Convert RGB to gray / other color spaces

Convert RGB to gray / other color spaces

cv2.cvtColor(src, code[, dst[, dstCn]]) → dst

Parameters:	src – input image: 8-bit unsigned, 16-bit unsigned ( CV_16UC... ), or single-precision floating-point. dst – output image of the same size and depth as src. code – color space conversion code (see the description below). dstCn – number of channels in the destination image; if the parameter is 0, the number of the channels is derived automatically from src and code .

This function converts one image from one colorspace to another.The default color format in openCV is RGB.But is is actually BGR(byte reversed).so in an 24 bit color image the first 8 bits are blue components,2nd byte is green and third one is red.

The conventional ranges for R, G, and B channel values are:

• 0 to 255 for CV_8U images
• 0 to 65535 for CV_16U images
• 0 to 1 for CV_32F images

Example:

Converting to grayscale:

Steps:

1. Load an image 
2. Convert to gray scale
3. Show result

Code:

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import cv2

# Load a color image
img = cv2.imread('image1.jpg',1)

#convert RGB image to Gray
gray=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

#Display the color image
cv2.imshow('color_image',img)

#Display the gray image
cv2.imshow('gray_image',gray)

cv2.waitKey(0)
cv2.destroyAllWindows()

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