Re: Draw in bitmap - 256 color palette -- Envision Support Forum

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Date Posted: 07:30:26 01/03/01 Wed
Author: Michel
Subject: Re: Draw in bitmap - 256 color palette
In reply to: Poul Halgaard 's message, "Draw in bitmap - 256 color palette" on 15:34:50 01/02/01 Tue

Dear Poul,

I would use a TBitmapGraphic instead of a TBitmap to do the conversion. For example,

var

Bitmap24, Bitmap8 : TBitmapGraphic

begin
Bitmap24 := TBitmapGraphic.Create;
Bitmap8 := TBitmapGraphic.Create;
ImageFormatTransform := TImageFormatTransform.Create;

Bitmap24.LoadFromFile( 'c:\24bit.bmp' );

ImageFormatTransform.ImageFormat := ifColor256;
ImageFormatTransform.Quantize := true;
ImageFormatTransform.Dither := true;
ImageFormatTransform.ApplyOnDest(Bitmap24, Bitmap8);

Bitmap8.SaveToFile( 'c:\8bit.bmp' );

ImageFormatTransform.Free;
Bitmap8.Free;
Bitmap24.Free;

end;

Best regards,

Michel

>I want to convert a 24 bit image to 8 bit and assign the result to a bitmap. Why does this code not work? The colors are messed up, no matter what I try. How should it be done? 
> 
>var 
> ABitmap: TBitmap; 
> ADibGfx: TDibGraphic; 
> AImageFormatTransform: TImageFormatTransform; 
>begin 
> ABitmap := TBitmap.Create; 
> try 
> ABitmap.LoadFromFile('c:\24bit.bmp'); 
> ADibGfx := TDibGraphic.Create; 
> try 
> ADibGfx.Assign(ABitmap); 
> 
> AImageFormatTransform := TImageFormatTransform.Create; 
> try 
> AImageFormatTransform.ImageFormat := ifColor256; 
> AImageFormatTransform.Quantize := true; 
> AImageFormatTransform.Dither := true; 
> AImageFormatTransform.Apply(ADibGfx); 
> finally 
> AImageFormatTransform.Free; 
> end; 
> 
> ABitmap.PixelFormat := pf8bit; 
> ABitmap.Palette := ADibGfx.PaletteHandle; 
> 
> ADibGfx.Draw( 
> ABitmap.Canvas, 
> Rect( 
> 0, 0, 
> ADibGfx.Width, 
> ADibGfx.Height)); 
> 
> ABitmap.SaveToFile('c:\8bit.bmp'); 
> 
> finally 
> ADibGfx.Free; 
> end; 
> finally 
> ABitmap.Free; 
> end; 
>end; 

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Replies:

Re: Draw in bitmap - 256 color palette -- Poul Halgaard, 15:37:40 01/03/01 Wed
- Re: Draw in bitmap - 256 color palette -- Michel, 07:28:37 01/04/01 Thu
  - Re: Draw in bitmap - 256 color palette -- Poul Halgaard, 17:17:42 01/05/01 Fri
    - Re: Draw in bitmap - 256 color palette -- Michel, 07:45:19 01/08/01 Mon
      - Re: Draw in bitmap - 256 color palette -- Poul Halgaard, 16:47:53 01/08/01 Mon
        Re: Draw in bitmap - 256 color palette -- Michel, 07:36:03 01/09/01 Tue
        Re: Draw in bitmap - 256 color palette -- Poul Halgaard, 15:43:10 01/09/01 Tue
        Re: Draw in bitmap - 256 color palette -- Michel, 21:55:29 01/09/01 Tue
        Re: Draw in bitmap - 256 color palette -- Poul Halgaard, 17:22:55 01/10/01 Wed
        Re: Draw in bitmap - 256 color palette -- Michel, 17:31:45 01/10/01 Wed
        handle the pixels of bitmap -- nazish, 03:43:50 03/22/01 Thu
        Re: handle the pixels of bitmap -- Michel, 17:36:34 03/22/01 Thu

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