Reserved black and white

kornelski · Sep 24, 2011 · 97313d9 · 97313d9
1 parent 24f6b15
commit 97313d9
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/posterize.c b/posterize.c
@@ -86,7 +86,7 @@ void reduce(const int maxcolors, float histogram[], int palette[])
 
     int nextval=0;
     int lastval=0;
-    palette[255]=255;
+    palette[255]=255; // 0 and 255 are always included
     for(int val=0; val < 256; val++)
     {
         if (palette[val]==val) {
@@ -128,6 +128,10 @@ int main(int argc, char *argv[])
         }
     }
 
+    // reserve colors for black and white
+    if (histogram[0] && maxcolors>2) maxcolors--;
+    if (histogram[255] && maxcolors>2) maxcolors--;
+
     int palette[256] = {0};
     reduce(maxcolors, histogram, palette);