使用OpenCV裁剪黑色边缘 [英] Crop black edges with OpenCV

问题描述

我认为这应该是一个非常简单的问题，但我无法找到解决方案或有效的搜索关键字。

I think it should be a very simple problem, but I cannot find a solution or an effective keyword for search.

我只有这个图像。

黑色边缘没用，所以我想剪掉它们，只留下Windows图标（和蓝色背景）。

The black edges are useless so that I want to cut them, only leaving the Windows icon (and the blue background).

我不想要计算Windows图标的坐标和大小。 GIMP和Photoshop有一些autocrop功能。 OpenCV没有？

I do not want to calculate the coordinate and the size of the Windows icon. GIMP and Photoshop have sort of autocrop function. OpenCV does not have one?

推荐答案

我不确定你的所有图片是否都是这样的。但是对于这个图像，下面是一个简单的python-opencv代码来裁剪它。

I am not sure whether all your images are like this. But for this image, below is a simple python-opencv code to crop it.

第一个导入库：

import cv2
import numpy as np

Read图像，将其转换为灰度，并在二进制图像中生成阈值1。

Read the image, convert it into grayscale, and make in binary image for threshold value of 1.

img = cv2.imread('sofwin.png')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
_,thresh = cv2.threshold(gray,1,255,cv2.THRESH_BINARY)

现在找到轮廓。只有一个对象，所以找到它的边界矩形。

Now find contours in it. There will be only one object, so find bounding rectangle for it.

contours,hierarchy = cv2.findContours(thresh,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
cnt = contours[0]
x,y,w,h = cv2.boundingRect(cnt)

现在裁剪图像，并将其保存到另一个文件中。

Now crop the image, and save it into another file.

crop = img[y:y+h,x:x+w]
cv2.imwrite('sofwinres.png',crop)

以下是结果：

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