procedure ParsePNG(const AFileName: TFileName);
  var
    VFile: TFileStream;
    VReader: TPNGReader;
    VColSpace: ShortString;
    VHeight, VWidth: LongWord;
    VBitDepth, VColorType: Byte;
  begin
    VHeight := 0;
    VWidth := 0;
    VBitDepth := 0;
    VColorType := 0;
    VFile := TFileStream.Create(AFileName, fmOpenRead or fmShareDenyWrite);
    VReader := TPNGReader.Create;
    try
      if not VReader.CheckContents(VFile) then
        raise Exception.CreateFmt('Not a PNG file: %s', [AFileName]);
      if VReader.GetChunk.aType <> ctIHDR then
        raise Exception.CreateFmt('Incorrect PNG file: %s', [AFileName]);
      VBitDepth := VReader.Header.BitDepth;
      if VBitDepth > 8 then
        raise Exception.CreateFmt('16-bit depth not supported: %s', [AFileName]);
      VColorType := VReader.Header.ColorType;
      case VColorType of
        0, 4: VColSpace := 'DeviceGray';
        2, 6: VColSpace := 'DeviceRGB';
        3: VColSpace := 'Indexed';
      else
        raise Exception.CreateFmt('Unknown color type: %s', [AFileName]);
      end;
      if VReader.Header.Compression <> 0 then
        raise Exception.CreateFmt('Unknown compression method: %s', [AFileName]);
      if VReader.Header.Filter <> 0 then
        raise Exception.CreateFmt('Unknown filter method: %s', [AFileName]);
      if VReader.Header.Interlace <> 0 then
        raise Exception.CreateFmt('Interlacing not supported: %s', [AFileName]);
      VHeight := VReader.Header.Height;
      VWidth := VReader.Header.Width;

      { TODO: implement compress/uncompress, trns, pal, index, flate etc. }

      WriteLn('h: ', VHeight, ' w: ', VWidth, ' bpc: ', VBitDepth,
        ' colspace: ', VColSpace);
    finally
      VReader.Free;
      VFile.Free;
    end;
  end;