TImage32.Crop

procedure Crop(const rec: TRect);

 uses Img32, Img32.Fmt.PNG;
...
img := TImage32.Create;
img.LoadFromFile('star.png');
img.Crop(Rect(20,25, 225, 230));
img.SaveToFile('star_cropped.png');
img.Free;

Before:

After: