ii-pix/ntsc_colours.py

"""Precomputes all possible colours available via NTSC emulation."""

import colour
import numpy as np
from PIL import Image
import screen


def main():
    s = screen.DHGR560NTSCScreen(palette=None)

    colours = {}
    unique = set()

    print("import numpy as np")
    print()
    print("SRGB = {")
    # For each sequence of 8 pixels, compute the RGB colour of the right-most
    # pixel, using NTSC emulation.
    # Double Hi-Res has a timing shift that rotates the displayed bits one
    # position with respect to NTSC phase.
    # TODO: should be 3?  Do I have a compensating off-by-one in bitmap_to_ntsc?
    ntsc_shift = 2
    for j in range(ntsc_shift, ntsc_shift+4):
        bitmap = np.zeros((1, 11+ntsc_shift), dtype=np.bool)
        for bits in range(256):
            bits8 = np.empty((8,), dtype=np.bool)
            for i in range(8):
                bits8[i] = bits & (1 << i)

            bitmap[0, j:j+8] = bits8

            ntsc = s.bitmap_to_ntsc(bitmap)
            last_colour = ntsc[0, 3*(j+8)-1, :]
            colours[(bits, j-ntsc_shift)] = last_colour
            unique.add(tuple(last_colour))
            print("  (%d, %d): np.array((%d, %d, %d))," % (
                bits, j-ntsc_shift, last_colour[0], last_colour[1], last_colour[2]))
    print("}")
    print("# %d unique colours" % len(unique))

    # Show spectrum of available colours sorted by HSV hue value
    im = np.zeros((128*4, 256 * 16, 3), dtype=np.uint8)
    for x, j in colours:
        im[128*j:128*(j+1), x * 16: (x + 1) * 16, :] = colours[x,j]

    Image.fromarray(im).show()


if __name__ == "__main__":
    main()