* pipi_dither_ordered() now takes two arguments; any image can be used as

the ordered dithering matrix. To get the old behaviour, use:
      pipi image.png pipi:bayer8 --dither ordered out.png

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2696 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/context.c

@@ -93,7 +93,13 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
         else if(!strcmp(method, "sost"))
             dst = pipi_dither_ostromoukhov(src, 1);
         else if(!strcmp(method, "ordered"))
-            dst = pipi_dither_ordered(src);
+        {
+            if(ctx->nimages < 2)
+                return -1;
+            dst = pipi_dither_ordered(ctx->images[ctx->nimages - 2], src);
+            pipi_free(ctx->images[ctx->nimages - 2]);
+            ctx->nimages--;
+        }
         else if(!strcmp(method, "random"))
             dst = pipi_dither_random(src);
         else if(!strcmp(method, "dbs"))

pipi/dither/ordered.c

@@ -22,32 +22,25 @@
 #include "pipi.h"
 #include "pipi_internals.h"
 
-static const int kernel8x8[8 * 8] =
-{
-   0,  32,   8,  40,   2,  34,  10,  42,
-  48,  16,  56,  24,  50,  18,  58,  26,
-  12,  44,   4,  36,  14,  46,   6,  38,
-  60,  28,  52,  20,  62,  30,  54,  22,
-   3,  35,  11,  43,   1,  33,   9,  41,
-  51,  19,  59,  27,  49,  17,  57,  25,
-  15,  47,   7,  39,  13,  45,   5,  37,
-  63,  31,  55,  23,  61,  29,  53,  21,
-};
-
-pipi_image_t *pipi_dither_ordered(pipi_image_t *img)
+pipi_image_t *pipi_dither_ordered(pipi_image_t *img, pipi_image_t *kernel)
 {
     pipi_image_t *dst;
-    pipi_pixels_t *dstp;
-    float *dstdata;
-    int x, y, w, h;
+    pipi_pixels_t *dstp, *kernelp;
+    float *dstdata, *kerneldata;
+    int x, y, w, h, kw, kh;
 
     w = img->w;
     h = img->h;
+    kw = kernel->w;
+    kh = kernel->h;
 
     dst = pipi_copy(img);
     dstp = pipi_getpixels(dst, PIPI_PIXELS_Y_F);
     dstdata = (float *)dstp->pixels;
 
+    kernelp = pipi_getpixels(kernel, PIPI_PIXELS_Y_F);
+    kerneldata = (float *)kernelp->pixels;
+
     for(y = 0; y < h; y++)
     {
         for(x = 0; x < w; x++)
@@ -55,7 +48,7 @@ pipi_image_t *pipi_dither_ordered(pipi_image_t *img)
             float p, q;
 
             p = dstdata[y * w + x];
-            q = p > (1. + kernel8x8[(y % 8) * 8 + (x % 8)]) / 65. ? 1. : 0.;
+            q = p > kerneldata[(y % kh) * kw + (x % kw)] ? 1. : 0.;
             dstdata[y * w + x] = q;
         }
     }

pipi/pipi.h

@@ -97,7 +97,7 @@ extern int pipi_flood_fill(pipi_image_t *,
                            int, int, float, float, float, float);
 
 extern pipi_image_t *pipi_dither_floydsteinberg(pipi_image_t *, pipi_scan_t);
-extern pipi_image_t *pipi_dither_ordered(pipi_image_t *);
+extern pipi_image_t *pipi_dither_ordered(pipi_image_t *, pipi_image_t *);
 extern pipi_image_t *pipi_dither_random(pipi_image_t *);
 extern pipi_image_t *pipi_dither_ostromoukhov(pipi_image_t *, pipi_scan_t);
 extern pipi_image_t *pipi_dither_dbs(pipi_image_t *);