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cc-stuff
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cc-stuff/img2cpi.c

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// x-run: make img2cpi CC=clang
// x-run: ~/scripts/runc.sh % -Wall -Wextra -lm --- ~/images/boykisser.png cpi-images/boykisser.cpi
#include <math.h>
#include <assert.h>
#include <stb/stb_image.h>
#include <stb/stb_image_resize2.h>
#include <argp.h>
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <stdbool.h>
#include "cc-common.h"
#ifdef USE_OPENMP
#include <omp.h>
#endif
#define MAX_COLOR_DIFFERENCE 768
#define K_MEANS_ITERATIONS 4
struct cc_char {
unsigned char character;
unsigned char bg, fg;
};
struct arguments {
bool fast_mode;
int width, height;
enum cpi_version {
CPI_VERSION_AUTO,
CPI_VERSION_RAW,
CPI_VERSION_0,
CPI_VERSION_1,
CPI_VERSION_2,
} cpi_version;
enum placement {
PLACEMENT_CENTER,
PLACEMENT_COVER,
PLACEMENT_TILE,
PLACEMENT_FULL,
PLACEMENT_EXTEND,
PLACEMENT_FILL
} placement;
enum palette_type {
PALETTE_DEFAULT,
PALETTE_DEFAULT_GRAY,
PALETTE_AUTO,
PALETTE_PATH,
PALETTE_LIST
} palette_type;
char *palette;
char *input_path;
char *output_path;
} args = {
.fast_mode = false,
.width = 4 * 8 - 1, // 4x3 blocks screen
.height = 3 * 6 - 2,
.cpi_version = CPI_VERSION_AUTO,
.placement = PLACEMENT_FULL,
.input_path = NULL,
.output_path = NULL,
.palette = NULL,
.palette_type = PALETTE_DEFAULT // TODO(kc): change to PALETTE_AUTO when
// k-means is implemented
};
struct image {
int w, h;
union color *pixels;
};
struct image_pal {
int w, h;
uint8_t *pixels;
const struct palette *palette;
};
struct k_means_state {
const struct image *items;
struct palette *clusters;
uint8_t *predicted_cluster;
struct k_means_centroid_intermediate {
struct {
float r, g, b;
} sums;
size_t count;
union color closest_present_item;
float closest_present_distance;
} *centroid_intermediate;
size_t item_count;
};
bool parse_cmdline(int argc, char **argv);
void show_help(const char *progname, bool show_all, FILE *fp);
struct image *image_load(const char *fp);
struct image *image_new(int w, int h);
struct image *image_resize(struct image *original, int new_w, int new_h);
struct image_pal *image_quantize(struct image *original, const struct palette *palette);
void image_unload(struct image *img);
float get_color_difference(union color a, union color b);
float get_color_brightness(union color clr);
void get_size_keep_aspect(int w, int h, int dw, int dh, int *ow, int *oh);
void convert_2x3(const struct image_pal *img, struct cc_char *characters);
void convert_6x9(const struct image_pal *img, struct cc_char *characters);
int save_cpi_0(FILE *fp, const struct palette *pal, const struct cc_char *chars, int w, int h);
int save_cpi_1(FILE *fp, const struct palette *pal, const struct cc_char *chars, int w, int h);
// Only one global custom palette is maintained
struct palette *custom_palette_resize(uint8_t size);
struct palette *custom_palette_from(const struct palette *orig);
struct k_means_state k_means_init(const struct image *image, struct palette *starting_palette);
bool k_means_iteration(struct k_means_state *state);
void k_means_end(struct k_means_state *state);
struct palette *palette_k_means(const struct image *image, const struct palette *prototype);
const char *known_file_extensions[] = {
".png", ".jpg", ".jpeg", ".jfif", ".jpg", ".gif",
".tga", ".bmp", ".hdr", ".pnm", 0
};
static const struct optiondocs {
char shortopt;
char *longopt;
char *target;
char *doc;
struct optiondocs_choice { char *value; char *doc; } *choices;
} optiondocs[] = {
{ 'h', "help", 0, "Show help", 0 },
{ 'f', "fast", 0, "Use fast (old) method for picking characters and colors", 0 },
{ 'W', "width", "width", "Width in characters", 0 },
{ 'h', "height", "height", "Height in characters", 0 },
{ 'P', "palette", "palette", "Use specific palette.\n"
" `auto` uses automatic selection\n"
" `default` uses default palette\n"
" `defaultgray` uses default grayscale palette\n"
" `list:#RRGGBB,#RRGGBB,...` uses hard-coded one\n"
" `txt:PATH` reads hex colors from each line in a file\n", 0 },
{ 'V', "cpi_version", "version", "Force specific version of CPI",
(struct optiondocs_choice[]) {
{ "-2,raw", "Use raw format. No headers, no palette, just characters and colors" },
{ "-1,auto", "Choose best available" },
{ "0", "OG CPI, 255x255, uncompressed" },
{ "1", "CPIv1, huge images, uncompressed" },
{ "255", "In-dev version, may not work" },
{ 0, 0 } } },
{ 'p', "placement", "placement", "Image placement mode (same as in hsetroot)",
(struct optiondocs_choice[]){
{ "center", "Render image centered on the canvas" },
{ "cover", "Centered on screen, scaled to fill fully" },
{ "tile", "Render image tiled" },
{ "full", "Use maximum aspect ratio" },
{ "extend", "Same as \"full\", but filling borders" },
{ "fill", "Stretch to fill" },
{ 0, 0 } } },
{ 0, 0, "input.*", "Input file path", 0 },
{ 0, 0, "output.cpi", "Output file path", 0 },
{ 0 }
};
int main(int argc, char **argv) {
if (!parse_cmdline(argc, argv)) {
show_help(argv[0], false, stderr);
fprintf(stderr, "Fatal error occurred, exiting.\n");
return EXIT_FAILURE;
}
struct image *src_image = image_load(args.input_path);
if (!src_image) {
fprintf(stderr, "Error: failed to open the file\n");
return EXIT_FAILURE;
}
struct image *canvas;
if (args.fast_mode) {
canvas = image_new(args.width * 2, args.height * 3);
} else {
canvas = image_new(args.width * 6, args.height * 9);
}
if (!canvas) {
fprintf(stderr, "Error: failed to allocate second image buffer\n");
return EXIT_FAILURE;
}
// TODO: load palette, maybe calculate it too? k-means?
const struct palette *palette = &cc_default_palette;
switch (args.palette_type) {
case PALETTE_DEFAULT: palette = &cc_default_palette; break;
case PALETTE_DEFAULT_GRAY: palette = &cc_default_gray_palette; break;
case PALETTE_AUTO: palette = palette_k_means(src_image, &cc_default_palette); break;
case PALETTE_LIST: assert(0 && "Not implemented"); break;
case PALETTE_PATH: assert(0 && "Not implemented"); break;
default: assert(0 && "Unreachable");
}
// TODO: properly scale
struct image *scaled_image;
{
int new_w, new_h;
get_size_keep_aspect(src_image->w, src_image->h, canvas->w, canvas->h, &new_w, &new_h);
scaled_image = image_resize(src_image, new_w, new_h);
if (!scaled_image) {
fprintf(stderr, "Error: failed to open the file\n");
return EXIT_FAILURE;
}
}
// TODO: position image properly
int small_w = scaled_image->w < canvas->w ? scaled_image->w : canvas->w;
int small_h = scaled_image->h < canvas->h ? scaled_image->h : canvas->h;
for (int y = 0; y < small_h; y++) {
memcpy(&canvas->pixels[y * canvas->w],
&scaled_image->pixels[y * scaled_image->w],
small_w * sizeof(union color));
}
// TODO: actually do stuff
struct cc_char *characters = calloc(args.width * args.height, sizeof(struct cc_char));
struct image_pal *quantized_image = image_quantize(canvas, palette);
if (!quantized_image) {
fprintf(stderr, "Error: failed to open the file\n");
return EXIT_FAILURE;
}
if (args.fast_mode) {
convert_2x3(quantized_image, characters);
} else {
convert_6x9(quantized_image, characters);
}
FILE *fp = fopen(args.output_path, "wb");
if (args.width < 256) {
save_cpi_0(fp, palette, characters, args.width, args.height);
} else {
save_cpi_1(fp, palette, characters, args.width, args.height);
}
fclose(fp);
image_unload(src_image);
image_unload(canvas);
return EXIT_SUCCESS;
}
int _write_palette_full(FILE *fp, const struct palette *pal) {
int written = 0;
assert(pal->count == 16 && "Invalid palette size");
for (int i = 0; i < 16; i++) {
written += fputc(pal->colors[i].rgba.r, fp);
written += fputc(pal->colors[i].rgba.g, fp);
written += fputc(pal->colors[i].rgba.b, fp);
}
return written;
}
int _write_pixeldata_v0(FILE *fp, const struct cc_char *chars, int w, int h) {
int written = 0;
for (int i = 0; i < w * h; i++) {
written += fputc(chars[i].character, fp);
written += fputc(chars[i].bg | (chars[i].fg << 4), fp);
}
return written;
}
int save_cpi_0(FILE *fp, const struct palette *pal, const struct cc_char *chars, int w, int h) {
int written = 0;
written += fwrite("CCPI", 1, 4, fp);
written += fputc(w, fp);
written += fputc(h, fp);
written += fputc(0x00, fp);
written += _write_palette_full(fp, pal);
written += _write_pixeldata_v0(fp, chars, w, h);
return written;
}
int save_cpi_1(FILE *fp, const struct palette *pal, const struct cc_char *chars, int w, int h) {
int written = 0;
written += fwrite("CPI\x01", 1, 4, fp);
written += write_varint(fp, w);
written += write_varint(fp, h);
written += _write_palette_full(fp, pal);
written += _write_pixeldata_v0(fp, chars, w, h);
return written;
}
bool parse_cmdline(int argc, char **argv) {
static struct option options[] = {
{ "help", no_argument, 0, 'h' },
{ "fast", no_argument, 0, 'f' },
{ "width", required_argument, 0, 'W' },
{ "height", required_argument, 0, 'H' },
{ "cpi_version", required_argument, 0, 'V' },
{ "placement", required_argument, 0, 'p' },
{ "palette", required_argument, 0, 'P' },
{ 0, 0, 0, 0 }
};
while (true) {
int option_index = 0;
int c = getopt_long(argc, argv, "hfW:H:V:p:P:", options, &option_index);
if (c == -1) break;
if (c == 0) c = options[option_index].val;
if (c == '?') break;
switch (c) {
case 'h': // --help
show_help(argv[0], true, stdout);
exit(EXIT_SUCCESS);
break;
case 'f': // --fast
args.fast_mode = true;
if (args.cpi_version != CPI_VERSION_AUTO) {
fprintf(stderr, "Warning: text mode ignores version\n");
}
break;
case 'W': // --width
args.width = atoi(optarg);
break;
case 'H': // --height
args.height = atoi(optarg);
break;
case 'V': // --cpi_version
{
if (0 == strcmp(optarg, "auto") || 0 == strcmp(optarg, "-1")) {
args.cpi_version = CPI_VERSION_AUTO;
} else if (0 == strcmp(optarg, "raw") || 0 == strcmp(optarg, "-2")) {
args.cpi_version = CPI_VERSION_RAW;
} else if (0 == strcmp(optarg, "0")) {
args.cpi_version = CPI_VERSION_0;
} else if (0 == strcmp(optarg, "1")) {
args.cpi_version = CPI_VERSION_1;
} else if (0 == strcmp(optarg, "2")) {
args.cpi_version = CPI_VERSION_2;
}
}
break;
case 'p': // --placement
if (0 == strcmp(optarg, "center")) {
args.placement = PLACEMENT_CENTER;
} else if (0 == strcmp(optarg, "cover")) {
args.placement = PLACEMENT_COVER;
} else if (0 == strcmp(optarg, "tile")) {
args.placement = PLACEMENT_TILE;
} else if (0 == strcmp(optarg, "full")) {
args.placement = PLACEMENT_FULL; }
else if (0 == strcmp(optarg, "extend")) {
args.placement = PLACEMENT_EXTEND;
} else if (0 == strcmp(optarg, "fill")) {
args.placement = PLACEMENT_FILL;
} else {
fprintf(stderr, "Error: invaild placement %s\n", optarg);
return false;
}
break;
case 'P': // --palette
if (0 == strcmp(optarg, "default")) {
args.palette_type = PALETTE_DEFAULT;
} else if (0 == strcmp(optarg, "defaultgray")) {
args.palette_type = PALETTE_DEFAULT_GRAY;
} else if (0 == strcmp(optarg, "auto")) {
args.palette_type = PALETTE_AUTO;
} else if (0 == strncmp(optarg, "list:", 5)) {
args.palette_type = PALETTE_LIST;
args.palette = &optarg[5];
} else {
fprintf(stderr, "Error: invaild palette %s\n", optarg);
return false;
}
break;
}
}
if (optind == argc) {
fprintf(stderr, "Error: no input file provided\n");
return false;
} else if (optind + 1 == argc) {
fprintf(stderr, "Error: no output file provided\n");
return false;
} else if ((argc - optind) != 2) {
fprintf(stderr, "Error: too many arguments\n");
return false;
}
args.input_path = argv[optind];
args.output_path = argv[optind + 1];
const char *extension = strrchr(args.input_path, '.');
if (!extension) {
fprintf(stderr, "Warning: no file extension, reading may fail!\n");
} else {
bool known = false;
for (int i = 0; known_file_extensions[i] != 0; i++) {
if (0 == strcasecmp(known_file_extensions[i], extension)) {
known = true;
break;
}
}
if (!known) {
fprintf(stderr, "Warning: unknown file extension %s, reading may fail!\n", extension);
}
}
return true;
}
void show_help(const char *progname, bool show_all, FILE *fp) {
fprintf(fp, "usage: %s", progname);
for (int i = 0; optiondocs[i].doc != 0; i++) {
struct optiondocs doc = optiondocs[i];
fprintf(fp, " [");
if (doc.shortopt) fprintf(fp, "-%c", doc.shortopt);
if (doc.shortopt && doc.longopt) fprintf(fp, "|");
if (doc.longopt) fprintf(fp, "--%s", doc.longopt);
if (doc.target) {
if (doc.shortopt || doc.longopt) fprintf(fp, " ");
fprintf(fp, "%s", doc.target);
}
fprintf(fp, "]");
}
fprintf(fp, "\n");
if (!show_all) return;
fprintf(fp, "\n");
fprintf(fp, "ComputerCraft Palette Image converter\n");
fprintf(fp, "\n");
fprintf(fp, "positional arguments:\n");
for (int i = 0; optiondocs[i].doc != 0; i++) {
struct optiondocs doc = optiondocs[i];
if (!doc.shortopt && !doc.longopt) {
fprintf(fp, " %s\t%s\n", doc.target, doc.doc);
}
}
fprintf(fp, "\n");
fprintf(fp, "options:\n");
for (int i = 0; optiondocs[i].doc != 0; i++) {
struct optiondocs doc = optiondocs[i];
if (!doc.shortopt && !doc.longopt) { continue; }
fprintf(fp, " ");
int x = 2;
if (doc.shortopt) { fprintf(fp, "-%c", doc.shortopt); x += 2; }
if (doc.shortopt && doc.longopt) { fprintf(fp, ", "); x += 2; }
if (doc.longopt) { fprintf(fp, "--%s", doc.longopt); x += strlen(doc.longopt) + 2; }
if (doc.choices) {
fprintf(fp, " {");
for (int j = 0; doc.choices[j].value != 0; j++) {
if (j > 0) { fprintf(fp, ","); x += 1; }
fprintf(fp, "%s", doc.choices[j].value);
x += strlen(doc.choices[j].value);
}
fprintf(fp, "}");
x += 3;
} else if (doc.target) {
fprintf(fp, " ");
fprintf(fp, "%s", doc.target);
x += strlen(doc.target) + 1;
}
if (x > 24) fprintf(fp, "\n%24c", ' ');
else fprintf(fp, "%*c", 24 - x, ' ');
fprintf(fp, "%s\n", doc.doc);
if (doc.choices) {
for (int j = 0; doc.choices[j].value != 0; j++) {
fprintf(fp, "%26c", ' ');
if (doc.shortopt) fprintf(fp, "-%c ", doc.shortopt);
else if (doc.longopt) fprintf(fp, "--%s", doc.longopt);
fprintf(fp, "%-12s %s\n", doc.choices[j].value, doc.choices[j].doc);
}
}
}
}
struct image *image_load(const char *fp) {
struct image *img = calloc(1, sizeof(struct image));
if (!img) return NULL;
img->pixels = (union color*)stbi_load(fp, &img->w, &img->h, 0, 4);
if (!img->pixels) {
free(img);
return NULL;
}
return img;
}
struct image *image_new(int w, int h) {
struct image *img = calloc(1, sizeof(struct image));
if (!img) return NULL;
img->pixels = calloc(h, sizeof(union color) * w);
img->w = w;
img->h = h;
if (!img->pixels) {
free(img);
return NULL;
}
return img;
}
struct image *image_resize(struct image *original, int new_w, int new_h) {
struct image *resized = image_new(new_w, new_h);
if (!resized) return NULL;
stbir_resize_uint8_srgb((unsigned char *)original->pixels, original->w, original->h, 0,
(unsigned char *)resized->pixels, resized->w, resized->h, 0,
STBIR_RGBA);
return resized;
}
void image_unload(struct image *img) {
free(img->pixels);
free(img);
}
void get_size_keep_aspect(int w, int h, int dw, int dh, int *ow, int *oh)
{
*ow = dw;
*oh = dh;
float ratio = (float)w / (float)h;
float ratio_dst = (float)dw / (float)dh;
int tmp_1, tmp_2;
if (ratio_dst >= ratio)
{
tmp_1 = floor(dh * ratio);
tmp_2 = ceil(dh * ratio);
if (fabsf(ratio - (float)tmp_1 / dh) < fabsf(ratio - (float)tmp_2 / dh))
*ow = tmp_1 < 1 ? 1 : tmp_1;
else
*ow = tmp_2 < 1 ? 1 : tmp_2;
}
else
{
tmp_1 = floor(dw / ratio);
tmp_2 = ceil(dw / ratio);
if (tmp_2 == 0 ||
fabs(ratio - (float)dw / tmp_1) < fabs(ratio - (float)dw / tmp_2))
(*oh) = tmp_1 < 1 ? 1 : tmp_1;
else
(*oh) = tmp_2 < 1 ? 1 : tmp_2;
}
}
struct image_pal *image_quantize(struct image *original, const struct palette *palette) {
struct image_pal *out = calloc(1, sizeof(struct image_pal));
out->w = original->w;
out->h = original->h;
out->pixels = calloc(original->w, original->h);
out->palette = palette;
for (int i = 0; i < out->w * out->h; i++) {
int closest_color = 0;
float closest_distance = 1e20;
for (int color = 0; color < palette->count; color++) {
float dist = get_color_difference(palette->colors[color], original->pixels[i]);
if (dist <= closest_distance) {
closest_distance = dist;
closest_color = color;
}
}
out->pixels[i] = closest_color;
}
return out;
}
float get_color_difference(union color a, union color b) {
int dr = a.rgba.r - b.rgba.r,
dg = a.rgba.g - b.rgba.g,
db = a.rgba.b - b.rgba.b;
return dr * dr + dg * dg + db * db;
}
float get_color_brightness(union color clr) {
return get_color_difference(clr, (union color){ .v = 0 });
}
void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
int w = img->w / 2, h = img->h / 3;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
unsigned char darkest_i = 0, brightest_i = 0;
float darkest_diff = 0xffffff, brightest_diff = 0;
for (int oy = 0; oy < 3; oy++) {
for (int ox = 0; ox < 2; ox++) {
unsigned char pix = img->pixels[ox + (x + (y * 3 + oy) * w) * 2];
float brightness = get_color_brightness(img->palette->colors[pix]);
if (brightness >= brightest_diff) {
brightest_i = pix;
brightest_diff = brightness;
}
if (brightness <= darkest_diff) {
darkest_i = pix;
darkest_diff = brightness;
}
}
}
unsigned char bitmap = 0;
const static unsigned char pixel_bits[3][2] = { { 1, 2}, { 4, 8 }, { 16, 0 } };
for (int oy = 0; oy < 3; oy++) {
for (int ox = 0; ox < 2; ox++) {
if (ox == 1 && oy == 2) continue;
unsigned char pix = img->pixels[ox + (x + (y * 3 + oy) * w) * 2];
float diff_bg = get_color_difference(img->palette->colors[darkest_i], img->palette->colors[pix]);
float diff_fg = get_color_difference(img->palette->colors[brightest_i], img->palette->colors[pix]);
if (diff_fg < diff_bg) {
bitmap |= pixel_bits[oy][ox];
}
}
}
{
unsigned char pix = img->pixels[1 + (x + (y * 3 + 2) * w) * 2];
float diff_bg = get_color_difference(img->palette->colors[darkest_i], img->palette->colors[pix]);
float diff_fg = get_color_difference(img->palette->colors[brightest_i], img->palette->colors[pix]);
if (diff_fg < diff_bg) {
bitmap ^= 31;
unsigned char tmp = darkest_i;
darkest_i = brightest_i;
brightest_i = tmp;
}
}
characters[x + y * w].character = 0x80 + bitmap;
characters[x + y * w].bg = darkest_i;
characters[x + y * w].fg = brightest_i;
}
}
}
void convert_6x9(const struct image_pal *img, struct cc_char *characters) {
int w = img->w / 6, h = img->h / 9;
float palette_self_diffs[0x100][0x10] = {{(float) 0xffffff}};
for (int input_color = 0x0; input_color < 0x100 && input_color < img->palette->count; input_color++) {
for (int output_color = 0x0; output_color < 0x10 && output_color < img->palette->count; output_color++) {
palette_self_diffs[input_color][output_color] = get_color_difference(img->palette->colors[input_color], img->palette->colors[output_color]);
}
}
for (int y = 0; y < h; y++) {
#ifdef USE_OPENMP
#pragma omp parallel for
#endif
for (int x = 0; x < w; x++) {
float chunk_palette_diffs[6][9][0x10] = {{{(float) 0xffffff}}};
for (int ox = 0; ox < 6; ox++) {
for (int oy = 0; oy < 9; oy++) {
uint8_t pixel_unresolved = img->pixels[
ox + (x + (y * 9 + oy) * w) * 6
];
for (int color = 0x0; color < 0x10 && color < img->palette->count; color++) {
chunk_palette_diffs[ox][oy][color] = palette_self_diffs[pixel_unresolved][color];
}
}
}
float min_diff = 0xffffff;
char closest_sym = 0x00, closest_color = 0xae;
for (int sym = 0x01; sym <= 0xFF; sym++) {
if (sym == '\t' || sym == '\n' || sym == '\r' || sym == '\x0e') {
continue;
}
for (int color = 0x00; color <= 0xff; color++) {
float difference = 0;
for (int oy = 0; oy < 9; oy++) {
unsigned char sym_line = cc_font_atlas[sym][oy];
for (int ox = 0; ox < 6; ox++) {
bool lit = sym_line & (0x80 >> ox);
difference += chunk_palette_diffs[ox][oy][lit ? color >> 4 : color & 0xF];
}
}
if (difference <= min_diff) {
min_diff = difference;
closest_sym = sym;
closest_color = color;
}
}
}
characters[x + y * w].character = closest_sym;
characters[x + y * w].bg = closest_color & 0xF;
characters[x + y * w].fg = closest_color >> 4;
}
}
}
struct {
uint8_t count;
union color colors[256];
} custom_palette_data;
struct palette *custom_palette_resize(uint8_t size) {
custom_palette_data.count = size;
return (struct palette*)&custom_palette_data;
}
struct palette *custom_palette_from(const struct palette *orig) {
custom_palette_data.count = orig->count;
for (int i = 0; i < custom_palette_data.count; i++) {
custom_palette_data.colors[i] = orig->colors[i];
}
return (struct palette*)&custom_palette_data;
}
struct k_means_state k_means_init(const struct image *image, struct palette *starting_palette) {
size_t item_count = image->w * image->h;
uint8_t cluster_count = starting_palette->count;
struct k_means_state state = {
.items = image,
.clusters = starting_palette,
.predicted_cluster = calloc(image->w, image->h),
.centroid_intermediate = calloc(cluster_count, sizeof(struct k_means_centroid_intermediate)),
.item_count = item_count,
};
if (state.centroid_intermediate) {
for (size_t i = 0; i < cluster_count; i++) {
state.centroid_intermediate[i].closest_present_item = starting_palette->colors[i];
state.centroid_intermediate[i].closest_present_distance = 1e20;
}
}
return state;
}
bool k_means_iteration(struct k_means_state *state) {
if (!state->predicted_cluster || !state->centroid_intermediate) {
return false;
}
bool changed = false;
// Find closest cluster
for (int i = 0; i < state->item_count; i++) {
int closest_cluster = 0;
float closest_distance = 1e20;
for (int cluster = 0; cluster < state->clusters->count; cluster++) {
union color item = state->items->pixels[i];
float dist = get_color_difference(state->clusters->colors[cluster], item);
if (dist <= closest_distance) {
closest_distance = dist;
closest_cluster = cluster;
}
if (dist < state->centroid_intermediate[cluster].closest_present_distance) {
bool can_update = true;
for (int other_cluster = 0; other_cluster < state->clusters->count; other_cluster++) {
if (other_cluster == cluster) {
continue;
}
if (state->centroid_intermediate[other_cluster].closest_present_item.v == item.v) {
can_update = false;
break;
}
}
if (can_update) {
state->centroid_intermediate[cluster].closest_present_item = item;
state->centroid_intermediate[cluster].closest_present_distance = dist;
}
}
}
if (!changed) {
changed = state->predicted_cluster[i] != closest_cluster;
}
state->predicted_cluster[i] = closest_cluster;
state->centroid_intermediate[closest_cluster].count += 1;
state->centroid_intermediate[closest_cluster].sums.r += state->items->pixels[i].rgba.r;
state->centroid_intermediate[closest_cluster].sums.g += state->items->pixels[i].rgba.g;
state->centroid_intermediate[closest_cluster].sums.b += state->items->pixels[i].rgba.b;
}
// Update centroids
for (int i = 0; i < state->clusters->count; ++i) {
struct k_means_centroid_intermediate intermediate = state->centroid_intermediate[i];
if (intermediate.count) {
union color centroid = {
.rgba = {
.r = intermediate.sums.r / intermediate.count,
.g = intermediate.sums.g / intermediate.count,
.b = intermediate.sums.b / intermediate.count,
.a = 0xff,
}
};
if (!changed) {
changed = state->clusters->colors[i].v != centroid.v;
}
state->clusters->colors[i] = centroid;
} else {
// No pixels are closest to this color
// Warp the centroid onto the closest item
state->clusters->colors[i] = intermediate.closest_present_item;
}
state->centroid_intermediate[i] = (struct k_means_centroid_intermediate) { .sums = {0, 0, 0}, .count = 0, .closest_present_item = state->clusters->colors[i], .closest_present_distance = 1e20 };
}
return changed;
}
void k_means_end(struct k_means_state *state) {
if (state->predicted_cluster) {
free(state->predicted_cluster);
}
if (state->centroid_intermediate) {
free(state->centroid_intermediate);
}
}
struct palette *palette_k_means(const struct image *image, const struct palette *prototype) {
if (!prototype) {
prototype = &cc_default_palette;
}
struct palette *palette = custom_palette_from(prototype);
struct k_means_state state = k_means_init(image, palette);
for (int i = 0; i < K_MEANS_ITERATIONS; i++) {
if (!k_means_iteration(&state)) {
fprintf(stderr, "early k-means stop at iteration %d\n", i);
break;
}
}
k_means_end(&state);
return palette;
}
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