关于将BMP转化成JPG的问题????

nixinfei 2005-09-29 06:12:50

请问有没有方法可以直接将缓冲区中的BMP图象数据转化成JPG图象格式的数据???

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xianshiqi 2005-10-02

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网上有很多现成的，

phoenix96_2000 2005-09-30

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CxImage:

CxImage img;
if(img.Load("a.bmp"))
{
img.Save("a.jpg",CXIMAGE_FORMAT_JPG);
}

GDI+:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdicpp/GDIPlus/usingGDIPlus/usingimageencodersanddecoders/convertingabmpimagetoapngimage.asp

这是转换位PNG的例子,把encoder名字改为"image/jpeg"就可以了

gxning 2005-09-30

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//生成Bitmap
AM_MEDIA_TYPE mt;
JIF(hr = pSampleGrabber->GetConnectedMediaType(&mt));
if (FAILED(hr)) return E_FAIL;

VIDEOINFOHEADER *pVideoHeader = (VIDEOINFOHEADER*)mt.pbFormat;
if(pVideoHeader==NULL) return E_FAIL;

BITMAPINFO BitmapInfo;
ZeroMemory(&BitmapInfo, sizeof(BitmapInfo));
CopyMemory(&BitmapInfo.bmiHeader, &(pVideoHeader->bmiHeader), sizeof(BITMAPINFOHEADER));

HBITMAP hBitmap;
hBitmap = ::CreateDIBitmap(::GetDC(NULL), &(pVideoHeader->bmiHeader), CBM_INIT, pBuffer, &BitmapInfo, DIB_RGB_COLORS);

HRESULT CVMR_Capture::SaveJpg(HBITMAP hbmp,CString filename)
{
if(hbmp==NULL)
return -1;
//warning: this code snippet is not bullet proof.
//do error check by yourself [masterz]
PICTDESC picdesc;
picdesc.cbSizeofstruct = sizeof(PICTDESC);
picdesc.picType = PICTYPE_BITMAP ;
picdesc.bmp.hpal = NULL;
picdesc.bmp.hbitmap = hbmp;
IPicture* pPicture=NULL;
OleCreatePictureIndirect(&picdesc, IID_IPicture, TRUE,(VOID**)&pPicture);
//LPSTREAM pStream;

IStream* pStream=NULL;
HRESULT hr;
//JIF(hr=CreateStreamOnHGlobal(NULL,TRUE,&pStream));
JIF(hr=CreateStreamOnHGlobal(NULL, TRUE, (LPSTREAM*)&pStream));

Bitmap bit2(hbmp, NULL);

CLSID pngClsid;
GetEncoderClsid(L"image/jpeg", &pngClsid);

// Setup encoder parameters
EncoderParameters encoderParameters;
encoderParameters.Count = 1;
encoderParameters.Parameter[0].Guid = EncoderQuality;
encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParameters.Parameter[0].NumberOfValues = 1;

// setup compression level
ULONG quality = 90;
encoderParameters.Parameter[0].Value = &quality;

// Save the image to the stream

Status SaveStatus = bit2.Save(pStream, &pngClsid, &encoderParameters);

if(SaveStatus != Ok)
{
// this shoud free global memory used by the stream
// according to MSDN
pStream->Release();
AfxMessageBox(_T("Failed to save to stream!"));
return -1;
}

// get the size of the stream
ULARGE_INTEGER ulnSize;
LARGE_INTEGER lnOffset;
lnOffset.QuadPart = 0;
if(pStream->Seek(lnOffset, STREAM_SEEK_END, &ulnSize) != S_OK)
{
pStream->Release();
AfxMessageBox(_T("Failed to get the size of the stream!"));
return -1;
}

// now move the pointer to the begining of the file
if(pStream->Seek(lnOffset, STREAM_SEEK_SET, NULL) != S_OK)
{
pStream->Release();
AfxMessageBox(_T("Failed to smove the file pointer to the beginning of the stream!"));
return -1;
}

// I am going to save it to the file just so we can load the jpg to a gfx program
CFile fFile;

if(fFile.Open(_T(filename), CFile::modeCreate | CFile::modeWrite))
{
//ULONGLONG 是 unsigned __int64使用前要进行转化(int)、(unsigned long)
char *pBuff = new char[(int)ulnSize.QuadPart];

// Read the stream directly into the buffer

ULONG ulBytesRead;
if(pStream->Read(pBuff, (unsigned long)ulnSize.QuadPart, &ulBytesRead) != S_OK)
{
pStream->Release();
delete pBuff;
return -1 ;
}

fFile.Write(pBuff, ulBytesRead);
fFile.Close();
delete pBuff;
}
else AfxMessageBox(_T("Failed to save data to the disk!"));

// Free memory used by the stream
pStream->Release();
return 0;

}