基础函数：YUV与RGB的转换

从现在起，整理一些自己常用的库函数。

//File   : img.h
//Author : Loonzhong <[e-mail]>

#ifndef __IMG_H
#define __IMG_H


class img {
public:
    img()  {};
    ~img() {};

    void yuv_to_rgb16(unsigned char y, unsigned char u, unsigned char v, unsigned char *rgb);
    void yuv_to_rgb32(unsigned char y, unsigned char u, unsigned char v, unsigned char *rgb);

private:

};


#endif  /* __IMG_H */

//File   : img.cpp
//Author : Loonzhong <[e-mail]>

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <errno.h>

#include "img.h"

void img::yuv_to_rgb16(unsigned char y,
                       unsigned char u,
                       unsigned char v,
                       unsigned char *rgb)
{
    register int r, g, b;
    int rgb16;

    r = (1192 * (y - 16) + 1634 * (v - 128) )                  >> 10;
    g = (1192 * (y - 16) - 833  * (v - 128) - 400 * (u -128) ) >> 10;
    b = (1192 * (y - 16) + 2066 * (u - 128) )                  >> 10;

    r = r > 255 ? 255 : r < 0 ? 0 : r;
    g = g > 255 ? 255 : g < 0 ? 0 : g;
    b = b > 255 ? 255 : b < 0 ? 0 : b;

    rgb16 = (int)(((r >> 3)<<11) | ((g >> 2) << 5)| ((b >> 3) << 0));

    *(rgb++) = (unsigned char)(rgb16 & 0xFF);
    *(rgb++) = (unsigned char)((rgb16 & 0xFF00) >> 8);
}

void img::yuv_to_rgb32(unsigned char y,
                       unsigned char u,
                       unsigned char v,
                       unsigned char *rgb)
{
    register int r, g, b;

        r = (y + (359 * v))             >> 8;
        g = (y - (88  * u) - (183 * v)) >> 8;
        b = (y + (454 * u))             >> 8;

        b = (b > 255) ? 255 : ((b < 0) ? 0 : b);
        g = (g > 255) ? 255 : ((g < 0) ? 0 : g);
        r = (r > 255) ? 255 : ((r < 0) ? 0 : r);

        *(rgb++) = b;
        *(rgb++) = g;
        *(rgb++) = r;
        *(rgb++) = 0x0;
}