Returns D3D format equivalent to the given TImageFormatInfo.

function ImageFormatToD3DFormat(const Format: TImageFormat; 
                                var ConversionTo: TImageFormat): TD3DFormat;

ImagingDirect3D9 (at line 64)

It returns D3DFMT_UNKNOWN if equivalent cannot be found. If returned ConversionTo is not the same as input format then image must be first converted to this format for the returned D3D format to be valid. You should also check if returned D3D format is supported by the current D3D device using IsD3DFormatSupported.