Marc Carson wrote:

I've been scanning inks into GIMP, then moving them over to Inkscape for tracing to make the lines smoother. Is there a way to do this in GIMP alone? I don't mean vector tracing, just getting rid of the smaller abnormalities or fuzziness around my inked lines. I already scan at 600 dpi.

I expect there are; what have you tried? One of the first that comes to my mind is the unsharp mask (found in 2.6 under Filters > enhance?

This is something I've struggled with as well. I'm not sure if I've ever found a good solution, but Selective Gaussian blur comes to mind. It's in Filters > Blur > Selective Gaussian Blur. Just tinker with the settings and see what happens.

Is there somewhere we can see one of the scans you're working with?

On Wed, Jul 14, 2010 at 3:35 PM, Marc Carson wrote:

I've been scanning inks into GIMP, then moving them over to Inkscape for tracing to make the lines smoother. Is there a way to do this in GIMP alone? I don't mean vector tracing, just getting rid of the smaller abnormalities or fuzziness around my inked lines. I already scan at 600 dpi. Here's an example:
http://www.friendlyskies.net/projects/comics/before-after.png Thanks!

OK, try this: apply a Gaussian Blur to the image (I used it at 7 or 8 pixels) to smooth those lines up, and then apply a Unsharp Mask to sharpen it again. You should end up with fairly smooth lines. You can, of course, tinker with the settings of both filters to fine-tune the result.

On Wed, Jul 14, 2010 at 4:09 PM, Marc Carson wrote:

Is there somewhere we can see one of the scans you're working with?

Sure. Here's an original panel straight from the scanner: http://friendlyskies.net/projects/comics/originalpanel.png I tried unsharp mask and selective gaussian blur, but no luck either way (converted to RGB).

Hi,
marc@marccarson.com (2010-07-14 at 1409.01 -0700):

Is there somewhere we can see one of the scans you're working with?

Sure. Here's an original panel straight from the scanner: http://friendlyskies.net/projects/comics/originalpanel.png I tried unsharp mask and selective gaussian blur, but no luck either way (converted to RGB).

Pretty old tech and that works in greyscale: gaussian blur (different scans, different values, try 5-15 for your png) followed by curves with a sigmoid shape (make flat zones both at start and end with a sharp / in the middle, for your png start with with 3 squares flat at min, then 2 for the climb, and 3 at max).

At worst case, mask the plants and apply different settings: big blur in the plants destroys them, and small blur keeps lots of noise in the car lines.

GSR

On Thu, Jul 15, 2010 at 6:05 AM, Marc Carson wrote:

I've been scanning inks into GIMP, then moving them over to Inkscape for tracing to make the lines smoother. Is there a way to do this in GIMP alone? I don't mean vector tracing, just getting rid of the smaller abnormalities or fuzziness around my inked lines. I already scan at 600 dpi. Here's an example:
http://www.friendlyskies.net/projects/comics/before-after.png Thanks!

Yes, you may want a combination of 1. Despeckle (to eliminate specks)
2. GMIC Anisotropic Smoothing (GMIC plugin: gmic.sf.net) with a relatively large radius, large tensor-smoothing value, and anisotropy = 1.0. Experiment with different values of 'sharpness' -- you may need to reduce it below the default 0.70 to get as much smoothing as you want.

Another solution: If you are running linux, you will probably have the tools to make a batch-processing script or Python GIMP plugin that uses PoTrace (commandline tool;same algorithym as is integrated into Inkscape). Potrace has options to output a PGM (ie a greyscale raster, rather than a vector -- like SVG etc) to do tracing/smoothing. This could be the fastest and most reliable, high quality option, once you have worked out the options appropriate for your work.

The most important options for Potrace would probably be

--alphamax #how smooth the output is. 0..1.43, default 1.0. --blacklevel #the black/white threshold -- in the range 0..1. --turdsize #this discards junk pixels -- pixel islands of N size --pgm #set output format to PGM raster, or.. --svg #you could get an SVG -- if you wanted a larger output than input. --width
--height # set output dimensions

Hope one of those suggestions help. :)

Here's what I'd do. Gaussian blur, by 8 pixels radius. Then do COLOURS > BRIGHTNESS-CONTRAST, increase the contrast slider to 70.