YUV4:2:2 UYVY图像旋转

原文：http://blog.csdn.net/zhangyonggen/article/details/48522593

YUV4:2:2 UYVY 格式在内存中的存储方式为交织类型，内存中的存储方式为：UYVY UYVY UYVY...........，Y为亮度信息，UV为色度信息，YUV4:2:2是每两个像素点共用一对UV分量，每个像素点的Y分量是独立的，UV分量是共享的，所以一幅图像的总的字节数totalBytes = width × height + width * height / 2 + width * height / 2 = width * height * 2；在进行旋转操作是必须满足UYVY的结构不变即4个字节为一组，否则会产生颜色不对、锯齿等，也必须保证Y分量在相应的位置上：

1、旋转90度

bool Rotate90(unsigned char *src, int width, int height){        const int copyBytes    = 4;        const int bytesPerLine = width << 1;        const int step         = height  << 2;        const int offset       = (height - 1) * bytesPerLine;        unsigned char *dst     = new (std::nothrow)BYTE[bytesPerLine * height];        if(NULL == dst)        {             return false;        }        unsigned char * dest       = dst;        unsigned char * source  = src;        unsigned char * psrc       = NULL;        unsigned char * pdst[2]   = {NULL, NULL};for (int i = 0; i < bytesPerLine; i += copyBytes){pdst[0] = dest;pdst[1] = dest   + (height << 1);psrc    = source + offset;for (int j = 0; j < height; ++j){int k = j % 2;// 拷贝4个字节*((unsigned int *)pdst[k]) = *((unsigned int *)psrc);            // Y分量交换，保证每个像素点的亮度不改变否则产生锯齿if(1 == k){unsigned char temp = *(pdst[0] - 1);*(pdst[0] - 1) = *(pdst[1] + 1);*(pdst[1] + 1) = temp;}            pdst[k] += copyBytes;psrc    -= bytesPerLine;}dest   += step;source += copyBytes;}        memcpy(src, dst, width * height * 2);        delete[] dst;        return true;}

2、旋转180度

旋转180度相对来说较为简单，从左上角开始与右下角相互交换，由于每两个像素点共享一对UV分量，所以交换的字节数为4字节，但是还需要保证Y分量的位置正确，所以还需要交换Y分量。

bool Rotate180(unsigned char *src, int width, int height){        const int copyBytes  = 4;const int totalBytes = height * width << 1;        const int end           = totalBytes >> 1;unsigned char *dst   = src + totalBytes - copyBytes;for (int i = 0; i < end; i += copyBytes){                unsigned int tmp       = *((unsigned int *)dst);*((unsigned int *)dst) = *((unsigned int *)src);                *((unsigned int *)src) = tmp;               // 交换Y分量unsigned char temp = dst[1];dst[1] = dst[3];dst[3] = temp;                temp   = src[1];src[1] = src[3];src[3] = temp;dst -= copyBytes;src += copyBytes;}    return true;}

3、旋转270度

与旋转90度相类似

bool Rotate270(unsigned char *src, int width, int height){        const int copyBytes    = 4;const int bytesPerLine = width << 1;const int step         = height << 2;const int offset       = bytesPerLine - copyBytes;        unsigned char *dst     = new (std::nothrow)BYTE[bytesPerLine * height];        if(NULL == dst)        {             return false;        }        unsigned char *dest    = dst;        unsigned char *source  = src;        unsigned char *psrc    = NULL;        unsigned char *pdst[2] = {NULL, NULL};for (int i = 0; i < bytesPerLine; i += copyBytes){pdst[1] = dest;pdst[0] = dest + (height << 1);psrc    = source + offset;for (int j = 0; j < height; ++j){int k = j % 2;*((unsigned int *)pdst[k]) = *((unsigned int *)psrc);if(1 == k){unsigned char temp      = *(pdst[1] + 1);*(pdst[1] + 1) = *(pdst[0] - 1);*(pdst[0] - 1) = temp;}pdst[k] += copyBytes;psrc    += bytesPerLine;}dest   += step;source -= copyBytes;}        memcpy(src, dst, width * height * 2);        delete[] dst;        return true;}