How do I convert an image from PNG to BMP in Delphi VCL?

When I convert PNG picture to BMP picture via the routine below, then the colors are not the same in BMP as they are in the original PNG.

procedure TForm1.Button4Click(Sender: TObject);
var
  R: TRect;
  Bmp: TBitmap;
  Png: TPngImage;
begin
  Png := TPngImage.Create;
  try
    Png.LoadFromFile('C:\temp\Source.png');
    bmp := TBitmap.Create(Png.Width, Png.Height);
    try
      R := Rect(0, 0, Png.Width, Png.Height);
      bmp.Canvas.CopyRect(R, png.Canvas, R);
      bmp.SaveToFile('C:\temp\target.bmp')
    finally
      Bmp.Free;
    end;
  finally
    Png.Free;
  end;
end;

Could you provide me a hint on how to solve this issue, please?

I just tested the following procedure and it works without any issues. The colors look identical to my human eyes when comparing the original PNG and the result BMP:

procedure ConvertPNGtoBMP(const PNGFileName, BMPFileName: string);
begin
  var PNG := TPNGObject.Create;
  var BMP := TBitmap.Create;
  try
    PNG.LoadFromFile(PNGFileName); // Load the PNG image
    BMP.Assign(PNG); // Assign the PNG image to the BMP object
    BMP.SaveToFile(BMPFileName); // Save the BMP image
  finally
    PNG.Free;
    BMP.Free;
  end;
end;

Results:

I simply called it like this:

ConvertPNGtoBMP('MyPhoto.png', 'MyPhoto.bmp');