Procedure for setting pixel colors.

procedure SetPixelFP(const Image: TImageData; 
                     X: LongInt; 
                     Y: LongInt; 
                     const Color: TColorFPRec);

Imaging (at line 255)

Input FP ARGB color is translated to native format and then written to Image. Works for all image formats (except special) so it is not very fast.