HatchBackground

procedure HatchBackground(img: TImage32; color1, color2: TColor32; hatchSize: Integer);

Assumes the current image is semi-transparent.

uses Image32, Image32_Extra, Image32_PNG;
...
img := TImage32.Create;
img.LoadFromFile('star.png');
HatchBackground(img, clWhite32, clSilver32, 10);
img.SaveToFile('star_hatched.png');
img.Free;

Before:

After: