Python: Convert PIL.Image to OpenCV BGR(A)/grayscale image (NumPy array). This supports the most common image modes, but there are more! Patches for those are welcome.

pil2cv.py

from PIL import Image

import numpy as np
import cv2

def pil2cv(image: Image) -> np.ndarray:
    mode = image.mode
    new_image: np.ndarray
    if mode == '1':
        new_image = np.array(image, dtype=np.uint8)
        new_image *= 255
    elif mode == 'L':
        new_image = np.array(image, dtype=np.uint8)
    elif mode == 'LA' or mode == 'La':
        new_image = np.array(image.convert('RGBA'), dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_RGBA2BGRA)
    elif mode == 'RGB':
        new_image = np.array(image, dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_RGB2BGR)
    elif mode == 'RGBA':
        new_image = np.array(image, dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_RGBA2BGRA)
    elif mode == 'LAB':
        new_image = np.array(image, dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_LAB2BGR)
    elif mode == 'HSV':
        new_image = np.array(image, dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_HSV2BGR)
    elif mode == 'YCbCr':
        # XXX: not sure if YCbCr == YCrCb
        new_image = np.array(image, dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_YCrCb2BGR)
    elif mode == 'P' or mode == 'CMYK':
        new_image = np.array(image.convert('RGB'), dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_RGB2BGR)
    elif mode == 'PA' or mode == 'Pa':
        new_image = np.array(image.convert('RGBA'), dtype=np.uint8)
        new_image = cv2.cvtColor(new_image, cv2.COLOR_RGBA2BGRA)
    else:
        raise ValueError(f'unhandled image color mode: {mode}')

    return new_image