灰度图像上的颜色轮廓

Question

我编写了一个简单的代码来查找图像中对象的轮廓。

    img = cv2.imread(file_path, cv2.IMREAD_GRAYSCALE)

    blur = cv2.GaussianBlur(img_enhanced,(25,25),0) # apply blur for contour
    ret, binary = cv2.threshold(blur,1,255,cv2.THRESH_BINARY) # apply threshold to blur image

    contours, hierarchy = cv2.findContours(binary, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) # find countour
    obj_index = contours.index(max(contours, key=len)) # find index of largest object
    contour_img = cv2.drawContours(img, contours, obj_index, (0,255,0), 3) # draw coutour on original image

    plt.imshow(contour_img)
    plt.show()

原图已经是灰度图了，反正我在导入图的时候应用了cv2.IMREAD_GRAYSCALE。

我想如果我在 'Draw' 轮廓时应用灰度图像，语法如下，

contour_img = cv2.drawContours(img, contours, obj_index, (0,255,0), 3)

我可以得到一个带有彩色轮廓的灰度图像，但它显示奇怪的彩色图像。

如何在灰度图上绘制彩色轮廓线？

提前致谢

图像样本：黑色背景和白色物体

Answer 1

根据我的评论：

试试这样的东西，告诉我它是否有效

编辑：我更改了阈值范围。 cv2.threshold(blur,25,255,cv2.THRESH_BINARY)

img = cv2.imread(file_path, 1) 
print(img.shape) # this should give you (img_h, img_w, 3)
img2 = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

blur = cv2.GaussianBlur(img2,(25,25),0) # apply blur for contour
ret, binary = cv2.threshold(blur,25,255,cv2.THRESH_BINARY) # apply threshold to blur image

contours, hierarchy = cv2.findContours(binary, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) # find countour
obj_index = contours.index(max(contours, key=len)) # find index of largest object
contour_img = cv2.drawContours(img, contours, obj_index, (0,255,0), 3) # draw coutour on original image

plt.imshow(contour_img, cmap='gray')
plt.show()

plt.hist(blur.ravel(), bins=50)

灰度图像上的颜色轮廓

colour contour on grayscale image

python

contour

cv2