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利用FreeImage将gif图像转为opencv中的Mat

2024-07-18 19:59:47   222人阅读

网上有将gif转为iplimg的版本，只是用惯了C++的接口，所以就写了个转Mat的版本，代码比较简单

一、读文件

 1     int MatFun::gif2Mat(char* data, size_t dataSize, vector<Mat>& gifImgs, Mat& singleImg) 2     { 3         /* initialise 4         ->open memory 5         ->getImageType 6         ->load bitmaps 7         ->bitmaps to Mat 8         ->free all resource 9         */10         // condition1: data is not null11         if (NULL == data || dataSize == 0)12             return -1;13         FreeImage_Initialise();14         FIMEMORY* memory = FreeImage_OpenMemory((BYTE*)data, dataSize);15         if (NULL==memory)16         {17             FreeImage_DeInitialise();   //condition 2: memory is not null 18         }19 20         FREE_IMAGE_FORMAT fif = FreeImage_GetFileTypeFromMemory(memory);21         if (FIF_UNKNOWN == fif)    //condition 3: type of image should be know22         {23             fprintf(stderr, "unknown type of image");24             if (NULL != memory) FreeImage_CloseMemory(memory);25             FreeImage_DeInitialise();26             return -1;27         }28         else if (FIF_GIF != fif)  //condition 4: type of image should be GIF29         {30             if (NULL != memory) FreeImage_CloseMemory(memory);31             FreeImage_DeInitialise();32             return 0;33         }34 35         FIMULTIBITMAP * fiBmp = FreeImage_LoadMultiBitmapFromMemory(fif, memory, GIF_DEFAULT);36         if (NULL==fiBmp)37         {38             if (NULL != memory) FreeImage_CloseMemory(memory);   //condition 5: bitmaps is not null39             FreeImage_DeInitialise();40             return -1;41         }42 43         int num = FreeImage_GetPageCount(fiBmp);44 45         for (int i = 0; i < num; i++)46         {47             if (i==0 || i==2)48             {49                 FIBITMAP *mfibmp = FreeImage_LockPage(fiBmp, i);50                 if (mfibmp)     51                 {52                     Mat dst = bitMap2Mat(mfibmp, fif);53                     FreeImage_UnlockPage(fiBmp, mfibmp, false);54                     if (dst.empty())55                     {56                         if (NULL != memory) FreeImage_CloseMemory(memory);57                         if (NULL != fiBmp) FreeImage_CloseMultiBitmap(fiBmp, GIF_DEFAULT);58                         FreeImage_DeInitialise();59                         return -1;60                     }61                     gifImgs.push_back(dst);62                     dst.release();63                 }64             }65         }66 67         if (NULL != memory)68             FreeImage_CloseMemory(memory);69         if (NULL != fiBmp)70             FreeImage_CloseMultiBitmap(fiBmp);71         FreeImage_DeInitialise();72 73         return 0;74     }

这部分其实功能很简单，代码里面大部分都是检查，实际执行就初始化、打开内存、内存中读bitmap这几步。

二、gif转Mat

    Mat MatFun::bitMap2Mat(FIBITMAP* fiBmp, const FREE_IMAGE_FORMAT &fif)    {        if (NULL == fiBmp || FIF_GIF != fif)            return Mat();        int width = FreeImage_GetWidth(fiBmp);        int height = FreeImage_GetHeight(fiBmp);        BYTE intensity;        BYTE* pIntensity = &intensity;        if(FreeImage_GetBPP(fiBmp) !=8)            fiBmp = FreeImage_ConvertTo8Bits(fiBmp); //必须转化为8bit        RGBQUAD* pixels = new RGBQUAD;         pixels = FreeImage_GetPalette(fiBmp);        Mat img=Mat::zeros(height, width, CV_8UC3);        uchar* p;        for (int i = 0; i < height; i++)        {            p = img.ptr<uchar>(i);            for (int j = 0; j < width; j++)            {                FreeImage_GetPixelIndex(fiBmp, j, i, pIntensity);                                p[3 * j] = pixels[intensity].rgbBlue;                p[3 * j + 1] = pixels[intensity].rgbGreen;                p[3 * j + 2] = pixels[intensity].rgbRed;            }        }        return img;    }

具体的将byte像素转化为mat里面的像素值即可，注意rgb图像的Mat里是一个像素包含三通道的值，知道这点，代码就很好理解了。


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