From: "Earl F. Glynn"
Subject: Re: Converting 256 Color Bitmaps to monochrome (D4)
Date: Thursday, May 18, 2000 4:30 PM

"Andreas Vossloh" <service@kiup.de> wrote in message
news:3924593C.E815B12@kiup.de...

> how can I convert 256 color bitmaps (which are definitly black an white
> - only 255 and 0 values in the file) to monochrome (1-bit-per-pixel)
> bitmap. I want to save memory in my paradox-blob.

Just setting the PixelFormat to pf1bit will change the scanlines, but your
palette is likely wrong.  Yes, pf1bit bitmaps have a palette.  This seems
to work in defining a black/white palette:

procedure TForm1.Button1Click(Sender: TObject);
  VAR
    Bitmap:  TBitmap;
    Palette: TMaxLogPalette;
BEGIN
  Palette.palVersion := $300;
  Palette.palNumEntries := 2;
  WITH Palette.palPalEntry[0] DO
  BEGIN
    peRed   := 0;
    peGreen := 0;
    peBlue  := 0;
    peFlags := 0
  END;

  WITH Palette.palPalEntry[1] DO
  BEGIN
    peRed   := 255;
    peGreen := 255;
    peBlue  := 255;
    peFlags := 0
  END;

  Bitmap := TBitmap.Create;
  TRY
    Bitmap.LoadFromFile('BlackWhite.BMP');
    Bitmap.Palette := CreatePalette(pLogPalette(@Palette)^);
    Bitmap.PixelFormat := pf1bit;
    Bitmap.SavetoFile('NewBlackWhite.BMP');
    Image1.Picture.Graphic := Bitmap
  FINALLY
    Bitmap.Free
  END
end;


--
efg

Earl F. Glynn
Overland Park, KS  USA

efg's Computer Lab:  http://www.efg2.com/Lab