mirror of
https://github.com/KrisKennaway/ii-pix.git
synced 2024-06-07 00:29:29 +00:00
83b047b73f
to mutate our source image! Fix another bug introduced in the previous commit: convert from linear rgb before quantizing //gs RGB palette since //gs RGB values are in Rec.601 colour space. Switch to double for colour_squared_distance and related variables, not sure if it matters though. When iterating palette clustering, reject the new palettes if they would increase the total image error. This prevents accepting changes that are local improvements to one palette but which would introduce more net errors elsewhere when this palette is reused. This now seems to give monotonic improvements in image quality so no need to write out intermediate images any more.
549 lines
23 KiB
Cython
549 lines
23 KiB
Cython
# cython: infer_types=True
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# cython: profile=False
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cimport cython
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import numpy as np
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from libc.stdlib cimport malloc, free
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# TODO: use a cdef class
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# C representation of dither_pattern.DitherPattern data, for efficient access.
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cdef struct Dither:
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float* pattern # Flattened dither pattern
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int x_shape
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int y_shape
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int x_origin
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int y_origin
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cdef float clip(float a, float min_value, float max_value) nogil:
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return min(max(a, min_value), max_value)
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# Compute left-hand bounding box for dithering at horizontal position x.
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cdef int dither_bounds_xl(Dither *dither, int x) nogil:
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cdef int el = max(dither.x_origin - x, 0)
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cdef int xl = x - dither.x_origin + el
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return xl
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#Compute right-hand bounding box for dithering at horizontal position x.
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cdef int dither_bounds_xr(Dither *dither, int x_res, int x) nogil:
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cdef int er = min(dither.x_shape, x_res - x)
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cdef int xr = x - dither.x_origin + er
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return xr
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# Compute upper bounding box for dithering at vertical position y.
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cdef int dither_bounds_yt(Dither *dither, int y) nogil:
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cdef int et = max(dither.y_origin - y, 0)
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cdef int yt = y - dither.y_origin + et
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return yt
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# Compute lower bounding box for dithering at vertical position y.
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cdef int dither_bounds_yb(Dither *dither, int y_res, int y) nogil:
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cdef int eb = min(dither.y_shape, y_res - y)
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cdef int yb = y - dither.y_origin + eb
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return yb
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cdef inline unsigned char shift_pixel_window(
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unsigned char last_pixels,
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unsigned int next_pixels,
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unsigned char shift_right_by,
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unsigned char window_width) nogil:
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"""Right-shift a sliding window of n pixels to incorporate new pixels.
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Args:
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last_pixels: n-bit value representing n pixels from left up to current position (MSB = current pixel).
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next_pixels: n-bit value representing n pixels to right of current position (LSB = pixel to right)
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shift_right_by: how many pixels of next_pixels to shift into the sliding window
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window_width: how many pixels to maintain in the sliding window (must be <= 8)
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Returns: n-bit value representing shifted pixel window
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"""
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cdef unsigned char window_mask = 0xff >> (8 - window_width)
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cdef unsigned int shifted_next_pixels
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if window_width > shift_right_by:
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shifted_next_pixels = next_pixels << (window_width - shift_right_by)
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else:
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shifted_next_pixels = next_pixels >> (shift_right_by - window_width)
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return ((last_pixels >> shift_right_by) | shifted_next_pixels) & window_mask
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# Look ahead a number of pixels and compute choice for next pixel with lowest total squared error after dithering.
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#
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# Args:
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# dither: error diffusion pattern to apply
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# palette_rgb: matrix of all n-bit colour palette RGB values
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# image_rgb: RGB image in the process of dithering
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# x: current horizontal screen position
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# y: current vertical screen position
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# options_nbit: matrix of (2**lookahead, lookahead) possible n-bit colour choices at positions x .. x + lookahead
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# lookahead: how many horizontal pixels to look ahead
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# distances: matrix of (24-bit RGB, n-bit palette) perceptual colour distances
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# x_res: horizontal screen resolution
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#
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# Returns: index from 0 .. 2**lookahead into options_nbit representing best available choice for position (x,y)
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#
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef int dither_lookahead(Dither* dither, float[:, :, ::1] palette_cam16, float[:, :, ::1] palette_rgb,
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float[:, :, ::1] image_rgb, int x, int y, int lookahead, unsigned char last_pixels,
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int x_res, float[:,::1] rgb_to_cam16ucs, unsigned char palette_depth) nogil:
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cdef int candidate_pixels, i, j
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cdef float[3] quant_error
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cdef int best
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cdef float best_error = 2**31-1
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cdef float total_error
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cdef unsigned char next_pixels
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cdef int phase
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cdef float[::1] lah_cam16ucs
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# Don't bother dithering past the lookahead horizon or edge of screen.
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cdef int xxr = min(x + lookahead, x_res)
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cdef int lah_shape1 = xxr - x
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cdef int lah_shape2 = 3
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cdef float *lah_image_rgb = <float *> malloc(lah_shape1 * lah_shape2 * sizeof(float))
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# For each 2**lookahead possibilities for the on/off state of the next lookahead pixels, apply error diffusion
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# and compute the total squared error to the source image. Since we only have two possible colours for each
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# given pixel (dependent on the state already chosen for pixels to the left), we need to look beyond local minima.
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# i.e. it might be better to make a sub-optimal choice for this pixel if it allows access to much better pixel
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# colours at later positions.
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for candidate_pixels in range(1 << lookahead):
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# Working copy of input pixels
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for i in range(xxr - x):
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for j in range(3):
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lah_image_rgb[i * lah_shape2 + j] = image_rgb[y, x+i, j]
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total_error = 0
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# Apply dithering to lookahead horizon or edge of screen
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for i in range(xxr - x):
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xl = dither_bounds_xl(dither, i)
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xr = dither_bounds_xr(dither, xxr - x, i)
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phase = (x + i) % 4
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next_pixels = shift_pixel_window(
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last_pixels, next_pixels=candidate_pixels, shift_right_by=i+1, window_width=palette_depth)
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# We don't update the input at position x (since we've already chosen fixed outputs), but we do propagate
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# quantization errors to positions >x so we can compensate for how good/bad these choices were. i.e. the
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# next_pixels choices are fixed, but we can still distribute quantization error from having made these
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# choices, in order to compute the total error.
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for j in range(3):
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quant_error[j] = lah_image_rgb[i * lah_shape2 + j] - palette_rgb[next_pixels, phase, j]
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apply_one_line(dither, xl, xr, i, lah_image_rgb, lah_shape2, quant_error)
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lah_cam16ucs = convert_rgb_to_cam16ucs(
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rgb_to_cam16ucs, lah_image_rgb[i*lah_shape2], lah_image_rgb[i*lah_shape2+1],
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lah_image_rgb[i*lah_shape2+2])
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total_error += colour_distance_squared(lah_cam16ucs, palette_cam16[next_pixels, phase])
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if total_error >= best_error:
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# No need to continue
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break
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if total_error < best_error:
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best_error = total_error
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best = candidate_pixels
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free(lah_image_rgb)
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return best
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef inline float[::1] convert_rgb_to_cam16ucs(float[:, ::1] rgb_to_cam16ucs, float r, float g, float b) nogil:
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cdef int rgb_24bit = (<int>(r*255) << 16) + (<int>(g*255) << 8) + <int>(b*255)
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return rgb_to_cam16ucs[rgb_24bit]
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef inline float fabs(float value) nogil:
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return -value if value < 0 else value
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef inline double colour_distance_squared(float[::1] colour1, float[::1] colour2) nogil:
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return (colour1[0] - colour2[0]) ** 2 + (colour1[1] - colour2[1]) ** 2 + (colour1[2] - colour2[2]) ** 2
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef inline float colour_distance(float[::1] colour1, float[::1] colour2) nogil:
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return fabs(colour1[0] - colour2[0]) + fabs(colour1[1] - colour2[1]) + fabs(colour1[2] - colour2[2])
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# Perform error diffusion to a single image row.
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#
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# Args:
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# dither: dither pattern to apply
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# xl: lower x bounding box
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# xr: upper x bounding box
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# x: starting horizontal position to apply error diffusion
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# image: array of shape (image_shape1, 3) representing RGB pixel data for a single image line, to be mutated.
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# image_shape1: horizontal dimension of image
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# quant_error: RGB quantization error to be diffused
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#
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cdef void apply_one_line(Dither* dither, int xl, int xr, int x, float[] image, int image_shape1,
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float[] quant_error) nogil:
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cdef int i, j
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cdef float error_fraction
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for i in range(xl, xr):
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error_fraction = dither.pattern[i - x + dither.x_origin]
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for j in range(3):
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image[i * image_shape1 + j] = clip(image[i * image_shape1 + j] + error_fraction * quant_error[j], 0, 1)
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# Perform error diffusion across multiple image rows.
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#
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# Args:
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# dither: dither pattern to apply
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# x_res: horizontal image resolution
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# y_res: vertical image resolution
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# x: starting horizontal position to apply error diffusion
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# y: starting vertical position to apply error diffusion
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# image: RGB pixel data, to be mutated
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# quant_error: RGB quantization error to be diffused
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#
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef void apply(Dither* dither, int x_res, int y_res, int x, int y, float[:,:,::1] image, float[] quant_error) nogil:
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cdef int i, j, k
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cdef int yt = dither_bounds_yt(dither, y)
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cdef int yb = dither_bounds_yb(dither, y_res, y)
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cdef int xl = dither_bounds_xl(dither, x)
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cdef int xr = dither_bounds_xr(dither, x_res, x)
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cdef float error_fraction
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for i in range(yt, yb):
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for j in range(xl, xr):
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error_fraction = dither.pattern[(i - y) * dither.x_shape + j - x + dither.x_origin]
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for k in range(3):
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image[i,j,k] = clip(image[i,j,k] + error_fraction * quant_error[k], 0, 1)
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@cython.boundscheck(False)
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@cython.wraparound(False)
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cdef image_nbit_to_bitmap(
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(unsigned char)[:, ::1] image_nbit, unsigned int x_res, unsigned int y_res, unsigned char palette_depth):
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cdef unsigned int x, y
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bitmap = np.zeros((y_res, x_res), dtype=bool)
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for y in range(y_res):
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for x in range(x_res):
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# MSB of each array element is the pixel state at (x, y)
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bitmap[y, x] = image_nbit[y, x] >> (palette_depth - 1)
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return bitmap
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# Dither a source image
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#
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# Args:
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# screen: screen.Screen object
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# image_rgb: input RGB image
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# dither: dither_pattern.DitherPattern to apply during dithering
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# lookahead: how many x positions to look ahead to optimize colour choices
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# verbose: whether to output progress during image conversion
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#
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# Returns: tuple of n-bit output image array and RGB output image array
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#
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@cython.boundscheck(False)
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@cython.wraparound(False)
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def dither_image(
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screen, float[:, :, ::1] image_rgb, dither, int lookahead, unsigned char verbose, float[:,::1] rgb_to_cam16ucs):
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cdef int y, x
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cdef unsigned char i, j, pixels_nbit, phase
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# cdef float[3] input_pixel_rgb
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cdef float[3] quant_error
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cdef unsigned char output_pixel_nbit
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cdef unsigned char best_next_pixels
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cdef float[3] output_pixel_rgb
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# Hoist some python attribute accesses into C variables for efficient access during the main loop
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cdef int yres = screen.Y_RES
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cdef int xres = screen.X_RES
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# TODO: convert this instead of storing on palette?
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cdef float[:, :, ::1] palette_cam16 = np.zeros((len(screen.palette.CAM16UCS), 4, 3), dtype=np.float32)
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for pixels_nbit, phase in screen.palette.CAM16UCS.keys():
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for i in range(3):
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palette_cam16[pixels_nbit, phase, i] = screen.palette.CAM16UCS[pixels_nbit, phase][i]
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cdef float[:, :, ::1] palette_rgb = np.zeros((len(screen.palette.RGB), 4, 3), dtype=np.float32)
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for pixels_nbit, phase in screen.palette.RGB.keys():
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for i in range(3):
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palette_rgb[pixels_nbit, phase, i] = screen.palette.RGB[pixels_nbit, phase][i] / 255
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cdef Dither cdither
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cdither.y_shape = dither.PATTERN.shape[0]
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cdither.x_shape = dither.PATTERN.shape[1]
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cdither.y_origin = dither.ORIGIN[0]
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cdither.x_origin = dither.ORIGIN[1]
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# TODO: should be just as efficient to use a memoryview?
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cdither.pattern = <float *> malloc(cdither.x_shape * cdither.y_shape * sizeof(float))
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for i in range(cdither.y_shape):
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for j in range(cdither.x_shape):
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cdither.pattern[i * cdither.x_shape + j] = dither.PATTERN[i, j]
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cdef unsigned char palette_depth = screen.palette.PALETTE_DEPTH
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# The nbit image representation contains the trailing n dot values as an n-bit value with MSB representing the
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# current pixel. This choice (cf LSB) is slightly awkward but matches the DHGR behaviour that bit positions in
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# screen memory map LSB to MSB from L to R. The value of n is chosen by the palette depth, i.e. how many trailing
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# dot positions are used to determine the colour of a given pixel.
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cdef (unsigned char)[:, ::1] image_nbit = np.empty((image_rgb.shape[0], image_rgb.shape[1]), dtype=np.uint8)
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for y in range(yres):
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if verbose:
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print("%d/%d" % (y, yres))
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output_pixel_nbit = 0
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for x in range(xres):
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# Compute all possible 2**N choices of n-bit pixel colours for positions x .. x + lookahead
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# lookahead_palette_choices_nbit = lookahead_options(lookahead, output_pixel_nbit)
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# Apply error diffusion for each of these 2**N choices, and compute which produces the closest match
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# to the source image over the succeeding N pixels
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best_next_pixels = dither_lookahead(
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&cdither, palette_cam16, palette_rgb, image_rgb, x, y, lookahead, output_pixel_nbit, xres,
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rgb_to_cam16ucs, palette_depth)
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# Apply best choice for next 1 pixel
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output_pixel_nbit = shift_pixel_window(
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output_pixel_nbit, best_next_pixels, shift_right_by=1, window_width=palette_depth)
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# Apply error diffusion from chosen output pixel value
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for i in range(3):
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output_pixel_rgb[i] = palette_rgb[output_pixel_nbit, x % 4, i]
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quant_error[i] = image_rgb[y,x,i] - output_pixel_rgb[i]
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apply(&cdither, xres, yres, x, y, image_rgb, quant_error)
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# Update image with our chosen image pixel
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image_nbit[y, x] = output_pixel_nbit
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for i in range(3):
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image_rgb[y, x, i] = output_pixel_rgb[i]
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free(cdither.pattern)
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return image_nbit_to_bitmap(image_nbit, xres, yres, palette_depth)
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import colour
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@cython.boundscheck(False)
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@cython.wraparound(False)
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def dither_shr(float[:, :, ::1] input_rgb, float[:, :, ::1] palettes_cam, float[:, :, ::1] palettes_rgb, float[:,::1] rgb_to_cam16ucs, float penalty):
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cdef int y, x, idx, best_colour_idx, best_palette
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cdef double best_distance, distance, total_image_error
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cdef float[::1] best_colour_rgb, pixel_cam, colour_rgb, colour_cam
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cdef float quant_error
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cdef float[:, ::1] palette_rgb
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cdef (unsigned char)[:, ::1] output_4bit = np.zeros((200, 320), dtype=np.uint8)
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cdef float[:, :, ::1] working_image = np.copy(input_rgb)
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cdef float[:, ::1] line_cam = np.zeros((320, 3), dtype=np.float32)
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cdef int[::1] line_to_palette = np.zeros(200, dtype=np.int32)
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best_palette = 15
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total_image_error = 0.0
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for y in range(200):
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# print(y)
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for x in range(320):
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colour_cam = convert_rgb_to_cam16ucs(
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rgb_to_cam16ucs, working_image[y,x,0], working_image[y,x,1], working_image[y,x,2])
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line_cam[x, :] = colour_cam
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best_palette = best_palette_for_line(line_cam, palettes_cam, <int>(y * 16 / 200), best_palette, penalty)
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# print("-->", best_palette)
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palette_rgb = palettes_rgb[best_palette, :, :]
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line_to_palette[y] = best_palette
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for x in range(320):
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pixel_cam = convert_rgb_to_cam16ucs(
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rgb_to_cam16ucs, working_image[y, x, 0], working_image[y, x, 1], working_image[y, x, 2])
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best_distance = 1e9
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best_colour_idx = -1
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for idx in range(16):
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colour_rgb = palette_rgb[idx, :]
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colour_cam = convert_rgb_to_cam16ucs(rgb_to_cam16ucs, colour_rgb[0], colour_rgb[1], colour_rgb[2])
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distance = colour_distance_squared(pixel_cam, colour_cam)
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if distance < best_distance:
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best_distance = distance
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best_colour_idx = idx
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best_colour_rgb = palette_rgb[best_colour_idx]
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output_4bit[y, x] = best_colour_idx
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total_image_error += best_distance
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# print(y,x,best_distance,total_image_error)
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for i in range(3):
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quant_error = working_image[y, x, i] - best_colour_rgb[i]
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# Floyd-Steinberg dither
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# 0 * 7
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# 3 5 1
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working_image[y, x, i] = best_colour_rgb[i]
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if x < 319:
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working_image[y, x + 1, i] = clip(
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working_image[y, x + 1, i] + quant_error * (7 / 16), 0, 1)
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if y < 199:
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if x > 0:
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working_image[y + 1, x - 1, i] = clip(
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working_image[y + 1, x - 1, i] + quant_error * (3 / 32), 0, 1)
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working_image[y + 1, x, i] = clip(
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working_image[y + 1, x, i] + quant_error * (5 / 32), 0, 1)
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if x < 319:
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working_image[y + 1, x + 1, i] = clip(
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working_image[y + 1, x + 1, i] + quant_error * (1 / 32), 0, 1)
|
|
|
|
# # 0 0 X 7 5
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|
# # 3 5 7 5 3
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# # 1 3 5 3 1
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#if x < 319:
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# working_image[y, x + 1, i] = clip(
|
|
# working_image[y, x + 1, i] + quant_error * (7 / 48), 0, 1)
|
|
#if x < 318:
|
|
# working_image[y, x + 2, i] = clip(
|
|
# working_image[y, x + 2, i] + quant_error * (5 / 48), 0, 1)
|
|
#if y < 199:
|
|
# if x > 1:
|
|
# working_image[y + 1, x - 2, i] = clip(
|
|
# working_image[y + 1, x - 2, i] + quant_error * (3 / 48), 0,
|
|
# 1)
|
|
# if x > 0:
|
|
# working_image[y + 1, x - 1, i] = clip(
|
|
# working_image[y + 1, x - 1, i] + quant_error * (5 / 48), 0,
|
|
# 1)
|
|
# working_image[y + 1, x, i] = clip(
|
|
# working_image[y + 1, x, i] + quant_error * (7 / 48), 0, 1)
|
|
# if x < 319:
|
|
# working_image[y + 1, x + 1, i] = clip(
|
|
# working_image[y + 1, x + 1, i] + quant_error * (5 / 48),
|
|
# 0, 1)
|
|
# if x < 318:
|
|
# working_image[y + 1, x + 2, i] = clip(
|
|
# working_image[y + 1, x + 2, i] + quant_error * (3 / 48),
|
|
# 0, 1)
|
|
#if y < 198:
|
|
# if x > 1:
|
|
# working_image[y + 2, x - 2, i] = clip(
|
|
# working_image[y + 2, x - 2, i] + quant_error * (1 / 48), 0,
|
|
# 1)
|
|
# if x > 0:
|
|
# working_image[y + 2, x - 1, i] = clip(
|
|
# working_image[y + 2, x - 1, i] + quant_error * (3 / 48), 0,
|
|
# 1)
|
|
# working_image[y + 2, x, i] = clip(
|
|
# working_image[y + 2, x, i] + quant_error * (5 / 48), 0, 1)
|
|
# if x < 319:
|
|
# working_image[y + 2, x + 1, i] = clip(
|
|
# working_image[y + 2, x + 1, i] + quant_error * (3 / 48),
|
|
# 0, 1)
|
|
# if x < 318:
|
|
# working_image[y + 2, x + 2, i] = clip(
|
|
# working_image[y + 2, x + 2, i] + quant_error * (1 / 48),
|
|
# 0, 1)
|
|
|
|
return np.array(output_4bit, dtype=np.uint8), line_to_palette, total_image_error
|
|
|
|
import collections
|
|
import random
|
|
|
|
@cython.boundscheck(False)
|
|
@cython.wraparound(False)
|
|
def k_means_with_fixed_centroids(
|
|
int n_clusters, float[:, ::1] data, float[:, ::1] fixed_centroids = None,
|
|
int iterations = 10000, float tolerance = 1e-3):
|
|
cdef int i, iteration, centroid_idx, num_fixed_centroids, num_random_centroids, best_centroid_idx
|
|
cdef float[::1] point, centroid, new_centroid, old_centroid
|
|
cdef float[:, ::1] centroids
|
|
cdef float best_dist, centroid_movement, dist
|
|
|
|
centroids = np.zeros((n_clusters, 3), dtype=np.float32)
|
|
if fixed_centroids is not None:
|
|
centroids[:fixed_centroids.shape[0], :] = fixed_centroids
|
|
num_fixed_centroids = fixed_centroids.shape[0] if fixed_centroids is not None else 0
|
|
num_random_centroids = n_clusters - num_fixed_centroids
|
|
|
|
# TODO: kmeans++ initialization
|
|
cdef int rand_idx = random.randint(0, data.shape[0])
|
|
for i in range(num_random_centroids):
|
|
centroids[num_fixed_centroids + i, :] = data[rand_idx, :]
|
|
|
|
cdef int[::1] centroid_weights = np.zeros(n_clusters, dtype=np.int32)
|
|
for iteration in range(iterations):
|
|
# print("centroids ", centroids)
|
|
closest_points = collections.defaultdict(list)
|
|
for point in data:
|
|
best_dist = 1e9
|
|
best_centroid_idx = 0
|
|
for centroid_idx in range(n_clusters):
|
|
centroid = centroids[centroid_idx, :]
|
|
dist = colour_distance(centroid, point)
|
|
if dist < best_dist:
|
|
best_dist = dist
|
|
best_centroid_idx = centroid_idx
|
|
closest_points[best_centroid_idx].append(point)
|
|
|
|
centroid_movement = 0
|
|
for centroid_idx, points in closest_points.items():
|
|
centroid_weights[centroid_idx] = len(points)
|
|
if centroid_idx < num_fixed_centroids:
|
|
continue
|
|
new_centroid = np.median(np.array(points), axis=0)
|
|
old_centroid = centroids[centroid_idx]
|
|
centroid_movement += colour_distance(old_centroid, new_centroid)
|
|
centroids[centroid_idx, :] = new_centroid
|
|
# print("iteration %d: movement %f" % (iteration, centroid_movement))
|
|
if centroid_movement < tolerance:
|
|
break
|
|
|
|
weighted_centroids = list(zip(centroid_weights, [tuple(c) for c in centroids]))
|
|
print(weighted_centroids)
|
|
return np.array([c for w, c in sorted(weighted_centroids, reverse=True)], dtype=np.float32)
|
|
|
|
@cython.boundscheck(False)
|
|
@cython.wraparound(False)
|
|
cdef int best_palette_for_line(float [:, ::1] line_cam, float[:, :, ::1] palettes_cam, int base_palette_idx, int last_palette_idx, float last_penalty) nogil:
|
|
cdef int palette_idx, best_palette_idx, palette_entry_idx, pixel_idx
|
|
cdef double best_total_dist, total_dist, best_pixel_dist, pixel_dist
|
|
cdef float[:, ::1] palette_cam
|
|
cdef float[::1] pixel_cam, palette_entry
|
|
|
|
best_total_dist = 1e9
|
|
best_palette_idx = -1
|
|
cdef float penalty
|
|
cdef int line_size = line_cam.shape[0]
|
|
for palette_idx in range(16):
|
|
palette_cam = palettes_cam[palette_idx, :, :]
|
|
if palette_idx < (base_palette_idx - 1) or palette_idx > (base_palette_idx + 1):
|
|
continue
|
|
if palette_idx == last_palette_idx:
|
|
penalty = last_penalty
|
|
else:
|
|
penalty = 1.0
|
|
total_dist = 0
|
|
best_pixel_dist = 1e9
|
|
for pixel_idx in range(line_size):
|
|
pixel_cam = line_cam[pixel_idx]
|
|
for palette_entry_idx in range(16):
|
|
palette_entry = palette_cam[palette_entry_idx, :]
|
|
pixel_dist = colour_distance_squared(pixel_cam, palette_entry) * penalty
|
|
if pixel_dist < best_pixel_dist:
|
|
best_pixel_dist = pixel_dist
|
|
total_dist += best_pixel_dist
|
|
# print(total_dist)
|
|
if total_dist < best_total_dist:
|
|
best_total_dist = total_dist
|
|
best_palette_idx = palette_idx
|
|
return best_palette_idx
|
|
|