Changeset 3523Tweet

Timestamp:

05/25/09 02:17:02 (4 years ago)

Author:

sam

Message:

Make img2twit message length configurable at runtime, improve the initial
guess by smoothing hard colour gradients, and fixed the bitstack copy
constructor to avoid corruption on exit.

File:

• libpipi/trunk/examples/img2twit.cpp (modified) (23 diffs)

libpipi/trunk/examples/img2twit.cpp

@@ +1 @@
+/*
+ *  img2twit      Image to short text message encoder/decoder
+ *  Copyright (c) 2009 Sam Hocevar <sam@hocevar.net>
+ *                All Rights Reserved
+ *
+ *  This program is free software. It comes without any warranty, to
+ *  the extent permitted by applicable law. You can redistribute it
+ *  and/or modify it under the terms of the Do What The Fuck You Want
+ *  To Public License, Version 2, as published by Sam Hocevar. See
+ *  http://sam.zoy.org/wtfpl/COPYING for more details.
+ */
+
 #include "config.h"
 
@@ -56 +68 @@
 /* How does the algorithm work: one point per cell, or two */
 #define POINTS_PER_CELL 2
+
+/*
+ * These values can be overwritten at runtime
+ */
+
+/* Debug mode */
+static bool DEBUG_MODE = false;
+
+/* The maximum message length */
+static int MAX_MSG_LEN = 140;
+
+/* Iterations per point -- larger means slower but nicer */
+static int ITERATIONS_PER_POINT = 50;
 
 /* The range value for point parameters: X Y, red/green/blue, "strength"
@@ -72 +97 @@
 
 /*
- * These values can be overwritten at runtime
- */
-
-static bool DEBUG = false;
-
-/* The maximum message length */
-static int MAX_MSG_LEN = 1140;
-
-static int ITERATIONS_PER_POINT = 50;
-
-/*
  * These values are computed at runtime
  */
@@ -273 +287 @@
 private:
     bitstack(uint32_t i) { alloc(); init(i); }
+
+    bitstack(bitstack &b)
+    {
+        alloc();
+        msb = b.msb;
+        memcpy(digits, b.digits, (MAX_MSG_LEN + 1) * sizeof(uint32_t));
+    }
 
     bitstack(bitstack const &b)
@@ -687 +708 @@
         for(unsigned int dx = 0; dx < dw; dx++)
         {
-            float min = 1.1f, max = -0.1f;
+            float min = 1.1f, max = -0.1f, mr = 0.0f, mg = 0.0f, mb = 0.0f;
             float total = 0.0;
             int xmin = 0, xmax = 0, ymin = 0, ymax = 0;
@@ -700 +721 @@
                     lum += data[4 * (ix + iy * p->w) + 1];
                     lum += data[4 * (ix + iy * p->w) + 2];
+                    lum /= 3;
+
+                    mr += data[4 * (ix + iy * p->w) + 0];
+                    mg += data[4 * (ix + iy * p->w) + 1];
+                    mb += data[4 * (ix + iy * p->w) + 2];
 
                     if(lum < min)
@@ -720 +746 @@
 
             total /= npixels;
+            mr /= npixels;
+            mg /= npixels;
+            mb /= npixels;
 
             float wmin, wmax;
@@ -731 +760 @@
 
 #if 0
-add_random_point();
-add_random_point();
+            add_random_point();
+            add_random_point();
 #else
+            /* 0.80 and 0.20 were chosen empirically, it gives a 10% better
+             * initial distance. Definitely worth it. */
 #if POINTS_PER_CELL == 1
             if(total < min + (max - min) / 2)
@@ -739 +770 @@
 #endif
             add_point(xmin, ymin,
-                      data[4 * (xmin + ymin * p->w) + 0],
-                      data[4 * (xmin + ymin * p->w) + 1],
-                      data[4 * (xmin + ymin * p->w) + 2],
+                      data[4 * (xmin + ymin * p->w) + 0] * 0.80 + mr * 0.20,
+                      data[4 * (xmin + ymin * p->w) + 1] * 0.80 + mg * 0.20,
+                      data[4 * (xmin + ymin * p->w) + 2] * 0.80 + mb * 0.20,
                       wmin);
 #if POINTS_PER_CELL == 1
@@ -749 +780 @@
 #endif
             add_point(xmax, ymax,
-                      data[4 * (xmax + ymax * p->w) + 0],
-                      data[4 * (xmax + ymax * p->w) + 1],
-                      data[4 * (xmax + ymax * p->w) + 2],
+                      data[4 * (xmax + ymax * p->w) + 0] * 0.80 + mr * 0.20,
+                      data[4 * (xmax + ymax * p->w) + 1] * 0.80 + mg * 0.20,
+                      data[4 * (xmax + ymax * p->w) + 2] * 0.80 + mb * 0.20,
                       wmax);
 #if POINTS_PER_CELL == 1
@@ -765 +796 @@
 {
     int opstats[2 * NB_OPS];
-    bitstack b;
     char const *srcname = NULL, *dstname = NULL;
     pipi_image_t *src, *tmp, *dst;
@@ -778 +808 @@
         {
             { "output",      1, NULL, 'o' },
+            { "length",      1, NULL, 'l' },
             { "quality",     1, NULL, 'q' },
             { "debug",       0, NULL, 'd' },
@@ -783 +814 @@
             { NULL,          0, NULL, 0   },
         };
-        int c = mygetopt(argc, argv, "o:q:dh", long_options, &option_index);
+        int c = mygetopt(argc, argv, "o:l:q:dh", long_options, &option_index);
 
         if(c == -1)
@@ -792 +823 @@
         case 'o':
             dstname = myoptarg;
+            break;
+        case 'l':
+            MAX_MSG_LEN = atoi(myoptarg);
+            if(MAX_MSG_LEN < 16)
+            {
+                fprintf(stderr, "Warning: rounding minimum message length to 16\n");
+                MAX_MSG_LEN = 16;
+            }
             break;
         case 'q':
@@ -797 +836 @@
             if(ITERATIONS_PER_POINT < 0)
                 ITERATIONS_PER_POINT = 0;
-            else if(ITERATIONS_PER_POINT > 10)
-                ITERATIONS_PER_POINT = 10;
+            else if(ITERATIONS_PER_POINT > 100)
+                ITERATIONS_PER_POINT = 100;
             break;
         case 'd':
-            DEBUG = true;
+            DEBUG_MODE = true;
             break;
         case 'h':
@@ -810 +849 @@
             printf("Mandatory arguments to long options are mandatory for short options too.\n");
             printf("  -o, --output <filename>   output resulting image to filename\n");
+            printf("  -l, --length <size>       message length in characters (default 140)\n");
             printf("  -q, --quality <rate>      set image quality (0 - 10) (default 5)\n");
             printf("  -d, --debug               print debug information\n");
@@ -859 +899 @@
     MAX_ITERATIONS = ITERATIONS_PER_POINT * POINTS_PER_CELL * TOTAL_CELLS;
 
+    bitstack b; /* We cannot declare this before, because MAX_MSG_LEN
+                 * wouldn't be defined. */
+
     if(dstname)
     {
@@ -910 +953 @@
 
     /* Print debug information */
-    if(DEBUG)
+    if(DEBUG_MODE)
     {
         fprintf(stderr, "Maximum message size: %i\n", MAX_MSG_LEN);
@@ -936 +979 @@
         src = pipi_median_ext(tmp, 1, 1);
         pipi_free(tmp);
-pipi_save(src, "lol.bmp");
 
         /* Analyse image */
@@ -944 +986 @@
         tmp = pipi_new(dw * RANGE_X, dh * RANGE_Y);
         render(tmp, 0, 0, dw * RANGE_X, dh * RANGE_Y);
-pipi_save(tmp, "lol2.bmp");
         error = pipi_measure_rmsd(src, tmp);
 
-        if(DEBUG)
+        if(DEBUG_MODE)
             fprintf(stderr, "Initial distance: %2.10g\n", error);
 
@@ -961 +1002 @@
             }
 
-            if(!DEBUG && !(iter % 16))
+            if(!DEBUG_MODE && !(iter % 16))
                 fprintf(stderr, "\rEncoding... %i%%",
                         iter * 100 / MAX_ITERATIONS);
@@ -1027 +1068 @@
                 tmp = scrap;
 
-                if(DEBUG)
+                if(DEBUG_MODE)
                     fprintf(stderr, "%08i -.%08i %2.010g after op%i(%i)\n",
                             iter, (int)((error - besterr) * 100000000), error,
@@ -1052 +1093 @@
         }
 
-        if(DEBUG)
+        if(DEBUG_MODE)
         {
             for(int j = 0; j < 2; j++)