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a:= getrvalue(colortorgb(image1.Canvas.Pixels[x,y]));					

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a:= getrvalue(colortorgb(image1.Picture.Bitmap.Canvas.Pixels[x,y]));					

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a:= getrvalue(colortorgb(image1.Picture.Bitmap.Canvas.Pixels[x,y]));					

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procedure TForm1.BuLoadClick(Sender: TObject);
var
  jp :TJpegImage;
begin
  if OpenPictureDialog1.Execute then begin
    jp :=TJpegImage.Create;
    try
      jp.LoadFromFile(OpenPictureDialog1.FileName);
      jp.DIBNeeded;
      Image1.Picture.Bitmap.Assign(jp);
    finally
      jp.Free;
    end;
  end;
end;

procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  ShowMessage(ColorToString(image1.Picture.Bitmap.Canvas.Pixels[x,y]));
end;