460 lines
19 KiB
Python
460 lines
19 KiB
Python
from collections import defaultdict
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import os.path
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import random
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from typing import Tuple
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from PIL import Image
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import colour
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import numpy as np
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from sklearn import cluster
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from os import environ
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environ['PYGAME_HIDE_SUPPORT_PROMPT'] = '1'
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import pygame
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import dither_shr as dither_shr_pyx
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import image as image_py
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class ClusterPalette:
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def __init__(
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self, image: np.ndarray, rgb12_iigs_to_cam16ucs, rgb24_to_cam16ucs,
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fixed_colours=0):
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# Conversion matrix from 12-bit //gs RGB colour space to CAM16UCS
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# colour space
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self._rgb12_iigs_to_cam16ucs = rgb12_iigs_to_cam16ucs
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# Conversion matrix from 24-bit linear RGB colour space to CAM16UCS
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# colour space
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self._rgb24_to_cam16ucs = rgb24_to_cam16ucs
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# Preprocessed source image in 24-bit linear RGB colour space. We
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# first dither the source image using the full 12-bit //gs RGB colour
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# palette, ignoring SHR palette limitations (i.e. 4096 independent
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# colours for each pixel). This gives much better results for e.g.
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# solid blocks of colour, which would be dithered inconsistently if
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# targeting the source image directly.
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self._image_rgb = self._perfect_dither(image)
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# Preprocessed source image in CAM16UCS colour space
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self._colours_cam = self._image_colours_cam(self._image_rgb)
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# We fit a 16-colour palette against the entire image which is used
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# as starting values for fitting the reserved colours in the 16 SHR
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# palettes.
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self._global_palette = np.empty((16, 3), dtype=np.uint8)
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# How many image colours to fix identically across all 16 SHR
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# palettes. These are taken to be the most prevalent colours from
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# _global_palette.
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self._fixed_colours = fixed_colours
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# 16 SHR palettes each of 16 colours, in CAM16UCS colour space
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self._palettes_cam = np.empty((16, 16, 3), dtype=np.float32)
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# 16 SHR palettes each of 16 colours, in //gs 4-bit RGB colour space
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self._palettes_rgb = np.empty((16, 16, 3), dtype=np.uint8)
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# defaultdict(list) mapping palette index to the lines that use this
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# palette
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self._palette_lines = self._init_palette_lines()
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@staticmethod
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def _image_colours_cam(image: Image):
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colours_rgb = np.asarray(image) # .reshape((-1, 3))
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with colour.utilities.suppress_warnings(colour_usage_warnings=True):
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colours_cam = colour.convert(colours_rgb, "RGB",
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"CAM16UCS").astype(np.float32)
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return colours_cam
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def _init_palette_lines(self, init_random=False):
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palette_lines = defaultdict(list)
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if init_random:
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lines = list(range(200))
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random.shuffle(lines)
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idx = 0
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while lines:
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palette_lines[idx].append(lines.pop())
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idx += 1
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else:
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palette_splits = self._equal_palette_splits()
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for i, lh in enumerate(palette_splits):
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l, h = lh
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palette_lines[i].extend(list(range(l, h)))
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return palette_lines
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@staticmethod
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def _equal_palette_splits(palette_height=35):
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# The 16 palettes are striped across consecutive (overlapping) line
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# ranges. Since nearby lines tend to have similar colours, this has
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# the effect of smoothing out the colour transitions across palettes.
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# If we want to overlap 16 palettes in 200 lines, where each palette
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# has height H and overlaps the previous one by L lines, then the
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# boundaries are at lines:
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# (0, H), (H-L, 2H-L), (2H-2L, 3H-2L), ..., (15H-15L, 16H - 15L)
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# i.e. 16H - 15L = 200, so for a given palette height H we need to
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# overlap by:
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# L = (16H - 200)/15
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palette_overlap = (16 * palette_height - 200) / 15
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palette_ranges = []
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for palette_idx in range(16):
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palette_lower = palette_idx * (palette_height - palette_overlap)
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palette_upper = palette_lower + palette_height
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palette_ranges.append((int(np.round(palette_lower)),
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int(np.round(palette_upper))))
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return palette_ranges
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def _perfect_dither(self, source_image: np.ndarray):
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"""Dither a "perfect" image using the full 12-bit //gs RGB colour
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palette, ignoring restrictions."""
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# Suppress divide by zero warning,
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# https://github.com/colour-science/colour/issues/900
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with colour.utilities.suppress_warnings(python_warnings=True):
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full_palette_linear_rgb = colour.convert(
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self._rgb12_iigs_to_cam16ucs, "CAM16UCS", "RGB").astype(
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np.float32)
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total_image_error, image_rgb = dither_shr_pyx.dither_shr_perfect(
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source_image, self._rgb12_iigs_to_cam16ucs, full_palette_linear_rgb,
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self._rgb24_to_cam16ucs)
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# print("Perfect image error:", total_image_error)
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return image_rgb
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def _dither_image(self, palettes_cam):
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# Suppress divide by zero warning,
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# https://github.com/colour-science/colour/issues/900
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with colour.utilities.suppress_warnings(python_warnings=True):
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palettes_linear_rgb = colour.convert(
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palettes_cam, "CAM16UCS", "RGB").astype(np.float32)
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output_4bit, line_to_palette, total_image_error, palette_line_errors = \
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dither_shr_pyx.dither_shr(
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self._image_rgb, palettes_cam, palettes_linear_rgb,
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self._rgb24_to_cam16ucs)
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# Update map of palettes to image lines for which the palette was the
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# best match
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palette_lines = defaultdict(list)
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for line, palette in enumerate(line_to_palette):
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palette_lines[palette].append(line)
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self._palette_lines = palette_lines
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self._palette_line_errors = palette_line_errors
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return (output_4bit, line_to_palette, palettes_linear_rgb,
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total_image_error)
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def iterate(self, max_inner_iterations: int,
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max_outer_iterations: int):
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total_image_error = 1e9
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outer_iterations_since_improvement = 0
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while outer_iterations_since_improvement < max_outer_iterations:
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inner_iterations_since_improvement = 0
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self._palette_lines = self._init_palette_lines()
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while inner_iterations_since_improvement < max_inner_iterations:
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# print("Iterations %d" % inner_iterations_since_improvement)
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new_palettes_cam, new_palettes_rgb12_iigs = (
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self._fit_shr_palettes())
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# Recompute image with proposed palettes and check whether it
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# has lower total image error than our previous best.
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(output_4bit, line_to_palette, palettes_linear_rgb,
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new_total_image_error) = self._dither_image(new_palettes_cam)
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self._reassign_unused_palettes(
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line_to_palette, new_palettes_rgb12_iigs)
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if new_total_image_error >= total_image_error:
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inner_iterations_since_improvement += 1
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continue
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# We found a globally better set of palettes, so restart the
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# clocks
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inner_iterations_since_improvement = 0
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outer_iterations_since_improvement = -1
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total_image_error = new_total_image_error
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self._palettes_cam = new_palettes_cam
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self._palettes_rgb = new_palettes_rgb12_iigs
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yield (new_total_image_error, output_4bit, line_to_palette,
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new_palettes_rgb12_iigs, palettes_linear_rgb)
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outer_iterations_since_improvement += 1
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def _fit_shr_palettes(self) -> Tuple[np.ndarray, np.ndarray]:
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"""Attempt to find new palettes that locally improve image quality.
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Re-fit a set of 16 palettes from (overlapping) line ranges of the
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source image, using k-means clustering in CAM16-UCS colour space.
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We maintain the total image error for the pixels on which the 16
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palettes are clustered. A new palette that increases this local
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image error is rejected.
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New palettes that reduce local error cannot be applied immediately
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though, because they may cause an increase in *global* image error
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when dithering. i.e. they would reduce the overall image quality.
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The current (locally) best palettes are returned and can be applied
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using accept_palettes()
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XXX update
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"""
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new_palettes_cam = np.empty_like(self._palettes_cam)
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new_palettes_rgb12_iigs = np.empty_like(self._palettes_rgb)
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# Compute a new 16-colour global palette for the entire image,
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# used as the starting center positions for k-means clustering of the
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# individual palettes
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self._fit_global_palette()
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for palette_idx in range(16):
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palette_pixels = (
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self._colours_cam[self._palette_lines[
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palette_idx], :, :].reshape(-1, 3))
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# Fix reserved colours from the global palette.
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initial_centroids = np.copy(self._global_palette)
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pixels_rgb_iigs = dither_shr_pyx.convert_cam16ucs_to_rgb12_iigs(
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palette_pixels)
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seen_colours = set()
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for i in range(self._fixed_colours):
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seen_colours.add(tuple(initial_centroids[i, :]))
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# Pick unique random colours from the sample points for the
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# remaining initial centroids.
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for i in range(self._fixed_colours, 16):
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choice = np.random.randint(0, pixels_rgb_iigs.shape[0])
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new_colour = pixels_rgb_iigs[choice, :]
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if tuple(new_colour) in seen_colours:
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continue
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seen_colours.add(tuple(new_colour))
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initial_centroids[i, :] = new_colour
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# If there are any single colours in our source //gs RGB pixels that
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# represent more than fixed_colour_fraction_threshold of the total,
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# then fix these colours for the palette instead of clustering
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# them. This reduces artifacting on blocks of colour.
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fixed_colour_fraction_threshold = 0.1
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most_frequent_colours = sorted(list(zip(
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*np.unique(pixels_rgb_iigs, return_counts=True, axis=0))),
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key=lambda kv: kv[1], reverse=True)
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fixed_colours = self._fixed_colours
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for palette_colour, freq in most_frequent_colours:
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if (freq < (palette_pixels.shape[0] *
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fixed_colour_fraction_threshold)) or (
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fixed_colours == 16):
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break
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if tuple(palette_colour) not in seen_colours:
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seen_colours.add(tuple(palette_colour))
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initial_centroids[fixed_colours, :] = palette_colour
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fixed_colours += 1
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palette_rgb12_iigs = dither_shr_pyx.k_means_with_fixed_centroids(
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n_clusters=16, n_fixed=fixed_colours,
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samples=palette_pixels,
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initial_centroids=initial_centroids,
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max_iterations=1000,
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rgb12_iigs_to_cam16ucs=self._rgb12_iigs_to_cam16ucs)
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# If the k-means clustering returned fewer than 16 unique colours,
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# fill out the remainder with the most common pixels colours that
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# have not yet been used.
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#
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# TODO: this seems like an opportunity to do something better -
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# e.g. forcibly split clusters and iterate the clustering
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palette_rgb12_iigs = self._fill_short_palette(
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palette_rgb12_iigs, most_frequent_colours)
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for i in range(16):
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new_palettes_cam[palette_idx, i, :] = (
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np.array(dither_shr_pyx.convert_rgb12_iigs_to_cam(
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self._rgb12_iigs_to_cam16ucs, palette_rgb12_iigs[
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i]), dtype=np.float32))
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new_palettes_rgb12_iigs[palette_idx, :, :] = palette_rgb12_iigs
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self._palettes_accepted = False
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return new_palettes_cam, new_palettes_rgb12_iigs
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def _fit_global_palette(self):
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"""Compute a 16-colour palette for the entire image to use as
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starting point for the sub-palettes. This should help when the image
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has large blocks of colour since the sub-palettes will tend to pick the
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same colours."""
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clusters = cluster.MiniBatchKMeans(n_clusters=16, max_iter=10000)
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clusters.fit_predict(self._colours_cam.reshape(-1, 3))
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# Dict of {palette idx : frequency count}
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palette_freq = {idx: 0 for idx in range(16)}
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for idx, freq in zip(*np.unique(clusters.labels_, return_counts=True)):
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palette_freq[idx] = freq
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frequency_order = [
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k for k, v in sorted(
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list(palette_freq.items()), key=lambda kv: kv[1], reverse=True)]
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self._global_palette = (
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dither_shr_pyx.convert_cam16ucs_to_rgb12_iigs(
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clusters.cluster_centers_[frequency_order].astype(
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np.float32)))
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@staticmethod
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def _fill_short_palette(palette_iigs_rgb, most_frequent_colours):
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"""Fill out the palette to 16 unique entries."""
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# We want to maintain order of insertion so that we respect the
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# ordering of fixed colours in the palette. Python doesn't have an
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# orderedset but dicts preserve insertion order.
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palette_set = {}
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for palette_entry in palette_iigs_rgb:
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palette_set[tuple(palette_entry)] = True
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if len(palette_set) == 16:
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return palette_iigs_rgb
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# Add most frequent image colours that are not yet in the palette
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for palette_colour, freq in most_frequent_colours:
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if tuple(palette_colour) in palette_set:
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continue
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palette_set[tuple(palette_colour)] = True
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if len(palette_set) == 16:
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break
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# We couldn't find any more unique colours, fill out with random ones.
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while len(palette_set) < 16:
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palette_set[
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tuple(np.random.randint(0, 16, size=3, dtype=np.uint8))] = True
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return np.array(tuple(palette_set.keys()), dtype=np.uint8)
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def _reassign_unused_palettes(self, line_to_palette, palettes_iigs_rgb):
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palettes_used = [False] * 16
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for palette in line_to_palette:
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palettes_used[palette] = True
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best_palette_lines = [v for k, v in sorted(list(zip(
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self._palette_line_errors, range(200))))]
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all_palettes = set()
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for palette_idx, palette_iigs_rgb in enumerate(palettes_iigs_rgb):
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palette_set = set()
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for palette_entry in palette_iigs_rgb:
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palette_set.add(tuple(palette_entry))
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palette_set = frozenset(palette_set)
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if palette_set in all_palettes:
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print("Duplicate palette", palette_idx, palette_set)
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palettes_used[palette_idx] = False
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for palette_idx, palette_used in enumerate(palettes_used):
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if palette_used:
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continue
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# TODO: also remove from old entry
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worst_line = best_palette_lines.pop()
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self._palette_lines[palette_idx] = [worst_line]
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def convert(screen, image: Image, args):
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rgb = np.array(image).astype(np.float32) / 255
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# Conversion matrix from RGB to CAM16UCS colour values. Indexed by
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# 24-bit RGB value
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base_dir = os.path.dirname(__file__)
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rgb24_to_cam16ucs = np.load(
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os.path.join(base_dir, "data/rgb24_to_cam16ucs.npy"))
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rgb12_iigs_to_cam16ucs = np.load(
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os.path.join(base_dir, "data/rgb12_iigs_to_cam16ucs.npy"))
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# TODO: flags
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inner_iterations = 10
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outer_iterations = 20
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if args.show_output:
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pygame.init()
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canvas = pygame.display.set_mode((640, 400))
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canvas.fill((0, 0, 0))
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pygame.display.set_caption("][-Pix image preview")
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pygame.event.pump() # Update caption
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pygame.display.flip()
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total_image_error = None
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cluster_palette = ClusterPalette(
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rgb, fixed_colours=args.fixed_colours,
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rgb12_iigs_to_cam16ucs=rgb12_iigs_to_cam16ucs,
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rgb24_to_cam16ucs=rgb24_to_cam16ucs)
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output_base, output_ext = os.path.splitext(args.output)
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seq = 0
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for (
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new_total_image_error, output_4bit, line_to_palette,
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palettes_rgb12_iigs,
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palettes_linear_rgb
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) in cluster_palette.iterate(inner_iterations, outer_iterations):
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if args.verbose and total_image_error is not None:
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print("Improved quality +%f%% (%f)" % (
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(1 - new_total_image_error / total_image_error) * 100,
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new_total_image_error))
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total_image_error = new_total_image_error
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for i in range(16):
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screen.set_palette(i, palettes_rgb12_iigs[i, :, :])
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# Recompute current screen RGB image
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screen.set_pixels(output_4bit)
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output_rgb = np.empty((200, 320, 3), dtype=np.uint8)
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for i in range(200):
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screen.line_palette[i] = line_to_palette[i]
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output_rgb[i, :, :] = (
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palettes_linear_rgb[line_to_palette[i]][
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output_4bit[i, :]] * 255
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).astype(np.uint8)
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output_srgb = (image_py.linear_to_srgb(output_rgb)).astype(np.uint8)
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out_image = image_py.resize(
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Image.fromarray(output_srgb), screen.X_RES * 2, screen.Y_RES * 2,
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srgb_output=True)
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if args.show_output:
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surface = pygame.surfarray.make_surface(
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np.asarray(out_image).transpose((1, 0, 2))) # flip y/x axes
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canvas.blit(surface, (0, 0))
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pygame.display.set_caption("][-Pix image preview [Iteration %d]"
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% seq)
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pygame.event.pump() # Update caption
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pygame.display.flip()
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unique_colours = np.unique(
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palettes_rgb12_iigs.reshape(-1, 3), axis=0).shape[0]
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if args.verbose:
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print("%d unique colours" % unique_colours)
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if args.save_preview:
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# Save super hi-res image
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if args.save_intermediate:
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outfile = "%s-%d-preview.png" % (output_base, seq)
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else:
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outfile = "%s-preview.png" % output_base
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out_image.save(outfile, "PNG")
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screen.pack()
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if args.save_intermediate:
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outfile = "%s-%d%s" % (output_base, seq, output_ext)
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else:
|
|
outfile = "%s%s" % (output_base, output_ext)
|
|
with open(outfile, "wb") as f:
|
|
f.write(bytes(screen.memory))
|
|
|
|
seq += 1
|
|
|
|
if args.show_final_score:
|
|
print("FINAL_SCORE:", total_image_error)
|