how to change a 24bit bitmap to a 32bit bitmap using GDI+

[hobnob]

I mean 32bit to 24bit image.

Hi,

I have a bitmap file temp.bmp that is a 32bit image, now I want to resave it as 24bit image but for some reason the code below is still saving it as a 32bit image (temp2.bmp) even though 24bit has been specified as the colorDepth.
Any ideas? do I need to re-render it first? if so, how?

Status stat;
Image* image = new Image(_T("temp.bmp"));

Gdiplus::EncoderParameters EncoderParameters1;
ULONG colorDeph = 24;
EncoderParameters1.Count = 1;
EncoderParameters1.Parameter[0].Guid = EncoderColorDepth;
EncoderParameters1.Parameter[0].Type = EncoderParameterValueTypeLong;
EncoderParameters1.Parameter[0].NumberOfValues = 1;
EncoderParameters1.Parameter[0].Value = &colorDeph;


CLSID m_clsidGdiplusBmpEncoder;
GetEncoderClsid( L"image/bmp", &m_clsidGdiplusBmpEncoder );
stat = image->Save( _T("temp2.bmp"), &m_clsidGdiplusBmpEncoder, &EncoderParameters1 );


Thanks,
Hobnob