source: libpipi/trunk/pipi/filter/yuv.c @ 4697

Last change on this file since 4697 was 4697, checked in by Sam Hocevar, 10 years ago

Add functions to convert from RGB to YUV and back.

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1/*
2 *  libpipi       Pathetic image processing interface library
3 *  Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
4 *                All Rights Reserved
5 *
6 *  $Id: yuv.c 4697 2010-10-17 14:33:57Z sam $
7 *
8 *  This library is free software. It comes without any warranty, to
9 *  the extent permitted by applicable law. You can redistribute it
10 *  and/or modify it under the terms of the Do What The Fuck You Want
11 *  To Public License, Version 2, as published by Sam Hocevar. See
12 *  http://sam.zoy.org/wtfpl/COPYING for more details.
13 */
14
15/*
16 * yuv.c: YUV conversion functions
17 */
18
19#include "config.h"
20
21#include <stdlib.h>
22#include <stdio.h>
23#include <string.h>
24#include <math.h>
25
26#include "pipi.h"
27#include "pipi_internals.h"
28
29pipi_image_t *pipi_rgb2yuv(pipi_image_t *src)
30{
31    pipi_image_t *dst;
32    pipi_pixels_t *srcp, *dstp;
33    float *srcdata, *dstdata;
34    int x, y, w, h, gray;
35
36    w = src->w;
37    h = src->h;
38
39    srcp = pipi_get_pixels(src, PIPI_PIXELS_RGBA_F32);
40    srcdata = (float *)srcp->pixels;
41
42    dst = pipi_new(w, h);
43    dstp = pipi_get_pixels(dst, PIPI_PIXELS_RGBA_F32);
44    dstdata = (float *)dstp->pixels;
45
46    for(y = 0; y < h; y++)
47    {
48        for(x = 0; x < w; x++)
49        {
50            double r, g, b, a, yp, u, v;
51            int d = 4 * (y * w + x);
52
53            r = srcdata[d];
54            g = srcdata[d + 1];
55            b = srcdata[d + 2];
56            a = srcdata[d + 3];
57
58            yp = 0.299 * r + 0.587 * g + 0.114 * b;
59            u = 0.5 - 0.14713 * r - 0.28886 * g + 0.436 * b;
60            if (u < 0.0) u = 0.0;
61            if (u > 1.0) u = 1.0;
62            v = 0.5 + 0.615 * r - 0.51499 * g - 0.10001 * b;
63            if (v < 0.0) v = 0.0;
64            if (v > 1.0) v = 1.0;
65
66            dstdata[d] = v;
67            dstdata[d + 1] = yp;
68            dstdata[d + 2] = u;
69            dstdata[d + 3] = a;
70        }
71    }
72
73    return dst;
74}
75
76pipi_image_t *pipi_yuv2rgb(pipi_image_t *src)
77{
78    pipi_image_t *dst;
79    pipi_pixels_t *srcp, *dstp;
80    float *srcdata, *dstdata;
81    int x, y, w, h, gray;
82
83    w = src->w;
84    h = src->h;
85
86    srcp = pipi_get_pixels(src, PIPI_PIXELS_RGBA_F32);
87    srcdata = (float *)srcp->pixels;
88
89    dst = pipi_new(w, h);
90    dstp = pipi_get_pixels(dst, PIPI_PIXELS_RGBA_F32);
91    dstdata = (float *)dstp->pixels;
92
93    for(y = 0; y < h; y++)
94    {
95        for(x = 0; x < w; x++)
96        {
97            double r, g, b, a, yp, u, v;
98            int d = 4 * (y * w + x);
99
100            v = srcdata[d] - 0.5;
101            yp = srcdata[d + 1];
102            u = srcdata[d + 2] - 0.5;
103            a = srcdata[d + 3];
104
105            r = yp + 1.13983 * v;
106            if (r < 0.0) r = 0.0;
107            if (r > 1.0) r = 1.0;
108            g = yp - 0.39465 * u - 0.58060 * v;
109            if (g < 0.0) g = 0.0;
110            if (g > 1.0) g = 1.0;
111            b = yp + 2.03211 * u;
112            if (b < 0.0) b = 0.0;
113            if (b > 1.0) b = 1.0;
114
115            dstdata[d] = r;
116            dstdata[d + 1] = g;
117            dstdata[d + 2] = b;
118            dstdata[d + 3] = a;
119        }
120    }
121
122    return dst;
123}
124
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