"""
 Implemented an algorithm using opencv to tone an image with sepia technique
"""
from cv2 import destroyAllWindows, imread, imshow, waitKey


def make_sepia(img, factor: int):
 """
 Function create sepia tone.
 Source: https://en.wikipedia.org/wiki/Sepia_(color)
 """
 pixel_h, pixel_v = img.shape[0], img.shape[1]

 def to_grayscale(blue, green, red):
 """
 Helper function to create pixel's greyscale representation
 Src: https://pl.wikipedia.org/wiki/YUV
 """
 return 0.2126 * red + 0.587 * green + 0.114 * blue

 def normalize(value):
 """ Helper function to normalize R/G/B value -> return 255 if value > 255"""
 return min(value, 255)

 for i in range(pixel_h):
 for j in range(pixel_v):
 greyscale = int(to_grayscale(*img[i][j]))
 img[i][j] = [
 normalize(greyscale),
 normalize(greyscale + factor),
 normalize(greyscale + 2 * factor),
 ]

 return img


if __name__ == "__main__":
 # read original image
 images = {
 percentage: imread("image_data/lena.jpg", 1) for percentage in (10, 20, 30, 40)
 }

 for percentage, img in images.items():
 make_sepia(img, percentage)

 for percentage, img in images.items():
 imshow(f"Original image with sepia (factor: {percentage})", img)

 waitKey(0)
 destroyAllWindows()