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325 lines
10 KiB
C
325 lines
10 KiB
C
/* pam.c - pam (portable alpha map) utility library
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**
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** Copyright (C) 1989, 1991 by Jef Poskanzer.
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** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by
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** Stefan Schneider.
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** © 2009-2013 by Kornel Lesinski.
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**
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** Permission to use, copy, modify, and distribute this software and its
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** documentation for any purpose and without fee is hereby granted, provided
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** that the above copyright notice appear in all copies and that both that
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** copyright notice and this permission notice appear in supporting
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** documentation. This software is provided "as is" without express or
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** implied warranty.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "libimagequant.h"
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#include "pam.h"
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#include "mempool.h"
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/* *INDENT-OFF* */
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LIQ_PRIVATE bool
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pam_computeacolorhash (struct acolorhash_table *acht,
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const rgba_pixel * const pixels[], unsigned int cols, unsigned int rows,
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const unsigned char *importance_map)
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/* *INDENT-ON* */
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{
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const unsigned int maxacolors = acht->maxcolors, ignorebits =
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acht->ignorebits;
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const unsigned int channel_mask = 255U >> ignorebits << ignorebits;
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const unsigned int channel_hmask = (255U >> ignorebits) ^ 0xFFU;
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const unsigned int posterize_mask =
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channel_mask << 24 | channel_mask << 16 | channel_mask << 8 |
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channel_mask;
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const unsigned int posterize_high_mask =
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channel_hmask << 24 | channel_hmask << 16 | channel_hmask << 8 |
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channel_hmask;
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struct acolorhist_arr_head *const buckets = acht->buckets;
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unsigned int colors = acht->colors;
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const unsigned int hash_size = acht->hash_size;
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const unsigned int stacksize =
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sizeof (acht->freestack) / sizeof (acht->freestack[0]);
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struct acolorhist_arr_item **freestack = acht->freestack;
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unsigned int freestackp = acht->freestackp;
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/* Go through the entire image, building a hash table of colors. */
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for (unsigned int row = 0; row < rows; ++row) {
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float boost = 1.0;
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for (unsigned int col = 0; col < cols; ++col) {
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union rgba_as_int px = { pixels[row][col] };
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unsigned int hash;
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struct acolorhist_arr_head *achl;
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if (importance_map) {
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boost = 0.5f + (double) *importance_map++ / 255.f;
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}
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// RGBA color is casted to long for easier hasing/comparisons
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if (!px.rgba.a) {
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// "dirty alpha" has different RGBA values that end up being the same fully transparent color
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px.l = 0;
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hash = 0;
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} else {
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// mask posterizes all 4 channels in one go
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px.l =
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(px.l & posterize_mask) | ((px.l & posterize_high_mask) >> (8 -
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ignorebits));
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// fancier hashing algorithms didn't improve much
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hash = px.l % hash_size;
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}
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/* head of the hash function stores first 2 colors inline (achl->used = 1..2),
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to reduce number of allocations of achl->other_items.
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*/
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achl = &buckets[hash];
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if (achl->inline1.color.l == px.l && achl->used) {
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achl->inline1.perceptual_weight += boost;
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continue;
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}
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if (achl->used) {
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if (achl->used > 1) {
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struct acolorhist_arr_item *other_items;
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unsigned int i = 0;
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struct acolorhist_arr_item *new_items;
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unsigned int capacity;
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if (achl->inline2.color.l == px.l) {
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achl->inline2.perceptual_weight += boost;
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continue;
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}
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// other items are stored as an array (which gets reallocated if needed)
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other_items = achl->other_items;
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for (i = 0; i < achl->used - 2; i++) {
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if (other_items[i].color.l == px.l) {
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other_items[i].perceptual_weight += boost;
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goto continue_outer_loop;
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}
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}
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// the array was allocated with spare items
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if (i < achl->capacity) {
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other_items[i] = (struct acolorhist_arr_item) {
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.color = px,.perceptual_weight = boost,
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};
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achl->used++;
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++colors;
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continue;
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}
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if (++colors > maxacolors) {
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acht->colors = colors;
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acht->freestackp = freestackp;
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return false;
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}
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if (!other_items) { // there was no array previously, alloc "small" array
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capacity = 8;
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if (freestackp <= 0) {
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// estimate how many colors are going to be + headroom
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const int mempool_size =
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((acht->rows + rows - row) * 2 * colors / (acht->rows + row +
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1) + 1024) * sizeof (struct acolorhist_arr_item);
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new_items =
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mempool_alloc (&acht->mempool,
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sizeof (struct acolorhist_arr_item) * capacity, mempool_size);
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} else {
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// freestack stores previously freed (reallocated) arrays that can be reused
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// (all pesimistically assumed to be capacity = 8)
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new_items = freestack[--freestackp];
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}
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} else {
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// simply reallocs and copies array to larger capacity
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capacity = achl->capacity * 2 + 16;
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if (freestackp < stacksize - 1) {
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freestack[freestackp++] = other_items;
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}
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{
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const int mempool_size =
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((acht->rows + rows - row) * 2 * colors / (acht->rows + row +
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1) + 32 * capacity) * sizeof (struct acolorhist_arr_item);
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new_items =
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mempool_alloc (&acht->mempool,
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sizeof (struct acolorhist_arr_item) * capacity, mempool_size);
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}
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if (!new_items)
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return false;
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memcpy (new_items, other_items,
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sizeof (other_items[0]) * achl->capacity);
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}
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achl->other_items = new_items;
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achl->capacity = capacity;
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new_items[i] = (struct acolorhist_arr_item) {
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.color = px,.perceptual_weight = boost,
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};
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achl->used++;
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} else {
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// these are elses for first checks whether first and second inline-stored colors are used
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achl->inline2.color.l = px.l;
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achl->inline2.perceptual_weight = boost;
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achl->used = 2;
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++colors;
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}
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} else {
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achl->inline1.color.l = px.l;
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achl->inline1.perceptual_weight = boost;
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achl->used = 1;
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++colors;
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}
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continue_outer_loop:;
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}
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}
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acht->colors = colors;
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acht->cols = cols;
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acht->rows += rows;
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acht->freestackp = freestackp;
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return true;
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}
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LIQ_PRIVATE struct acolorhash_table *
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pam_allocacolorhash (unsigned int maxcolors, unsigned int surface,
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unsigned int ignorebits, void *(*malloc) (size_t), void (*free) (void *))
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{
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const unsigned int estimated_colors =
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MIN (maxcolors, surface / (ignorebits + (surface > 512 * 512 ? 5 : 4)));
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const unsigned int hash_size =
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estimated_colors < 66000 ? 6673 : (estimated_colors <
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200000 ? 12011 : 24019);
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mempool m = NULL;
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const unsigned int buckets_size =
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hash_size * sizeof (struct acolorhist_arr_head);
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const unsigned int mempool_size =
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sizeof (struct acolorhash_table) + buckets_size +
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estimated_colors * sizeof (struct acolorhist_arr_item);
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struct acolorhash_table *t =
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mempool_create (&m, sizeof (*t) + buckets_size, mempool_size, malloc,
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free);
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if (!t)
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return NULL;
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*t = (struct acolorhash_table) {
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.mempool = m,.hash_size = hash_size,.maxcolors = maxcolors,.ignorebits =
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ignorebits,
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};
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memset (t->buckets, 0, hash_size * sizeof (struct acolorhist_arr_head));
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return t;
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}
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#define PAM_ADD_TO_HIST(entry) { \
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hist->achv[j].acolor = to_f(gamma_lut, entry.color.rgba); \
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total_weight += hist->achv[j].adjusted_weight = hist->achv[j].perceptual_weight = MIN(entry.perceptual_weight, max_perceptual_weight); \
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++j; \
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}
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LIQ_PRIVATE histogram *
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pam_acolorhashtoacolorhist (const struct acolorhash_table *acht,
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const double gamma, void *(*malloc) (size_t), void (*free) (void *))
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{
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histogram *hist = malloc (sizeof (hist[0]));
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float gamma_lut[256];
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float max_perceptual_weight;
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double total_weight;
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unsigned int i, j, k;
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if (!hist || !acht)
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return NULL;
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*hist = (histogram) {
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.achv = malloc (acht->colors * sizeof (hist->achv[0])),.size =
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acht->colors,.free = free,.ignorebits = acht->ignorebits,};
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if (!hist->achv)
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return NULL;
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to_f_set_gamma (gamma_lut, gamma);
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/* Limit perceptual weight to 1/10th of the image surface area to prevent
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a single color from dominating all others. */
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max_perceptual_weight = 0.1f * acht->cols * acht->rows;
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total_weight = 0;
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for (j = 0, i = 0; i < acht->hash_size; ++i) {
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const struct acolorhist_arr_head *const achl = &acht->buckets[i];
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if (achl->used) {
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PAM_ADD_TO_HIST (achl->inline1);
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if (achl->used > 1) {
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PAM_ADD_TO_HIST (achl->inline2);
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for (k = 0; k < achl->used - 2; k++) {
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PAM_ADD_TO_HIST (achl->other_items[k]);
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}
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}
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}
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}
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hist->total_perceptual_weight = total_weight;
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return hist;
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}
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LIQ_PRIVATE void
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pam_freeacolorhash (struct acolorhash_table *acht)
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{
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mempool_destroy (acht->mempool);
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}
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LIQ_PRIVATE void
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pam_freeacolorhist (histogram * hist)
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{
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hist->free (hist->achv);
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hist->free (hist);
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}
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LIQ_PRIVATE colormap *
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pam_colormap (unsigned int colors, void *(*malloc) (size_t),
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void (*free) (void *))
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{
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const size_t colors_size = colors * sizeof (colormap_item);
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colormap *map;
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assert (colors > 0 && colors < 65536);
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map = malloc (sizeof (colormap) + colors_size);
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if (!map)
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return NULL;
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*map = (colormap) {
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.malloc = malloc,.free = free,.subset_palette = NULL,.colors = colors,};
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memset (map->palette, 0, colors_size);
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return map;
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}
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LIQ_PRIVATE colormap *
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pam_duplicate_colormap (colormap * map)
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{
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colormap *dupe = pam_colormap (map->colors, map->malloc, map->free);
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for (unsigned int i = 0; i < map->colors; i++) {
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dupe->palette[i] = map->palette[i];
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}
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if (map->subset_palette) {
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dupe->subset_palette = pam_duplicate_colormap (map->subset_palette);
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}
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return dupe;
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}
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LIQ_PRIVATE void
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pam_freecolormap (colormap * c)
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{
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if (c->subset_palette)
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pam_freecolormap (c->subset_palette);
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c->free (c);
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}
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LIQ_PRIVATE void
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to_f_set_gamma (float gamma_lut[], const double gamma)
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{
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for (int i = 0; i < 256; i++) {
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gamma_lut[i] = pow ((double) i / 255.0, internal_gamma / gamma);
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}
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}
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