如何在同一图像中美白背景和消隐网格 [英] How to whiten background and blaken grid in a same image

问题描述

我有这样的图像。我想使用HoughLine检测但图像太暗而无法识别线条。有没有办法可以使背景变白并使网格变黑？我可以应用openCV或python中的算法吗？谢谢

I have an image like this. I wan to use HoughLine detection but the image is too dark to recognize the line. Is there a way that can whiten the background and blacken the grid? Is there any algorithms in openCV or python that I can apply? Thank you

推荐答案

我首先尝试扩大图像，然后将它放在中间，这样我就得到了背景。使用原始的灰色图像来分配背景，我得到了前景（即网格）。然后做一些其他步骤，我得到这样的结果。

I try to dilate the image first, then medianBlur it, so I get the background. Use the original gray image to sub the background, I get the frontground ( that is the grids). Then do some other steps, I get the result like this.

代码如下：

#!/usr/bin/python3
# 2017.10.04 19:37:43 CST

filename = "data/paper.png"
img = cv2.imread(filename)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

## do morph-dilate-op
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5,5))
dilated = cv2.morphologyEx(gray, cv2.MORPH_DILATE, kernel)
diff1 = 255 - cv2.subtract(dilated, gray)

## do medianBlur
median = cv2.medianBlur(dilated, 15)
diff2 = 255 - cv2.subtract(median, gray)

## do normalize 
normed = cv2.normalize(diff2,None, 0, 255, cv2.NORM_MINMAX )

## save the result 
dst = np.hstack((gray, normed))
cv2.imwrite("result_paper1.png", dst)
res = np.hstack((gray,dilated, diff1,  median, diff2, normed))
cv2.imwrite("result_paper2.png", res)

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