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Date Posted: 06:41:38 10/12/01 Fri
Author: Michel
Subject: Re: incorrect values in a colormap
In reply to: Heiko 's message, "incorrect values in a colormap" on 05:51:03 10/11/01 Thu


Hi Heiko,

I have found and corrected the problem.

In EnTifGr.Pas,

the function Cvt becomes:

function Cvt( Value : Word ) : Byte;
begin
Result := (((Value) * LongInt(256)) div ((1 shl 16)-1));
end;

and in SetTiffPalette, 255 is replaced by 256:

{ a 16 bit palette is more common for TIFF, so multiple each entry by 255. }
pBlueColorMap^[PaletteIndex] :=
Palette.palPalEntry[PaletteIndex].peBlue*256;
pGreenColorMap^[PaletteIndex] :=
Palette.palPalEntry[PaletteIndex].peGreen*256;
pRedColorMap^[PaletteIndex] :=
Palette.palPalEntry[PaletteIndex].peRed*256;

Best regards,

Michel

>Hello Michel,
>
>thank you for the response to my question 'Convert 4
>bit to 16bit Tif'. It works now!
>
>But i have a new problem. Itīs importend for me, that
>the colors in my images have exactly values.
>I define the RGB values with the 'tagPALETTEENTRY'
>type:
>
>e.g. newtifgraphic.PalettePtr^.palPalEntry[n].peRed :=
>85;
>
>newtifgraphic is a TTIFFGraphic. I repeat this for
>each colorvalue in each color in my colormap and save
>the TIFFGraphic. And now, when I reload the graphic
>all values are reduced by 1. Only the value 0 is
>correct. The result of the line above is 84.
>
>I can't increase the value by 1, because I need often
>the value 255 and the value 256 isn't valid in a Byte
>array.
>
>Have you an idea?
>
>Many thanks
>Heiko

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