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Smoothing inked lines?

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Smoothing inked lines? Marc Carson 14 Jul 22:35
  Smoothing inked lines? Noel Stoutenburg 14 Jul 22:53
  Smoothing inked lines? mac9416 14 Jul 22:56
   Smoothing inked lines? Marc Carson 14 Jul 23:09
    Smoothing inked lines? mac9416 14 Jul 23:35
    Smoothing inked lines? GSR - FR 15 Jul 00:28
  Smoothing inked lines? David Gowers 15 Jul 01:53
  Smoothing inked lines? bktheman34 16 Jul 11:46
   Smoothing inked lines? Marc Carson 21 Jul 02:00
Marc Carson
2010-07-14 22:35:21 UTC (over 10 years ago)

Smoothing inked lines?

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!

Noel Stoutenburg
2010-07-14 22:53:27 UTC (over 10 years ago)

Smoothing inked lines?

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?

mac9416
2010-07-14 22:56:17 UTC (over 10 years ago)

Smoothing inked lines?

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!

Marc Carson
2010-07-14 23:09:01 UTC (over 10 years ago)

Smoothing inked lines?

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).

mac9416
2010-07-14 23:35:41 UTC (over 10 years ago)

Smoothing inked lines?

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).

GSR - FR
2010-07-15 00:28:25 UTC (over 10 years ago)

Smoothing inked lines?

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

David Gowers
2010-07-15 01:53:06 UTC (over 10 years ago)

Smoothing inked lines?

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. :)

2010-07-16 11:46:53 UTC (over 10 years ago)
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Smoothing inked lines?

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

Marc Carson
2010-07-21 02:00:33 UTC (over 10 years ago)

Smoothing inked lines?

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

Thanks for that (and everyone else for the other great ideas). I'm using this trick for now until I get a direct potrace solution working. I also noticed that G'MIC has a "XSmooth Comic Lines" or something like that...sounded awesome but I wasn't able to get a good result from it. Maybe it's for a different purpose. Too many sliders to tell... :-)