Functions to allocate, reallocate, assign palettes

Deprecates --fast

Makefile

@@ -7,13 +7,13 @@ test-cpi2png: cpi2png
 	./cpi2png ./cpi-images/rat.cpi /tmp/rat.png
 
 img2cpi: img2cpi.c cc-common.o dependencies/stb/stb_image.o dependencies/stb/stb_image_resize2.o
-	$(CC) $(LDFLAGS) $^ $(LDLIBS) -o "$@" $(CPPFLAGS)
+	$(CC) $(LDFLAGS) $^ $(LDLIBS) -o "$@" $(CPPFLAGS) $(CFLAGS) $(INCPATH)
 
 cpi2png: cpi2png.c cc-common.o dependencies/stb/stb_image_write.o
-	$(CC) $(LDFLAGS) $^ $(LDLIBS) -o "$@" $(CPPFLAGS)
+	$(CC) $(LDFLAGS) $^ $(LDLIBS) -o "$@" $(CPPFLAGS) $(CFLAGS) $(INCPATH)
 
 dependencies/stb/%.o: dependencies/stb/%.h
-	$(CC) -DSTB_IMAGE_IMPLEMENTATION -DSTB_IMAGE_RESIZE_IMPLEMENTATION -DSTB_IMAGE_WRITE_IMPLEMENTATION -x c $^ -c -o "$@"
+	$(CC) -DSTB_IMAGE_IMPLEMENTATION -DSTB_IMAGE_RESIZE_IMPLEMENTATION -DSTB_IMAGE_WRITE_IMPLEMENTATION -x c $^ -c -o "$@" $(CFLAGS)
 
 wsvpn: wsvpn.o dependencies/mongoose/mongoose.o
 	$(CC) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) -o "$@"

cc-common.c

@@ -1,5 +1,51 @@
 #include "cc-common.h"
 
+#include <stdlib.h>
+
+struct palette *cc_alloc_palette(uint8_t count) {
+  struct palette *palette = calloc(1, sizeof(struct palette) + count * sizeof(union color));
+  if (!palette) {
+    return NULL;
+  }
+  uint8_t *count_ptr = (uint8_t*)&palette->count;
+  *count_ptr = count;
+  return palette;
+}
+
+struct palette *cc_realloc_palette(struct palette* ptr, uint8_t count) {
+  if (!ptr) {
+    return cc_alloc_palette(count);
+  }
+  struct palette *palette;
+  if (count > ptr->count) {
+    palette = realloc(ptr, sizeof(struct palette) + count * sizeof(union color));
+    if (!palette) {
+      return NULL;
+    }
+    for (int i = palette->count; i < count; i++) {
+      palette->colors[i] = (union color){ .v = 0 };
+    }
+  } else {
+    palette = ptr;
+  }
+  uint8_t *count_ptr = (uint8_t*)&palette->count;
+  *count_ptr = count;
+  return palette;
+}
+
+void cc_assign_palette(struct palette *dst, const struct palette *src) {
+  if (!dst || !src) {
+    return;
+  }
+  int count = dst->count;
+  if (count > src->count) {
+    count = src->count;
+  }
+  for (int i = 0; i < count; ++i) {
+    dst->colors[i] = src->colors[i];
+  }
+}
+
 const struct palette cc_default_palette = PALETTE(
   { { 0xf0, 0xf0, 0xf0, 0xff } },
   { { 0xf2, 0xb2, 0x33, 0xff } },

cc-common.h

@@ -19,6 +19,10 @@ struct palette {
 #define LENGTHOF(...) (sizeof(__VA_ARGS__) / sizeof(*(__VA_ARGS__)))
 #define PALETTE(...) { .count = LENGTHOF((union color[]){__VA_ARGS__}), .colors = {__VA_ARGS__} }
 
+struct palette *cc_alloc_palette(uint8_t count);
+struct palette *cc_realloc_palette(struct palette* ptr, uint8_t count);
+void cc_assign_palette(struct palette *dst, const struct palette *src);
+
 const extern GlyphBitmap cc_font_atlas[256];
 const extern struct palette cc_default_palette, cc_default_gray_palette;
 

img2cpi.c

@@ -16,6 +16,9 @@
 
 #define MAX_COLOR_DIFFERENCE 768
 #define K_MEANS_ITERATIONS 4
+#ifndef HAS_POPCNT
+# define HAS_POPCNT 1
+#endif
 
 struct cc_char {
   unsigned char character;
@@ -23,8 +26,12 @@ struct cc_char {
 };
 
 struct arguments {
-  bool fast_mode;
   int width, height;
+  enum conversion_mode {
+    CONVERSION_BLOCK,
+    CONVERSION_CHAR_PRECISE,
+    CONVERSION_CHAR_FAST,
+  } conversion_mode;
   enum cpi_version {
     CPI_VERSION_AUTO,
     CPI_VERSION_RAW,
@@ -51,9 +58,9 @@ struct arguments {
   char *input_path;
   char *output_path;
 } args = {
-  .fast_mode = false,
   .width = 4 * 8 - 1, // 4x3 blocks screen
   .height = 3 * 6 - 2,
+  .conversion_mode = CONVERSION_CHAR_PRECISE,
   .cpi_version = CPI_VERSION_AUTO,
   .placement = PLACEMENT_FULL,
   .input_path = NULL,
@@ -101,7 +108,7 @@ void image_unload(struct image *img);
 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);
+void convert_8x11(const struct image_pal *img, struct cc_char *characters, bool precise);
 
 // Only one global custom palette is maintained
 struct palette *custom_palette_resize(uint8_t size);
@@ -112,6 +119,14 @@ 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);
 
+inline static int popcnt32(uint32_t mask);
+inline static int glyph_hamming_distance(const GlyphBitmap *lhs, const GlyphBitmap *rhs);
+inline static float weighted_glyph_hamming_distance(const GlyphBitmap *lhs, const GlyphBitmap *rhs, const typeof(float[11][8]) *weights);
+uint8_t closest_glyph_symbol_fast(const GlyphBitmap *target);
+uint8_t closest_glyph_symbol_precise(const GlyphBitmap *target, const typeof(float[11][8]) *weights);
+void construct_chunk_color_glyph(GlyphBitmap *result, typeof(float[11][8]) *weights, const typeof(float[8][11][0x10]) *chunk_palette_diffs, uint8_t color_pair);
+inline static uint8_t closest_chunk_color_symbol(const typeof(float[8][11][0x10]) *chunk_palette_diffs, uint8_t color_pair, bool precise);
+
 const char *known_file_extensions[] = {
   ".png", ".jpg", ".jpeg", ".jfif", ".jpg", ".gif",
   ".tga", ".bmp", ".hdr", ".pnm", 0
@@ -125,7 +140,14 @@ static const struct optiondocs {
   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 },
+  { 'f', "fast",        0,            "Use fast (old) method for picking characters and colors\n"
+             "                        DEPRECATED: use `--mode block` instead\n", 0 },
+  { 'm', "mode",        "mode",       "Set conversion mode",
+    (struct optiondocs_choice[]) {
+      { "block", "Use fast (old) method for picking characters and colors" },
+      { "char-precise", "Select among all characters with maximum precision" },
+      { "char-fast", "Select among all characters with reduced precision" },
+      { 0, 0 } } },
   { 'W', "width",       "width",      "Width in characters", 0 },
   { 'h', "height",      "height",     "Height in characters", 0 },
   { 'P', "palette",     "palette",    "Use specific palette.\n"
@@ -169,7 +191,7 @@ int main(int argc, char **argv) {
   }
 
   struct image *canvas;
-  if (args.fast_mode) {
+  if (args.conversion_mode == CONVERSION_BLOCK) {
     canvas = image_new(args.width * 2, args.height * 3);
   } else {
     canvas = image_new(args.width * 8, args.height * 11);
@@ -222,10 +244,19 @@ int main(int argc, char **argv) {
     return EXIT_FAILURE;
   }
 
-  if (args.fast_mode) {
+  switch (args.conversion_mode) {
+  case CONVERSION_BLOCK:
     convert_2x3(quantized_image, characters);
-  } else {
-    convert_8x11(quantized_image, characters);
+    break;
+  case CONVERSION_CHAR_PRECISE:
+    convert_8x11(quantized_image, characters, true);
+    break;
+  case CONVERSION_CHAR_FAST:
+    convert_8x11(quantized_image, characters, false);
+    break;
+  default:
+    fprintf(stderr, "BUG: invalid args.conversion_mode\n");
+    return EXIT_FAILURE;
   }
 
   // TODO: implement something other than CPIv0
@@ -254,6 +285,7 @@ bool parse_cmdline(int argc, char **argv) {
   static struct option options[] = {
     { "help",         no_argument,        0, 'h' },
     { "fast",         no_argument,        0, 'f' },
+    { "mode",         required_argument,  0, 'm' },
     { "width",        required_argument,  0, 'W' },
     { "height",       required_argument,  0, 'H' },
     { "cpi_version",  required_argument,  0, 'V' },
@@ -264,7 +296,7 @@ bool parse_cmdline(int argc, char **argv) {
 
   while (true) {
     int option_index = 0;
-    int c = getopt_long(argc, argv, "hfW:H:V:p:P:", options, &option_index);
+    int c = getopt_long(argc, argv, "hfm:W:H:V:p:P:", options, &option_index);
     if (c == -1) break;
     if (c == 0) c = options[option_index].val;
     if (c == '?') break;
@@ -275,11 +307,23 @@ bool parse_cmdline(int argc, char **argv) {
         exit(EXIT_SUCCESS);
         break;
       case 'f': // --fast
-        args.fast_mode = true;
+        args.conversion_mode = CONVERSION_BLOCK;
+        fprintf(stderr, "Warning: `--fast` is deprecated, use `--mode block` instead\n");
         if (args.cpi_version != CPI_VERSION_AUTO) {
           fprintf(stderr, "Warning: text mode ignores version\n");
         }
         break;
+      case 'm': // --mode
+        {
+          if (0 == strcmp(optarg, "block") || 0 == strcmp(optarg, "fast") || 0 == strcmp(optarg, "2x3")) {
+            args.conversion_mode = CONVERSION_BLOCK;
+          } else if (0 == strcmp(optarg, "char") || 0 == strcmp(optarg, "char-precise") || 0 == strcmp(optarg, "8x11") || 0 == strcmp(optarg, "6x9")) {
+            args.conversion_mode = CONVERSION_CHAR_PRECISE;
+          } else if (0 == strcmp(optarg, "char-fast") || 0 == strcmp(optarg, "8x11-fast") || 0 == strcmp(optarg, "6x9-fast")) {
+            args.conversion_mode = CONVERSION_CHAR_FAST;
+          }
+        }
+        break;
       case 'W': // --width
         args.width = atoi(optarg);
         break;
@@ -593,7 +637,7 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
   }
 }
 
-void convert_8x11(const struct image_pal *img, struct cc_char *characters) {
+void convert_8x11(const struct image_pal *img, struct cc_char *characters, bool precise) {
   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++) {
@@ -618,11 +662,9 @@ void convert_8x11(const struct image_pal *img, struct cc_char *characters) {
 
       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++) {
+      for (int color = 0x00; color <= 0xff; color++) {
+        {
+          const int sym = closest_chunk_color_symbol(&chunk_palette_diffs, color, precise);
           float difference = 0;
           for (int oy = 0; oy < 11; oy++) {
             unsigned char sym_line = cc_font_atlas[sym][oy];
@@ -779,3 +821,99 @@ struct palette *palette_k_means(const struct image *image, const struct palette
 
   return palette;
 }
+
+int popcnt32(uint32_t mask) {
+#if HAS_POPCNT
+  return __builtin_popcount(mask);
+#else
+  int res = 0;
+  for (; mask; mask >>= 1) {
+    res += mask & 1;
+  }
+  return res;
+#endif
+}
+
+int glyph_hamming_distance(const GlyphBitmap *lhs, const GlyphBitmap *rhs) {
+  int dist = 0;
+  dist += popcnt32(*((uint32_t*)&((*lhs)[0])) ^ *((uint32_t*)&((*rhs)[0])));
+  dist += popcnt32(*((uint32_t*)&((*lhs)[4])) ^ *((uint32_t*)&((*rhs)[4])));
+  dist += popcnt32(*((uint16_t*)&((*lhs)[8])) ^ *((uint16_t*)&((*rhs)[8])));
+  dist += popcnt32( (           ((*lhs)[10])) ^  (           ((*rhs)[10])));
+  return dist;
+}
+
+float weighted_glyph_hamming_distance(const GlyphBitmap *lhs, const GlyphBitmap *rhs, const typeof(float[11][8]) *weights) {
+  float dist = 0;
+  for (int oy = 0; oy < 11; oy++) {
+    uint8_t sym_line = (*lhs)[oy] ^ (*rhs)[oy];
+    for (int ox = 0; ox < 8; ox++) {
+      bool lit = sym_line & (0x80 >> ox);
+      if (lit) {
+        dist += (*weights)[oy][ox];
+      }
+    }
+  }
+  return dist;
+}
+
+uint8_t closest_glyph_symbol_fast(const GlyphBitmap *target) {
+  uint8_t best = 0x01;
+  int best_dist = glyph_hamming_distance(target, &cc_font_atlas[best]);
+  for (int sym = 0x02; sym <= 0xFF; sym++) {
+    if (sym == '\t' || sym == '\n' || sym == '\r' || sym == '\x0e') {
+      continue;
+    }
+    int dist = glyph_hamming_distance(target, &cc_font_atlas[sym]);
+    if (dist <= best_dist) {
+      best_dist = dist;
+      best = sym;
+    }
+  }
+  return best;
+}
+
+uint8_t closest_glyph_symbol_precise(const GlyphBitmap *target, const typeof(float[11][8]) *weights) {
+  uint8_t best = 0x01;
+  float best_dist = weighted_glyph_hamming_distance(target, &cc_font_atlas[best], weights);
+  for (int sym = 0x02; sym <= 0xFF; sym++) {
+    if (sym == '\t' || sym == '\n' || sym == '\r' || sym == '\x0e') {
+      continue;
+    }
+    float dist = weighted_glyph_hamming_distance(target, &cc_font_atlas[sym], weights);
+    if (dist <= best_dist) {
+      best_dist = dist;
+      best = sym;
+    }
+  }
+  return best;
+}
+
+void construct_chunk_color_glyph(GlyphBitmap *result, typeof(float[11][8]) *weights, const typeof(float[8][11][0x10]) *chunk_palette_diffs, uint8_t color_pair) {
+  uint8_t fg = color_pair >> 4,
+          bg = color_pair & 0xF;
+  for (int oy = 0; oy < 11; oy++) {
+    uint8_t sym_line = 0;
+    for (int ox = 0; ox < 8; ox++) {
+      // We want lit to minimize distance, so lit should be trueish when background color is further from the pixel than foreground color
+      float dist_diff = (*chunk_palette_diffs)[ox][oy][bg] - (*chunk_palette_diffs)[ox][oy][fg];
+      uint8_t lit = dist_diff > 0;
+      sym_line |= lit << (7 - ox);
+      if (weights) {
+        (*weights)[oy][ox] = lit ? dist_diff : -dist_diff;
+      }
+    }
+    (*result)[oy] = sym_line;
+  }
+}
+
+uint8_t closest_chunk_color_symbol(const typeof(float[8][11][0x10]) *chunk_palette_diffs, uint8_t color_pair, bool precise) {
+  GlyphBitmap glyph;
+  float weights[11][8];
+  construct_chunk_color_glyph(&glyph, precise ? &weights : NULL, chunk_palette_diffs, color_pair);
+  if (precise) {
+    return closest_glyph_symbol_precise(&glyph, &weights);
+  } else {
+    return closest_glyph_symbol_fast(&glyph);
+  }
+}