/* pngquant.c - quantize the colors in an alphamap down to a specified number ** ** Copyright (C) 1989, 1991 by Jef Poskanzer. ** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by ** Stefan Schneider. ** © 2009-2013 by Kornel Lesinski. ** ** Permission to use, copy, modify, and distribute this software and its ** documentation for any purpose and without fee is hereby granted, provided ** that the above copyright notice appear in all copies and that both that ** copyright notice and this permission notice appear in supporting ** documentation. This software is provided "as is" without express or ** implied warranty. */ #include #include #include #include #include #include #include #if !(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199900L) && !(defined(_MSC_VER) && _MSC_VER >= 1800) #error "This program requires C99, e.g. -std=c99 switch in GCC or it requires MSVC 18.0 or higher." #error "Ignore torrent of syntax errors that may follow. It's only because compiler is set to use too old C version." #endif #ifdef _OPENMP #include #else #define omp_get_max_threads() 1 #define omp_get_thread_num() 0 #endif #include "libimagequant.h" #include "pam.h" #include "mediancut.h" #include "nearest.h" #include "blur.h" #include "viter.h" #define LIQ_HIGH_MEMORY_LIMIT (1<<26) /* avoid allocating buffers larger than 64MB */ // each structure has a pointer as a unique identifier that allows type checking at run time static const char *const liq_attr_magic = "liq_attr", *const liq_image_magic = "liq_image", *const liq_result_magic = "liq_result", *const liq_remapping_result_magic = "liq_remapping_result", *const liq_freed_magic = "free"; #define CHECK_STRUCT_TYPE(attr, kind) liq_crash_if_invalid_handle_pointer_given((const liq_attr*)attr, kind ## _magic) #define CHECK_USER_POINTER(ptr) liq_crash_if_invalid_pointer_given(ptr) struct liq_attr { const char *magic_header; void *(*malloc) (size_t); void (*free) (void *); double target_mse, max_mse, voronoi_iteration_limit; float min_opaque_val; unsigned int max_colors, max_histogram_entries; unsigned int min_posterization_output /* user setting */ , min_posterization_input /* speed setting */ ; unsigned int voronoi_iterations, feedback_loop_trials; bool last_index_transparent, use_contrast_maps, use_dither_map, fast_palette; unsigned int speed; liq_log_callback_function *log_callback; void *log_callback_user_info; liq_log_flush_callback_function *log_flush_callback; void *log_flush_callback_user_info; }; struct liq_image { const char *magic_header; void *(*malloc) (size_t); void (*free) (void *); f_pixel *f_pixels; rgba_pixel **rows; double gamma; unsigned int width, height; unsigned char *noise, *edges, *dither_map; rgba_pixel *pixels, *temp_row; f_pixel *temp_f_row; liq_image_get_rgba_row_callback *row_callback; void *row_callback_user_info; float min_opaque_val; f_pixel fixed_colors[256]; unsigned short fixed_colors_count; bool free_pixels, free_rows, free_rows_internal; }; typedef struct liq_remapping_result { const char *magic_header; void *(*malloc) (size_t); void (*free) (void *); unsigned char *pixels; colormap *palette; liq_palette int_palette; double gamma, palette_error; float dither_level; bool use_dither_map; } liq_remapping_result; struct liq_result { const char *magic_header; void *(*malloc) (size_t); void (*free) (void *); liq_remapping_result *remapping; colormap *palette; liq_palette int_palette; float dither_level; double gamma, palette_error; int min_posterization_output; bool use_dither_map, fast_palette; }; static liq_result *pngquant_quantize (histogram * hist, const liq_attr * options, const liq_image * img); static void modify_alpha (liq_image * input_image, rgba_pixel * const row_pixels); static void contrast_maps (liq_image * image); static histogram *get_histogram (liq_image * input_image, const liq_attr * options); static const rgba_pixel *liq_image_get_row_rgba (liq_image * input_image, unsigned int row); static const f_pixel *liq_image_get_row_f (liq_image * input_image, unsigned int row); static void liq_remapping_result_destroy (liq_remapping_result * result); static void liq_verbose_printf (const liq_attr * context, const char *fmt, ...) { if (context->log_callback) { va_list va; int required_space; char *buf; va_start (va, fmt); required_space = vsnprintf (NULL, 0, fmt, va) + 1; // +\0 va_end (va); buf = g_alloca (required_space); va_start (va, fmt); vsnprintf (buf, required_space, fmt, va); va_end (va); context->log_callback (context, buf, context->log_callback_user_info); } } inline static void verbose_print (const liq_attr * attr, const char *msg) { if (attr->log_callback) { attr->log_callback (attr, msg, attr->log_callback_user_info); } } static void liq_verbose_printf_flush (liq_attr * attr) { if (attr->log_flush_callback) { attr->log_flush_callback (attr, attr->log_flush_callback_user_info); } } #if USE_SSE inline static bool is_sse_available (void) { #if (defined(__x86_64__) || defined(__amd64)) return true; #else int a, b, c, d; cpuid (1, a, b, c, d); return d & (1 << 25); // edx bit 25 is set when SSE is present #endif } #endif /* make it clear in backtrace when user-supplied handle points to invalid memory */ NEVER_INLINE LIQ_EXPORT bool liq_crash_if_invalid_handle_pointer_given (const liq_attr * user_supplied_pointer, const char *const expected_magic_header); LIQ_EXPORT bool liq_crash_if_invalid_handle_pointer_given (const liq_attr * user_supplied_pointer, const char *const expected_magic_header) { if (!user_supplied_pointer) { return false; } if (user_supplied_pointer->magic_header == liq_freed_magic) { fprintf (stderr, "%s used after being freed", expected_magic_header); // this is not normal error handling, this is programmer error that should crash the program. // program cannot safely continue if memory has been used after it's been freed. // abort() is nasty, but security vulnerability may be worse. abort (); } return user_supplied_pointer->magic_header == expected_magic_header; } NEVER_INLINE LIQ_EXPORT bool liq_crash_if_invalid_pointer_given (void *pointer); LIQ_EXPORT bool liq_crash_if_invalid_pointer_given (void *pointer) { char test_access; if (!pointer) { return false; } // Force a read from the given (potentially invalid) memory location in order to check early whether this crashes the program or not. // It doesn't matter what value is read, the code here is just to shut the compiler up about unused read. test_access = *((volatile char *) pointer); return test_access || true; } static void liq_log_error (const liq_attr * attr, const char *msg) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return; liq_verbose_printf (attr, " error: %s", msg); } static double quality_to_mse (long quality) { const double extra_low_quality_fudge = MAX (0, 0.016 / (0.001 + quality) - 0.001); if (quality == 0) { return MAX_DIFF; } if (quality == 100) { return 0; } // curve fudged to be roughly similar to quality of libjpeg // except lowest 10 for really low number of colors return extra_low_quality_fudge + 2.5 / pow (210.0 + quality, 1.2) * (100.1 - quality) / 100.0; } static unsigned int mse_to_quality (double mse) { int i; for (i = 100; i > 0; i--) { if (mse <= quality_to_mse (i) + 0.000001) { // + epsilon for floating point errors return i; } } return 0; } LIQ_EXPORT liq_error liq_set_quality (liq_attr * attr, int minimum, int target) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return LIQ_INVALID_POINTER; if (target < 0 || target > 100 || target < minimum || minimum < 0) return LIQ_VALUE_OUT_OF_RANGE; attr->target_mse = quality_to_mse (target); attr->max_mse = quality_to_mse (minimum); return LIQ_OK; } LIQ_EXPORT int liq_get_min_quality (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return mse_to_quality (attr->max_mse); } LIQ_EXPORT int liq_get_max_quality (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return mse_to_quality (attr->target_mse); } LIQ_EXPORT liq_error liq_set_max_colors (liq_attr * attr, int colors) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return LIQ_INVALID_POINTER; if (colors < 2 || colors > 256) return LIQ_VALUE_OUT_OF_RANGE; attr->max_colors = colors; return LIQ_OK; } LIQ_EXPORT int liq_get_max_colors (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return attr->max_colors; } LIQ_EXPORT liq_error liq_set_min_posterization (liq_attr * attr, int bits) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return LIQ_INVALID_POINTER; if (bits < 0 || bits > 4) return LIQ_VALUE_OUT_OF_RANGE; attr->min_posterization_output = bits; return LIQ_OK; } LIQ_EXPORT int liq_get_min_posterization (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return attr->min_posterization_output; } LIQ_EXPORT liq_error liq_set_speed (liq_attr * attr, int speed) { int iterations; if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return LIQ_INVALID_POINTER; if (speed < 1 || speed > 10) return LIQ_VALUE_OUT_OF_RANGE; iterations = MAX (8 - speed, 0); iterations += iterations * iterations / 2; attr->voronoi_iterations = iterations; attr->voronoi_iteration_limit = 1.0 / (double) (1 << (23 - speed)); attr->feedback_loop_trials = MAX (56 - 9 * speed, 0); attr->max_histogram_entries = (1 << 17) + (1 << 18) * (10 - speed); attr->min_posterization_input = (speed >= 8) ? 1 : 0; attr->fast_palette = (speed >= 7); attr->use_dither_map = (speed <= (omp_get_max_threads () > 1 ? 7 : 5)); // parallelized dither map might speed up floyd remapping attr->use_contrast_maps = (speed <= 7) || attr->use_dither_map; attr->speed = speed; return LIQ_OK; } LIQ_EXPORT int liq_get_speed (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return attr->speed; } LIQ_EXPORT liq_error liq_set_output_gamma (liq_result * res, double gamma) { if (!CHECK_STRUCT_TYPE (res, liq_result)) return LIQ_INVALID_POINTER; if (gamma <= 0 || gamma >= 1.0) return LIQ_VALUE_OUT_OF_RANGE; if (res->remapping) { liq_remapping_result_destroy (res->remapping); res->remapping = NULL; } res->gamma = gamma; return LIQ_OK; } LIQ_EXPORT liq_error liq_set_min_opacity (liq_attr * attr, int min) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return LIQ_INVALID_POINTER; if (min < 0 || min > 255) return LIQ_VALUE_OUT_OF_RANGE; attr->min_opaque_val = (double) min / 255.0; return LIQ_OK; } LIQ_EXPORT int liq_get_min_opacity (const liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return -1; return MIN (255, 256.0 * attr->min_opaque_val); } LIQ_EXPORT void liq_set_last_index_transparent (liq_attr * attr, int is_last) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return; attr->last_index_transparent = !!is_last; } LIQ_EXPORT void liq_set_log_callback (liq_attr * attr, liq_log_callback_function * callback, void *user_info) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return; liq_verbose_printf_flush (attr); attr->log_callback = callback; attr->log_callback_user_info = user_info; } LIQ_EXPORT void liq_set_log_flush_callback (liq_attr * attr, liq_log_flush_callback_function * callback, void *user_info) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return; attr->log_flush_callback = callback; attr->log_flush_callback_user_info = user_info; } LIQ_EXPORT liq_attr * liq_attr_create (void) { return liq_attr_create_with_allocator (NULL, NULL); } LIQ_EXPORT void liq_attr_destroy (liq_attr * attr) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) { return; } liq_verbose_printf_flush (attr); attr->magic_header = liq_freed_magic; attr->free (attr); } LIQ_EXPORT liq_attr * liq_attr_copy (liq_attr * orig) { liq_attr *attr; if (!CHECK_STRUCT_TYPE (orig, liq_attr)) { return NULL; } attr = orig->malloc (sizeof (liq_attr)); if (!attr) return NULL; *attr = *orig; return attr; } static void * liq_aligned_malloc (size_t size) { unsigned char *ptr = malloc (size + 16); uintptr_t offset; if (!ptr) { return NULL; } offset = 16 - ((uintptr_t) ptr & 15); // also reserves 1 byte for ptr[-1] ptr += offset; assert (0 == (((uintptr_t) ptr) & 15)); ptr[-1] = offset ^ 0x59; // store how much pointer was shifted to get the original for free() return ptr; } static void liq_aligned_free (void *inptr) { unsigned char *ptr = inptr; size_t offset = ptr[-1] ^ 0x59; assert (offset > 0 && offset <= 16); free (ptr - offset); } LIQ_EXPORT liq_attr * liq_attr_create_with_allocator (void *(*custom_malloc) (size_t), void (*custom_free) (void *)) { liq_attr *attr; #if USE_SSE if (!is_sse_available ()) { return NULL; } #endif if (!custom_malloc && !custom_free) { custom_malloc = liq_aligned_malloc; custom_free = liq_aligned_free; } else if (!custom_malloc != !custom_free) { return NULL; // either specify both or none } attr = custom_malloc (sizeof (liq_attr)); if (!attr) return NULL; *attr = (liq_attr) { .magic_header = liq_attr_magic,.malloc = custom_malloc,.free = custom_free,.max_colors = 256,.min_opaque_val = 1, // whether preserve opaque colors for IE (1.0=no, does not affect alpha) .last_index_transparent = false, // puts transparent color at last index. This is workaround for blu-ray subtitles. .target_mse = 0,.max_mse = MAX_DIFF,}; liq_set_speed (attr, 3); return attr; } LIQ_EXPORT liq_error liq_image_add_fixed_color (liq_image * img, liq_color color) { float gamma_lut[256]; rgba_pixel pix = (rgba_pixel) { .r = color.r, .g = color.g, .b = color.b, .a = color.a }; if (!CHECK_STRUCT_TYPE (img, liq_image)) return LIQ_INVALID_POINTER; if (img->fixed_colors_count > 255) return LIQ_BUFFER_TOO_SMALL; to_f_set_gamma (gamma_lut, img->gamma); img->fixed_colors[img->fixed_colors_count++] = to_f (gamma_lut, pix); return LIQ_OK; } static bool liq_image_use_low_memory (liq_image * img) { img->temp_f_row = img->malloc (sizeof (img->f_pixels[0]) * img->width * omp_get_max_threads ()); return img->temp_f_row != NULL; } static bool liq_image_should_use_low_memory (liq_image * img, const bool low_memory_hint) { return img->width * img->height > (low_memory_hint ? LIQ_HIGH_MEMORY_LIMIT / 8 : LIQ_HIGH_MEMORY_LIMIT) / sizeof (f_pixel); // Watch out for integer overflow } static liq_image * liq_image_create_internal (liq_attr * attr, rgba_pixel * rows[], liq_image_get_rgba_row_callback * row_callback, void *row_callback_user_info, int width, int height, double gamma) { liq_image *img; if (gamma < 0 || gamma > 1.0) { liq_log_error (attr, "gamma must be >= 0 and <= 1 (try 1/gamma instead)"); return NULL; } if (!rows && !row_callback) { liq_log_error (attr, "missing row data"); return NULL; } img = attr->malloc (sizeof (liq_image)); if (!img) return NULL; *img = (liq_image) { .magic_header = liq_image_magic,.malloc = attr->malloc,.free = attr->free,.width = width,.height = height,.gamma = gamma ? gamma : 0.45455,.rows = rows,.row_callback = row_callback,.row_callback_user_info = row_callback_user_info,.min_opaque_val = attr->min_opaque_val,}; if (!rows || attr->min_opaque_val < 1.f) { img->temp_row = attr->malloc (sizeof (img->temp_row[0]) * width * omp_get_max_threads ()); if (!img->temp_row) return NULL; } // if image is huge or converted pixels are not likely to be reused then don't cache converted pixels if (liq_image_should_use_low_memory (img, !img->temp_row && !attr->use_contrast_maps && !attr->use_dither_map)) { verbose_print (attr, " conserving memory"); if (!liq_image_use_low_memory (img)) return NULL; } if (img->min_opaque_val < 1.f) { verbose_print (attr, " Working around IE6 bug by making image less transparent..."); } return img; } LIQ_EXPORT liq_error liq_image_set_memory_ownership (liq_image * img, int ownership_flags) { if (!CHECK_STRUCT_TYPE (img, liq_image)) return LIQ_INVALID_POINTER; if (!img->rows || !ownership_flags || (ownership_flags & ~(LIQ_OWN_ROWS | LIQ_OWN_PIXELS))) { return LIQ_VALUE_OUT_OF_RANGE; } if (ownership_flags & LIQ_OWN_ROWS) { if (img->free_rows_internal) return LIQ_VALUE_OUT_OF_RANGE; img->free_rows = true; } if (ownership_flags & LIQ_OWN_PIXELS) { img->free_pixels = true; if (!img->pixels) { // for simplicity of this API there's no explicit bitmap argument, // so the row with the lowest address is assumed to be at the start of the bitmap img->pixels = img->rows[0]; for (unsigned int i = 1; i < img->height; i++) { img->pixels = MIN (img->pixels, img->rows[i]); } } } return LIQ_OK; } static bool check_image_size (const liq_attr * attr, const int width, const int height) { if (!CHECK_STRUCT_TYPE (attr, liq_attr)) { return false; } if (width <= 0 || height <= 0) { liq_log_error (attr, "width and height must be > 0"); return false; } if (width > INT_MAX / height) { liq_log_error (attr, "image too large"); return false; } return true; } LIQ_EXPORT liq_image * liq_image_create_custom (liq_attr * attr, liq_image_get_rgba_row_callback * row_callback, void *user_info, int width, int height, double gamma) { if (!check_image_size (attr, width, height)) { return NULL; } return liq_image_create_internal (attr, NULL, row_callback, user_info, width, height, gamma); } LIQ_EXPORT liq_image * liq_image_create_rgba_rows (liq_attr * attr, void *rows[], int width, int height, double gamma) { if (!check_image_size (attr, width, height)) { return NULL; } for (int i = 0; i < height; i++) { if (!CHECK_USER_POINTER (rows + i) || !CHECK_USER_POINTER (rows[i])) { liq_log_error (attr, "invalid row pointers"); return NULL; } } return liq_image_create_internal (attr, (rgba_pixel **) rows, NULL, NULL, width, height, gamma); } LIQ_EXPORT liq_image * liq_image_create_rgba (liq_attr * attr, void *bitmap, int width, int height, double gamma) { rgba_pixel *pixels; rgba_pixel **rows; liq_image *image; if (!check_image_size (attr, width, height)) { return NULL; } if (!CHECK_USER_POINTER (bitmap)) { liq_log_error (attr, "invalid bitmap pointer"); return NULL; } pixels = bitmap; rows = attr->malloc (sizeof (rows[0]) * height); if (!rows) return NULL; for (int i = 0; i < height; i++) { rows[i] = pixels + width * i; } image = liq_image_create_internal (attr, rows, NULL, NULL, width, height, gamma); image->free_rows = true; image->free_rows_internal = true; return image; } NEVER_INLINE LIQ_EXPORT void liq_executing_user_callback (liq_image_get_rgba_row_callback * callback, liq_color * temp_row, int row, int width, void *user_info); LIQ_EXPORT void liq_executing_user_callback (liq_image_get_rgba_row_callback * callback, liq_color * temp_row, int row, int width, void *user_info) { assert (callback); assert (temp_row); callback (temp_row, row, width, user_info); } inline static bool liq_image_can_use_rows (liq_image * img) { const bool iebug = img->min_opaque_val < 1.f; return (img->rows && !iebug); } static const rgba_pixel * liq_image_get_row_rgba (liq_image * img, unsigned int row) { rgba_pixel *temp_row; if (liq_image_can_use_rows (img)) { return img->rows[row]; } assert (img->temp_row); temp_row = img->temp_row + img->width * omp_get_thread_num (); if (img->rows) { memcpy (temp_row, img->rows[row], img->width * sizeof (temp_row[0])); } else { liq_executing_user_callback (img->row_callback, (liq_color *) temp_row, row, img->width, img->row_callback_user_info); } if (img->min_opaque_val < 1.f) modify_alpha (img, temp_row); return temp_row; } static void convert_row_to_f (liq_image * img, f_pixel * row_f_pixels, const unsigned int row, const float gamma_lut[]) { assert (row_f_pixels); assert (!USE_SSE || 0 == ((uintptr_t) row_f_pixels & 15)); { const rgba_pixel *const row_pixels = liq_image_get_row_rgba (img, row); unsigned int col; for (col = 0; col < img->width; col++) { row_f_pixels[col] = to_f (gamma_lut, row_pixels[col]); } } } static const f_pixel * liq_image_get_row_f (liq_image * img, unsigned int row) { if (!img->f_pixels) { if (img->temp_f_row) { float gamma_lut[256]; f_pixel *row_for_thread; to_f_set_gamma (gamma_lut, img->gamma); row_for_thread = img->temp_f_row + img->width * omp_get_thread_num (); convert_row_to_f (img, row_for_thread, row, gamma_lut); return row_for_thread; } assert (omp_get_thread_num () == 0); if (!liq_image_should_use_low_memory (img, false)) { img->f_pixels = img->malloc (sizeof (img->f_pixels[0]) * img->width * img->height); } if (!img->f_pixels) { if (!liq_image_use_low_memory (img)) return NULL; return liq_image_get_row_f (img, row); } { float gamma_lut[256]; to_f_set_gamma (gamma_lut, img->gamma); for (unsigned int i = 0; i < img->height; i++) { convert_row_to_f (img, &img->f_pixels[i * img->width], i, gamma_lut); } } } return img->f_pixels + img->width * row; } LIQ_EXPORT int liq_image_get_width (const liq_image * input_image) { if (!CHECK_STRUCT_TYPE (input_image, liq_image)) return -1; return input_image->width; } LIQ_EXPORT int liq_image_get_height (const liq_image * input_image) { if (!CHECK_STRUCT_TYPE (input_image, liq_image)) return -1; return input_image->height; } typedef void free_func (void *); static free_func * get_default_free_func (liq_image * img) { // When default allocator is used then user-supplied pointers must be freed with free() if (img->free_rows_internal || img->free != liq_aligned_free) { return img->free; } return free; } static void liq_image_free_rgba_source (liq_image * input_image) { if (input_image->free_pixels && input_image->pixels) { get_default_free_func (input_image) (input_image->pixels); input_image->pixels = NULL; } if (input_image->free_rows && input_image->rows) { get_default_free_func (input_image) (input_image->rows); input_image->rows = NULL; } } LIQ_EXPORT void liq_image_destroy (liq_image * input_image) { if (!CHECK_STRUCT_TYPE (input_image, liq_image)) return; liq_image_free_rgba_source (input_image); if (input_image->noise) { input_image->free (input_image->noise); } if (input_image->edges) { input_image->free (input_image->edges); } if (input_image->dither_map) { input_image->free (input_image->dither_map); } if (input_image->f_pixels) { input_image->free (input_image->f_pixels); } if (input_image->temp_row) { input_image->free (input_image->temp_row); } if (input_image->temp_f_row) { input_image->free (input_image->temp_f_row); } input_image->magic_header = liq_freed_magic; input_image->free (input_image); } LIQ_EXPORT liq_result * liq_quantize_image (liq_attr * attr, liq_image * img) { histogram *hist; liq_result *result; if (!CHECK_STRUCT_TYPE (attr, liq_attr)) return NULL; if (!CHECK_STRUCT_TYPE (img, liq_image)) { liq_log_error (attr, "invalid image pointer"); return NULL; } hist = get_histogram (img, attr); if (!hist) { return NULL; } result = pngquant_quantize (hist, attr, img); pam_freeacolorhist (hist); return result; } LIQ_EXPORT liq_error liq_set_dithering_level (liq_result * res, float dither_level) { if (!CHECK_STRUCT_TYPE (res, liq_result)) return LIQ_INVALID_POINTER; if (res->remapping) { liq_remapping_result_destroy (res->remapping); res->remapping = NULL; } if (res->dither_level < 0 || res->dither_level > 1.0f) return LIQ_VALUE_OUT_OF_RANGE; res->dither_level = dither_level; return LIQ_OK; } static liq_remapping_result * liq_remapping_result_create (liq_result * result) { liq_remapping_result *res; if (!CHECK_STRUCT_TYPE (result, liq_result)) { return NULL; } res = result->malloc (sizeof (liq_remapping_result)); if (!res) return NULL; *res = (liq_remapping_result) { .magic_header = liq_remapping_result_magic,.malloc = result->malloc,.free = result->free,.dither_level = result->dither_level,.use_dither_map = result->use_dither_map,.palette_error = result->palette_error,.gamma = result->gamma,.palette = pam_duplicate_colormap (result->palette),}; return res; } LIQ_EXPORT double liq_get_output_gamma (const liq_result * result) { if (!CHECK_STRUCT_TYPE (result, liq_result)) return -1; return result->gamma; } static void liq_remapping_result_destroy (liq_remapping_result * result) { if (!CHECK_STRUCT_TYPE (result, liq_remapping_result)) return; if (result->palette) pam_freecolormap (result->palette); if (result->pixels) result->free (result->pixels); result->magic_header = liq_freed_magic; result->free (result); } LIQ_EXPORT void liq_result_destroy (liq_result * res) { if (!CHECK_STRUCT_TYPE (res, liq_result)) return; memset (&res->int_palette, 0, sizeof (liq_palette)); if (res->remapping) { memset (&res->remapping->int_palette, 0, sizeof (liq_palette)); liq_remapping_result_destroy (res->remapping); } pam_freecolormap (res->palette); res->magic_header = liq_freed_magic; res->free (res); } LIQ_EXPORT double liq_get_quantization_error (liq_result * result) { if (!CHECK_STRUCT_TYPE (result, liq_result)) return -1; if (result->palette_error >= 0) { return result->palette_error * 65536.0 / 6.0; } if (result->remapping && result->remapping->palette_error >= 0) { return result->remapping->palette_error * 65536.0 / 6.0; } return result->palette_error; } LIQ_EXPORT int liq_get_quantization_quality (liq_result * result) { if (!CHECK_STRUCT_TYPE (result, liq_result)) return -1; if (result->palette_error >= 0) { return mse_to_quality (result->palette_error); } if (result->remapping && result->remapping->palette_error >= 0) { return mse_to_quality (result->remapping->palette_error); } return result->palette_error; } static int compare_popularity (const void *ch1, const void *ch2) { const float v1 = ((const colormap_item *) ch1)->popularity; const float v2 = ((const colormap_item *) ch2)->popularity; return v1 > v2 ? -1 : 1; } static void sort_palette_qsort (colormap * map, int start, int nelem) { qsort (map->palette + start, nelem, sizeof (map->palette[0]), compare_popularity); } #define SWAP_PALETTE(map, a,b) { \ const colormap_item tmp = (map)->palette[(a)]; \ (map)->palette[(a)] = (map)->palette[(b)]; \ (map)->palette[(b)] = tmp; } static void sort_palette (colormap * map, const liq_attr * options) { unsigned int i; unsigned int num_transparent; /* ** Step 3.5 [GRR]: remap the palette colors so that all entries with ** the maximal alpha value (i.e., fully opaque) are at the end and can ** therefore be omitted from the tRNS chunk. */ if (options->last_index_transparent) { for (i = 0; i < map->colors; i++) { if (map->palette[i].acolor.a < 1.0 / 256.0) { const unsigned int old = i, transparent_dest = map->colors - 1; SWAP_PALETTE (map, transparent_dest, old); /* colors sorted by popularity make pngs slightly more compressible */ sort_palette_qsort (map, 0, map->colors - 1); return; } } } /* move transparent colors to the beginning to shrink trns chunk */ num_transparent = 0; for (i = 0; i < map->colors; i++) { if (map->palette[i].acolor.a < 255.0 / 256.0) { // current transparent color is swapped with earlier opaque one if (i != num_transparent) { SWAP_PALETTE (map, num_transparent, i); i--; } num_transparent++; } } liq_verbose_printf (options, " eliminated opaque tRNS-chunk entries...%d entr%s transparent", num_transparent, (num_transparent == 1) ? "y" : "ies"); /* colors sorted by popularity make pngs slightly more compressible * opaque and transparent are sorted separately */ sort_palette_qsort (map, 0, num_transparent); sort_palette_qsort (map, num_transparent, map->colors - num_transparent); if (map->colors > 16) { SWAP_PALETTE (map, 7, 1); // slightly improves compression SWAP_PALETTE (map, 8, 2); SWAP_PALETTE (map, 9, 3); } } inline static unsigned int posterize_channel (unsigned int color, unsigned int bits) { return (color & ~((1 << bits) - 1)) | (color >> (8 - bits)); } static void set_rounded_palette (liq_palette * const dest, colormap * const map, const double gamma, unsigned int posterize) { float gamma_lut[256]; to_f_set_gamma (gamma_lut, gamma); dest->count = map->colors; for (unsigned int x = 0; x < map->colors; ++x) { rgba_pixel px = to_rgb (gamma, map->palette[x].acolor); px.r = posterize_channel (px.r, posterize); px.g = posterize_channel (px.g, posterize); px.b = posterize_channel (px.b, posterize); px.a = posterize_channel (px.a, posterize); map->palette[x].acolor = to_f (gamma_lut, px); /* saves rounding error introduced by to_rgb, which makes remapping & dithering more accurate */ if (!px.a) { px.r = 'L'; px.g = 'i'; px.b = 'q'; } dest->entries[x] = (liq_color) { .r = px.r,.g = px.g,.b = px.b,.a = px.a}; } } LIQ_EXPORT const liq_palette * liq_get_palette (liq_result * result) { if (!CHECK_STRUCT_TYPE (result, liq_result)) return NULL; if (result->remapping && result->remapping->int_palette.count) { return &result->remapping->int_palette; } if (!result->int_palette.count) { set_rounded_palette (&result->int_palette, result->palette, result->gamma, result->min_posterization_output); } return &result->int_palette; } #define MAX_THREADS 8 static float remap_to_palette (liq_image * const input_image, unsigned char *const *const output_pixels, colormap * const map, const bool fast) { const int rows = input_image->height; const unsigned int cols = input_image->width; const float min_opaque_val = input_image->min_opaque_val; double remapping_error = 0; if (!liq_image_get_row_f (input_image, 0)) { // trigger lazy conversion return -1; } { struct nearest_map *const n = nearest_init (map, fast); const unsigned int max_threads = MIN (MAX_THREADS, omp_get_max_threads ()); viter_state *average_color = g_alloca (sizeof (viter_state) * (VITER_CACHE_LINE_GAP + map->colors) * MAX_THREADS); unsigned int row, col; viter_init (map, max_threads, average_color); #pragma omp parallel for if (rows*cols > 3000) \ schedule(static) default(none) shared(average_color) reduction(+:remapping_error) for (row = 0; row < rows; ++row) { const f_pixel *const row_pixels = liq_image_get_row_f (input_image, row); unsigned int last_match = 0; for (col = 0; col < cols; ++col) { f_pixel px = row_pixels[col]; float diff; output_pixels[row][col] = last_match = nearest_search (n, px, last_match, min_opaque_val, &diff); remapping_error += diff; viter_update_color (px, 1.0, map, last_match, omp_get_thread_num (), average_color); } } viter_finalize (map, max_threads, average_color); nearest_free (n); } return remapping_error / (input_image->width * input_image->height); } inline static f_pixel get_dithered_pixel (const float dither_level, const float max_dither_error, const f_pixel thiserr, const f_pixel px) { /* Use Floyd-Steinberg errors to adjust actual color. */ const float sr = thiserr.r * dither_level, sg = thiserr.g * dither_level, sb = thiserr.b * dither_level, sa = thiserr.a * dither_level; float a; float ratio = 1.0; float dither_error; // allowing some overflow prevents undithered bands caused by clamping of all channels if (px.r + sr > 1.03) ratio = MIN (ratio, (1.03 - px.r) / sr); else if (px.r + sr < 0) ratio = MIN (ratio, px.r / -sr); if (px.g + sg > 1.03) ratio = MIN (ratio, (1.03 - px.g) / sg); else if (px.g + sg < 0) ratio = MIN (ratio, px.g / -sg); if (px.b + sb > 1.03) ratio = MIN (ratio, (1.03 - px.b) / sb); else if (px.b + sb < 0) ratio = MIN (ratio, px.b / -sb); a = px.a + sa; if (a > 1.0) { a = 1.0; } else if (a < 0) { a = 0; } // If dithering error is crazy high, don't propagate it that much // This prevents crazy geen pixels popping out of the blue (or red or black! ;) dither_error = sr * sr + sg * sg + sb * sb + sa * sa; if (dither_error > max_dither_error) { ratio *= 0.8; } else if (dither_error < 2.f / 256.f / 256.f) { // don't dither areas that don't have noticeable error — makes file smaller return px; } return (f_pixel) { .r = px.r + sr * ratio,.g = px.g + sg * ratio,.b = px.b + sb * ratio,.a = a,}; } /** Uses edge/noise map to apply dithering only to flat areas. Dithering on edges creates jagged lines, and noisy areas are "naturally" dithered. If output_image_is_remapped is true, only pixels noticeably changed by error diffusion will be written to output image. */ static void remap_to_palette_floyd (liq_image * input_image, unsigned char *const output_pixels[], const colormap * map, const float max_dither_error, const bool use_dither_map, const bool output_image_is_remapped, float base_dithering_level) { const unsigned int rows = input_image->height, cols = input_image->width; const unsigned char *dither_map = use_dither_map ? (input_image-> dither_map ? input_image->dither_map : input_image->edges) : NULL; const float min_opaque_val = input_image->min_opaque_val; const colormap_item *acolormap = map->palette; struct nearest_map *const n = nearest_init (map, false); unsigned int col; /* Initialize Floyd-Steinberg error vectors. */ f_pixel *restrict thiserr, *restrict nexterr; thiserr = input_image->malloc ((cols + 2) * sizeof (*thiserr) * 2); // +2 saves from checking out of bounds access nexterr = thiserr + (cols + 2); srand (12345); /* deterministic dithering is better for comparing results */ if (!thiserr) return; for (col = 0; col < cols + 2; ++col) { const double rand_max = RAND_MAX; thiserr[col].r = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; thiserr[col].g = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; thiserr[col].b = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; thiserr[col].a = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; } // response to this value is non-linear and without it any value < 0.8 would give almost no dithering base_dithering_level = 1.0 - (1.0 - base_dithering_level) * (1.0 - base_dithering_level) * (1.0 - base_dithering_level); if (dither_map) { base_dithering_level *= 1.0 / 255.0; // convert byte to float } base_dithering_level *= 15.0 / 16.0; // prevent small errors from accumulating { bool fs_direction = true; unsigned int last_match = 0; for (unsigned int row = 0; row < rows; ++row) { unsigned int col = (fs_direction) ? 0 : (cols - 1); const f_pixel *const row_pixels = liq_image_get_row_f (input_image, row); memset (nexterr, 0, (cols + 2) * sizeof (*nexterr)); do { float dither_level = base_dithering_level; f_pixel spx, xp, err; unsigned int guessed_match; if (dither_map) { dither_level *= dither_map[row * cols + col]; } spx = get_dithered_pixel (dither_level, max_dither_error, thiserr[col + 1], row_pixels[col]); guessed_match = output_image_is_remapped ? output_pixels[row][col] : last_match; output_pixels[row][col] = last_match = nearest_search (n, spx, guessed_match, min_opaque_val, NULL); xp = acolormap[last_match].acolor; err.r = spx.r - xp.r; err.g = spx.r - xp.g; err.b = spx.r - xp.b; err.a = spx.r - xp.a; // If dithering error is crazy high, don't propagate it that much // This prevents crazy geen pixels popping out of the blue (or red or black! ;) if (err.r * err.r + err.g * err.g + err.b * err.b + err.a * err.a > max_dither_error) { dither_level *= 0.75; } { const float colorimp = (3.0f + acolormap[last_match].acolor.a) / 4.0f * dither_level; err.r *= colorimp; err.g *= colorimp; err.b *= colorimp; err.a *= dither_level; } /* Propagate Floyd-Steinberg error terms. */ if (fs_direction) { thiserr[col + 2].a += err.a * (7.f / 16.f); thiserr[col + 2].r += err.r * (7.f / 16.f); thiserr[col + 2].g += err.g * (7.f / 16.f); thiserr[col + 2].b += err.b * (7.f / 16.f); nexterr[col + 2].a = err.a * (1.f / 16.f); nexterr[col + 2].r = err.r * (1.f / 16.f); nexterr[col + 2].g = err.g * (1.f / 16.f); nexterr[col + 2].b = err.b * (1.f / 16.f); nexterr[col + 1].a += err.a * (5.f / 16.f); nexterr[col + 1].r += err.r * (5.f / 16.f); nexterr[col + 1].g += err.g * (5.f / 16.f); nexterr[col + 1].b += err.b * (5.f / 16.f); nexterr[col].a += err.a * (3.f / 16.f); nexterr[col].r += err.r * (3.f / 16.f); nexterr[col].g += err.g * (3.f / 16.f); nexterr[col].b += err.b * (3.f / 16.f); } else { thiserr[col].a += err.a * (7.f / 16.f); thiserr[col].r += err.r * (7.f / 16.f); thiserr[col].g += err.g * (7.f / 16.f); thiserr[col].b += err.b * (7.f / 16.f); nexterr[col].a = err.a * (1.f / 16.f); nexterr[col].r = err.r * (1.f / 16.f); nexterr[col].g = err.g * (1.f / 16.f); nexterr[col].b = err.b * (1.f / 16.f); nexterr[col + 1].a += err.a * (5.f / 16.f); nexterr[col + 1].r += err.r * (5.f / 16.f); nexterr[col + 1].g += err.g * (5.f / 16.f); nexterr[col + 1].b += err.b * (5.f / 16.f); nexterr[col + 2].a += err.a * (3.f / 16.f); nexterr[col + 2].r += err.r * (3.f / 16.f); nexterr[col + 2].g += err.g * (3.f / 16.f); nexterr[col + 2].b += err.b * (3.f / 16.f); } // remapping is done in zig-zag if (fs_direction) { ++col; if (col >= cols) break; } else { if (col <= 0) break; --col; } } while (1); { f_pixel *const temperr = thiserr; thiserr = nexterr; nexterr = temperr; } fs_direction = !fs_direction; } } input_image->free (MIN (thiserr, nexterr)); // MIN because pointers were swapped nearest_free (n); } /* fixed colors are always included in the palette, so it would be wasteful to duplicate them in palette from histogram */ static void remove_fixed_colors_from_histogram (histogram * hist, const liq_image * input_image, const float target_mse) { const float max_difference = MAX (target_mse / 2.0, 2.0 / 256.0 / 256.0); if (input_image->fixed_colors_count) { for (int j = 0; j < hist->size; j++) { for (unsigned int i = 0; i < input_image->fixed_colors_count; i++) { if (colordifference (hist->achv[j].acolor, input_image->fixed_colors[i]) < max_difference) { hist->achv[j] = hist->achv[--hist->size]; // remove color from histogram by overwriting with the last entry j--; break; // continue searching histogram } } } } } /* histogram contains information how many times each color is present in the image, weighted by importance_map */ static histogram * get_histogram (liq_image * input_image, const liq_attr * options) { unsigned int ignorebits = MAX (options->min_posterization_output, options->min_posterization_input); const unsigned int cols = input_image->width, rows = input_image->height; if (!input_image->noise && options->use_contrast_maps) { contrast_maps (input_image); } /* ** Step 2: attempt to make a histogram of the colors, unclustered. ** If at first we don't succeed, increase ignorebits to increase color ** coherence and try again. */ { unsigned int maxcolors = options->max_histogram_entries; struct acolorhash_table *acht; const bool all_rows_at_once = liq_image_can_use_rows (input_image); histogram *hist; do { acht = pam_allocacolorhash (maxcolors, rows * cols, ignorebits, options->malloc, options->free); if (!acht) return NULL; // histogram uses noise contrast map for importance. Color accuracy in noisy areas is not very important. // noise map does not include edges to avoid ruining anti-aliasing for (unsigned int row = 0; row < rows; row++) { bool added_ok; if (all_rows_at_once) { added_ok = pam_computeacolorhash (acht, (const rgba_pixel * const *) input_image->rows, cols, rows, input_image->noise); if (added_ok) break; } else { const rgba_pixel *rows_p[1] = { liq_image_get_row_rgba (input_image, row) }; added_ok = pam_computeacolorhash (acht, rows_p, cols, 1, input_image->noise ? &input_image->noise[row * cols] : NULL); } if (!added_ok) { ignorebits++; liq_verbose_printf (options, " too many colors! Scaling colors to improve clustering... %d", ignorebits); pam_freeacolorhash (acht); acht = NULL; break; } } } while (!acht); if (input_image->noise) { input_image->free (input_image->noise); input_image->noise = NULL; } if (input_image->free_pixels && input_image->f_pixels) { liq_image_free_rgba_source (input_image); // bow can free the RGBA source if copy has been made in f_pixels } hist = pam_acolorhashtoacolorhist (acht, input_image->gamma, options->malloc, options->free); pam_freeacolorhash (acht); if (hist) { liq_verbose_printf (options, " made histogram...%d colors found", hist->size); remove_fixed_colors_from_histogram (hist, input_image, options->target_mse); } return hist; } } static void modify_alpha (liq_image * input_image, rgba_pixel * const row_pixels) { /* IE6 makes colors with even slightest transparency completely transparent, thus to improve situation in IE, make colors that are less than ~10% transparent completely opaque */ const float min_opaque_val = input_image->min_opaque_val; const float almost_opaque_val = min_opaque_val * 169.f / 256.f; const unsigned int almost_opaque_val_int = (min_opaque_val * 169.f / 256.f) * 255.f; for (unsigned int col = 0; col < input_image->width; col++) { const rgba_pixel px = row_pixels[col]; /* ie bug: to avoid visible step caused by forced opaqueness, linearily raise opaqueness of almost-opaque colors */ if (px.a >= almost_opaque_val_int) { float al = px.a / 255.f; al = almost_opaque_val + (al - almost_opaque_val) * (1.f - almost_opaque_val) / (min_opaque_val - almost_opaque_val); al *= 256.f; row_pixels[col].a = al >= 255.f ? 255 : al; } } } /** Builds two maps: noise - approximation of areas with high-frequency noise, except straight edges. 1=flat, 0=noisy. edges - noise map including all edges */ static void contrast_maps (liq_image * image) { const int cols = image->width, rows = image->height; unsigned char *restrict noise, *restrict edges, *restrict tmp; const f_pixel *curr_row, *prev_row, *next_row; int i, j; if (cols < 4 || rows < 4 || (3 * cols * rows) > LIQ_HIGH_MEMORY_LIMIT) { return; } noise = image->malloc (cols * rows); edges = image->malloc (cols * rows); tmp = image->malloc (cols * rows); if (!noise || !edges || !tmp) { return; } curr_row = prev_row = next_row = liq_image_get_row_f (image, 0); for (j = 0; j < rows; j++) { f_pixel prev, curr, next; prev_row = curr_row; curr_row = next_row; next_row = liq_image_get_row_f (image, MIN (rows - 1, j + 1)); curr = curr_row[0]; next = curr; for (i = 0; i < cols; i++) { prev = curr; curr = next; next = curr_row[MIN (cols - 1, i + 1)]; // contrast is difference between pixels neighbouring horizontally and vertically { const float a = fabsf (prev.a + next.a - curr.a * 2.f), r = fabsf (prev.r + next.r - curr.r * 2.f), g = fabsf (prev.g + next.g - curr.g * 2.f), b = fabsf (prev.b + next.b - curr.b * 2.f); const f_pixel prevl = prev_row[i]; const f_pixel nextl = next_row[i]; const float a1 = fabsf (prevl.a + nextl.a - curr.a * 2.f), r1 = fabsf (prevl.r + nextl.r - curr.r * 2.f), g1 = fabsf (prevl.g + nextl.g - curr.g * 2.f), b1 = fabsf (prevl.b + nextl.b - curr.b * 2.f); const float horiz = MAX (MAX (a, r), MAX (g, b)); const float vert = MAX (MAX (a1, r1), MAX (g1, b1)); const float edge = MAX (horiz, vert); float z = edge - fabsf (horiz - vert) * .5f; z = 1.f - MAX (z, MIN (horiz, vert)); z *= z; // noise is amplified z *= z; z *= 256.f; noise[j * cols + i] = z < 256 ? z : 255; z = (1.f - edge) * 256.f; edges[j * cols + i] = z < 256 ? z : 255; } } } // noise areas are shrunk and then expanded to remove thin edges from the map liq_max3 (noise, tmp, cols, rows); liq_max3 (tmp, noise, cols, rows); liq_blur (noise, tmp, noise, cols, rows, 3); liq_max3 (noise, tmp, cols, rows); liq_min3 (tmp, noise, cols, rows); liq_min3 (noise, tmp, cols, rows); liq_min3 (tmp, noise, cols, rows); liq_min3 (edges, tmp, cols, rows); liq_max3 (tmp, edges, cols, rows); for (int i = 0; i < cols * rows; i++) edges[i] = MIN (noise[i], edges[i]); image->free (tmp); image->noise = noise; image->edges = edges; } /** * Builds map of neighbor pixels mapped to the same palette entry * * For efficiency/simplicity it mainly looks for same consecutive pixels horizontally * and peeks 1 pixel above/below. Full 2d algorithm doesn't improve it significantly. * Correct flood fill doesn't have visually good properties. */ static void update_dither_map (unsigned char *const *const row_pointers, liq_image * input_image) { const unsigned int width = input_image->width; const unsigned int height = input_image->height; unsigned char *const edges = input_image->edges; for (unsigned int row = 0; row < height; row++) { unsigned char lastpixel = row_pointers[row][0]; unsigned int lastcol = 0; for (unsigned int col = 1; col < width; col++) { const unsigned char px = row_pointers[row][col]; if (px != lastpixel || col == width - 1) { float neighbor_count = 2.5f + col - lastcol; unsigned int i = lastcol; while (i < col) { if (row > 0) { unsigned char pixelabove = row_pointers[row - 1][i]; if (pixelabove == lastpixel) neighbor_count += 1.f; } if (row < height - 1) { unsigned char pixelbelow = row_pointers[row + 1][i]; if (pixelbelow == lastpixel) neighbor_count += 1.f; } i++; } while (lastcol <= col) { float e = edges[row * width + lastcol] / 255.f; e *= 1.f - 2.5f / neighbor_count; edges[row * width + lastcol++] = e * 255.f; } lastpixel = px; } } } input_image->dither_map = input_image->edges; input_image->edges = NULL; } static colormap * add_fixed_colors_to_palette (colormap * palette, const int max_colors, const f_pixel fixed_colors[], const int fixed_colors_count, void *(*malloc) (size_t), void (*free) (void *)) { colormap *newpal; unsigned int i, palette_max; int j; if (!fixed_colors_count) return palette; newpal = pam_colormap (MIN (max_colors, (palette ? palette->colors : 0) + fixed_colors_count), malloc, free); i = 0; if (palette && fixed_colors_count < max_colors) { palette_max = MIN (palette->colors, max_colors - fixed_colors_count); for (; i < palette_max; i++) { newpal->palette[i] = palette->palette[i]; } } for (j = 0; j < MIN (max_colors, fixed_colors_count); j++) { newpal->palette[i++] = (colormap_item) { .acolor = fixed_colors[j],.fixed = true,}; } if (palette) pam_freecolormap (palette); return newpal; } static void adjust_histogram_callback (hist_item * item, float diff) { item->adjusted_weight = (item->perceptual_weight + item->adjusted_weight) * (sqrtf (1.f + diff)); } /** Repeats mediancut with different histogram weights to find palette with minimum error. feedback_loop_trials controls how long the search will take. < 0 skips the iteration. */ static colormap * find_best_palette (histogram * hist, const liq_attr * options, const double max_mse, const f_pixel fixed_colors[], const unsigned int fixed_colors_count, double *palette_error_p) { unsigned int max_colors = options->max_colors; // if output is posterized it doesn't make sense to aim for perfrect colors, so increase target_mse // at this point actual gamma is not set, so very conservative posterization estimate is used const double target_mse = MIN (max_mse, MAX (options->target_mse, pow ((1 << options->min_posterization_output) / 1024.0, 2))); int feedback_loop_trials = options->feedback_loop_trials; colormap *acolormap = NULL; double least_error = MAX_DIFF; double target_mse_overshoot = feedback_loop_trials > 0 ? 1.05 : 1.0; const double percent = (double) (feedback_loop_trials > 0 ? feedback_loop_trials : 1) / 100.0; do { colormap *newmap; double total_error; if (hist->size && fixed_colors_count < max_colors) { newmap = mediancut (hist, options->min_opaque_val, max_colors - fixed_colors_count, target_mse * target_mse_overshoot, MAX (MAX (90.0 / 65536.0, target_mse), least_error) * 1.2, options->malloc, options->free); } else { feedback_loop_trials = 0; newmap = NULL; } newmap = add_fixed_colors_to_palette (newmap, max_colors, fixed_colors, fixed_colors_count, options->malloc, options->free); if (!newmap) { return NULL; } if (feedback_loop_trials <= 0) { return newmap; } // after palette has been created, total error (MSE) is calculated to keep the best palette // at the same time Voronoi iteration is done to improve the palette // and histogram weights are adjusted based on remapping error to give more weight to poorly matched colors { const bool first_run_of_target_mse = !acolormap && target_mse > 0; total_error = viter_do_iteration (hist, newmap, options->min_opaque_val, first_run_of_target_mse ? NULL : adjust_histogram_callback, !acolormap || options->fast_palette); } // goal is to increase quality or to reduce number of colors used if quality is good enough if (!acolormap || total_error < least_error || (total_error <= target_mse && newmap->colors < max_colors)) { if (acolormap) pam_freecolormap (acolormap); acolormap = newmap; if (total_error < target_mse && total_error > 0) { // voronoi iteration improves quality above what mediancut aims for // this compensates for it, making mediancut aim for worse target_mse_overshoot = MIN (target_mse_overshoot * 1.25, target_mse / total_error); } least_error = total_error; // if number of colors could be reduced, try to keep it that way // but allow extra color as a bit of wiggle room in case quality can be improved too max_colors = MIN (newmap->colors + 1, max_colors); feedback_loop_trials -= 1; // asymptotic improvement could make it go on forever } else { for (unsigned int j = 0; j < hist->size; j++) { hist->achv[j].adjusted_weight = (hist->achv[j].perceptual_weight + hist->achv[j].adjusted_weight) / 2.0; } target_mse_overshoot = 1.0; feedback_loop_trials -= 6; // if error is really bad, it's unlikely to improve, so end sooner if (total_error > least_error * 4) feedback_loop_trials -= 3; pam_freecolormap (newmap); } liq_verbose_printf (options, " selecting colors...%d%%", 100 - MAX (0, (int) (feedback_loop_trials / percent))); } while (feedback_loop_trials > 0); *palette_error_p = least_error; return acolormap; } static liq_result * pngquant_quantize (histogram * hist, const liq_attr * options, const liq_image * img) { colormap *acolormap; double palette_error = -1; // no point having perfect match with imperfect colors (ignorebits > 0) const bool fast_palette = options->fast_palette || hist->ignorebits > 0; const bool few_input_colors = hist->size + img->fixed_colors_count <= options->max_colors; liq_result *result; // If image has few colors to begin with (and no quality degradation is required) // then it's possible to skip quantization entirely if (few_input_colors && options->target_mse == 0) { acolormap = pam_colormap (hist->size, options->malloc, options->free); for (unsigned int i = 0; i < hist->size; i++) { acolormap->palette[i].acolor = hist->achv[i].acolor; acolormap->palette[i].popularity = hist->achv[i].perceptual_weight; } acolormap = add_fixed_colors_to_palette (acolormap, options->max_colors, img->fixed_colors, img->fixed_colors_count, options->malloc, options->free); palette_error = 0; } else { const double max_mse = options->max_mse * (few_input_colors ? 0.33 : 1.0); // when degrading image that's already paletted, require much higher improvement, since pal2pal often looks bad and there's little gain const double iteration_limit = options->voronoi_iteration_limit; unsigned int iterations = options->voronoi_iterations; acolormap = find_best_palette (hist, options, max_mse, img->fixed_colors, img->fixed_colors_count, &palette_error); if (!acolormap) { return NULL; } // Voronoi iteration approaches local minimum for the palette if (!iterations && palette_error < 0 && max_mse < MAX_DIFF) iterations = 1; // otherwise total error is never calculated and MSE limit won't work if (iterations) { double previous_palette_error = MAX_DIFF; unsigned int i; // likely_colormap_index (used and set in viter_do_iteration) can't point to index outside colormap if (acolormap->colors < 256) for (unsigned int j = 0; j < hist->size; j++) { if (hist->achv[j].tmp.likely_colormap_index >= acolormap->colors) { hist->achv[j].tmp.likely_colormap_index = 0; // actual value doesn't matter, as the guess is out of date anyway } } verbose_print (options, " moving colormap towards local minimum"); for (i = 0; i < iterations; i++) { palette_error = viter_do_iteration (hist, acolormap, options->min_opaque_val, NULL, i == 0 || options->fast_palette); if (fabs (previous_palette_error - palette_error) < iteration_limit) { break; } if (palette_error > max_mse * 1.5) { // probably hopeless if (palette_error > max_mse * 3.0) break; // definitely hopeless i++; } previous_palette_error = palette_error; } } if (palette_error > max_mse) { liq_verbose_printf (options, " image degradation MSE=%.3f (Q=%d) exceeded limit of %.3f (%d)", palette_error * 65536.0 / 6.0, mse_to_quality (palette_error), max_mse * 65536.0 / 6.0, mse_to_quality (max_mse)); pam_freecolormap (acolormap); return NULL; } } sort_palette (acolormap, options); result = options->malloc (sizeof (liq_result)); if (!result) return NULL; *result = (liq_result) { .magic_header = liq_result_magic,.malloc = options->malloc,.free = options->free,.palette = acolormap,.palette_error = palette_error,.fast_palette = fast_palette,.use_dither_map = options->use_dither_map,.gamma = img->gamma,.min_posterization_output = options->min_posterization_output,}; return result; } LIQ_EXPORT liq_error liq_write_remapped_image (liq_result * result, liq_image * input_image, void *buffer, size_t buffer_size) { size_t required_size; unsigned char **rows; unsigned char *buffer_bytes; unsigned i; if (!CHECK_STRUCT_TYPE (result, liq_result)) { return LIQ_INVALID_POINTER; } if (!CHECK_STRUCT_TYPE (input_image, liq_image)) { return LIQ_INVALID_POINTER; } if (!CHECK_USER_POINTER (buffer)) { return LIQ_INVALID_POINTER; } required_size = input_image->width * input_image->height; if (buffer_size < required_size) { return LIQ_BUFFER_TOO_SMALL; } rows = g_alloca (sizeof (unsigned char *) * input_image->height); buffer_bytes = buffer; for (i = 0; i < input_image->height; i++) { rows[i] = &buffer_bytes[input_image->width * i]; } return liq_write_remapped_image_rows (result, input_image, rows); } LIQ_EXPORT liq_error liq_write_remapped_image_rows (liq_result * quant, liq_image * input_image, unsigned char **row_pointers) { unsigned int i; liq_remapping_result *result; float remapping_error; if (!CHECK_STRUCT_TYPE (quant, liq_result)) return LIQ_INVALID_POINTER; if (!CHECK_STRUCT_TYPE (input_image, liq_image)) return LIQ_INVALID_POINTER; for (i = 0; i < input_image->height; i++) { if (!CHECK_USER_POINTER (row_pointers + i) || !CHECK_USER_POINTER (row_pointers[i])) return LIQ_INVALID_POINTER; } if (quant->remapping) { liq_remapping_result_destroy (quant->remapping); } result = quant->remapping = liq_remapping_result_create (quant); if (!result) return LIQ_OUT_OF_MEMORY; if (!input_image->edges && !input_image->dither_map && quant->use_dither_map) { contrast_maps (input_image); } /* ** Step 4: map the colors in the image to their closest match in the ** new colormap, and write 'em out. */ remapping_error = result->palette_error; if (result->dither_level == 0) { set_rounded_palette (&result->int_palette, result->palette, result->gamma, quant->min_posterization_output); remapping_error = remap_to_palette (input_image, row_pointers, result->palette, quant->fast_palette); } else { const bool generate_dither_map = result->use_dither_map && (input_image->edges && !input_image->dither_map); if (generate_dither_map) { // If dithering (with dither map) is required, this image is used to find areas that require dithering remapping_error = remap_to_palette (input_image, row_pointers, result->palette, quant->fast_palette); update_dither_map (row_pointers, input_image); } // remapping above was the last chance to do voronoi iteration, hence the final palette is set after remapping set_rounded_palette (&result->int_palette, result->palette, result->gamma, quant->min_posterization_output); remap_to_palette_floyd (input_image, row_pointers, result->palette, MAX (remapping_error * 2.4, 16.f / 256.f), result->use_dither_map, generate_dither_map, result->dither_level); } // remapping error from dithered image is absurd, so always non-dithered value is used // palette_error includes some perceptual weighting from histogram which is closer correlated with dssim // so that should be used when possible. if (result->palette_error < 0) { result->palette_error = remapping_error; } return LIQ_OK; } LIQ_EXPORT int liq_version (void) { return LIQ_VERSION; }