彩色图转灰度图、二值图

通道分离与合并

读取图片

img = cv.imread('./pic/cubic500x500.jpg')
show(img)

通道分离

b,g,r = cv.split(img)
show(r)

img.shape

(500, 500, 3)

通道合并

img2 = cv.merge([b,g,r])
show(img2)

img3 = cv.merge([r,g,b])
show(img3)

彩色图转换为灰度图

将三个通道进行加权

gray1 = 1/3*b + 1/3*g + 1/3*r
gray1 = np.uint8(gray1)# 或者gray1 = gray1.astype(np.uint8)

利用cv现成的api

gray4 = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
show(gray4)

二值化

thresh = 125
gray4[gray4 > thresh] = 255
gray4[gray4 <= thresh] = 0
show(gray4)

利用cv.threshold来进行二值化

show(gray1)

_, img_bin = cv.threshold(gray1, 125, 255, cv.THRESH_BINARY)

show(img_bin)