OpenCV | cv2.cvtcolor() 色域转换

reference：

Python OpenCV | cv2.cvtColor() method

Syntax: cv2.cvtColor(src, code[, dst[, dstCn]])
Parameters:
src: It is the image whose color space is to be changed.
code: It is the color space conversion code.

需要注意输入图像 src 的类型需要为 float32 或 uint8

常用

灰度转BGR

code 参数为 cv2.COLOR_BGR2GRAY

image = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)

BGR转灰度

image = cv2.cvtColor(src, cv2.COLOR_GRAY2BGR)

Eg. 从彩色转为灰度

# Python program to explain cv2.cvtColor() method 

# importing cv2 
import cv2 

# path 
path = '...'

# Reading an image in default mode 
src = cv2.imread(path) 

# Window name in which image is displayed 
window_name = 'Image'

# Using cv2.cvtColor() method 
# Using cv2.COLOR_BGR2GRAY color space 
# conversion code 
#---------------------------------------------
image = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)
#---------------------------------------------

# Displaying the image 
cv2.imshow(window_name, image) 

Errors

reference：

python: OpenCV depth of image unsupported (CV_64F)

>Unsupported depth of input image:
>     'VDepth::contains(depth)'
> where
>     'depth' is 6 (CV_64F).

CV_64F means the numpy array ‘dtype’ is 64bit floating-point opencv only works with ‘float32’ (32-bit floating point) where image range for imshow is 0.0-1.0 or ‘uint8’ (unsigned 8-bit) 0-255

cvtcolor能接受的参数只能为 float32 或者 uint8 ，需要使用 astype 方法将其转化为需要的类型

img.astype(“float32”)