C++图像处理NV21转RGBA颜色空间的转换算法

最近做的项目涉及到NV21转RGBA，网上找到的方法黑白图像显示正常，但是加上伪彩后颜色不对，折腾了好几天还是不行。最后只好研究YUV原理，才弄明白网上的算法有疏漏，修改后再运行程序，图像的颜色终于显示正常了，这里把最终的算法记录一下，希望能给大家提供帮助。

void libyuvNV21ToRGBA(const unsigned char *src, unsigned char *dst, int width, int height, int mode) {
    
    

    //nv21
    int total = width * height;
    char Y, U, V;
    float R, G, B;
    int index = 0;


    for (int h = 0; h < height; h++) {
    
    
        for (int w = 0; w < width / 2; w++) {
    
    

            Y = src[h * width + w * 2];
            V = src[total + (h >> 1) * width + w * 2];
            U = src[total + (h >> 1) * width + w * 2 + 1];
            R = Y + 1.4075 * (V - 128);
            G = Y - 0.3455 * (U - 128) - 0.7169 * (V - 128);
            B = Y + 1.779 * (U - 128);

            if (R < 0) R = 0;
            if (R > 255) R = 255;
            if (G < 0) G = 0;
            if (G > 255) G = 255;
            if (B < 0) B = 0;
            if (B > 255) B = 255;

            dst[index++] = B;
            dst[index++] = G;
            dst[index++] = R;
            dst[index++] = 255;

            Y = src[h * width + w * 2 + 1];
            R = Y + 1.4075 * (V - 128);
            G = Y - 0.3455 * (U - 128) - 0.7169 * (V - 128);
            B = Y + 1.779 * (U - 128);

            if (R < 0) R = 0;
            if (R > 255) R = 255;
            if (G < 0) G = 0;
            if (G > 255) G = 255;
            if (B < 0) B = 0;
            if (B > 255) B = 255;

            dst[index++] = B;
            dst[index++] = G;
            dst[index++] = R;
            dst[index++] = 255;
           }
        }
	}