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ii-pix
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ii-pix/ntsc_colours.py

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Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
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"""Precomputes all possible colours available via NTSC emulation."""
import colour
import numpy as np
from PIL import Image
import screen
def main():
Tidy up a bit to prepare for merge
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s = screen.DHGR560NTSCScreen(palette=None)
Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
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bitmap = np.zeros((1, 8), dtype=np.bool)
colours = {}
unique = set()
print("SRGB = {")
# For each sequence of 8 pixels, compute the RGB colour of the right-most
# pixel, using NTSC emulation.
for bits in range(256):
Reimplement NTSC conversion to closely match openemulator output. I can't figure out why contrast=2 is needed (openemulator uses a default value of 1, so there must be a factor of 2x somewhere), or where the slight hue rotation comes from - perhaps this is somehow introduced by the more complex band-pass filtering that openemulator does? I needed to also account for the DHGR timing difference that introduces a phase offset of 1 pixel between the memory values and displayed pixel timings. Fix a last-minute bug with palette precomputation.
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bits8 = np.empty((8,), dtype=np.bool)
Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
2021-02-14 23:34:25 +00:00
for i in range(8):
Reimplement NTSC conversion to closely match openemulator output. I can't figure out why contrast=2 is needed (openemulator uses a default value of 1, so there must be a factor of 2x somewhere), or where the slight hue rotation comes from - perhaps this is somehow introduced by the more complex band-pass filtering that openemulator does? I needed to also account for the DHGR timing difference that introduces a phase offset of 1 pixel between the memory values and displayed pixel timings. Fix a last-minute bug with palette precomputation.
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bits8[i] = bits & (1 << i)
# Double Hi-Res has a timing shift that rotates the displayed bits one
# position with respect to NTSC phase.
bitmap[0, :] = bits8[[3, 0, 1, 2, 7, 4, 5, 6]]
Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
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ntsc = s.bitmap_to_ntsc(bitmap)
last_colour = ntsc[0, -1, :]
colours[bits] = last_colour
unique.add(tuple(last_colour))
print("%d: np.array((%d, %d, %d))," % (
Reimplement NTSC conversion to closely match openemulator output. I can't figure out why contrast=2 is needed (openemulator uses a default value of 1, so there must be a factor of 2x somewhere), or where the slight hue rotation comes from - perhaps this is somehow introduced by the more complex band-pass filtering that openemulator does? I needed to also account for the DHGR timing difference that introduces a phase offset of 1 pixel between the memory values and displayed pixel timings. Fix a last-minute bug with palette precomputation.
2021-02-17 21:29:43 +00:00
bits, last_colour[0], last_colour[1], last_colour[2]))
Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
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print("}")
print("# %d unique colours" % len(unique))
# Show spectrum of available colours sorted by HSV hue value
im = np.zeros((128, 256 * 16, 3), dtype=np.uint8)
for x, hsv in enumerate(sorted([tuple(colour.RGB_to_HSV(c / 256)) for c in
colours.values()])):
im[0:128, x * 16: (x + 1) * 16, :] = colour.HSV_to_RGB(hsv) * 256
Reimplement NTSC conversion to closely match openemulator output. I can't figure out why contrast=2 is needed (openemulator uses a default value of 1, so there must be a factor of 2x somewhere), or where the slight hue rotation comes from - perhaps this is somehow introduced by the more complex band-pass filtering that openemulator does? I needed to also account for the DHGR timing difference that introduces a phase offset of 1 pixel between the memory values and displayed pixel timings. Fix a last-minute bug with palette precomputation.
2021-02-17 21:29:43 +00:00
Implement NTSC emulation, using an 8 pixel window for chroma signal. Use this to precompute a new ntsc palette with 256 entries (though only 84 unique colours) that are available by appropriate pixel sequences. Unfortunately the precomputed distance matrix for this palette is 4GB! Optimize the precomputation to be less memory hungry, while also making efficient use of the mmapped output file. Add support for dithering images using this 8-bit palette depth, i.e. to optimize for NTSC rendering. This often gives better image quality since more colours are available, especially when modulating areas of similar colour. Fix 140 pixel dithering and render the output including NTSC fringing instead of the unrealistic 140px output that doesn't include it. Add support for rendering output image using any target palette, which is useful e.g. for comparing how an 8-pixel NTSC rendered image will be displayed on an emulator using 4-pixel ntsc emulation (there is usually some colour bias, because the 8 pixel chroma blending tends to average away colours). Switch the output binary format to write AUX memory first, which matches the image format of other utilities.
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Image.fromarray(im).show()
if __name__ == "__main__":
main()