GIMP Version: 2.10.34
Operating System: Windows
OS Version: 10
GIMP Experience: New User

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Hi to all.

Maybe I didn't formulate the title of my question correctly, but here's what I'm trying to do: There is curved line in layer, that layer has transparency. I want to move all pixels from this line hoziontally or vertically, so that line become straight. Something like this:



Is there way to do this?

I used the 'color chooser' to sample the top and then swapped the active color and used the chooser to select bottom of your curved line. You'll notice where these colors are in the tools menu.
Then I used rectangle select to make a new virtual line. Then went to the gradient tool with FG to BG. I went from bottom up. (forget the HSV counter- clockwise, just use FG to BG)

Tas_mania - Thank you for the fast response.

But if the curved line looks like the example below is there way to acheive what in the first post is shown?



Have a nice and sunny day

That would be possible with many gradient stops.

Not sure if there is a plug-in out there that creates a straight line or rectangle from image colors.
Not even sure if its possible.
Maybe ask one of the scripters here.

Good luck with everything. And welcome to Gimp Chat!

Probably doable with G'MIC. Could you post the original image here so I can try something with it ?

Would it be possible with sample colors?

Tried with a custom-made sample :



G'MIC plug-in, filter 'Custom Code' :



Result in GIMP:



Not sure that helps, but at least I've tried

Just a possibility,

Divide the image up strips using guides. I use that old essential guides-grid.scm and a compiled plugin guillotine into layers to get a stack of strips. samj does a Windows version of that or ofnuts has a python plugin (+ align tool after)

Duplicate/shift laterally/merge your layer so that you have a complete vertical slice. Since you double the width each time this doesn't require so many iterations.



If necessary you can apply a horizontal Gaussian blur (I had to do this because working from your image my erasure of your background wasn't perfect).



Then cut a vertical slice

Another possibility
Filters -> Blur -> Linear Motion Blur extended out of the canvas
the pixels vanish, recover with
Layer -> Transparency -> Threshold Alpha and reduce value slider.

40 second example https://i.imgur.com/QNhDaMT.mp4

My solution could be similar to ofnuts.



I used the original image and I've called it 'The Snake'

Here's how I made it.



I used PhotoComix Smoothing from G'MIC also.

BTW. Why are we doing this why not just start with a straight line?

Could it be done using the filter in GMIC under deformations 'Distort [RBF]'

Best I could do is using the GMIC filter 'Gradient from line'

Thank you all for your cooperation and help!

Maybe I should have started by explaining the final goal. By making a vertical straight line containing part of the image and then stretching that line left or right, I want to get the example shown below.



In the example shown, this effect was created by making straight vertikal line copy of image and it looks good.



But it doesn't work so well with other images. For this reason, it is better when I make a copy of the end, (the edge) of the image. Thus, the stretch of the copy will look much better together with the image.

I will try with Tas_mania's 'The snake' solution and share the results as soon as I can.

Thank you, guys

P.S. As I looking for PhotoComix Smoothing from G'MIC I have found G'MIC Online (https://gmicol.greyc.fr/) - a web service to allow users applying image processing algorithms on their images, directly from a web browser. There's a "Pixel Sort" plugin out there that did the job for me.

Yeah it's called pixel stretch.



Hey David is it possible to add more moveable points in the gradient from line code?

It was fun doing this. Gradient from curve looks interesting, pity the Debian version has not been updated

You could also select rectangular regions from each part of the curve and align them to the image horizontally.
Then merge the rectangular regions together in one layer then just scale them using the shift key.
Another way to do a pixel stretch.

That's a good idea indeed. The current filter was only able to extract a gradient from a straight line.
So after recoding some parts of this filter, here we are:



(available if you use G'MIC 3.5.1+, after a filter update).

Another example:

Nice David. Thank you very much.

Pixel stretch images with ease now!



Probably only needed 5 points though.