ConvertUnsignedToSigned example for C++ Builder
void __fastcall TForm1::Button1Click(TObject *Sender)
{
LEADImage1->LoadSigned= true;
/* load the bitmap, keeping the bits per pixel of the file */
LEADImage1->Load( "c:\\Image1.tif", 0, 0, 1 );
if ( ! LEADImage1->IsSigned)
/* convert bitmap to signed */
LEADImage1->ConvertUnsignedToSigned( PROCESS_RANGE_ONLY );
}