[Gimp-user] Changing Layer Opacity produces visible color gradient steps

[erickfis <forums gimpusers com>]

I created a layer filled with black, above the original image layer, and then
changed the opacity of the black layer, so it would darken the original image. I
have to do this because its a mask created from a selection.

Works like I wanted BUT produces a visible gradient color steps  which are not
wanted on my final exported jpg. See attachment and you will understand what I'm
talking about.

Please help me to fix it.

Attachments:
* http://www.gimpusers.com/system/attachments/216/original/gimp-gradual.jpg

-- 
erickfis (via www.gimpusers.com/forums)