YUV422(YUYV)、NV21、YUV420P、RGB24(RGB888)之间转换C/C++代码

   在图像处理、视频开发中，因为不同设备、不同平台、摄像头获取的原始数据都不一样，经常要完成颜色之间转换，下面列出一些常见的颜色格式转换代码。

比如：

Android系统的摄像头返回的图像格式NV21

X264编码需要的图像格式YUV420P

Linux下摄像头返回的图像格式一般是YUYV

GUI图形控件一般显示图片需要RGB数据

 

如果想查看原始的YUV图片windows下可以使用7yuv软件。

列出转换代码列表:

void YUV420P_to_RGB24(unsigned char *data, unsigned char *rgb, int width, int height);
void NV21_TO_RGB24(unsigned char *data, unsigned char *rgb, int width, int height);
void YUV420P_TO_RGB24(unsigned char *yuv420p, unsigned char *rgb24, int width, int height);
void yuyv_to_rgb(unsigned char *yuv_buffer,unsigned char *rgb_buffer,int iWidth,int iHeight);
int yuyv_to_yuv420p(const unsigned char *in, unsigned char *out, unsigned int width, unsigned int height);
void NV21_YUV420P(const unsigned char* image_src, unsigned char* image_dst,int image_width, int image_height);
bool RGB24_TO_YUV420(unsigned char *RgbBuf,int w,int h,unsigned char *yuvBuf)

核心代码:  下面是纯C代码，不依赖任何库，可以在任何平台复制粘贴移植调用

/*
函数功能: 将YUV数据转为RGB格式
函数参数:
unsigned char *yuv_buffer: YUV源数据
unsigned char *rgb_buffer: 转换之后的RGB数据
int iWidth,int iHeight   : 图像的宽度和高度
*/
void VideoReadThread::yuyv_to_rgb(unsigned char *yuv_buffer,unsigned char *rgb_buffer,int iWidth,int iHeight)
{
    int x;
    int z=0;
    unsigned char *ptr = rgb_buffer;
    unsigned char *yuyv= yuv_buffer;
    for (x = 0; x < iWidth*iHeight; x++)
    {
        int r, g, b;
        int y, u, v;

        if (!z)
        y = yuyv[0] << 8;
        else
        y = yuyv[2] << 8;
        u = yuyv[1] - 128;
        v = yuyv[3] - 128;

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

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

        if(z++)
        {
            z = 0;
            yuyv += 4;
        }
    }
}



// image_src是源图像，image_dst是转换后的图像
void VideoReadThread::NV21_YUV420P(const unsigned char* image_src, unsigned char* image_dst,int image_width, int image_height)
{
    unsigned char* p = image_dst;
    memcpy(p, image_src, image_width * image_height * 3 / 2);
    const unsigned char *pNV = image_src + image_width * image_height;
    unsigned char *pU = p + image_width * image_height;
    unsigned char *pV = p + image_width * image_height + ((image_width * image_height)>>2);
    for (int i=0; i<(image_width * image_height)/2; i++)
    {
        if((i%2)==0)
           *pV++=*(pNV+i);
        else
           *pU++=*(pNV+i);
    }
}


//YUYV==YUV422
int VideoReadThread::yuyv_to_yuv420p(const unsigned char *in, unsigned char *out, unsigned int width, unsigned int height)
{
    unsigned char *y = out;
    unsigned char *u = out + width*height;
    unsigned char *v = out + width*height + width*height/4;

    unsigned int i,j;
    unsigned int base_h;
    unsigned int  is_u = 1;
    unsigned int y_index = 0, u_index = 0, v_index = 0;

    unsigned long yuv422_length = 2 * width * height;

    //序列为YU YV YU YV，一个yuv422帧的长度 width * height * 2 个字节
    //丢弃偶数行 u v
    for(i=0; i 255)   r = 255;
                if(g > 255)   g = 255;
                if(b > 255)   b = 255;
                if(r < 0)     r = 0;
                if(g < 0)     g = 0;
                if(b < 0)     b = 0;

                index = rgb_index % width + (height - i - 1) * width;
                //rgb[index * 3+0] = b;
                //rgb[index * 3+1] = g;
                //rgb[index * 3+2] = r;

                //颠倒图像
                //rgb[height * width * 3 - i * width * 3 - 3 * j - 1] = b;
                //rgb[height * width * 3 - i * width * 3 - 3 * j - 2] = g;
                //rgb[height * width * 3 - i * width * 3 - 3 * j - 3] = r;

                //正面图像
                rgb[i * width * 3 + 3 * j + 0] = b;
                rgb[i * width * 3 + 3 * j + 1] = g;
                rgb[i * width * 3 + 3 * j + 2] = r;

                rgb_index++;
            }
        }
}

void VideoReadThread::YUV420P_TO_RGB24(unsigned char *yuv420p, unsigned char *rgb24, int width, int height) {
    int index = 0;
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int indexY = y * width + x;
            int indexU = width * height + y / 2 * width / 2 + x / 2;
            int indexV = width * height + width * height / 4 + y / 2 * width / 2 + x / 2;

            u_char Y = yuv420p[indexY];
            u_char U = yuv420p[indexU];
            u_char V = yuv420p[indexV];

            rgb24[index++] = Y + 1.402 * (V - 128); //R
            rgb24[index++] = Y - 0.34413 * (U - 128) - 0.71414 * (V - 128); //G
            rgb24[index++] = Y + 1.772 * (U - 128); //B
        }
    }
}


unsigned char clip_value(unsigned char x,unsigned char min_val,unsigned char  max_val){
    if(x>max_val){
        return max_val;
    }else if(x> 8) + 16  ;
            u = (unsigned char)( ( -38 * r -  74 * g + 112 * b + 128) >> 8) + 128 ;
            v = (unsigned char)( ( 112 * r -  94 * g -  18 * b + 128) >> 8) + 128 ;
            *(ptrY++) = clip_value(y,0,255);
            if (j%2==0&&i%2 ==0){
                *(ptrU++) =clip_value(u,0,255);
            }
            else{
                if (i%2==0){
                *(ptrV++) =clip_value(v,0,255);
                }
            }
        }
    }
    return true;
}

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