];
    offset++;
    out.compress = data[offset];
    offset++;
    out.filter = data[offset];
    offset++;
    out.interlace = data[offset];
    offset++;
}

UPNG._bin = {
    nextZero: function (data, p) {
        while (data[p] != 0) p++;
        return p;
    },
    readUshort: function (buff, p) {
        return (buff[p] << 8) | buff[p + 1];
    },
    writeUshort: function (buff, p, n) {
        buff[p] = (n >> 8) & 255;
        buff[p + 1] = n & 255;
    },
    readUint: function (buff, p) {
        return (buff[p] * (256 * 256 * 256)) + ((buff[p + 1] << 16) | (buff[p + 2] << 8) | buff[p + 3]);
    },
    writeUint: function (buff, p, n) {
        buff[p] = (n >> 24) & 255;
        buff[p + 1] = (n >> 16) & 255;
        buff[p + 2] = (n >> 8) & 255;
        buff[p + 3] = n & 255;
    },
    readASCII: function (buff, p, l) {
        var s = "";
        for (var i = 0; i < l; i++) s += String.fromCharCode(buff[p + i]);
        return s;
    },
    writeASCII: function (data, p, s) {
        for (var i = 0; i < s.length; i++) data[p + i] = s.charCodeAt(i);
    },
    readBytes: function (buff, p, l) {
        var arr = [];
        for (var i = 0; i < l; i++) arr.push(buff[p + i]);
        return arr;
    },
    pad: function (n) {
        return n.length < 2 ? "0" + n : n;
    },
    readUTF8: function (buff, p, l) {
        var s = "",
            ns;
        for (var i = 0; i < l; i++) s += "%" + UPNG._bin.pad(buff[p + i].toString(16));
        try {
            ns = decodeURIComponent(s);
        } catch (e) {
            return UPNG._bin.readASCII(buff, p, l);
        }
        return ns;
    }
}
UPNG._copyTile = function (sb, sw, sh, tb, tw, th, xoff, yoff, mode) {
    var w = Math.min(sw, tw),
        h = Math.min(sh, th);
    var si = 0,
        ti = 0;
    for (var y = 0; y < h; y++)
        for (var x = 0; x < w; x++) {
            if (xoff >= 0 && yoff >= 0) {
                si = (y * sw + x) << 2;
                ti = ((yoff + y) * tw + xoff + x) << 2;
            } else {
                si = ((-yoff + y) * sw - xoff + x) << 2;
                ti = (y * tw + x) << 2;
            }

            if (mode == 0) {
                tb[ti] = sb[si];
                tb[ti + 1] = sb[si + 1];
                tb[ti + 2] = sb[si + 2];
                tb[ti + 3] = sb[si + 3];
            } else if (mode == 1) {
                var fa = sb[si + 3] * (1 / 255),
                    fr = sb[si] * fa,
                    fg = sb[si + 1] * fa,
                    fb = sb[si + 2] * fa;
                var ba = tb[ti + 3] * (1 / 255),
                    br = tb[ti] * ba,
                    bg = tb[ti + 1] * ba,
                    bb = tb[ti + 2] * ba;

                var ifa = 1 - fa,
                    oa = fa + ba * ifa,
                    ioa = (oa == 0 ? 0 : 1 / oa);
                tb[ti + 3] = 255 * oa;
                tb[ti + 0] = (fr + br * ifa) * ioa;
                tb[ti + 1] = (fg + bg * ifa) * ioa;
                tb[ti + 2] = (fb + bb * ifa) * ioa;
            } else if (mode == 2) { // copy only differences, otherwise zero
                var fa = sb[si + 3],
                    fr = sb[si],
                    fg = sb[si + 1],
                    fb = sb[si + 2];
                var ba = tb[ti + 3],
                    br = tb[ti],
                    bg = tb[ti + 1],
                    bb = tb[ti + 2];
                if (fa == ba && fr == br && fg == bg && fb == bb) {
                    tb[ti] = 0;
                    tb[ti + 1] = 0;
                    tb[ti + 2] = 0;
                    tb[ti + 3] = 0;
                } else {
                    tb[ti] = fr;
                    tb[ti + 1] = fg;
                    tb[ti + 2] = fb;
                    tb[ti + 3] = fa;
                }
            } else if (mode == 3) { // check if can be blended
                var fa = sb[si + 3],
                    fr = sb[si],
                    fg = sb[si + 1],
                    fb = sb[si + 2];
                var ba = tb[ti + 3],
                    br = tb[ti],
                    bg = tb[ti + 1],
                    bb = tb[ti + 2];
                if (fa == ba && fr == br && fg == bg && fb == bb) continue;
                //if(fa!=255 && ba!=0) return false;
                if (fa < 220 && ba > 20) return false;
            }
        }
    return true;
}





UPNG.encode = function (bufs, w, h, ps, dels, tabs, forbidPlte) {
    if (ps == null) ps = 0;
    if (forbidPlte == null) forbidPlte = false;

    var nimg = UPNG.encode.compress(bufs, w, h, ps, [false, false, false, 0, forbidPlte, false]);
    UPNG.encode.compressPNG(nimg, -1);

    return UPNG.encode._main(nimg, w, h, dels, tabs);
}

UPNG.encodeLL = function (bufs, w, h, cc, ac, depth, dels, tabs) {
    var nimg = {
        ctype: 0 + (cc == 1 ? 0 : 2) + (ac == 0 ? 0 : 4),
        depth: depth,
        frames: []
    };

    var time = Date.now();
    var bipp = (cc + ac) * depth,
        bipl = bipp * w;
    for (var i = 0; i < bufs.length; i++)
        nimg.frames.push({
            rect: {
                x: 0,
                y: 0,
                width: w,
                height: h
            },
            img: new Uint8Array(bufs[i]),
            blend: 0,
            dispose: 1,
            bpp: Math.ceil(bipp / 8),
            bpl: Math.ceil(bipl / 8)
        });

    UPNG.encode.compressPNG(nimg, 0, true);

    var out = UPNG.encode._main(nimg, w, h, dels, tabs);
    return out;
}

UPNG.encode._main = function (nimg, w, h, dels, tabs) {
    if (tabs == null) tabs = {};
    var crc = UPNG.crc.crc,
        wUi = UPNG._bin.writeUint,
        wUs = UPNG._bin.writeUshort,
        wAs = UPNG._bin.writeASCII;
    var offset = 8,
        anim = nimg.frames.length > 1,
        pltAlpha = false;

    var leng = 8 + (16 + 5 + 4) /*+ (9+4)*/ + (anim ? 20 : 0);
    if (tabs["sRGB"] != null) leng += 8 + 1 + 4;
    if (tabs["pHYs"] != null) leng += 8 + 9 + 4;
    if (nimg.ctype == 3) {
        var dl = nimg.plte.length;
        for (var i = 0; i < dl; i++)
            if ((nimg.plte[i] >>> 24) != 255) pltAlpha = true;
        leng += (8 + dl * 3 + 4) + (pltAlpha ? (8 + dl * 1 + 4) : 0);
    }
    for (var j = 0; j < nimg.frames.length; j++) {
        var fr = nimg.frames[j];
        if (anim) leng += 38;
        leng += fr.cimg.length + 12;
        if (j != 0) leng += 4;
    }
    leng += 12;

    var data = new Uint8Array(leng);
    var wr = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
    for (var i = 0; i < 8; i++) data[i] = wr[i];

    wUi(data, offset, 13);
    offset += 4;
    wAs(data, offset, "IHDR");
    offset += 4;
    wUi(data, offset, w);
    offset += 4;
    wUi(data, offset, h);
    offset += 4;
    data[offset] = nimg.depth;
    offset++; // depth
    data[offset] = nimg.ctype;
    offset++; // ctype
    data[offset] = 0;
    offset++; // compress
    data[offset] = 0;
    offset++; // filter
    data[offset] = 0;
    offset++; // interlace
    wUi(data, offset, crc(data, offset - 17, 17));
    offset += 4; // crc

    // 13 bytes to say, that it is sRGB
    if (tabs["sRGB"] != null) {
        wUi(data, offset, 1);
        offset += 4;
        wAs(data, offset, "sRGB");
        offset += 4;
        data[offset] = tabs["sRGB"];
        offset++;
        wUi(data, offset, crc(data, offset - 5, 5));
        offset += 4; // crc
    }
    if (tabs["pHYs"] != null) {
        wUi(data, offset, 9);
        offset += 4;
        wAs(data, offset, "pHYs");
        offset += 4;
        wUi(data, offset, tabs["pHYs"][0]);
        offset += 4;
        wUi(data, offset, tabs["pHYs"][1]);
        offset += 4;
        data[offset] = tabs["pHYs"][2];
        offset++;
        wUi(data, offset, crc(data, offset - 13, 13));
        offset += 4; // crc
    }

    if (anim) {
        wUi(data, offset, 8);
        offset += 4;
        wAs(data, offset, "acTL");
        offset += 4;
        wUi(data, offset, nimg.frames.length);
        offset += 4;
        wUi(data, offset, tabs["loop"] != null ? tabs["loop"] : 0);
        offset += 4;
        wUi(data, offset, crc(data, offset - 12, 12));
        offset += 4; // crc
    }

    if (nimg.ctype == 3) {
        var dl = nimg.plte.length;
        wUi(data, offset, dl * 3);
        offset += 4;
        wAs(data, offset, "PLTE");
        offset += 4;
        for (var i = 0; i < dl; i++) {
            var ti = i * 3,
                c = nimg.plte[i],
                r = (c) & 255,
                g = (c >>> 8) & 255,
                b = (c >>> 16) & 255;
            data[offset + ti + 0] = r;
            data[offset + ti + 1] = g;
            data[offset + ti + 2] = b;
        }
        offset += dl * 3;
        wUi(data, offset, crc(data, offset - dl * 3 - 4, dl * 3 + 4));
        offset += 4; // crc

        if (pltAlpha) {
            wUi(data, offset, dl);
            offset += 4;
            wAs(data, offset, "tRNS");
            offset += 4;
            for (var i = 0; i < dl; i++) data[offset + i] = (nimg.plte[i] >>> 24) & 255;
            offset += dl;
            wUi(data, offset, crc(data, offset - dl - 4, dl + 4));
            offset += 4; // crc
        }
    }

    var fi = 0;
    for (var j = 0; j < nimg.frames.length; j++) {
        var fr = nimg.frames[j];
        if (anim) {
            wUi(data, offset, 26);
            offset += 4;
            wAs(data, offset, "fcTL");
            offset += 4;
            wUi(data, offset, fi++);
            offset += 4;
            wUi(data, offset, fr.rect.width);
            offset += 4;
            wUi(data, offset, fr.rect.height);
            offset += 4;
            wUi(data, offset, fr.rect.x);
            offset += 4;
            wUi(data, offset, fr.rect.y);
            offset += 4;
            wUs(data, offset, dels[j]);
            offset += 2;
            wUs(data, offset, 1000);
            offset += 2;
            data[offset] = fr.dispose;
            offset++; // dispose
            data[offset] = fr.blend;
            offset++; // blend
            wUi(data, offset, crc(data, offset - 30, 30));
            offset += 4; // crc
        }

        var imgd = fr.cimg,
            dl = imgd.length;
        wUi(data, offset, dl + (j == 0 ? 0 : 4));
        offset += 4;
        var ioff = offset;
        wAs(data, offset, (j == 0) ? "IDAT" : "fdAT");
        offset += 4;
        if (j != 0) {
            wUi(data, offset, fi++);
            offset += 4;
        }
        data.set(imgd, offset);
        offset += dl;
        wUi(data, offset, crc(data, ioff, offset - ioff));
        offset += 4; // crc
    }

    wUi(data, offset, 0);
    offset += 4;
    wAs(data, offset, "IEND");
    offset += 4;
    wUi(data, offset, crc(data, offset - 4, 4));
    offset += 4; // crc

    return data.buffer;
}

UPNG.encode.compressPNG = function (out, filter, levelZero) {
    for (var i = 0; i < out.frames.length; i++) {
        var frm = out.frames[i],
            nw = frm.rect.width,
            nh = frm.rect.height;
        var fdata = new Uint8Array(nh * frm.bpl + nh);
        frm.cimg = UPNG.encode._filterZero(frm.img, nh, frm.bpp, frm.bpl, fdata, filter, levelZero);
    }
}



UPNG.encode.compress = function (bufs, w, h, ps, prms) // prms:  onlyBlend, minBits, forbidPlte
{
    //var time = Date.now();
    var onlyBlend = prms[0],
        evenCrd = prms[1],
        forbidPrev = prms[2],
        minBits = prms[3],
        forbidPlte = prms[4],
        dither = prms[5];

    var ctype = 6,
        depth = 8,
        alphaAnd = 255

    for (var j = 0; j < bufs.length; j++) { // when not quantized, other frames can contain colors, that are not in an initial frame
        var img = new Uint8Array(bufs[j]),
            ilen = img.length;
        for (var i = 0; i < ilen; i += 4) alphaAnd &= img[i + 3];
    }
    var gotAlpha = (alphaAnd != 255);

    //console.log("alpha check", Date.now()-time);  time = Date.now();

    //var brute = gotAlpha && forGIF;		// brute : frames can only be copied, not "blended"
    var frms = UPNG.encode.framize(bufs, w, h, onlyBlend, evenCrd, forbidPrev);
    //console.log("framize", Date.now()-time);  time = Date.now();

    var cmap = {},
        plte = [],
        inds = [];

    if (ps != 0) {
        var nbufs = [];
        for (var i = 0; i < frms.length; i++) nbufs.push(frms[i].img.buffer);

        var abuf = UPNG.encode.concatRGBA(nbufs),
            qres = UPNG.quantize(abuf, ps);

        for (var i = 0; i < qres.plte.length; i++) plte.push(qres.plte[i].est.rgba);

        var cof = 0;
        for (var i = 0; i < frms.length; i++) {
            var frm = frms[i],
                bln = frm.img.length,
                ind = new Uint8Array(qres.inds.buffer, cof >> 2, bln >> 2);
            inds.push(ind);
            var bb = new Uint8Array(qres.abuf, cof, bln);

            //console.log(frm.img, frm.width, frm.height);
            //var time = Date.now();
            if (dither) UPNG.encode.dither(frm.img, frm.rect.width, frm.rect.height, plte, bb, ind);
            //console.log(Date.now()-time);
            frm.img.set(bb);
            cof += bln;
        }

        //console.log("quantize", Date.now()-time);  time = Date.now();
    } else {
        // what if ps==0, but there are <=256 colors?  we still need to detect, if the palette could be used
        for (var j = 0; j < frms.length; j++) { // when not quantized, other frames can contain colors, that are not in an initial frame
            var frm = frms[j],
                img32 = new Uint32Array(frm.img.buffer),
                nw = frm.rect.width,
                ilen = img32.length;
            var ind = new Uint8Array(ilen);
            inds.push(ind);
            for (var i = 0; i < ilen; i++) {
                var c = img32[i];
                if (i != 0 && c == img32[i - 1]) ind[i] = ind[i - 1];
                else if (i > nw && c == img32[i - nw]) ind[i] = ind[i - nw];
                else {
                    var cmc = cmap[c];
                    if (cmc == null) {
                        cmap[c] = cmc = plte.length;
                        plte.push(c);
                        if (plte.length >= 300) break;
                    }
                    ind[i] = cmc;
                }
            }
        }
        //console.log("make palette", Date.now()-time);  time = Date.now();
    }

    var cc = plte.length; //console.log("colors:",cc);
    if (cc <= 256 && forbidPlte == false) {
        if (cc <= 2) depth = 1;
        else if (cc <= 4) depth = 2;
        else if (cc <= 16) depth = 4;
        else depth = 8;
        depth = Math.max(depth, minBits);
    }

    for (var j = 0; j < frms.length; j++) {
        var frm = frms[j],
            nx = frm.rect.x,
            ny = frm.rect.y,
            nw = frm.rect.width,
            nh = frm.rect.height;
        var cimg = frm.img,
            cimg32 = new Uint32Array(cimg.buffer);
        var bpl = 4 * nw,
            bpp = 4;
        if (cc <= 256 && forbidPlte == false) {
            bpl = Math.ceil(depth * nw / 8);
            var nimg = new Uint8Array(bpl * nh);
            var inj = inds[j];
            for (var y = 0; y < nh; y++) {
                var i = y * bpl,
                    ii = y * nw;
                if (depth == 8)
                    for (var x = 0; x < nw; x++) nimg[i + (x)] = (inj[ii + x]);
                else if (depth == 4)
                    for (var x = 0; x < nw; x++) nimg[i + (x >> 1)] |= (inj[ii + x] << (4 - (x & 1) * 4));
                else if (depth == 2)
                    for (var x = 0; x < nw; x++) nimg[i + (x >> 2)] |= (inj[ii + x] << (6 - (x & 3) * 2));
                else if (depth == 1)
                    for (var x = 0; x < nw; x++) nimg[i + (x >> 3)] |= (inj[ii + x] << (7 - (x & 7) * 1));
            }
            cimg = nimg;
            ctype = 3;
            bpp = 1;
        } else if (gotAlpha == false && frms.length == 1) { // some next "reduced" frames may contain alpha for blending
            var nimg = new Uint8Array(nw * nh * 3),
                area = nw * nh;
            for (var i = 0; i < area; i++) {
                var ti = i * 3,
                    qi = i * 4;
                nimg[ti] = cimg[qi];
                nimg[ti + 1] = cimg[qi + 1];
                nimg[ti + 2] = cimg[qi + 2];
            }
            cimg = nimg;
            ctype = 2;
            bpp = 3;
            bpl = 3 * nw;
        }
        frm.img = cimg;
        frm.bpl = bpl;
        frm.bpp = bpp;
    }
    //console.log("colors => palette indices", Date.now()-time);  time = Date.now();

    return {
        ctype: ctype,
        depth: depth,
        plte: plte,
        frames: frms
    };
}
UPNG.encode.framize = function (bufs, w, h, alwaysBlend, evenCrd, forbidPrev) {
    /*  DISPOSE
        - 0 : no change
    	- 1 : clear to transparent
    	- 2 : retstore to content before rendering (previous frame disposed)
    	BLEND
    	- 0 : replace
    	- 1 : blend
    */
    var frms = [];
    for (var j = 0; j < bufs.length; j++) {
        var cimg = new Uint8Array(bufs[j]),
            cimg32 = new Uint32Array(cimg.buffer);
        var nimg;

        var nx = 0,
            ny = 0,
            nw = w,
            nh = h,
            blend = alwaysBlend ? 1 : 0;
        if (j != 0) {
            var tlim = (forbidPrev || alwaysBlend || j == 1 || frms[j - 2].dispose != 0) ? 1 : 2,
                tstp = 0,
                tarea = 1e9;
            for (var it = 0; it < tlim; it++) {
                var pimg = new Uint8Array(bufs[j - 1 - it]),
                    p32 = new Uint32Array(bufs[j - 1 - it]);
                var mix = w,
                    miy = h,
                    max = -1,
                    may = -1;
                for (var y = 0; y < h; y++)
                    for (var x = 0; x < w; x++) {
                        var i = y * w + x;
                        if (cimg32[i] != p32[i]) {
                            if (x < mix) mix = x;
                            if (x > max) max = x;
                            if (y < miy) miy = y;
                            if (y > may) may = y;
                        }
                    }
                if (max == -1) mix = miy = max = may = 0;
                if (evenCrd) {
                    if ((mix & 1) == 1) mix--;
                    if ((miy & 1) == 1) miy--;
                }
                var sarea = (max - mix + 1) * (may - miy + 1);
                if (sarea < tarea) {
                    tarea = sarea;
                    tstp = it;
                    nx = mix;
                    ny = miy;
                    nw = max - mix + 1;
                    nh = may - miy + 1;
                }
            }

            // alwaysBlend: pokud zjistím, že blendit nelze, nastavím předchozímu snímku dispose=1. Zajistím, aby obsahoval můj obdélník.
            var pimg = new Uint8Array(bufs[j - 1 - tstp]);
            if (tstp == 1) frms[j - 1].dispose = 2;

            nimg = new Uint8Array(nw * nh * 4);
            UPNG._copyTile(pimg, w, h, nimg, nw, nh, -nx, -ny, 0);

            blend = UPNG._copyTile(cimg, w, h, nimg, nw, nh, -nx, -ny, 3) ? 1 : 0;
            if (blend == 1) UPNG.encode._prepareDiff(cimg, w, h, nimg, {
                x: nx,
                y: ny,
                width: nw,
                height: nh
            });
            else UPNG._copyTile(cimg, w, h, nimg, nw, nh, -nx, -ny, 0);
            //UPNG._copyTile(cimg,w,h, nimg,nw,nh, -nx,-ny, blend==1?2:0);
        } else nimg = cimg.slice(0); // img may be rewritten further ... don't rewrite input

        frms.push({
            rect: {
                x: nx,
                y: ny,
                width: nw,
                height: nh
            },
            img: nimg,
            blend: blend,
            dispose: 0
        });
    }


    if (alwaysBlend)
        for (var j = 0; j < frms.length; j++) {
            var frm = frms[j];
            if (frm.blend == 1) continue;
            var r0 = frm.rect,
                r1 = frms[j - 1].rect
            var miX = Math.min(r0.x, r1.x),
                miY = Math.min(r0.y, r1.y);
            var maX = Math.max(r0.x + r0.width, r1.x + r1.width),
                maY = Math.max(r0.y + r0.height, r1.y + r1.height);
            var r = {
                x: miX,
                y: miY,
                width: maX - miX,
                height: maY - miY
            };

            frms[j - 1].dispose = 1;
            if (j - 1 != 0)
                UPNG.encode._updateFrame(bufs, w, h, frms, j - 1, r, evenCrd);
            UPNG.encode._updateFrame(bufs, w, h, frms, j, r, evenCrd);
        }
    var area = 0;
    if (bufs.length != 1)
        for (var i = 0; i < frms.length; i++) {
            var frm = frms[i];
            area += frm.rect.width * frm.rect.height;
            //if(i==0 || frm.blend!=1) continue;
            //var ob = new Uint8Array(
            //console.log(frm.blend, frm.dispose, frm.rect);
        }
    //if(area!=0) console.log(area);
    return frms;
}
UPNG.encode._updateFrame = function (bufs, w, h, frms, i, r, evenCrd) {
    var U8 = Uint8Array,
        U32 = Uint32Array;
    var pimg = new U8(bufs[i - 1]),
        pimg32 = new U32(bufs[i - 1]),
        nimg = i + 1 < bufs.length ? new U8(bufs[i + 1]) : null;
    var cimg = new U8(bufs[i]),
        cimg32 = new U32(cimg.buffer);

    var mix = w,
        miy = h,
        max = -1,
        may = -1;
    for (var y = 0; y < r.height; y++)
        for (var x = 0; x < r.width; x++) {
            var cx = r.x + x,
                cy = r.y + y;
            var j = cy * w + cx,
                cc = cimg32[j];
            // no need to draw transparency, or to dispose it. Or, if writing the same color and the next one does not need transparency.
            if (cc == 0 || (frms[i - 1].dispose == 0 && pimg32[j] == cc && (nimg == null || nimg[j * 4 + 3] != 0)) /**/ ) {} else {
                if (cx < mix) mix = cx;
                if (cx > max) max = cx;
                if (cy < miy) miy = cy;
                if (cy > may) may = cy;
            }
        }
    if (max == -1) mix = miy = max = may = 0;
    if (evenCrd) {
        if ((mix & 1) == 1) mix--;
        if ((miy & 1) == 1) miy--;
    }
    r = {
        x: mix,
        y: miy,
        width: max - mix + 1,
        height: may - miy + 1
    };

    var fr = frms[i];
    fr.rect = r;
    fr.blend = 1;
    fr.img = new Uint8Array(r.width * r.height * 4);
    if (frms[i - 1].dispose == 0) {
        UPNG._copyTile(pimg, w, h, fr.img, r.width, r.height, -r.x, -r.y, 0);
        UPNG.encode._prepareDiff(cimg, w, h, fr.img, r);
        //UPNG._copyTile(cimg,w,h, fr.img,r.width,r.height, -r.x,-r.y, 2);
    } else
        UPNG._copyTile(cimg, w, h, fr.img, r.width, r.height, -r.x, -r.y, 0);
}
UPNG.encode._prepareDiff = function (cimg, w, h, nimg, rec) {
    UPNG._copyTile(cimg, w, h, nimg, rec.width, rec.height, -rec.x, -rec.y, 2);
    /*
    var n32 = new Uint32Array(nimg.buffer);
    var og = new Uint8Array(rec.width*rec.height*4), o32 = new Uint32Array(og.buffer);
    UPNG._copyTile(cimg,w,h, og,rec.width,rec.height, -rec.x,-rec.y, 0);
    for(var i=4; i>>2]==o32[(i>>>2)-1]) {
    		n32[i>>>2]=o32[i>>>2];
    		//var j = i, c=p32[(i>>>2)-1];
    		//while(p32[j>>>2]==c) {  n32[j>>>2]=c;  j+=4;  }
    	}
    }
    for(var i=nimg.length-8; i>0; i-=4) {
    	if(nimg[i+7]!=0 && nimg[i+3]==0 && o32[i>>>2]==o32[(i>>>2)+1]) {
    		n32[i>>>2]=o32[i>>>2];
    		//var j = i, c=p32[(i>>>2)-1];
    		//while(p32[j>>>2]==c) {  n32[j>>>2]=c;  j+=4;  }
    	}
    }*/
}

UPNG.encode._filterZero = function (img, h, bpp, bpl, data, filter, levelZero) {
    var fls = [],
        ftry = [0, 1, 2, 3, 4];
    if (filter != -1) ftry = [filter];
    else if (h * bpl > 500000 || bpp == 1) ftry = [0];
    var opts;
    if (levelZero) opts = {
        level: 0
    };


    var CMPR = (data.length > 10e6 && UZIP != null) ? UZIP : pako;

    var time = Date.now();
    for (var i = 0; i < ftry.length; i++) {
        for (var y = 0; y < h; y++) UPNG.encode._filterLine(data, img, y, bpl, bpp, ftry[i]);
        //var nimg = new Uint8Array(data.length);
        //var sz = UZIP.F.deflate(data, nimg);  fls.push(nimg.slice(0,sz));
        //var dfl = pako["deflate"](data), dl=dfl.length-4;
        //var crc = (dfl[dl+3]<<24)|(dfl[dl+2]<<16)|(dfl[dl+1]<<8)|(dfl[dl+0]<<0);
        //console.log(crc, UZIP.adler(data,2,data.length-6));
        fls.push(CMPR["deflate"](data, opts));
    }

    var ti, tsize = 1e9;
    for (var i = 0; i < fls.length; i++)
        if (fls[i].length < tsize) {
            ti = i;
            tsize = fls[i].length;
        }
    return fls[ti];
}
UPNG.encode._filterLine = function (data, img, y, bpl, bpp, type) {
    var i = y * bpl,
        di = i + y,
        paeth = UPNG.decode._paeth
    data[di] = type;
    di++;

    if (type == 0) {
        if (bpl < 500)
            for (var x = 0; x < bpl; x++) data[di + x] = img[i + x];
        else data.set(new Uint8Array(img.buffer, i, bpl), di);
    } else if (type == 1) {
        for (var x = 0; x < bpp; x++) data[di + x] = img[i + x];
        for (var x = bpp; x < bpl; x++) data[di + x] = (img[i + x] - img[i + x - bpp] + 256) & 255;
    } else if (y == 0) {
        for (var x = 0; x < bpp; x++) data[di + x] = img[i + x];

        if (type == 2)
            for (var x = bpp; x < bpl; x++) data[di + x] = img[i + x];
        if (type == 3)
            for (var x = bpp; x < bpl; x++) data[di + x] = (img[i + x] - (img[i + x - bpp] >> 1) + 256) & 255;
        if (type == 4)
            for (var x = bpp; x < bpl; x++) data[di + x] = (img[i + x] - paeth(img[i + x - bpp], 0, 0) + 256) & 255;
    } else {
        if (type == 2) {
            for (var x = 0; x < bpl; x++) data[di + x] = (img[i + x] + 256 - img[i + x - bpl]) & 255;
        }
        if (type == 3) {
            for (var x = 0; x < bpp; x++) data[di + x] = (img[i + x] + 256 - (img[i + x - bpl] >> 1)) & 255;
            for (var x = bpp; x < bpl; x++) data[di + x] = (img[i + x] + 256 - ((img[i + x - bpl] + img[i + x - bpp]) >> 1)) & 255;
        }
        if (type == 4) {
            for (var x = 0; x < bpp; x++) data[di + x] = (img[i + x] + 256 - paeth(0, img[i + x - bpl], 0)) & 255;
            for (var x = bpp; x < bpl; x++) data[di + x] = (img[i + x] + 256 - paeth(img[i + x - bpp], img[i + x - bpl], img[i + x - bpp - bpl])) & 255;
        }
    }
}

UPNG.crc = {
    table: (function () {
        var tab = new Uint32Array(256);
        for (var n = 0; n < 256; n++) {
            var c = n;
            for (var k = 0; k < 8; k++) {
                if (c & 1) c = 0xedb88320 ^ (c >>> 1);
                else c = c >>> 1;
            }
            tab[n] = c;
        }
        return tab;
    })(),
    update: function (c, buf, off, len) {
        for (var i = 0; i < len; i++) c = UPNG.crc.table[(c ^ buf[off + i]) & 0xff] ^ (c >>> 8);
        return c;
    },
    crc: function (b, o, l) {
        return UPNG.crc.update(0xffffffff, b, o, l) ^ 0xffffffff;
    }
}


UPNG.quantize = function (abuf, ps) {
    var sb = new Uint8Array(abuf),
        tb = sb.slice(0),
        tb32 = new Uint32Array(tb.buffer);

    var KD = UPNG.quantize.getKDtree(tb, ps);
    var root = KD[0],
        leafs = KD[1];

    var planeDst = UPNG.quantize.planeDst;
    var len = sb.length;

    var inds = new Uint8Array(len >> 2),
        nd;
    if (sb.length < 20e6) // precise, but slow :(
        for (var i = 0; i < len; i += 4) {
            var r = sb[i] * (1 / 255),
                g = sb[i + 1] * (1 / 255),
                b = sb[i + 2] * (1 / 255),
                a = sb[i + 3] * (1 / 255);

            nd = UPNG.quantize.getNearest(root, r, g, b, a);
            inds[i >> 2] = nd.ind;
            tb32[i >> 2] = nd.est.rgba;
        }
    else
        for (var i = 0; i < len; i += 4) {
            var r = sb[i] * (1 / 255),
                g = sb[i + 1] * (1 / 255),
                b = sb[i + 2] * (1 / 255),
                a = sb[i + 3] * (1 / 255);

            nd = root;
            while (nd.left) nd = (planeDst(nd.est, r, g, b, a) <= 0) ? nd.left : nd.right;
            inds[i >> 2] = nd.ind;
            tb32[i >> 2] = nd.est.rgba;
        }
    return {
        abuf: tb.buffer,
        inds: inds,
        plte: leafs
    };
}

UPNG.quantize.getKDtree = function (nimg, ps, err) {
    if (err == null) err = 0.0001;
    var nimg32 = new Uint32Array(nimg.buffer);

    var root = {
        i0: 0,
        i1: nimg.length,
        bst: null,
        est: null,
        tdst: 0,
        left: null,
        right: null
    }; // basic statistic, extra statistic
    root.bst = UPNG.quantize.stats(nimg, root.i0, root.i1);
    root.est = UPNG.quantize.estats(root.bst);
    var leafs = [root];

    while (leafs.length < ps) {
        var maxL = 0,
            mi = 0;
        for (var i = 0; i < leafs.length; i++)
            if (leafs[i].est.L > maxL) {
                maxL = leafs[i].est.L;
                mi = i;
            }
        if (maxL < err) break;
        var node = leafs[mi];

        var s0 = UPNG.quantize.splitPixels(nimg, nimg32, node.i0, node.i1, node.est.e, node.est.eMq255);
        var s0wrong = (node.i0 >= s0 || node.i1 <= s0);
        //console.log(maxL, leafs.length, mi);
        if (s0wrong) {
            node.est.L = 0;
            continue;
        }


        var ln = {
            i0: node.i0,
            i1: s0,
            bst: null,
            est: null,
            tdst: 0,
            left: null,
            right: null
        };
        ln.bst = UPNG.quantize.stats(nimg, ln.i0, ln.i1);
        ln.est = UPNG.quantize.estats(ln.bst);
        var rn = {
            i0: s0,
            i1: node.i1,
            bst: null,
            est: null,
            tdst: 0,
            left: null,
            right: null
        };
        rn.bst = {
            R: [],
            m: [],
            N: node.bst.N - ln.bst.N
        };
        for (var i = 0; i < 16; i++) rn.bst.R[i] = node.bst.R[i] - ln.bst.R[i];
        for (var i = 0; i < 4; i++) rn.bst.m[i] = node.bst.m[i] - ln.bst.m[i];
        rn.est = UPNG.quantize.estats(rn.bst);

        node.left = ln;
        node.right = rn;
        leafs[mi] = ln;
        leafs.push(rn);
    }
    leafs.sort(function (a, b) {
        return b.bst.N - a.bst.N;
    });
    for (var i = 0; i < leafs.length; i++) leafs[i].ind = i;
    return [root, leafs];
}

UPNG.quantize.getNearest = function (nd, r, g, b, a) {
    if (nd.left == null) {
        nd.tdst = UPNG.quantize.dist(nd.est.q, r, g, b, a);
        return nd;
    }
    var planeDst = UPNG.quantize.planeDst(nd.est, r, g, b, a);

    var node0 = nd.left,
        node1 = nd.right;
    if (planeDst > 0) {
        node0 = nd.right;
        node1 = nd.left;
    }

    var ln = UPNG.quantize.getNearest(node0, r, g, b, a);
    if (ln.tdst <= planeDst * planeDst) return ln;
    var rn = UPNG.quantize.getNearest(node1, r, g, b, a);
    return rn.tdst < ln.tdst ? rn : ln;
}
UPNG.quantize.planeDst = function (est, r, g, b, a) {
    var e = est.e;
    return e[0] * r + e[1] * g + e[2] * b + e[3] * a - est.eMq;
}
UPNG.quantize.dist = function (q, r, g, b, a) {
    var d0 = r - q[0],
        d1 = g - q[1],
        d2 = b - q[2],
        d3 = a - q[3];
    return d0 * d0 + d1 * d1 + d2 * d2 + d3 * d3;
}

UPNG.quantize.splitPixels = function (nimg, nimg32, i0, i1, e, eMq) {
    var vecDot = UPNG.quantize.vecDot;
    i1 -= 4;
    var shfs = 0;
    while (i0 < i1) {
        while (vecDot(nimg, i0, e) <= eMq) i0 += 4;
        while (vecDot(nimg, i1, e) > eMq) i1 -= 4;
        if (i0 >= i1) break;

        var t = nimg32[i0 >> 2];
        nimg32[i0 >> 2] = nimg32[i1 >> 2];
        nimg32[i1 >> 2] = t;

        i0 += 4;
        i1 -= 4;
    }
    while (vecDot(nimg, i0, e) > eMq) i0 -= 4;
    return i0 + 4;
}
UPNG.quantize.vecDot = function (nimg, i, e) {
    return nimg[i] * e[0] + nimg[i + 1] * e[1] + nimg[i + 2] * e[2] + nimg[i + 3] * e[3];
}
UPNG.quantize.stats = function (nimg, i0, i1) {
    var R = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
    var m = [0, 0, 0, 0];
    var N = (i1 - i0) >> 2;
    for (var i = i0; i < i1; i += 4) {
        var r = nimg[i] * (1 / 255),
            g = nimg[i + 1] * (1 / 255),
            b = nimg[i + 2] * (1 / 255),
            a = nimg[i + 3] * (1 / 255);
        //var r = nimg[i], g = nimg[i+1], b = nimg[i+2], a = nimg[i+3];
        m[0] += r;
        m[1] += g;
        m[2] += b;
        m[3] += a;

        R[0] += r * r;
        R[1] += r * g;
        R[2] += r * b;
        R[3] += r * a;
        R[5] += g * g;
        R[6] += g * b;
        R[7] += g * a;
        R[10] += b * b;
        R[11] += b * a;
        R[15] += a * a;
    }
    R[4] = R[1];
    R[8] = R[2];
    R[9] = R[6];
    R[12] = R[3];
    R[13] = R[7];
    R[14] = R[11];

    return {
        R: R,
        m: m,
        N: N
    };
}
UPNG.quantize.estats = function (stats) {
    var R = stats.R,
        m = stats.m,
        N = stats.N;

    // when all samples are equal, but N is large (millions), the Rj can be non-zero ( 0.0003.... - precission error)
    var m0 = m[0],
        m1 = m[1],
        m2 = m[2],
        m3 = m[3],
        iN = (N == 0 ? 0 : 1 / N);
    var Rj = [
        R[0] - m0 * m0 * iN, R[1] - m0 * m1 * iN, R[2] - m0 * m2 * iN, R[3] - m0 * m3 * iN,
        R[4] - m1 * m0 * iN, R[5] - m1 * m1 * iN, R[6] - m1 * m2 * iN, R[7] - m1 * m3 * iN,
        R[8] - m2 * m0 * iN, R[9] - m2 * m1 * iN, R[10] - m2 * m2 * iN, R[11] - m2 * m3 * iN,
        R[12] - m3 * m0 * iN, R[13] - m3 * m1 * iN, R[14] - m3 * m2 * iN, R[15] - m3 * m3 * iN
    ];

    var A = Rj,
        M = UPNG.M4;
    var b = [Math.random(), Math.random(), Math.random(), Math.random()],
        mi = 0,
        tmi = 0;

    if (N != 0)
        for (var i = 0; i < 16; i++) {
            b = M.multVec(A, b);
            tmi = Math.sqrt(M.dot(b, b));
            b = M.sml(1 / tmi, b);
            if (i != 0 && Math.abs(tmi - mi) < 1e-9) break;
            mi = tmi;
        }
    //b = [0,0,1,0];  mi=N;
    var q = [m0 * iN, m1 * iN, m2 * iN, m3 * iN];
    var eMq255 = M.dot(M.sml(255, q), b);

    return {
        Cov: Rj,
        q: q,
        e: b,
        L: mi,
        eMq255: eMq255,
        eMq: M.dot(b, q),
        rgba: (((Math.round(255 * q[3]) << 24) | (Math.round(255 * q[2]) << 16) | (Math.round(255 * q[1]) << 8) | (Math.round(255 * q[0]) << 0)) >>> 0)
    };
}
UPNG.M4 = {
    multVec: function (m, v) {
        return [
            m[0] * v[0] + m[1] * v[1] + m[2] * v[2] + m[3] * v[3],
            m[4] * v[0] + m[5] * v[1] + m[6] * v[2] + m[7] * v[3],
            m[8] * v[0] + m[9] * v[1] + m[10] * v[2] + m[11] * v[3],
            m[12] * v[0] + m[13] * v[1] + m[14] * v[2] + m[15] * v[3]
        ];
    },
    dot: function (x, y) {
        return x[0] * y[0] + x[1] * y[1] + x[2] * y[2] + x[3] * y[3];
    },
    sml: function (a, y) {
        return [a * y[0], a * y[1], a * y[2], a * y[3]];
    }
}

UPNG.encode.concatRGBA = function (bufs) {
    var tlen = 0;
    for (var i = 0; i < bufs.length; i++) tlen += bufs[i].byteLength;
    var nimg = new Uint8Array(tlen),
        noff = 0;
    for (var i = 0; i < bufs.length; i++) {
        var img = new Uint8Array(bufs[i]),
            il = img.length;
        for (var j = 0; j < il; j += 4) {
            var r = img[j],
                g = img[j + 1],
                b = img[j + 2],
                a = img[j + 3];
            if (a == 0) r = g = b = 0;
            nimg[noff + j] = r;
            nimg[noff + j + 1] = g;
            nimg[noff + j + 2] = b;
            nimg[noff + j + 3] = a;
        }
        noff += il;
    }
    return nimg.buffer;
}

UPNG.encode.dither = function (sb, w, h, plte, tb, oind) {

    function addErr(er, tg, ti, f) {
        tg[ti] += (er[0] * f) >> 4;
        tg[ti + 1] += (er[1] * f) >> 4;
        tg[ti + 2] += (er[2] * f) >> 4;
        tg[ti + 3] += (er[3] * f) >> 4;
    }

    function N(x) {
        return Math.max(0, Math.min(255, x));
    }

    function D(a, b) {
        var dr = a[0] - b[0],
            dg = a[1] - b[1],
            db = a[2] - b[2],
            da = a[3] - b[3];
        return (dr * dr + dg * dg + db * db + da * da);
    }


    var pc = plte.length,
        nplt = [],
        rads = [];
    for (var i = 0; i < pc; i++) {
        var c = plte[i];
        nplt.push([((c >>> 0) & 255), ((c >>> 8) & 255), ((c >>> 16) & 255), ((c >>> 24) & 255)]);
    }
    for (var i = 0; i < pc; i++) {
        var ne = 0xffffffff,
            ni = 0;
        for (var j = 0; j < pc; j++) {
            var ce = D(nplt[i], nplt[j]);
            if (j != i && ce < ne) {
                ne = ce;
                ni = j;
            }
        }
        var hd = Math.sqrt(ne) / 2;
        rads[i] = ~~(hd * hd);
    }

    var tb32 = new Uint32Array(tb.buffer);
    var err = new Int16Array(w * h * 4);

    for (var y = 0; y < h; y++) {
        for (var x = 0; x < w; x++) {
            var i = (y * w + x) * 4;

            var cc = [N(sb[i] + err[i]), N(sb[i + 1] + err[i + 1]), N(sb[i + 2] + err[i + 2]), N(sb[i + 3] + err[i + 3])];

            var ni = 0,
                nd = 0xffffff;
            for (var j = 0; j < pc; j++) {
                var cd = D(cc, nplt[j]);
                if (cd < nd) {
                    nd = cd;
                    ni = j;
                }
            }

            //ni = oind[i>>2];
            var nc = nplt[ni];
            var er = [cc[0] - nc[0], cc[1] - nc[1], cc[2] - nc[2], cc[3] - nc[3]];

            //addErr(er, err, i+4, 16);

            //*
            if (x != w - 1) addErr(er, err, i + 4, 7);
            if (y != h - 1) {
                if (x != 0) addErr(er, err, i + 4 * w - 4, 3);
                addErr(er, err, i + 4 * w, 5);
                if (x != w - 1) addErr(er, err, i + 4 * w + 4, 1); //*/
            }

            oind[i >> 2] = ni;
            tb32[i >> 2] = plte[ni];
        }
    }
}


module.exports = UPNG

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• 再将png数据转化为Base64数据，所使用的工具包Base64Util:

 export default {
 
arrayBufferToBase64(buffer) {
var binary = '';
var bytes = new Uint8Array(buffer);
var len = bytes.byteLength;
for (var i = 0; i < len; i++) {
	binary += String.fromCharCode(bytes[i]);
}


var btoa = function(string) {
	var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
    string = String(string);
    var bitmap, a, b, c,
        result = "", i = 0,
        rest = string.length % 3; // To determine the final padding

    for (; i < string.length;) {
        if ((a = string.charCodeAt(i++)) > 255
                || (b = string.charCodeAt(i++)) > 255
                || (c = string.charCodeAt(i++)) > 255)
            throw new TypeError("Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.");

        bitmap = (a << 16) | (b << 8) | c;
        result += b64.charAt(bitmap >> 18 & 63) + b64.charAt(bitmap >> 12 & 63)
                + b64.charAt(bitmap >> 6 & 63) + b64.charAt(bitmap & 63);
    }

    // If there's need of padding, replace the last 'A's with equal signs
    return rest ? result.slice(0, rest - 3) + "===".substring(rest) : result;
}


return "data:image/png;base64," + btoa(binary);
}

}
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---

4.2 控制帧数据采集频率

• 特别注意：对于微信的这个数据帧采集接口onCameraFrame，它是处于一个以60ms采集一次用户的数据的频率运行的，很多时候我们用不到这么高的频率！我们可以通过setInteerval定时器来控制摄像头采集用户数据的频率。

let task = setInterval(function() {
var timeStart = Date.now();
//在此处处理store[0](图像的数据)；
// store.shift();
var frame = that.frameQueue.shift()
console.log("开始运行===",frame,that.flag);
that.flag = true;

if(frame != undefined){
	
	let pngData = UPNG.encode([frame.data], frame.width, frame.height),  
		base64 = Base64Util.arrayBufferToBase64(pngData)
														
	uni.request({
		url: 'http://127.0.0.1:8000/miniapp/faceEngine/faceLogin' ,
		method: 'post',
		data: {openId:uni.getStorageSync("openId"),base64Img:base64} ,
		dataType:'json',
		header: {
			   'content-type':'application/json'//自定义请求头信息
			},
		success:(res)=>{
				console.log("====执行成功===",res)
				if(res.statusCode != undefined){
					clearInterval(task)
					that.isAuthCamera = false
					uni.navigateTo({
						url:'./login'
					})
				}
		},
		fail:(err)=>{
				console.log("====执行失败===",err)
				clearInterval(task)
				that.isAuthCamera = false
				uni.navigateTo({
					url:'./login'
				})
		}
	})
}
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---

五、实时人脸采集功能实现

---