根据图像形状绘制轮廓蒙版 - 使用 Canny 边缘 - 更新

Question

我想根据图像形状绘制轮廓蒙版（形状）。 我正在使用 opencv-python 版本 4.9.0.80.

所以当我们有这样的图像时。

我们想要这样的输出，里面没有图像。避免灰色背景。

我已经尝试了

cv.convexHull()

但是结果没有达到预期的效果。

我正在尝试这段代码。

import cv2 as cv
import numpy as np

path = '/opt/boundary-remover/SW_test2-01.png'
# path = '/opt/boundary-remover/scaled_2x.png'
# Load image
src = cv.imread(cv.samples.findFile(path))
cv.imwrite('1_original.png', src)

# Convert image to gray and blur it
src_gray = cv.cvtColor(src, cv.COLOR_BGR2GRAY)
cv.imwrite('2_gray.png', src_gray)

# Detect edges using Canny
canny_output = cv.Canny(src_gray, 100, 200)
cv.imwrite('3_canny.png', canny_output)

# Find contours
contours, _ = cv.findContours(canny_output, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)

# Combine all contours into a single contour
all_contours = np.concatenate(contours)

# Find the convex hull object for the combined contour
hull = cv.convexHull(all_contours)

# Draw the combined contour and its convex hull
drawing = np.zeros((canny_output.shape[0], canny_output.shape[1], 3), dtype=np.uint8)
color = (0, 255, 0)  # Green color
# cv.drawContours(drawing, [all_contours], 0, color)
# cv.imwrite('4_all_contours.png', drawing)
cv.drawContours(drawing, [hull], 0, color)
cv.imwrite('5_hull.png', drawing)

cv.drawContours(drawing, [hull], -1, color, thickness=cv.FILLED)
cv.imwrite('7_filled.png', drawing)

Answer 1

如果我根据您在这里所说的内容正确理解了您的问题：避免灰色背景，那么这是一种方法：

def replaceGrayWithWhite(im):
    imGray = cv2.cvtColor(im, cv2.COLOR_BGR2GRAY)
    mask = (imGray>250).astype(np.uint8)
    contours, _ = cv2.findContours(mask, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
    maskFilled = cv2.drawContours(mask.copy(), contours, -1, 1, -1)
    maskFilledInv = cv2.bitwise_not(maskFilled) - 254
    '''
    Took this from here: https://stackoverflow.com/a/38493075/16815358
    '''
    foreground = cv2.bitwise_or(im, im, mask=maskFilled)
    background = 255*np.ones_like(im)
    background = cv2.bitwise_and(background, background, mask=maskFilledInv)
    final = cv2.bitwise_or(foreground, background)
    return final

导入 numpy 和 opencv，结果如下：