Merge branch 'vftdan-palette-k-means'

.gitignore

@@ -0,0 +1,4 @@
+img2cpi
+img2cpi.o
+wsvpn
+wsvpn.o

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "dependencies/stb"]
+	path = dependencies/stb
+	url = https://github.com/nothings/stb
+[submodule "dependencies/mongoose"]
+	path = dependencies/mongoose
+	url = https://github.com/cesanta/mongoose

Makefile

@@ -0,0 +1,9 @@
+CPPFLAGS += -Idependencies -Idependencies/mongoose
+LDLIBS += -lm
+
+all: img2cpi wsvpn
+
+wsvpn: wsvpn.o dependencies/mongoose/mongoose.o
+	$(CC) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) -o "$@"
+
+.PHONY: all

dependencies/mongoose

@@ -0,0 +1 @@
+Subproject commit 3525f044f551816dc1469f445fc16b94d51a1e78

dependencies/stb

@@ -0,0 +1 @@
+Subproject commit f75e8d1cad7d90d72ef7a4661f1b994ef78b4e31

img2cpi.c

@@ -13,6 +13,7 @@
 #include <stdbool.h>
 
 #define MAX_COLOR_DIFFERENCE 768
+#define K_MEANS_ITERATIONS 4
 
 struct rgba { uint8_t r, g, b, a; };
 union color {
@@ -23,9 +24,15 @@ struct cc_char {
   unsigned char character;
   unsigned char bg, fg;
 };
+struct palette {
+  const uint8_t count;
+  union color colors[] __attribute__((counted_by(count)));
+};
+#define LENGTHOF(...) (sizeof(__VA_ARGS__) / sizeof(*(__VA_ARGS__)))
+#define PALETTE(...) { .count = LENGTHOF((union color[]){__VA_ARGS__}), .colors = {__VA_ARGS__} }
 
 const extern char font_atlas[256][11];
-const extern union color DEFAULT_PALETTE[16], DEFAULT_GRAY_PALETTE[16];
+const extern struct palette DEFAULT_PALETTE, DEFAULT_GRAY_PALETTE;
 
 struct arguments {
   bool fast_mode;
@@ -76,8 +83,22 @@ struct image {
 struct image_pal {
   int w, h;
   uint8_t *pixels;
-  const union color *palette;
+  const struct palette *palette;
-  size_t palette_size;
+};
+
+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);
@@ -85,7 +106,7 @@ 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 union color *colors, size_t n_colors);
+struct image_pal *image_quantize(struct image *original, const struct palette *palette);
 float get_color_difference(union color a, union color b);
 float get_color_brightness(union color clr);
 void image_unload(struct image *img);
@@ -94,6 +115,15 @@ 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_8x11(const struct image_pal *img, struct cc_char *characters);
 
+// 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
@@ -163,11 +193,11 @@ int main(int argc, char **argv) {
   }
 
   // TODO: load palette, maybe calculate it too? k-means?
-  const union color *palette = DEFAULT_PALETTE;
+  const struct palette *palette = &DEFAULT_PALETTE;
   switch (args.palette_type) {
-    case PALETTE_DEFAULT: palette = DEFAULT_PALETTE; break;
+    case PALETTE_DEFAULT: palette = &DEFAULT_PALETTE; break;
-    case PALETTE_DEFAULT_GRAY: palette = DEFAULT_GRAY_PALETTE; break;
+    case PALETTE_DEFAULT_GRAY: palette = &DEFAULT_GRAY_PALETTE; break;
-    case PALETTE_AUTO: assert(0 && "Not implemented"); break;
+    case PALETTE_AUTO: palette = palette_k_means(src_image, &DEFAULT_PALETTE); break;
     case PALETTE_LIST: assert(0 && "Not implemented"); break;
     case PALETTE_PATH: assert(0 && "Not implemented"); break;
     default: assert(0 && "Unreachable");
@@ -198,7 +228,7 @@ int main(int argc, char **argv) {
   // 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, 16);
+  struct image_pal *quantized_image = image_quantize(canvas, palette);
   if (!quantized_image) {
     fprintf(stderr, "Error: failed to open the file\n");
     return EXIT_FAILURE;
@@ -217,9 +247,9 @@ int main(int argc, char **argv) {
   fputc(args.height, fp);
   fputc(0x00, fp);
   for (int i = 0; i < 16; i++) {
-    fputc(palette[i].rgba.r, fp);
+    fputc(palette->colors[i].rgba.r, fp);
-    fputc(palette[i].rgba.g, fp);
+    fputc(palette->colors[i].rgba.g, fp);
-    fputc(palette[i].rgba.b, fp);
+    fputc(palette->colors[i].rgba.b, fp);
   }
   for (int i = 0; i < args.width * args.height; i++) {
     fputc(characters[i].character, fp);
@@ -486,19 +516,18 @@ void get_size_keep_aspect(int w, int h, int dw, int dh, int *ow, int *oh)
   }
 }
 
-struct image_pal *image_quantize(struct image *original, const union color *colors, size_t n_colors) {
+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 = colors;
+  out->palette = palette;
-  out->palette_size = n_colors;
 
   for (int i = 0; i < out->w * out->h; i++) {
     int closest_color = 0;
     float closest_distance = 1e20;
-    for (int color = 0; color < n_colors; color++) {
+    for (int color = 0; color < palette->count; color++) {
-      float dist = get_color_difference(colors[color], original->pixels[i]);
+      float dist = get_color_difference(palette->colors[color], original->pixels[i]);
       if (dist <= closest_distance) {
         closest_distance = dist;
         closest_color = color;
@@ -531,7 +560,7 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
       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[pix]);
+          float brightness = get_color_brightness(img->palette->colors[pix]);
           if (brightness >= brightest_diff) {
             brightest_i = pix;
             brightest_diff = brightness;
@@ -549,8 +578,8 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
         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[darkest_i], img->palette[pix]);
+          float diff_bg = get_color_difference(img->palette->colors[darkest_i], img->palette->colors[pix]);
-          float diff_fg = get_color_difference(img->palette[brightest_i], img->palette[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];
           }
@@ -559,8 +588,8 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
 
       {
         unsigned char pix = img->pixels[1 + (x + (y * 3 + 2) * w) * 2];
-        float diff_bg = get_color_difference(img->palette[darkest_i], img->palette[pix]);
+        float diff_bg = get_color_difference(img->palette->colors[darkest_i], img->palette->colors[pix]);
-        float diff_fg = get_color_difference(img->palette[brightest_i], img->palette[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;
@@ -578,8 +607,27 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
 
 void convert_8x11(const struct image_pal *img, struct cc_char *characters) {
   int w = img->w / 8, h = img->h / 11;
+  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++) {
     for (int x = 0; x < w; x++) {
+      float chunk_palette_diffs[8][11][0x10] = {{{(float) 0xffffff}}};
+      for (int ox = 0; ox < 8; ox++) {
+        for (int oy = 0; oy < 11; oy++) {
+          uint8_t pixel_unresolved = img->pixels[
+            ox + (x + (y * 11 + oy) * w) * 8
+          ];
+          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++) {
@@ -587,17 +635,12 @@ void convert_8x11(const struct image_pal *img, struct cc_char *characters) {
           continue;
         }
         for (int color = 0x00; color <= 0xff; color++) {
-          union color cell_bg = img->palette[color & 0xF],
-          cell_fg = img->palette[color >> 4];
           float difference = 0;
           for (int oy = 0; oy < 11; oy++) {
             unsigned char sym_line = font_atlas[sym][oy];
             for (int ox = 0; ox < 8; ox++) {
               bool lit = sym_line & (0x80 >> ox);
-              union color pixel = img->palette[img->pixels[
+              difference += chunk_palette_diffs[ox][oy][lit ? color >> 4 : color & 0xF];
-                ox + (x + (y * 11 + oy) * w) * 8
-              ]];
-              difference += get_color_difference(pixel, lit ? cell_fg : cell_bg);
             }
           }
           if (difference <= min_diff) {
@@ -614,7 +657,142 @@ void convert_8x11(const struct image_pal *img, struct cc_char *characters) {
   }
 }
 
-const union color DEFAULT_PALETTE[16] = {
+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 = &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;
+}
+
+const struct palette DEFAULT_PALETTE = PALETTE(
   { { 0xf0, 0xf0, 0xf0, 0xff } },
   { { 0xf2, 0xb2, 0x33, 0xff } },
   { { 0xe5, 0x7f, 0xd8, 0xff } },
@@ -631,7 +809,7 @@ const union color DEFAULT_PALETTE[16] = {
   { { 0x57, 0xa6, 0x4e, 0xff } },
   { { 0xcc, 0x4c, 0x4c, 0xff } },
   { { 0x11, 0x11, 0x11, 0xff } }
-}, DEFAULT_GRAY_PALETTE[16] = {
+), DEFAULT_GRAY_PALETTE = PALETTE(
   { { 0xf0, 0xf0, 0xf0, 0xff } },
   { { 0x9d, 0x9d, 0x9d, 0xff } },
   { { 0xbe, 0xbe, 0xbe, 0xff } },
@@ -648,7 +826,7 @@ const union color DEFAULT_PALETTE[16] = {
   { { 0x6e, 0x6e, 0x6e, 0xff } },
   { { 0x76, 0x76, 0x76, 0xff } },
   { { 0x11, 0x11, 0x11, 0xff } }
-};
+);
 
 const char font_atlas[256][11] = {
   { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, },