GGR from Image

[Krikor]

(10-06-2022, 04:19 AM)PixLab Wrote: Because it's only 27 pixels =27 columns, and you got problem with script/G'MIC/etc... I would create it manually, just not bothering anymore, and picking color on your original with left and right end point, and all in the middle

Ehhh... it's embarrassing to say this, but I don't know how to edit/create gradients with the gradient editor. Last week I even tried, but after frustrated attempts I gave up.

(10-06-2022, 08:12 AM)rich2005 Wrote: The RobA sample along path certainly has problems picking up that extreme right-side white-black strips, so using the gmic plugin.

The 27 pix width is a problem for gmic, it creates an error, solution scale the image up say 500% using interpolation None to preserve the hard edges.



Now we can use the gmic filter Gradient from line
I would enter start and finish (0, 100) rather than eye-balling the points
Sampling = 27, for the 27 bands, length = 0 to preserve the hard edges
Give it a name, OK it, and it puts the .ggr straight into the gradients folder. Only problem I can see is your portable Gimp and where is the gradients folder ?



Back into a tiny canvas, not as easy as you might think, needs a steady hand  



Attached as an example (zipped) 01.ggr :

Yesterday, when I tried Gradient from Line (G'MIC), even with the error that appears in the preview window, after unchecking the "Preview gradient" option, I managed to generate an image with a very good, even acceptable gradient. But I was unable to get the .ggr from that filter.

My gradients folder are in default locations (for Samj's portable), I think. 
   

rich2005, thanks for the 27lines.svg and 01.ggr.zip!

(10-06-2022, 08:22 AM)Ofnuts Wrote: Try this:

• Open the palette editor (in the Palettes list click the "Create new palette" button
  
• Color sample each band in turn, then clikc the + button in the palette editor to add it (the ruler is my screen ruler app that I used to keep track of where I was)
  

• Give a name to your palette. It should appear in the Palettes list
  
• Right click that palette, and Color to gradient
  
• In the Gradients list, you should now have a Gradient with the name of your palette
  
• Create a rectangular selection on part of your image
  
• Set the active gradient to the one sampled from your palette
  
• Start the Blend tool and drag the gradient across your image
  
• Adjust the stops (more or less in the middle of their bands) so that the bottom is aligned to the top (yes, I probably missed a color on the right)
  

• At the top of the Gradients list, right click the Custom gradient (which is the one you creating on the fly), and duplicate and rename it
  

Wow that was fantastic!
I thought it would be complicated, but I managed to follow the steps of this mini-tutorial. The part of adjusting the stops was a little more complex but it all worked out!

After reviewing the result, I think that the lighting that was on the monitor at the time of editing may have prevented me from finding a better fit (I didn't notice it at the time). But I was satisfied with the result!

I used the original layer on top with a mask revealing only the top half. Underneath I edited the new gradient based on the top layer.
   

(10-06-2022, 02:17 PM)rich2005 Wrote: Just a mention of SVG gradients. Gimp can use this format. I thought I had a linux script to generate one from an image but alas not.

This one made by hand, I grouped the colour bands to show the hard edges, usually the stops blend from colour-to-colour. All in text so easy to edit. 

Attached the same example as before: It is not a image, put the file 27lines.svg in your gradients folder.

Since you brought up the subject of SVG gradients, it reminded me that a little over 1 year ago I tried to play around with it. But I had some kind of difficulty (I don't remember exactly what the difficulty was) so I put it aside and ended up never touching it again.

So after your comment and having downloaded your attachment (27lines.svg) I tried again to understand myself with this resource (SVG gradients with Gimp), but without success.

I think I found the plugin to create this kind of gradient.
So I decided to venture out and even without knowing for sure how to use the plugin I gave it a try.

A strange error appears:

I checked, and that folder and path exist (see screenshot below)
   
But... looking more closely, he mentions Drive D:/Gimp21021/... I think this must have been when I was using version 2.10.21 (and even then the D: drive with Gimp was only used on the LapTop and not on PC)

I don't know why it's tied to this path nor where to try to edit to fix it.


PixLab, rich2005 and Ofnuts,

I really appreciate the help everyone has given me. Thank you very much!