[Gimp-user] Thickening/darkening lines of scanned images

[rich404 <forums gimpusers com>]

> Hello
>
> I’m a newbie to Gimp. Please could you help! 
>
> I’ve collated self portraits from a class of 30 pupils to create
> artwork for a printed tea towel. Each self portrait is very different,
> varying from, pencil, felt tip pens, crayons to biro. Some black and
> white, most are in colour. Every picture has been scanned in ready to
> create the artwork.
>
> My problem is, how can I thicken and darken very thin/faint lines of
> scanned images? And is there a quick way of doing this?
> I really don’t want to be using a paint brush/or pencil tool going
> round each image, as this will take me a very long time!
>
> Thanks

As with everything graphics, all depends on the image(s).  Assuming Gimp 2.10
and Windows

First thing to try is Filters -> Generic -> Erode which grows dark areas. Try
applying a couple of times. See: comparison screenshot.

If they are reasonably clean scans  then you should get a result. Otherwise:

For something more sophisticated but still easy to use, try the Gimp gmic
plug-in www.gmic.eu  There is a Windows installer for Gimp 2.10. This has
hundreds of filters for various effects but there is one - repair scanned
documents. See: screenshot.  Adjust sliders to suit.

Attachments:
* https://www.gimpusers.com/system/attachments/1207/original/01-darken.jpg
* https://www.gimpusers.com/system/attachments/1208/original/02-darken.jpg

-- 
rich404 (via www.gimpusers.com/forums)