* img2rubik.c: add quick and dirty dithering code to img2rubik.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2738 92316355-f0b4-4df1-b90c-862c8a59935f

examples/img2rubik.c

@@ -12,16 +12,105 @@ int main(int argc, char *argv[])
 {
     static double const mypal[] =
     {
-        0.900, 0.001, 0.001, /* red */
-        0.001, 0.800, 0.001, /* green */
-        0.005, 0.001, 0.500, /* blue */
+#if 1
+        0.800, 0.001, 0.001, /* red */
+        0.001, 0.700, 0.001, /* green */
+        0.005, 0.001, 0.600, /* blue */
         0.900, 0.900, 0.900, /* white */
         0.900, 0.900, 0.001, /* yellow */
-        0.800, 0.400, 0.001, /* orange */
+        0.850, 0.450, 0.001, /* orange */
+#else
+        1,1,1,
+        0,.05,.60,
+        1,0,0,
+        .15,.76,0,
+        .96,1,0,
+        1,.61,0,
+#endif
     };
+#define NCOLORS ((int)(sizeof(mypal)/sizeof(*mypal)/3))
+
+    int x, y, w, h;
 
     pipi_image_t *src = pipi_load(argv[1]);
-    pipi_image_t *dst = pipi_reduce(src, 6, mypal);
+    pipi_image_t *dst = pipi_reduce(src, NCOLORS, mypal);
+
+    pipi_pixels_t *p = pipi_getpixels(dst, PIPI_PIXELS_RGBA_F);
+    float *data = (float *)p->pixels;
+    w = p->w;
+    h = p->h;
+
+    for(y = 0; y < h; y++)
+        for(x = 0; x < w; x++)
+        {
+            double pr, pg, pb, qr, qg, qb, er, eg, eb;
+
+            pr = data[4 * (y * w + x) + 2];
+            pg = data[4 * (y * w + x) + 1];
+            pb = data[4 * (y * w + x)];
+
+            double dist = 10.0;
+            int n, best = -1;
+
+            for(n = 0; n < NCOLORS; n++)
+            {
+                double dr, dg, db, d;
+
+                dr = pr - mypal[n * 3];
+                dg = pg - mypal[n * 3 + 1];
+                db = pb - mypal[n * 3 + 2];
+
+                d = dr * dr + dg * dg + db * db;
+                //d = 0.299 * dr * dr + 0.587 * dg * dg + 0.114 * db * db;
+
+                if(d < dist)
+                {
+                    best = n;
+                    dist = d;
+                }
+            }
+
+            qr = mypal[best * 3];
+            qg = mypal[best * 3 + 1];
+            qb = mypal[best * 3 + 2];
+
+            er = (pr - qr) / 16;
+            eg = (pg - qg) / 16;
+            eb = (pb - qb) / 16;
+
+            if(x < w - 1)
+            {
+                data[4 * (y * w + x + 1) + 2] += 7 * er;
+                data[4 * (y * w + x + 1) + 1] += 7 * eg;
+                data[4 * (y * w + x + 1)] += 7 * eb;
+            }
+
+            if(y < h - 1)
+            {
+                if(x < w - 1)
+                {
+                    data[4 * (y * w + x + w + 1) + 2] += 1 * er;
+                    data[4 * (y * w + x + w + 1) + 1] += 1 * eg;
+                    data[4 * (y * w + x + w + 1)] += 1 * eb;
+                }
+
+                data[4 * (y * w + x + w) + 2] += 5 * er;
+                data[4 * (y * w + x + w) + 1] += 5 * eg;
+                data[4 * (y * w + x + w)] += 5 * eb;
+
+                if(x > 0)
+                {
+                    data[4 * (y * w + x + w - 1) + 2] += 3 * er;
+                    data[4 * (y * w + x + w - 1) + 1] += 3 * eg;
+                    data[4 * (y * w + x + w - 1)] += 3 * eb;
+                }
+            }
+
+            data[4 * (y * w + x) + 2] = qr;
+            data[4 * (y * w + x) + 1] = qg;
+            data[4 * (y * w + x)] = qb;
+        }
+
     pipi_save(dst, argv[2]);
 
     return 0;