procedure TForm1.Curves1Click(Sender: TObject);
begin
  if Assigned(PageControl1.ActivePage) then
  begin
    ImageEnView := TImageEnView(PageControl1.ActivePage.Controls[0]);
    if Assigned(ImageEnView) then
    begin
      FormCurves := TFormCurves.Create(Self);
      try
        FormCurves.IEColorCurve1.AssignSource(ImageEnView.IEBitmap);
        if FormCurves.ShowModal = mrOK then
          FormCurves.IEColorCurve1.ApplyCurve(ImageEnView.IEBitmap); << Exception in  TIEColorCurve.UpdateHistograms
        ImageEnView.Update();
      finally
        FormCurves.Free;
      end;
    end;
  end;
end;

procedure TIEColorCurve.UpdateHistograms();
var
  bmp: TIEBitmap;
  iRow: PCurvesRGBArray;
  X, Y, RFill: Integer;
  iRGB: TRGB;
  iR, iG, iB, iZ: Byte;
begin
  if fBitmap.IsEmpty then
    Exit;

  if fPreviewValid then
    bmp := fPreviewBitmap
  else
    bmp := fBitmap;

  for Y := 0 to 3 do
  begin
    fHistogramsMax[Y] := 0;
    for X := 0 to 255 do
      fHistograms[Y, X] := 0;
  end;

  iRow := PCurvesRGBArray( bmp.Scanline[0]);
  RFill := Integer( bmp.Scanline[1]) - Integer(iRow);
  for Y := 0 to bmp.Height - 1 do
  begin
    for X := 0 to bmp.Width - 1 do
    begin
      iRGB := iRow[X]; << Exception