GNOME Bugzilla – Bug 55366
Filter out jitter in hand-drawn curves / draw smooth lines
Last modified: 2012-08-25 22:25:15 UTC
The path editing tool (or bezier select, although I hope they will be merged in 1.3.x) should have an option to filter out the small "bumps" that are created when you draw a curve by hand. The curves or straight lines will then look smoother and closer to what was intended (unless the user really wanted to have a shaky line). It would be nice if the degree of smoothness could be configured, so that one could choose between "almost perfect" curves and "shaky" style. Some drawing programs have a similar feature and they can filter out the small bumps. Roy Katz <katz@Glue.umd.edu> wrote in comp.graphics.apps.gimp: > 4. Jitters in hand-drawn lines > > this I'm particularly interested in. Drawing with the Wacom tablet > (calcomp is grittier.. doesn't seem to have that probelm), all my lines > come out jittery. Particularly when the disk is accessed -- then we get > scritches in the curve. How do other people solve this? > Perhaps a feature that can be implemented is a 'jitter corrector' (of > which its threshold/magnitude can be set): since a jitter is > basically a small scritchy curve, can we make some sort of algorithm to > detect & remove? I see something like this: the artist draws a > curve, freehand, with a stylus. Jitters are introduced along the > way. It is improbable that the artist is intentionally drawing small > curves quickly if she is moving her hand slowly as she her curve; so > these small curves must /be/ jitters. Solution: find a spline or > function to interpolate between the beginning & end of the jitter.
Reassigned to current CVS because it's a wishlist item.
*** Bug 55405 has been marked as a duplicate of this bug. ***
I just saw another article posted yesterday in the newsgroup comp.graphics.apps.gimp. I am copying it here for information: > The Wacom support is good -- at least for my 9x12 usb intuos it is. > There are a few annoying (perhaps hindering) bugs: > > 1. The macro strip is not supported (there may be patches for it, > but AFAIK the button strip is not supported currently). > > 2. There are jagged jitters that occur when you try to draw curves > freehand. That *really* sucks. I posted a note about > this to the wacom-dev list, but no one seemed to > care. Ah well. > > Otherwise the tablet works as expected: pressure sensitivity is > perfect. I don't know about speed or tilt sensitivity. The > airbrush and ink pen are supported as well. Multiple styli are > supported. If they could only solve the jitter problem! grr! I > don't know if this is the tablet driver, or just GIMP -- but I'm > getting really frustrated about this. It's been half a year since > I reported this, and the problem has not been resolved. > I don't get this behaviour under Win2k. > > Besides that.. I dunno, I could never draw freehand under GIMP. > It looks like something a five year old would draw: too jagged. > I tend to just scan in a line drawing and then color it in with > the tablet. Sigh.
Did you try if tuning the value for Suppress in your X config helps (see man 4 wacom) ?
Roy Katz was not on the CC list, so he probably did not see your question. I have added him now. But anyway, as explained in bug #55405, changing the X config is not a very good solution (even if it might solve the problem in this case). It would be better to have a setting for this in the Gimp, so that it could also be used by mouse users and the threshold could be changed without having to quit all applications and restart X.
*** Bug 79446 has been marked as a duplicate of this bug. ***
*** Bug 90218 has been marked as a duplicate of this bug. ***
Both bug #79446 and bug #90218 use Flash as an example. The latter explains how the amount of smoothing is linked to the zoom factor and gives a good use case: if you want to draw a smooth circle, zoom out so that you will get a lot of smoothing, draw your freehand shape, then zoom in again and it will look perfect. Read the description of bug #90218 for more details. This feature applies to all users (mouse or tablet) and it should be easy to enable or disable it. It should also be easy to specify the amount of smoothing/straightening to be applied to the lines and that smoothing should be applied to the screen coordinates, not to the image coordinates (so that it is linked to the zoom factor).
Setting to future, it doesn't look like anyone is working on this. Dave.
*** Bug 315478 has been marked as a duplicate of this bug. ***
Maybe we could use the newly introduced Jitter setting here and introduce a negative setting that would smooth the curve.
Has any work been done on this bug? This seems to be a deal-breaker for many artists trying gimp/Linux. If nobody is working on this, how would you suggest I get started? It couldn't be that hard, the algorithms are pretty much known and Sven here says there's already a nice setting in the UI for it...
If any work would have been done, then there would be a note here in the bug report. If you want to help with it, I suggest that you start reading the code. If you have problems, feel free to ask on the gimp-developer mailing-list.
This has actually been implemented in 2.8.