Re: [Gimp-user] How to spice up my background colors

[Steve Kinney <admin pilobilus net>]

On 06/30/2018 12:09 AM, GerryPeters wrote:
> I'd like to add some variation to some of my backgrounds which are just 1 plain
> color. What's the best way to change that to a gradient or pattern? Or any other
> suggestions to spice up my colors, so they're not so generic. So far I've been
> using the bucket tool

Sounds like it's time to start using layer masks.  A layer mask enables
you to make any part of a layer completely or partially transparent:
Paint in black (or fill a selection, etc.) on a layer mask, and the
layer becomes transparent just there.

If you "mask out" the background in your top layer, leaving only the
foreground objects visible, you can do anything at all to the layer(s)
under it, or add new ones, to change the visible background.

I found masks very confusing at first, this illustrated explanation
might be useful:

http://pilobilus.net/gimp_tutorial.html#layers

To add a mask to a layer, right-click the layer thumbnail in your Layers
dock and select 'add layer mask.'  Left click on the mask to make it
active, so for instance you can paint on it.  Click the 'main' part of
the layer to switch back and do things to the layer's visible content.

Shades of gray make the layer partially transparent; for instance, use
the Gradient tool's default setting, with black and white as foreground
and background in your color selector, to make a layer fade out from top
to bottom, side to side, or etc. with the layer(s) under it showing
through.  Other gradient settings, especially radial, also have their
uses here.

If you want to apply a filter to just some parts of a layer, leaving the
rest unchanged, and blend the altered parts in for a 'natural'
appearance, try this:  Make a copy of the layer you want to alter, apply
the filter to the new layer, and add a layer mask to it.  Then fill the
whole mask with black - making it vanish.  Now you can paint on the top
layer's mask with white - using a soft edged brush - to 'replace' the
bits of your original layer with content from the altered copy.  Made a
mistake?  No problem, switch to black and paint the errors away.
Trouble getting the altered bits to blend in smoothly?  Try applying the
Gaussian Blur filter to the mask, either the whole thing or parts
selected with the Free Select tool.

:o)