Functions to allocate, reallocate, assign palettes

Deprecates --fast

Makefile

@@ -7,18 +7,15 @@ 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) $(LDLIBS) -o "$@"
 
-clean:
-	$(RM) -v img2cpi cpi2png wsvpn wsvpn.o cc-common.o dependencies/stb/*.o
-
 .PHONY: all

cc-common.c

@@ -1,33 +1,48 @@
 #include "cc-common.h"
 
-int read_varint(FILE *fp, unsigned int *out) {
-  int position = 0;
+#include <stdlib.h>
 
-  while (true) {
-    unsigned char curr = fgetc(fp);
-    *out |= (curr & 0x7F) << position;
-
-    if ((curr & 0x80) == 0) break;
-
-    position += 7;
-
-    if (position >= 32) return -position / 7;
+struct palette *cc_alloc_palette(uint8_t count) {
+  struct palette *palette = calloc(1, sizeof(struct palette) + count * sizeof(union color));
+  if (!palette) {
+    return NULL;
   }
-
-  return (position + 7) / 7;
+  uint8_t *count_ptr = (uint8_t*)&palette->count;
+  *count_ptr = count;
+  return palette;
 }
 
-int write_varint(FILE *fp, unsigned int in) {
-  unsigned mask = 0xFFFFFF80;
-  int written = 0;
-  while (true) {
-    if ((in & mask) == 0) {
-      fputc(in & 0xff, fp);
-      return written + 1;
+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;
     }
-    fputc((in & 0x7F) | 0x80, fp);
-    written++;
-    in >>= 7;
+    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];
   }
 }
 

cc-common.h

@@ -2,8 +2,6 @@
 #define _CC_COMMON_H_
 
 #include <stdint.h>
-#include <stdio.h>
-#include <stdbool.h>
 
 typedef uint8_t GlyphBitmap[11];
 
@@ -21,11 +19,11 @@ 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;
 
-
-int read_varint(FILE *fp, unsigned int *out);
-int write_varint(FILE *fp, unsigned int in);
-
 #endif

cpi2png.c

@@ -10,6 +10,8 @@
 
 #include "cc-common.h"
 
+bool read_varint(FILE *fp, unsigned int *out);
+
 int main(int argc, char **argv) {
   if (argc < 3) {
     fprintf(stderr, "Usage: %s [input.cpi] [output.png]\n", argv[0]);
@@ -41,8 +43,8 @@ int main(int argc, char **argv) {
     height = fgetc(fp_in);
     (void)fgetc(fp_in); // XXX: ignore scale
   } else if (version == 1) {
-    assert(read_varint(fp_in, &width) > 0 && "Failed to read width varint");
-    assert(read_varint(fp_in, &height) > 0 && "Failed to read height varint");
+    assert(read_varint(fp_in, &width) && "Failed to read width varint");
+    assert(read_varint(fp_in, &height) && "Failed to read height varint");
   } else {
     assert(false && "Failed to read size: unsupported version");
   }
@@ -53,7 +55,7 @@ int main(int argc, char **argv) {
   // XXX: may change in future when we introduce variable-size palettes
   // though, it may never change, if I'm being honest. Why would I choose
   // worse image quality with less colors when I can use all of them?
-  union color colors[16] = { 0 };
+  union color *colors = calloc(16, sizeof(union color));
 
   // NOTE: our `union color` type is 4 bytes long, while palette stored in the
   // file itself uses 3 bytes per color, so we can't just `fread` them at once,
@@ -65,13 +67,10 @@ int main(int argc, char **argv) {
     colors[i].rgba.a = 0xff;
   }
 
-  unsigned char *buffer = calloc(width * height, 2);
-  fread(buffer, 2, width * height, fp_in);
-
   for (int y = 0; y < height; y++) {
     for (int x = 0; x < width; x++) {
-      unsigned char sym = buffer[(x + y * width) * 2];
-      unsigned char color = buffer[(x + y * width) * 2 + 1];
+      unsigned char sym = fgetc(fp_in);
+      unsigned char color = fgetc(fp_in);
       union color background = colors[color & 0xF];
       union color foreground = colors[color >> 4];
       for (int oy = 0; oy < 9; oy++) {
@@ -85,7 +84,25 @@ int main(int argc, char **argv) {
 
   stbi_write_png(argv[2], width * 6, height * 9, 4, canvas, 0);
 
+  free(colors);
   free(canvas);
   fclose(fp_in);
   return EXIT_SUCCESS;
 }
+
+bool read_varint(FILE *fp, unsigned int *out) {
+  int position = 0;
+
+  while (true) {
+    unsigned char curr = fgetc(fp);
+    *out |= (curr & 0x7F) << position;
+
+    if ((curr & 0x80) == 0) break;
+
+    position += 7;
+
+    if (position >= 32) return false;
+  }
+
+  return true;
+}

img2cpi.c

@@ -13,16 +13,12 @@
 #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
-#define PROGRESS_BAR_WIDTH 24
-
-#define TOSTRNAME(M) #M
-#define TOSTR(M) TOSTRNAME(M)
+#ifndef HAS_POPCNT
+# define HAS_POPCNT 1
+#endif
 
 struct cc_char {
   unsigned char character;
@@ -30,9 +26,12 @@ struct cc_char {
 };
 
 struct arguments {
-  bool fast_mode;
-  bool verbose;
   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,
@@ -59,16 +58,16 @@ struct arguments {
   char *input_path;
   char *output_path;
 } args = {
-  .fast_mode = false,
-  .verbose = 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,
   .output_path = NULL,
   .palette = NULL,
-  .palette_type = PALETTE_AUTO
+  .palette_type = PALETTE_DEFAULT // TODO(kc): change to PALETTE_AUTO when
+                                  // k-means is implemented
 };
 
 struct image {
@@ -99,23 +98,17 @@ struct k_means_state {
 
 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 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_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);
+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);
@@ -126,6 +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
@@ -139,8 +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 },
-  { 'v', "verbose",     0,            "Increase verbosity", 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"
@@ -171,8 +178,6 @@ static const struct optiondocs {
   { 0 }
 };
 
-static char progress_bar[PROGRESS_BAR_WIDTH];
-
 int main(int argc, char **argv) {
   if (!parse_cmdline(argc, argv)) {
     show_help(argv[0], false, stderr);
@@ -185,16 +190,11 @@ int main(int argc, char **argv) {
     return EXIT_FAILURE;
   }
 
-  if (args.verbose) {
-    memset(progress_bar, '#', PROGRESS_BAR_WIDTH);
-    printf("Input image: %dx%d\n", src_image->w, src_image->h);
-  }
-
   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 * 6, args.height * 9);
+    canvas = image_new(args.width * 8, args.height * 11);
   }
 
   if (!canvas) {
@@ -202,18 +202,14 @@ int main(int argc, char **argv) {
     return EXIT_FAILURE;
   }
 
-  if (args.verbose) {
-    printf("Output image canvas: %dx%d\n", canvas->w, canvas->h);
-  }
-
   // 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; // TODO
-    case PALETTE_PATH: assert(0 && "Not implemented"); break; // TODO
+    case PALETTE_LIST: assert(0 && "Not implemented"); break;
+    case PALETTE_PATH: assert(0 && "Not implemented"); break;
     default: assert(0 && "Unreachable");
   }
 
@@ -223,10 +219,6 @@ int main(int argc, char **argv) {
     int new_w, new_h;
     get_size_keep_aspect(src_image->w, src_image->h, canvas->w, canvas->h, &new_w, &new_h);
 
-    if (args.verbose) {
-      printf("Scaling down to: %dx%d\n", 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");
@@ -252,33 +244,35 @@ int main(int argc, char **argv) {
     return EXIT_FAILURE;
   }
 
-  if (args.verbose) {
-    printf("Converting image ");
-  }
-
-  if (args.fast_mode) {
-    if (args.verbose) {
-      printf(" using fast method\n");
-    }
+  switch (args.conversion_mode) {
+  case CONVERSION_BLOCK:
     convert_2x3(quantized_image, characters);
-  } else {
-    if (args.verbose) {
-      printf(" using slow method\n");
-    }
-    convert_6x9(quantized_image, characters);
-  }
-
-  if (args.verbose) {
-    printf("Conversion done, saving image ");
+    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
   FILE *fp = fopen(args.output_path, "wb");
-  if (args.width < 256 && args.height < 256) {
-    printf(" using cpiv0\n");
-    save_cpi_0(fp, palette, characters, args.width, args.height);
-  } else {
-    printf(" using cpiv1\n");
-    save_cpi_1(fp, palette, characters, args.width, args.height);
+  fwrite("CCPI", 1, 4, fp);
+  fputc(args.width, fp);
+  fputc(args.height, fp);
+  fputc(0x00, fp);
+  for (int i = 0; i < 16; i++) {
+    fputc(palette->colors[i].rgba.r, fp);
+    fputc(palette->colors[i].rgba.g, fp);
+    fputc(palette->colors[i].rgba.b, fp);
+  }
+  for (int i = 0; i < args.width * args.height; i++) {
+    fputc(characters[i].character, fp);
+    fputc(characters[i].bg | (characters[i].fg << 4), fp);
   }
   fclose(fp);
 
@@ -287,51 +281,11 @@ int main(int argc, char **argv) {
   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' },
+    { "mode",         required_argument,  0, 'm' },
     { "width",        required_argument,  0, 'W' },
     { "height",       required_argument,  0, 'H' },
     { "cpi_version",  required_argument,  0, 'V' },
@@ -342,7 +296,7 @@ bool parse_cmdline(int argc, char **argv) {
 
   while (true) {
     int option_index = 0;
-    int c = getopt_long(argc, argv, "hvfW: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;
@@ -353,13 +307,22 @@ 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 'v': // --verbose
-        args.verbose = true;
+      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);
@@ -622,14 +585,6 @@ float get_color_brightness(union color clr) {
 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++) {
-    if (args.verbose) {
-      int sz = PROGRESS_BAR_WIDTH - (y * PROGRESS_BAR_WIDTH / h);
-      printf("\r[%-" TOSTR(PROGRESS_BAR_WIDTH) ".*s|%7.3f%%|%4d/%4d]",
-          PROGRESS_BAR_WIDTH - sz, progress_bar + sz,
-          100.0 * (y + 1) / h,
-          y + 1, h);
-      fflush(stdout);
-    }
     for (int x = 0; x < w; x++) {
       unsigned char darkest_i = 0, brightest_i = 0;
       float darkest_diff = 0xffffff, brightest_diff = 0;
@@ -680,13 +635,10 @@ void convert_2x3(const struct image_pal *img, struct cc_char *characters) {
       characters[x + y * w].fg = brightest_i;
     }
   }
-  if (args.verbose) {
-    printf("\n");
-  }
 }
 
-void convert_6x9(const struct image_pal *img, struct cc_char *characters) {
-  int w = img->w / 6, h = img->h / 9;
+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++) {
     for (int output_color = 0x0; output_color < 0x10 && output_color < img->palette->count; output_color++) {
@@ -695,23 +647,12 @@ void convert_6x9(const struct image_pal *img, struct cc_char *characters) {
   }
 
   for (int y = 0; y < h; y++) {
-    if (args.verbose) {
-      int sz = PROGRESS_BAR_WIDTH - (y * PROGRESS_BAR_WIDTH / h);
-      printf("\r[%-" TOSTR(PROGRESS_BAR_WIDTH) ".*s|%7.3f%%|%4d/%4d]",
-          PROGRESS_BAR_WIDTH - sz, progress_bar + sz,
-          100.0 * (y + 1) / h,
-          y + 1, h);
-      fflush(stdout);
-    }
-#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++) {
+      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 * 9 + oy) * w) * 6
+            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];
@@ -721,15 +662,13 @@ void convert_6x9(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 < 9; oy++) {
+          for (int oy = 0; oy < 11; oy++) {
             unsigned char sym_line = cc_font_atlas[sym][oy];
-            for (int ox = 0; ox < 6; ox++) {
+            for (int ox = 0; ox < 8; ox++) {
               bool lit = sym_line & (0x80 >> ox);
               difference += chunk_palette_diffs[ox][oy][lit ? color >> 4 : color & 0xF];
             }
@@ -746,9 +685,6 @@ void convert_6x9(const struct image_pal *img, struct cc_char *characters) {
       characters[x + y * w].fg = closest_color >> 4;
     }
   }
-  if (args.verbose) {
-    printf("\n");
-  }
 }
 
 struct {
@@ -885,3 +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);
+  }
+}

mess/gen-weights.py

@@ -1,25 +0,0 @@
-from PIL import Image
-from collections import Counter
-
-with Image.open("./cc_font.png") as im:
-    pixels = im.load()
-    weights = [0 for _ in range(6 * 9)]
-    for char in range(256):
-        ctx, cty = (char % 16) * 8, (char // 16) * 11
-        for oy in range(9):
-            for ox in range(6):
-                pix = int(pixels[ctx + ox + 1, cty + oy + 1][0])  # type: ignore
-                weights[ox + 6 * oy] += 1 if pix else 0
-
-    with Image.new("L", (6, 9), 0) as im_out:
-        for y in range(9):
-            for x in range(6):
-                print("%3d" % weights[x + 6 * y], end="\t")
-                im_out.putpixel((x, y), weights[x + 6 * y])
-            print()
-
-        im_out.save("avg.png")
-
-    print(dict(enumerate([
-        iv[0] for iv in sorted(enumerate(weights), key=lambda iv: iv[1])
-    ])))