mirror of
https://github.com/KrisKennaway/ii-pix.git
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71 lines
2.2 KiB
Python
71 lines
2.2 KiB
Python
"""Precompute CIE2000 perceptual colour distance matrices.
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The matrix of delta-E values is computed for all pairs of 24-bit RGB values,
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and 4-bit Apple II target palette. This is a 256MB file that is mmapped at
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runtime for efficient access.
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"""
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import argparse
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import image
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import palette as palette_py
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import colour.difference
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import numpy as np
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COLOURS = 256
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def rgb_to_lab(rgb: np.ndarray):
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srgb = np.clip(
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image.linear_to_srgb_array(rgb.astype(np.float32) / 255), 0.0,
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1.0)
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xyz = colour.sRGB_to_XYZ(srgb)
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return colour.XYZ_to_Lab(xyz)
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def all_lab_colours():
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all_rgb = np.array(tuple(np.ndindex(COLOURS, COLOURS, COLOURS)),
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dtype=np.uint8)
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return rgb_to_lab(all_rgb)
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def nearest_colours(palette, all_lab):
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diffs = np.empty((COLOURS ** 3, 16), dtype=np.float32)
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for i, palette_rgb in sorted(palette.RGB.items()):
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print("...palette colour %d" % i)
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palette_lab = rgb_to_lab(palette_rgb)
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diffs[:, i] = colour.difference.delta_E_CIE2000(all_lab, palette_lab)
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norm = np.max(diffs)
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return (diffs / norm * 255).astype(np.uint8)
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def main():
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parser = argparse.ArgumentParser()
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parser.add_argument('--palette', type=str, choices=list(
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palette_py.PALETTES.keys()),
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default=palette_py.DEFAULT_PALETTE,
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help="Palette for which to compute distance matrix.")
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parser.add_argument('--all', type=bool, default=False,
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help="Whether to compute distances for all palettes")
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args = parser.parse_args()
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if args.all:
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palette_names = list(palette_py.PALETTES.keys())
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else:
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palette_names = [args.palette]
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print("Precomputing matrix of all 24-bit LAB colours")
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all_lab = all_lab_colours()
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for palette_name in palette_names:
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print("Processing palette %s" % palette_name)
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palette = palette_py.PALETTES[palette_name](load_distances=False)
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n = nearest_colours(palette, all_lab)
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out = np.memmap(filename=palette.DISTANCES_PATH, mode="w+",
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dtype=np.uint8, shape=n.shape)
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out[:] = n[:]
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if __name__ == "__main__":
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main()
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