Creating a path from a picture

[piscvau]

Hello
I am using GIMP and INKSCAPE to do cloth personalisation and up-cycling, on LINUX 16.04 Xubuntu.
I have a picture of a stitch garment in 2 colours. (see attachement for a picture with reduced definition)
I would like to get a path from this picture in order to use it in INKSCAPE.
I have tried to use colour selection then selection to path; But the path contains some 35000 nodes and when open in INKSCAPE it never comes back.

I have a high picture definition. I thought about reducing the definition but I am afraid to get "staircases" instead of curves. Do you have any suggestion on howx I could reduce the number of nodes. Is there a modificcation of the image before doing the selection which could help. The "contiguous coulor "selection does not work any better. So any help would be welcomed.

Piscvau

[Ofnuts]

1. No attachment in sight, see here for help. Beware of size limitations.
   
2. 35000 nodes isn't that big.
   
3. On the contrary, a small size could help getting less nodes. If necessary, just apply  a small blur.
   
4. If the picture has enough contrast, load it in InkScape and use the "Trace bitmap" function to generate the path in Inkscape.
   
5. Doing the paths manually is often easier that you think and often gives better results.
   

[rich2005]

Came up on another forum. The type of image to be processed

http://www.gimpusers.com/system/attachme...1508168549

Lots of jagged edges to give lots of nodes. I suggested threshold -> blur -> threshold again to get a smoother edge. Bound to be other ways.

As (3) above, a small image is no disadvantage since a path can be scaled without degradation.

[piscvau]

(10-18-2017, 07:39 AM)rich2005 Wrote: Came up on another forum. The type of image to be processed

http://www.gimpusers.com/system/attachme...1508168549

Lots of jagged edges to give lots of nodes. I suggested  threshold -> blur -> threshold again to get a smoother edge. Bound to be other ways.

As (3) above, a small image is no disadvantage since a path can be scaled without degradation.

Thank you very much for both responses.
I am not a gimp professionnal and I am afraid I need some more details.
As I a not a GIMP specialist and moreover I use french version I need to translate your suggestion to make sure I understand it. 
I do a "contiguous sélection" using the threshold then I apply the filter blur 'gaussien" on the image then I do a contiguous selection again with threshol.I tried it and it seems to help a lot.

For "security" reasons, my browser does not allow me to uplaod images on this forum!... Supposedly a certificate problem?....
Thanks again for your help

[Ofnuts]

Scaling to 971x1200, blurring, thresholding, fuzzy select and select-to-path gives a path of 400+ anchors. But the result isn't too accurate, since any technique that involves blurring rounds off the sharp points.


  Paths-Collants.xcf (Size: 109.19 KB / Downloads: 307)

However, IMHO, doing it by hand would take 20-30 minutes and give a much better result. I reckon this an be done with 50 anchors or less, giving regular lines and sharps ends where needed.

[Ofnuts]

Quick 5-minutes shot at it:


  Paths-Collants2-PathOnly.xcf (Size: 8.1 KB / Downloads: 304)

(picture layer removed to reduce size)

[rich2005]

Both of ofnuts examples make the point. The second - hand tracing will give the best result.

This a short video using my original proposal: threshold -> blur -> threshold About 3 minutes, Gimp and Inkscape

https://youtu.be/6ghGIKewT0w

might help

[piscvau]

(10-18-2017, 10:04 AM)rich2005 Wrote: Both of ofnuts examples make the point. The second - hand tracing will give the best result.

This a short video using my original proposal: threshold -> blur -> threshold About 3 minutes, Gimp and Inkscape

https://youtu.be/6ghGIKewT0w

might help

Hey this is so nice from you. I get a lot of ways to make progress in my use of GIMP. I am going to take the time to go deeply in it. By the way this morning I used your suggestion to do it manually. I did it and it does not take so long. I just had to really understand the 3 modes of paths edition in the tool and I finally discovered how to add a point on the path and drag it to place it exactly where I want.
Thanks again.