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From: Vinzent Hoefler <ada.rocks@jlfencey.com>
Newsgroups: comp.lang.ada
Subject: Re: Saturated Math
Date: Fri, 30 May 2003 16:45:30 +0200
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Robert A Duff wrote:

>Vinzent Hoefler <ada.rocks@jlfencey.com> writes:
>
>> Because its more intuitive for their problem domain. It would be in
>> mine. I have a lot of color value conversions that should stop at
>> black or white but I still need the grey values inbetween even after
>> some of these pixels have saturated.
>
>I still don't get it.  By "sticky", I mean that arithmetic is sticky.

Yes, I think I know what you mean.

>You can still set the thing to any value you like.  In your example of
>0..255, if X =3D 200, and you say "X :=3D X + 100;", then X =3D 255.

Yep, exactly.

>If you then subtract 100 from X, you go "too far" in the other
>direction, it seems to me.

Well, no. But this might be specific to the problem domain.

If I am going back that is because I compress the output color space,
so subtracting -100 from a black pixel that saturated before is
perfectly correct.

>  So if you want to, say, set it back to 200,
>you should say "X :=3D 200;", not "X :=3D X - 100;".

Yes, but this is what I don't want to do. I want to subtract 100 from
each pixel, either it was saturated before or not.


Vinzent.

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