详解cv2.copyMakeBorder函数【OpenCV图像边界填充Python版本】

简介

做深度学习图像数据集时，有时候需要调整一张图片的长和宽。如果直接使用cv2.resize函数会造成图像扭曲失真，因此我们可以采取填充图像短边的方法解决这个问题。cv2.copyMakeBorder函数提供了相关操作。本篇博客详细介绍了cv2.copyMakeBorder使用方法，并给出了代码示例。🚀🚀🚀

函数原型

def copyMakeBorder(
    src: Any,
    top: int,
    bottom: int,
    left: int,
    right: int,
    borderType: int,
    dst: Any | None = ...,
    value: Any = ...
)
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代码示例

import cv2
import matplotlib.pyplot as plt


lenna = cv2.imread(filename="Lenna.png", flags=cv2.IMREAD_ANYCOLOR)
lenna_constant = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_CONSTANT, value=0)
lenna_default = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_DEFAULT)
lenna_isolated = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_ISOLATED)
lenna_reflect = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_REFLECT)
lenna_reflect101 = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_REFLECT101)
lenna_reflect_101 = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_REFLECT_101)
lenna_replicate = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_REPLICATE)
lenna_wrap = cv2.copyMakeBorder(src=lena, top=10, bottom=10, left=20, right=30, borderType=cv2.BORDER_WRAP)


fig = plt.figure()
ax1 = fig.add_subplot(3, 3, 1)
ax1.axes.xaxis.set_visible(b=False)
ax1.axes.yaxis.set_visible(b=False)
ax1.spines["top"].set_visible(b=False)
ax1.spines["bottom"].set_visible(b=False)
ax1.spines["right"].set_visible(b=False)
ax1.spines["left"].set_visible(b=False)
ax1.set_title(label="original Lenna")
ax1.imshow(cv2.cvtColor(src=lenna, code=cv2.COLOR_BGR2RGB))

ax2 = fig.add_subplot(3, 3, 2)
ax2.axes.xaxis.set_visible(b=False)
ax2.axes.yaxis.set_visible(b=False)
ax2.spines["top"].set_visible(b=False)
ax2.spines["bottom"].set_visible(b=False)
ax2.spines["right"].set_visible(b=False)
ax2.spines["left"].set_visible(b=False)
ax2.set_title(label="cv2.BORDER_CONSTANT")
ax2.imshow(cv2.cvtColor(src=lenna_constant, code=cv2.COLOR_BGR2RGB))

ax3 = fig.add_subplot(3, 3, 3)
ax3.axes.xaxis.set_visible(b=False)
ax3.axes.yaxis.set_visible(b=False)
ax3.spines["top"].set_visible(b=False)
ax3.spines["bottom"].set_visible(b=False)
ax3.spines["right"].set_visible(b=False)
ax3.spines["left"].set_visible(b=False)
ax3.set_title(label="cv2.BORDER_DEFAULT")
ax3.imshow(cv2.cvtColor(src=lenna_default, code=cv2.COLOR_BGR2RGB))

ax4 = fig.add_subplot(3, 3, 4)
ax4.axes.xaxis.set_visible(b=False)
ax4.axes.yaxis.set_visible(b=False)
ax4.spines["top"].set_visible(b=False)
ax4.spines["bottom"].set_visible(b=False)
ax4.spines["right"].set_visible(b=False)
ax4.spines["left"].set_visible(b=False)
ax4.set_title(label="cv2.BORDER_ISOLATED")
ax4.imshow(cv2.cvtColor(src=lenna_isolated, code=cv2.COLOR_BGR2RGB))

ax5 = fig.add_subplot(3, 3, 5)
ax5.axes.xaxis.set_visible(b=False)
ax5.axes.yaxis.set_visible(b=False)
ax5.spines["top"].set_visible(b=False)
ax5.spines["bottom"].set_visible(b=False)
ax5.spines["right"].set_visible(b=False)
ax5.spines["left"].set_visible(b=False)
ax5.set_title(label="cv2.BORDER_REFLECT")
ax5.imshow(cv2.cvtColor(src=lenna_reflect, code=cv2.COLOR_BGR2RGB))

ax6 = fig.add_subplot(3, 3, 6)
ax6.axes.xaxis.set_visible(b=False)
ax6.axes.yaxis.set_visible(b=False)
ax6.spines["top"].set_visible(b=False)
ax6.spines["bottom"].set_visible(b=False)
ax6.spines["right"].set_visible(b=False)
ax6.spines["left"].set_visible(b=False)
ax6.set_title(label="cv2.BORDER_REFLECT101")
ax6.imshow(cv2.cvtColor(src=lenna_reflect101, code=cv2.COLOR_BGR2RGB))

ax7 = fig.add_subplot(3, 3, 7)
ax7.axes.xaxis.set_visible(b=False)
ax7.axes.yaxis.set_visible(b=False)
ax7.spines["top"].set_visible(b=False)
ax7.spines["bottom"].set_visible(b=False)
ax7.spines["right"].set_visible(b=False)
ax7.spines["left"].set_visible(b=False)
ax7.set_title(label="cv2.BORDER_REFLECT_101")
ax7.imshow(cv2.cvtColor(src=lenna_reflect_101, code=cv2.COLOR_BGR2RGB))

ax8 = fig.add_subplot(3, 3, 8)
ax8.axes.xaxis.set_visible(b=False)
ax8.axes.yaxis.set_visible(b=False)
ax8.spines["top"].set_visible(b=False)
ax8.spines["bottom"].set_visible(b=False)
ax8.spines["right"].set_visible(b=False)
ax8.spines["left"].set_visible(b=False)
ax8.set_title(label="cv2.BORDER_REPLICATE")
ax8.imshow(cv2.cvtColor(src=lenna_replicate, code=cv2.COLOR_BGR2RGB))

ax9 = fig.add_subplot(3, 3, 9)
ax9.axes.xaxis.set_visible(b=False)
ax9.axes.yaxis.set_visible(b=False)
ax9.spines["top"].set_visible(b=False)
ax9.spines["bottom"].set_visible(b=False)
ax9.spines["right"].set_visible(b=False)
ax9.spines["left"].set_visible(b=False)
ax9.set_title(label="cv2.BORDER_WRAP")
ax9.imshow(cv2.cvtColor(src=lenna_wrap, code=cv2.COLOR_BGR2RGB))

plt.show()

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参考资料

1. OpenCV文档：Adding borders to your images
2. CSDN：图像处理作窗口运算时边界的几种扩展方法(详解OpenCV中的参数borderType)
3. CSDN：【opencv4.3.0教程】11之调整图像边缘（copyMakeBorder 与 borderInterpolate）

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