procedure TForm1.FormCreate( Sender: TObject );
begin
  ImageEnView1.EnableAlphaChannel := True;
  ImageEnView2.EnableAlphaChannel := True;
  ImageEnView1.IEBitmap.AlphaChannel.Location := ietbitmap;
  ImageEnView1.EnableAlphaChannel := True;
  ImageEnView1.IO.Params.Bmp_HandleTransparency := True;
  ImageEnView2.IEBitmap.AlphaChannel.Location := ietbitmap;
  ImageEnView2.EnableAlphaChannel := True;
  ImageEnView2.IO.Params.Bmp_HandleTransparency := True;
end;

procedure TForm1.Button1Click( Sender: TObject );
begin
  // paste to the clipboard
  ImageEnView1.Proc.SelCopyToClip;
  // if clipboard contains data valid for TImageEnProc
  if ImageEnView2.Proc.IsClipboardAvailable then
  begin
    // assuming X,Y = mouse coordinates, makes all colors the area transparent
    // tolerance specifies the maximum difference from the starting pixel
    ImageEnView2.Proc.CastAlpha( ImageEnView2.SelX1 + 1, ImageEnView2.SelY1 + 1, 0, 15 );
    // paste the contents of the Clipboard inside the ImageEnView2 selected area
    ImageEnView2.Proc.SelPasteFromClip( );
    ImageEnView2.Update;
  end;
end;