horizontal lines using edge detection

[salaam]

Why do I get these annoying horizontal lines when applying 'Roberts cross' or other special effects?

[gwpriester]

The question is, why do you want to apply Robert's Cross.

I have to admit, I never understood half those old filters.

Gary

[salaam]

I was satisfied with it's effect (apart from the phantom lines).
I needed to convert a photo into a line drawing for a website.
I also needed the same effect for a CD burn image.
The lines seem to be a bug.