image_to_ansi.py

from argparse import ArgumentParser
from io import BytesIO

from PIL.Image import open as open_image


def image_to_ansi(data, scale=1):
    # TODO: optimise this algorithm - it's pretty brute-force right now
    image = open_image(BytesIO(data))
    width, height = image.size
    ansi_width = int(scale * width // 8)                                    # assume font is 8 pixels wide
    ansi_height = int(scale * height // 8)                                  # assume font is 8×2 pixels high
    ansi_image = image.resize((ansi_width, ansi_height))
    pixels = list(ansi_image.getdata())
    lines = []
    p0 = 0
    while p0 < len(pixels):
        p1 = p0 + ansi_width
        p2 = p1 + ansi_width
        line0 = pixels[p0:p1]
        line1 = pixels[p1:p2]
        p0 = p2
        line = []
        for i, rgb0 in enumerate(line0):
            try:
                rgb1 = line1[i]
            except IndexError:
                rgb1 = [(0, 0, 0) for _ in range(len(rgb0))]
            line.append(f"\x1b[38;2;{rgb0[0]};{rgb0[1]};{rgb0[2]}m")        # Select RGB foreground color
            if rgb0 == rgb1:
                line.append("\u2588")                                       # U+2588 █ FULL BLOCK
            else:
                line.append(f"\x1b[48;2;{rgb1[0]};{rgb1[1]};{rgb1[2]}m")    # Select RGB background color
                line.append("\u2580")                                       # U+2580 ▀ UPPER HALF BLOCK
        line.append("\x1b[0m")
        lines.append("".join(line))
    return "\n".join(lines)


def main():
    parser = ArgumentParser()
    parser.add_argument("filename")
    parser.add_argument("-x", "--scale", type=float, default=1)
    parsed = parser.parse_args()
    with open(parsed.filename, "rb") as f:
        print(image_to_ansi(f.read(), scale=parsed.scale))


if __name__ == "__main__":
    main()