[英]How does one convert a grayscale image to RGB in OpenCV (Python)?
[英]OpenCV Python how to keep one color as is converting an image to Grayscale
您可以通过使用bitwise_and()
function 和thresholding
来实现您的目标。 脚步:
mask
。(此处使用thresholding
,但也可以使用其他方法)bitwise_and
(图像和掩码)提取所需regions
。masked regions
以获得 output。这是示例代码:
import cv2
import numpy as np
img = cv2.imread('input.jpg')
# creating mask using thresholding over `red` channel (use better use histogram to get threshoding value)
# I have used 200 as thershoding value it can be different for different images
ret, mask = cv2.threshold(img[:, :,2], 200, 255, cv2.THRESH_BINARY)
mask3 = np.zeros_like(img)
mask3[:, :, 0] = mask
mask3[:, :, 1] = mask
mask3[:, :, 2] = mask
# extracting `orange` region using `biteise_and`
orange = cv2.bitwise_and(img, mask3)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
img = cv2.cvtColor(gray, cv2.COLOR_GRAY2BGR)
# extracting non-orange region
gray = cv2.bitwise_and(img, 255 - mask3)
# orange masked output
out = gray + orange
cv2.imwrite('orange.png', orange)
cv2.imwrite('gray.png', gray)
cv2.imwrite("output.png", out)
结果:
这是在 Python/OpenCV 中执行此操作的另一种方法。
输入:
import cv2
import numpy as np
img = cv2.imread("orange_cone.jpg")
# threshold on orange
lower = (0,60,200)
upper = (110,160,255)
thresh = cv2.inRange(img, lower, upper)
# apply morphology and make 3 channels as mask
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5,5))
mask = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, kernel)
mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel)
mask = cv2.merge([mask,mask,mask])
# create 3-channel grayscale version
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray = cv2.cvtColor(gray, cv2.COLOR_GRAY2BGR)
# blend img with gray using mask
result = np.where(mask==255, img, gray)
# save images
cv2.imwrite('orange_cone_thresh.jpg', thresh)
cv2.imwrite('orange_cone_mask.jpg', mask)
cv2.imwrite('orange_cone_result.jpg', result)
# Display images
cv2.imshow("thresh", thresh)
cv2.imshow("mask", mask)
cv2.imshow("result", result)
cv2.waitKey(0)
阈值图像:
蒙版图片:
合并结果:
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