Softedge problem

vvvv beta question
1

the softedge shader seems to add a bright stripe at the end. its not very obvious and usually only visible on bright grey background. i’ve seen it before when doing a multiscreen installation but i thought its due to bad projector gamma.

is this an optical illusion or actually a wrong alpha ramp ?

http://vvvv.org/tiki-download_file.php?fileId=1995softedgeproblem.zip (2.01 Kb)

2

quite a nut:

i assume that this is some “division by zero” issue occuring when gamma 1.
try changing from
col.a = clamp(In.TexCd.x, 0, 1);

to
col.a = clamp(In.TexCd.x, 0, 0.99);

and see the result; you may get an idea now.

sorry, can’t go deeper inside.

3

it always there, no matter if i change the code and/or the gamma value. what i forgot to mention before, this shader is an essential part of the multiscreen nodes. people might run into problems using them with softedge. not a problem with black or very colorful background.

one easy solution is doing the softedge with a dynamic texture + quad.

4

i would vote for an optical illusion…
just cover the right side of your renderer.
is it still there?

5

you are right, i didnt cover the side but did some pipet tests in photoshop and vvvv (which i should have done initially)…no jump in brightness.

i guess this effect looks different from monitor to monitor…and some brains seem to be more affected than others :)

i’m going to investigate this.

6

my personal neuroscience specialist pointed my in the right direction, see: