[HELP] GIF(JPEG) <--> BMP

I want to transform BMP file into GIF(or JPEG) file format
Now I got 4 undocument function
WINOLECTLAPI OleLoadPicturePath( LPOLESTR szURLorPath, LPUNKNOWN punkCaller,
DWORD dwReserved, OLE_COLOR clrReserved, REFIID riid, LPVOID *pvRet );

WINOLECTLAPI OleLoadPictureFile(VARIANT varFileName,LPDISPATCH* plpdispPicture);

WINOLECTLAPI OleLoadPictureFileEx(VARIANT varFileName,
DWORD xSizeDesired, DWORD ySizeDesired, DWORD dwFlags,
LPDISPATCH* lplpdispPicture);

WINOLECTLAPI OleSavePictureFile(LPDISPATCH lpdispPicture,
BSTR bstrFileName);

But I don't know how to use it?! (include files? or import library?)
would you tell me how to make it or show some source code to explain it.
Thanx a lot...