Fixing scanned Ink Lines

[Hydro]

Is there a feature in GIMP that can quickly complete/fill in patchy, incomplete line-work like in the image attached? The image is part of a scanned inked-in drawing that has been converted to indexed colors using a black and white (1-bit) palette. No other modifications were made to the scanned image.

[Blighty]

The image is RGB (not indexed) with 256 colours.

The black lines have some white gaps in them. These are probably best fixed in the scanning process. Try and get light areas to scan as black.

In Gimp, I tried 3 different methods. In the image:

Top Left: Original

Top Right: Filters > Genric > Erode

Bottom Left:  Select the black with a high threshold. (I used 120.) Grow the selection by 1. Bucket Fill with black.

Bottom Right: G'MIC has a filter Repair Scanned Document.

[rich2005]

Much the same as Blighty

A couple of ways as a starter.

1. Filters -> Generic -> Erode grows darker areas. Apply and maybe repeat. sceenshot https://i.imgur.com/3E2u4G9.jpg
or
2. Since the original is black / white Blur the image Filters -> Blur -> Gaussian Blur then apply Colors -> Threshold moving the center slider to suit. https://i.imgur.com/No2TV2e.jpg

[Hydro]

Thanks for the responses. I ended up restarting from the same initial scanned image. I first maximized the contrast and then applied the erode filter several times. The end result was line-work without the white spots, but now there are unwanted black spots (see attached). I think these are unwanted markings from the original scan that have been enhanced. Is there a way I can prevent/remove these with GIMP?

[denzjos]

Smoothing your last image :
   
   

[rich2005]

No real easy way, the scan is not-too-good. One pixel magnified by however many times you applied erode. If you know where they are, paint them out first.

For speed. Back to gaussian blur, then Colors -> Threshold then the opposite of 'erode' Filters -> Generic -> Dilate.