Add functions to convert from RGB to YUV and back.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@4697 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/Makefile.am

@@ -81,7 +81,8 @@ filter_sources = \
 	filter/transform.c \
 	filter/median.c \
 	filter/dilate.c \
-	filter/wave.c
+	filter/wave.c \
+	filter/yuv.c
 
 quantize_sources = \
 	quantize/reduce.c

pipi/context.c

@@ -94,6 +94,8 @@ pipi_command_t const *pipi_get_command_list(void)
         { "line", 1 },
         { "sine", 1 },
         { "wave", 1 },
+        { "rgb2yuv", 0 },
+        { "yuv2rgb", 0 },
 
         /* End marker */
         { NULL, 0 }
@@ -708,6 +710,22 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
         pipi_free(src);
         ctx->images[ctx->nimages - 1] = dst;
     }
+    else if(!strcmp(cmd, "rgb2yuv") || !strcmp(cmd, "yuv2rgb"))
+    {
+        pipi_image_t *src, *dst = NULL;
+        if(ctx->nimages < 1)
+            return -1;
+        src = ctx->images[ctx->nimages - 1];
+        switch (cmd[0])
+        {
+            case 'r': dst = pipi_rgb2yuv(src); break;
+            case 'y': dst = pipi_yuv2rgb(src); break;
+        }
+        if(dst == NULL)
+            return -1;
+        pipi_free(src);
+        ctx->images[ctx->nimages - 1] = dst;
+    }
     else
     {
         return -1;

pipi/filter/yuv.c

@@ -0,0 +1,124 @@
+/*
+ *  libpipi       Pathetic image processing interface library
+ *  Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
+ *                All Rights Reserved
+ *
+ *  $Id$
+ *
+ *  This library 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.
+ */
+
+/*
+ * yuv.c: YUV conversion functions
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+#include "pipi.h"
+#include "pipi_internals.h"
+
+pipi_image_t *pipi_rgb2yuv(pipi_image_t *src)
+{
+    pipi_image_t *dst;
+    pipi_pixels_t *srcp, *dstp;
+    float *srcdata, *dstdata;
+    int x, y, w, h, gray;
+
+    w = src->w;
+    h = src->h;
+
+    srcp = pipi_get_pixels(src, PIPI_PIXELS_RGBA_F32);
+    srcdata = (float *)srcp->pixels;
+
+    dst = pipi_new(w, h);
+    dstp = pipi_get_pixels(dst, PIPI_PIXELS_RGBA_F32);
+    dstdata = (float *)dstp->pixels;
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            double r, g, b, a, yp, u, v;
+            int d = 4 * (y * w + x);
+
+            r = srcdata[d];
+            g = srcdata[d + 1];
+            b = srcdata[d + 2];
+            a = srcdata[d + 3];
+
+            yp = 0.299 * r + 0.587 * g + 0.114 * b;
+            u = 0.5 - 0.14713 * r - 0.28886 * g + 0.436 * b;
+            if (u < 0.0) u = 0.0;
+            if (u > 1.0) u = 1.0;
+            v = 0.5 + 0.615 * r - 0.51499 * g - 0.10001 * b;
+            if (v < 0.0) v = 0.0;
+            if (v > 1.0) v = 1.0;
+
+            dstdata[d] = v;
+            dstdata[d + 1] = yp;
+            dstdata[d + 2] = u;
+            dstdata[d + 3] = a;
+        }
+    }
+
+    return dst;
+}
+
+pipi_image_t *pipi_yuv2rgb(pipi_image_t *src)
+{
+    pipi_image_t *dst;
+    pipi_pixels_t *srcp, *dstp;
+    float *srcdata, *dstdata;
+    int x, y, w, h, gray;
+
+    w = src->w;
+    h = src->h;
+
+    srcp = pipi_get_pixels(src, PIPI_PIXELS_RGBA_F32);
+    srcdata = (float *)srcp->pixels;
+
+    dst = pipi_new(w, h);
+    dstp = pipi_get_pixels(dst, PIPI_PIXELS_RGBA_F32);
+    dstdata = (float *)dstp->pixels;
+
+    for(y = 0; y < h; y++)
+    {
+        for(x = 0; x < w; x++)
+        {
+            double r, g, b, a, yp, u, v;
+            int d = 4 * (y * w + x);
+
+            v = srcdata[d] - 0.5;
+            yp = srcdata[d + 1];
+            u = srcdata[d + 2] - 0.5;
+            a = srcdata[d + 3];
+
+            r = yp + 1.13983 * v;
+            if (r < 0.0) r = 0.0;
+            if (r > 1.0) r = 1.0;
+            g = yp - 0.39465 * u - 0.58060 * v;
+            if (g < 0.0) g = 0.0;
+            if (g > 1.0) g = 1.0;
+            b = yp + 2.03211 * u;
+            if (b < 0.0) b = 0.0;
+            if (b > 1.0) b = 1.0;
+
+            dstdata[d] = r;
+            dstdata[d + 1] = g;
+            dstdata[d + 2] = b;
+            dstdata[d + 3] = a;
+        }
+    }
+
+    return dst;
+}
+

pipi/pipi.h

@@ -209,6 +209,8 @@ __extern pipi_image_t *pipi_sine(pipi_image_t *, double, double,
                                  double, double);
 __extern pipi_image_t *pipi_wave(pipi_image_t *, double, double,
                                  double, double);
+__extern pipi_image_t *pipi_rgb2yuv(pipi_image_t *);
+__extern pipi_image_t *pipi_yuv2rgb(pipi_image_t *);
 
 __extern pipi_image_t *pipi_order(pipi_image_t *);