learnopencv/Photoshop-Filters-in-OpenCV/sepia.py

import cv2
import numpy as np

def sepia(img):
    res = img.copy()
    res = cv2.cvtColor(res, cv2.COLOR_BGR2RGB) # converting to RGB as sepia matrix is for RGB
    res = np.array(res, dtype=np.float64)
    res = cv2.transform(res, np.matrix([[0.393, 0.769, 0.189],
                                        [0.349, 0.686, 0.168],
                                        [0.272, 0.534, 0.131]]))
    res[np.where(res > 255)] = 255 # clipping values greater than 255 to 255
    res = np.array(res, dtype=np.uint8)
    res = cv2.cvtColor(res, cv2.COLOR_RGB2BGR)
    cv2.imshow("original", img)
    cv2.imshow("Sepia", res)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
    
if __name__ == "__main__":
    img = cv2.imread("image.jpg")
    sepia(img)