Converts one or more 3D images for red/blue 3D glasses into stereogram images

stereogram.py

"""
Converts one or more 3D images for red/blue 3D glasses into stereogram images. Example:

Download:
https://www.nasa.gov/sites/default/files/styles/full_width/public/thumbnails/image/nh-ut_stereo_bluered_030619.png

Then run:
python stereogram.py nh-ut_stereo_bluered_030619.png

This will generate:
nh-ut_stereo_bluered_030619_stereo.png

Run the following command for more options:
python stereogram.py --help
"""

import sys
import numpy as np
import argparse
from imageio import imread, imwrite

def convert_to_stereogram(filepath, left_channel=0, right_channel=1,
                          brightness=0, hpad=50, vpad=100, repeat=3,
                          extension="png"):
    img = imread(filepath)[:, :, :] # drop alpha channel, if any
    img = img.astype(np.float)
    left = img[:, :, left_channel]
    right = img[:, :, right_channel]
    if brightness:
        left_brightness = left.mean()
        right_brightness = right.mean()
        if left_brightness:
            left *= 255. * brightness / left_brightness
            left[left > 255.] = 255.
        if right_brightness:
            right *= 255. * brightness / right_brightness
            right[right > 255.] = 255.
    height = img.shape[0] + 2 * vpad
    width = 2 * repeat * img.shape[1] + 2 * hpad
    stereo = np.zeros((height, width), dtype=np.uint8)
    stereo[vpad:-vpad, hpad:-hpad] = np.concatenate(
        [left] * repeat + [right] * repeat, axis=1
    )
    stereo_filepath = filepath.rsplit(".", 1)[0] + "_stereo." + extension
    imwrite(stereo_filepath, stereo)

def parse_args():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('image_paths', metavar="IMAGEPATH", nargs='+',
                        help='3D image file path')
    parser.add_argument('--left_channel', type=int, default=0,
                        help='Color channel for the left view')
    parser.add_argument('--right_channel', type=int, default=1,
                        help='Color channel for the right view')
    parser.add_argument('--brightness', type=float, default=0.,
                        help='Set the brightness level')
    parser.add_argument('--hpad', type=int, default=50,
                        help='Horizontal padding')
    parser.add_argument('--vpad', type=int, default=100,
                        help='Vertical padding')
    parser.add_argument('--repeat', type=int, default=3,
                        help='Repetitions')
    parser.add_argument('--extension', default="png",
                        help='Stereo file extension')
    parser.add_argument('--verbose', '-v', action='count', default=0)
    args = parser.parse_args()
    return args

if __name__ == '__main__':
    args = parse_args()
    for filepath in args.image_paths:
        if args.verbose:
            print("Converting", filepath)
        try:
            convert_to_stereogram(filepath,
                                  left_channel=args.left_channel,
                                  right_channel=args.right_channel,
                                  brightness=args.brightness,
                                  hpad=args.hpad,
                                  vpad=args.vpad,
                                  repeat=args.repeat,
                                  extension=args.extension)
        except Exception as ex:
            print("Error:", ex)