trouble cleaning up lines from scan

[Soulman]

Hello all , new to the forum - 

I am trying to clean up lines from a sketch that I scanned into my computer.  The scan settings were the highest quality I could make it.  The sketch was outlined using an artist pen but it left some pixelation around the lines.

I looked up some tutorials and most of them instructed to use the "Levels" and "Threshold" tool to rid of the pixalation.  Except that it just doesn't work!  No matter what settings I use, following all the instructions, any slider changes don't result in anything, even in the most extreme settings!  Nothing changes.  The histogram shows no information.  What am I doing wrong or is this a bug in gimp?  All of my other tools work as expected except for the two I need! Of course, it's always the way things work out..


Here is info on the file, my system.

I am running Gimp 2.8 on Windows 7 (64bit)
It was opened as a RGB, JPG file.  it is one layer

[Ofnuts]

Attaching the actual image file is better. It seem that you scanned in black/white mode and not in greyscale, which would give more data to process (levels and treshold are only meaningful on greyscale or color).

In your case, a possible processing:

* Filter>Generic>Dilate applied twice will remove most of the random dots
* Filter>Blur>Gaussian blur (5 pixels) will smooth the edges
* Colors>Brightness contrast and increase contrast until the edges become jagged, then back off a bit (about 75)

   

Slightly differently:
* No Filter>Generic>Dilate
* Filter>Blur>Gaussian blur (10 pixels this time) will smooth the edges
* Colors>Brightness contrast and increase contrast until the edges become jagged, then back off a bit (about 100 this time)