C / C++ / MFC

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
	UINT  num = 0;          // number of image encoders
	UINT  size = 0;         // size of the image encoder array in bytes
 
	ImageCodecInfo* pImageCodecInfo = NULL;
 
	GetImageEncodersSize(&num, &size);
	if(size == 0)
		return -1;  // Failure
 
	pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
	if(pImageCodecInfo == NULL)
		return -1;  // Failure
 
	GetImageEncoders(num, size, pImageCodecInfo);
 
	for(UINT j = 0; j < num; ++j)
	{
		if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
		{
			*pClsid = pImageCodecInfo[j].Clsid;
			free(pImageCodecInfo);
			return j;  // Success
		}    
	}
 
	free(pImageCodecInfo);
	return -1;  // Failure
}
 
...
 
	// Resize an 640x480 image to 320x240
	// (I already know this source image is 640x480 - In real life use
	//   SrcBitmap.GetWidth() and SrcBitmap.GetHeight() to get an image's dimensions
 
	Gdiplus::Bitmap SrcBitmap(L"D:\\Source\\Images\\sony-cybershot.jpg", FALSE);
	Gdiplus::Bitmap DstBitmap(320,240,SrcBitmap.GetPixelFormat()); 
	Graphics DstGraphics(&DstBitmap);
	DstGraphics.DrawImage(&SrcBitmap, 0, 0, 320, 240);
	CLSID jpgClsid;
	GetEncoderClsid(L"image/jpeg", &jpgClsid);
	DstBitmap.Save(L"D:\\Source\\Images\\sony-cybershot_test.jpg", &jpgClsid, NULL);