FreeImage图像格式转换

由于opencv支持的图像格式有限，为了弥补这个不足，使用FreeImage进行格式转换。

基于磁盘文件的图像格式转换：

int main()
{
    FreeImage_Initialise();

    const char* srcImagePath = "E:/Desktop/01.tif";
    const char* dstImagePath = "E:/Desktop/01.png";

    int srcImageFormat = FreeImage_GetFIFFromFilename(srcImagePath);
    FIBITMAP *dib = FreeImage_Load(static_cast<FREE_IMAGE_FORMAT>(srcImageFormat), srcImagePath);
    if (dib == NULL)
    {
        cout << "图像加载失败" << endl;
        return 0;
    }

    unsigned int width = FreeImage_GetWidth(dib);    
    unsigned int height = FreeImage_GetHeight(dib);

    int dstImageFormat = FreeImage_GetFIFFromFilename(dstImagePath);
    if (!FreeImage_Save(static_cast<FREE_IMAGE_FORMAT>(dstImageFormat), dib, dstImagePath))
    {
        cout << "图像保存失败" << endl;
        return 0;
    }

    FreeImage_DeInitialise();

    return 0;
}

基于内存的图像格式转换：

IplImage* FIBITMAP2IplImage(FIBITMAP *dib)
{
    if (!dib)
        return NULL;
    int nClrUsed = FreeImage_GetColorsUsed(dib);
    int nBpp = FreeImage_GetBPP(dib);
    int height = FreeImage_GetHeight(dib);
    int width = FreeImage_GetWidth(dib);
    RGBQUAD* pPalette = FreeImage_GetPalette(dib);
    int nChannel = 3;
    if (!nClrUsed && !pPalette)        //无调色板图像处理
    {

        IplImage* iplImg = cvCreateImage(cvSize(width, height), IPL_DEPTH_8U, nChannel);
        iplImg->origin = 1;
        for (int y = 0; y < height; y++)
        {
            BYTE* pLine = (BYTE*)iplImg->imageData + y * iplImg->widthStep;
            BYTE* psrcLine = (BYTE*)FreeImage_GetScanLine(dib, y);
            for (int x = 0; x < nChannel*width; x++)
            {
                *pLine++ = *psrcLine++;

            }
        }
        FreeImage_Unload(dib);
        FreeImage_DeInitialise();
        return iplImg;
    }
    else if (pPalette)//索引图像处理
    {
        IplImage* iplImg = cvCreateImage(cvSize(width, height), IPL_DEPTH_8U, nChannel);
        iplImg->origin = 1;
        BYTE intensity;
        BYTE* pIntensity = &intensity;
        for (int y = 0; y < height; y++)
        {
            BYTE* pLine = (BYTE*)iplImg->imageData + y * iplImg->widthStep;
            for (int x = 0; x < width; x++)
            {

                FreeImage_GetPixelIndex(dib, x, y, pIntensity);
                pLine[x * 3] = pPalette[intensity].rgbBlue;
                pLine[x * 3 + 1] = pPalette[intensity].rgbGreen;
                pLine[x * 3 + 2] = pPalette[intensity].rgbRed;
            }
        }
        FreeImage_Unload(dib);
        FreeImage_DeInitialise();
        return iplImg;
    }
    else
    {
        FreeImage_Unload(dib);
        FreeImage_DeInitialise();
        return NULL;
    }

}

int main()
{
    const char* srcImagePath = "E:/Desktop/01.tif";
    const char* dstImagePath = "E:/Desktop/01.png";

    //read image file to bytes
    FILE* f = fopen(srcImagePath, "rb");
    fseek(f, 0, SEEK_END);
    long size = ftell(f);
    rewind(f);
    unsigned char* data = new unsigned char[size];
    fread(data, sizeof(char), size, f);
    fclose(f);

    FreeImage_Initialise();

    //read bytes to image object
    FIMEMORY * memory = FreeImage_OpenMemory(data, size);
    FREE_IMAGE_FORMAT srcformat = FreeImage_GetFileTypeFromMemory(memory, 0);
    FIBITMAP *bitmap = FreeImage_LoadFromMemory(srcformat, memory, 0);
    FreeImage_CloseMemory(memory);

    //show image object
    /*IplImage *pImg = FIBITMAP2IplImage(bitmap);
    cvNamedWindow("Test");
    cvShowImage("Test", pImg);
    cvWaitKey(0);*/

    //convert image object type
    FIMEMORY* hmem = FreeImage_OpenMemory();
    FreeImage_SaveToMemory(FreeImage_GetFIFFromFilename(dstImagePath), bitmap, hmem, 0);
    
    //save image object type to bytes
    FreeImage_SeekMemory(hmem, 0, SEEK_END);
    long bufferSize = FreeImage_TellMemory(hmem);
    unsigned char* buffer = new unsigned char[bufferSize];
    unsigned int actualReadCount = bufferSize;
    FreeImage_SeekMemory(hmem, 0, SEEK_SET);
    FreeImage_ReadMemory(buffer, bufferSize, actualReadCount, hmem);
    FreeImage_CloseMemory(hmem);
    FreeImage_DeInitialise();

    f = fopen(dstImagePath, "wb");
    fwrite(buffer, sizeof(char), bufferSize, f);
    fclose(f);

    return 0;
}