changing a line

[aka]

Hi,

Let say we have a layer with some lines, it can be pen or brush or something else ; that does no matter, I can take any of them for the following purpose : I would like to change the thickness of an already drown line through someting like options, preferences, etc.

Is it please possible ?

Best regards.

[Ofnuts]

(10-05-2021, 09:08 AM)aka Wrote: Hi,

Let say we have a layer with some lines, it can be pen or brush or something else ; that does no matter, I can take any of them for the following purpose : I would like to change the thickness of an already drown line through someting like options, preferences, etc.

Is it please possible ?

Best regards.

Not with just options. Two ways:

1) Filters ➤ Generic ➤ Erode (yes, assuming black over white background) after possibly making  a selection around said lines (plus some space to include the pixels that will be covered by the thickness increase)

2) Color select the line (perhaps with an intersection with a selection around the lines of interest, to not select the rest of the image (see here for techniques to do so)) then Select ➤ Grow to enlarge the selection and bucket-fill the selection.

[PixLab]

You can try Filters > Distorts > Value Propagate...
If you are on a transparent layer select "More opaque" to increase and "More transparent" to decrease

   

As you can see on the screenshot you have many option (More white/More black/colors and so...)
This will increase or decrease by 1 pixel (once you clicked OK, just do Ctrl+F to repeat until you are satisfied with the thickness)
If things start to look funky, un-check the different check boxes

   

More about this underrated tool https://docs.gimp.org/2.10/en/gimp-filte...agate.html