function GetNumColors: LongInt;
var
 BPP: Integer;
 DC: HDC;
begin
 DC := CreateDC('DISPLAY', nil, nil, nil);
 if DC <> 0 then begin
 try
 BPP := GetDeviceCaps(DC, BITPIXEL) * GetDeviceCaps(DC, PLANES);
 finally
 DeleteDC(DC);
 end;
 case BPP of
 1: Result := 2;
 4: Result := 16;
 8: Result := 256;
 15: Result := 32768;
 16: Result := 65536;
 24: Result := 16777216;
 end;
 end else
 Result := 0;
end;

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