procedure ConvertToOrdinal_8bit(PathToSave: string);
     var
      UsedColors: Integer;
      RGB_Palette: array of TRGB;
    begin
      with ImageEnView1 do
      begin
        UsedColors:= Proc.CalcImageNumColors;

        SetLength(RGB_Palette, UsedColors + 1);
        Proc.CalcImagePalette(RGB_Palette, UsedColors + 1);
        Proc.ConvertToPalette(UsedColors + 1, @RGB_Palette[0], ieOrdered);

        Refresh;
        Proc.Update;

        IO.Params.BitsPerSample := 8;
        IO.Params.SamplesPerPixel := 1;


        IO.SaveToFileBMP('c:\TestFile.bmp');
      end;
    end;

uses ieview, imageenview, imageenproc, hyieutils, hyiedefs, iexBitmaps, GraphUtil;
            
procedure TForm1.GetPaletteColors;
{ Fill TColorArray with palette colors. }
var
   i: Integer;
   iColorList: TColorArray;
begin
   ImageEnView1.IO.LoadFromFile(OpenPictureDialog1.FileName);
   { If the bitmap is not 8 bit paletted then convert it }
    if ImageEnView1.IEBitmap.PixelFormat <> ie8p then
       ImageEnView1.IEBitmap.PixelFormat := ie8p;
    SetLength(iColorList, ImageEnView1.IEBitmap.PaletteLength);
    { Add the colors to the TColorArray }
    for i := 0 to ImageEnView1.IEBitmap.PaletteLength - 1 do
    begin
       iColorList[i].Value := TRGB2TColor(ImageEnView1.IEBitmap.Palette[i]);
       iColorList[i].Name := '';
    end;
    { sort the colors by HUE - Optional}
    SortColorArray(iColorList, 0, 0, stHue, False);
end;

procedure TForm1.Open1Click(Sender: TObject);
var
  i: Integer;
  iColor: TColor;
begin
  if OpenPictureDialog1.Execute then
    if FileExists(OpenPictureDialog1.FileName) then
    begin
      { In order to be able to load the image palette colors, LegacyBitmap must be
        false, NativePixelFormat must be true and the bitmap must be 8-bit
        paletted }
      { Do not use Windows Bitmaps }
      ImageEnView1.LegacyBitmap := False;
      { Load images in native format }
      ImageEnView1.IO.NativePixelFormat := true;
      ImageEnView1.IO.LoadFromFile(OpenPictureDialog1.FileName);
      { if the bitmap is not 8 bit paletted then convert it }
      if ImageEnView1.IEBitmap.PixelFormat <> ie8p then
        ImageEnView1.IEBitmap.PixelFormat := ie8p;
      for i := 0 to ImageEnView1.IEBitmap.PaletteLength - 1 do
      begin
        iColor := TRGB2TColor(ImageEnView1.IEBitmap.Palette[i]);
        {Add the palette color to the color grid }
        mbColorPalette1.Colors.Add(ColorToString(iColor));
      end;
       StatusBar1.Panels[0].Text := ExtractFileDir(OpenPictureDialog1.FileName);
       StatusBar1.Panels[1].Text := ExtractFileName(OpenPictureDialog1.FileName);
    end;
end;

procedure TForm1.mbColorPalette1CellClick(Button: TMouseButton;
  Shift: TShiftState; index: Integer; AColor: TColor; var DontCheck: Boolean);
begin
  { Get the index of the selected color }
  AIndex := index;
  StatusBar1.Panels[2].Text := 'Index: ' + IntToStr(index);
end;

procedure TForm1.SetPaletteColors1Click(Sender: TObject);
begin
  { Set the selected color grid color to the new color }
  mbColorPalette1.Colors[AIndex] := ColorToString(ColorBox1.Selected);
  mbColorPalette1.Update;
  { Set the palette color to the new color }
  ImageEnView1.IEBitmap.Palette[AIndex] := TColor2TRGB(ColorBox1.Selected);
  ImageEnView1.Update;
end;

procedure TForm1.SaveAs1Click(Sender: TObject);
begin
  if SavePictureDialog1.Execute then
  begin
    ImageEnView1.IO.SaveToFile(SavePictureDialog1.FileName);
    if ImageEnView1.IO.Aborting then
    begin
      MessageBox(0, 'The image was not saved correctly.', 'Warning', MB_ICONWARNING or MB_OK);
      exit;
    end;
    StatusBar1.Panels[0].Text := ExtractFileDir(SavePictureDialog1.FileName);
    StatusBar1.Panels[1].Text := ExtractFileName(SavePictureDialog1.FileName);
  end;
end;

       for i := 1 to ImageEnView1.IEBitmap.Width do
         for j := 1 to imageEnView1.IEBitmap.Height do
           colorlist.Add(ColorToString(TRGB2TColor(ImageEnView1.IEBitmap.Pixels[j, i])));




        for i := 0 to ImageEnView1.IEBitmap.PaletteLength - 1 do
        begin
          iColor := TRGB2TColor(ImageEnView1.IEBitmap.Palette[i]);
          if (colorlist.IndexOf(ColorToString(iColor)) > 0) then
            mbColorPalette1.Colors.Add(ColorToString(iColor))
          else
            Continue;
        end;

for i := 0 to ImageEnView1.IEBitmap.PaletteLength - 1 do
        begin
          iColor := TRGB2TColor(ImageEnView1.IEBitmap.Palette[i]);
          ImageEnView1.SelectColors(TColor2TRGB(iColor));
          if ImageEnView1.Selected then
            mbColorPalette1.Colors.Add(ColorToString(iColor));
        end;

function GetColorFromBmp(X, Y: Integer; Bmp: TIEBitmap): TColor;
var
  Line: pRGBTripleArray;
begin
  Line := Bmp.ScanLine[Y];
  Result := RGBtoColor(Line^[X].rgbtRed, Line^[X].rgbtGreen, Line^[X].rgbtBlue);
end;

    pRGBTripleArray = ^TRGBTripleArray;
    TRGBTripleArray = ARRAY[0..MaxPixelCount-1] OF TRGBTriple;


procedure GetColorList(const Bitmap: TIEBitmap; out UsedColorList: TStringList);
  var
    Flags:  array[byte, byte] OF TBits;
    i    :  Integer;
    j    :  Integer;
    k    :  Integer;
    rowIn:  pRGBTripleArray;
BEGIN
  for j := 0 to 255 do
    for i := 0 to 255 do
      Flags[i,j] := nil;

  UsedColorList.Sorted:= True;
  UsedColorList.Duplicates:= dupIgnore;

  for j := 0 TO Bitmap.Height-1 do
  begin
    Application.ProcessMessages;
    rowIn  := Bitmap.Scanline[j];
    for i := 0 TO Bitmap.Width-1 do
    begin
      with rowIn[i] do
      begin

        if  (not Assigned(Flags[rgbtRed, rgbtGreen])) then
        begin
          Flags[rgbtRed, rgbtGreen]:= TBits.Create;
          Flags[rgbtRed, rgbtGreen].Size:= 256;
        end;

        Flags[rgbtRed,rgbtGreen].Bits[rgbtBlue]:= True;
        UsedColorList.Add(ColorToString(RGB(rgbtRed, rgbtGreen, rgbtBlue)));

      end
    end
  end;
end;