On Thu, 10 Feb 2000 17:44:38 -0800, "H.E. Day" <hed### [at] fcinet> wrote:

>My first suggestion deals with the Soft_Blur feature.  Could someone put
>a
>third value, "tolerance"  to the syntax?  This would be helpful if the
>artist wants only the bright parts to glow. (Like the lights on the
>surface of a spaceship :)  1 would be only the brightest parts and 0
>would be all the picture.

I had also thought of basically the same idea, but it would be better
grammar to use the word "Threshold" instead of "Tolerance", if you
don't mind my saying so. Basically any pixel who's brightness exceeds
a certain "threshold" would be made to glow. Alternately, one could
assign two numbers instead of one, and declare a "range" of values
that would have glow applied.  This might allow some interesting
experimental special effects, because you could selectively blur only
the shadows, midtones, or anything else that you desire.

My original idea was to keep track of the individual image pixel
values in floating point format and only apply effects to pixels that
*exceeded* 1.0 in value. The actual threshold would be changeable for
example, to something like 3, 12, or whatever you want. This way,
perfect white surfaces which might have a value of 1.0 would not be
blurred, but light sources which might exceed a value of 1.0 by a
significant amount *would* be blurred. 

In fact, this threshold could be applied to things other than the
current blur feature. Lens flare, comma distortion, and "cross" or
star-shaped highlights come to mind as possible candidates for effects
that would depend on a pixel brightness threshold.

Does anyone else like the idea?

later,
Glen Berry

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