The code below is commented and self explanatory. It converts all images in a folder “images>knowpapa” to its equivalent greyscale image and appends the word ‘grey’ to the original image name.
import sys
import os
import numpy as np
import cv2
def greyscale(img):
'''Convert an image to greyscale.
image - a numpy array of shape (rows, columns, 3).
output - a grey scale image which is a numpy array of shape (rows, columns)
containing the average of image's 3 channels.
'''
image = np.uint16(img)
avg = np.zeros((image.shape[0], image.shape[1],image.shape[2]))
avg[:, :,0] = (image[:, :, 0] + image[:, :, 1] + image[:, :, 2])/3
output = avg.astype(np.uint8)
return output[:,:,0]
def main():
'''Convert images to greyscale.
searches for images in directory images/knowapa, and applies the grey scale
functiony to each image in the same directory and saves greyscaleimage for
each file with the word grey appended to the image
'''
imagesfolder = os.path.join('images', 'knowpapa')
exts = ['.bmp', '.pbm', '.pgm', '.ppm', '.sr', '.ras', '.jpeg', '.jpg',
'.jpe', '.jp2', '.tiff', '.tif', '.png']
for dirname, dirnames, filenames in os.walk(imagesfolder):
for filename in filenames:
name, ext = os.path.splitext(filename)
if ext in exts and 'grey' not in name:
img = cv2.imread(os.path.join(dirname, filename))
greyimage = greyscale(img)
cv2.imwrite(os.path.join(dirname, name+"grey"+ext), greyimage)
if __name__ == "__main__":
main()
And here’s the sample input and output image
image courtesy: mengel
