RGB565图像转灰度图像解决办法

RGB565图像转灰度图像
各位大侠，我写了个RGB565转灰度图像的算法，但是转换后的灰度图像过暗，不知道是怎么回事，求帮助啊...

C/C++ code

#define RGB565_MASK_RED        0xF800   #define RGB565_MASK_GREEN      0x07E0   #define RGB565_MASK_BLUE       0x001F   void Convert(unsigned char *img565, unsigned char *imgGray, int iWidth, int iHeight){    WORD *pData565 = (WORD*)img565;    int iIndex = 0;    for (int x = 0; x < iHeight; ++x)    {        for (int y = 0; y < iWidth; ++y)        {            unsigned char chR = *(pData565 + iIndex) & RGB565_MASK_RED >> 11;            unsigned char chG = *(pData565 + iIndex) & RGB565_MASK_GREEN >> 5;            unsigned char chB = *(pData565 + iIndex) & RGB565_MASK_BLUE;//            unsigned char chGray = (chB*11 +chR*30 +chG*59+50)/100;            unsigned char chGray = (chB*0.3 +chR*0.11 +chG*0.59);//            unsigned char chGray = (chR + chG + chB) / 3.0;//            unsigned char chGray = (chB*29 +chR*77 +chG*150+128)/256;//            unsigned char chGray = (chB/31.0*0.3 +chR/31.0*0.11 +chG/63.0*0.59)*255;            *(imgGray + x * iWidth + y) = chGray;            ++iIndex;        }    }}

565图像

灰度图像


[解决办法]
unsigned char chR = ((*(pData565 + iIndex) & RGB565_MASK_RED) >> 11 ) << 3;
unsigned char chG = ((*(pData565 + iIndex) & RGB565_MASK_GREEN) >> 5) << 2;
unsigned char chB = (*(pData565 + iIndex) & RGB565_MASK_BLUE) << 3 ;

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