Thanks, Nidhogg, for your interesting feedbacks!

7) Program plug-ins with "GEGL graph"

You can use your "GEGL graph" directly in your code, like this:

If you want to replace a value by a variable, you can do it, for example, this way:

Replace:by:
Note: you have to have installed gegl_command.py plugins.

Have fun!

Here is a better example (photo to cartoon):


Here is a result of this example:

Enjoy!

8) Go further

The reference site is: gegl.org.

The available operations are at https://www.gegl.org/operations.
On the right side, an alphabetical (according to technical names) list of operations (friendly names).
On the left side, a classification of the operations.

For each operation, some pieces of information, here are the main ones:

• a list of parameters. Each parameter is indicated by a black thick vertical line at the left of it. For each parameters, some pieces of information, here are the main ones:
  
  • "name" : what you have to use in your "GEGL graph" (just before an "=" sign)
    
  • type : the type of value you can write just after the "=" sign. Here are the main ones:
    
    • boolean : 1 (that means "True") or something else (that means "False")
      
    • color : string that stands for a color (for example: #fff, #808080, aqua, rgb(0,1,0), rgba(0.0,0.5,0,0.8))
      
    • curve : I don't know.
      
    • double : number with decimal point
      
    • enum : string among a list of accepted ones. "gegl.org" doesn't give this list, but the "GEGL graph" window does (after you have typed the "=" sign).
      
    • filepath : I don't know (I guess it's a string)
      
    • format : I don't know.
      
    • int : number without decimal point
      
    • object : I think you can't use these parameters in "GEGL graph" window.
      
    • pointer : I think you can't use these parameters in "GEGL graph" window.
      
    • seed : integer ?
      
• "name" : what you have to use in your "GEGL graph" (as operation name). You don't have to write "gegl:".
• "pads" : Here, you can know if "aux=[ ]" can be used

Notes:

• "gegl.org" doesn't explain any "gimp:" operations
• I think you can't use parameters of "image-compare" in "GEGL graph" window.
• "threshold" is different from "gimp:threshold". The latter is equivalent to "Colors -> Threshold". The former is more powerful.

As you can see, my knowledge is based on experience, is incomplete and probably inaccurate. Feel free to complete or fix it.

I am very grateful for your helpful information. I haven't tried GEGL yet, but your information is inspirational.

GEGL Graph deprecates alpha to logo.

Learn the syntax guys at GEGL.org
https://streamable.com/xphvb0
https://streamable.com/ifmpxn
https://streamable.com/2in0g0
https://streamable.com/dajm7u

Finally a peek at the future
https://streamable.com/2uhfkv

Try this on medium large sized text.

gegl:color-overlay value=#fbff00

gegl:dropshadow x=0.00 y=0.00 radius=0.00 grow-shape=circle grow-radius=6 opacity=1 color=#2868ff

gegl:dropshadow x=0.00 y=0 radius=0.00 grow-shape=circle grow-radius=6 opacity=1 color=#dcfcff

gegl:dropshadow y=5 x=4 radius=0.90 grow-radius=0

Interesting but unless you post the GEGL command as a separate text file, very-very tedious to reproduce from a video.

recursive-transform time=0 transform=matrix(0.85676532983779907,-0.083190269768238068,-1.0763975295356106e-19,0.15398488938808441,1.0494217872619629,-2.1621131194246602e-19,35.636863708496094,106.15763092041016,1) first-iteration=1 iterations=0 fade-opacity=1 paste-below=no sampler-type=nohalo

gegl:color-overlay value=#dbdbdb


(IMAGE FILE OVERLAY)
svg:src-atop aux=[gegl:layer src=/home/contrast/Pictures/Magic/Gradient_overlays/green.png]



(bevel)
gaussian-blur
emboss type=bumpmap azimuth=30 elevation=45 depth=12

gegl:dropshadow x=0.00 y=0 radius=0.00 grow-shape=circle grow-radius=1 opacity=2 color=#ffffff

gegl:dropshadow x=0.00 y=0 radius=0.00 grow-shape=circle grow-radius=6 opacity=1 color=#ffffff

gegl:dropshadow x=0.00 y=0.00 radius=0.00 grow-shape=circle grow-radius=6 opacity=1 color=#000000


gegl:dropshadow opacity=0.4 radius=0.1 x=-1.8 y=2.8

gegl:long-shadow style=finite angle=152.94 length=11 midpoint=100 midpoint-rel=0.5 color=#000000 composition=shadow-plus-image




here is a link to the image file I used. https://imgur.com/1BveJug
you need to replace the file path with your own.

I want to make this into a GEGL filter but the only way I know how is to make two extra copies of saturation and hue-chroma.

cli345, Just by reading your post I can tell that you are a lot smarter then me. You should be able to look at my source code and figure out how to make gegl filters of your own. You will likely end up beating me at this game.

https://github.com/LinuxBeaver/

This is awesome. I want to make a GEGL filter of this that will run as a normal GEGL operation. Are you or anyone else interested? I'll give you full credit for discovering it and the only change I will make is to replace the noise-reduction at the last line with mean-curvature.

Levels, Difference of Gaussian, Saturation, Lighting, and Mean Curvature will be the editable parts of the filter.

I've tried all 3 and the GMIC version works best for me.

I'm trying to scale an image using GEGL graph, but it only applies to the layer.
I'd like it to scale the whole image.
My code looks like this:

It does scale the layer, but the image is still as big as it was.
Is it possible at all to do this with GEGL graph?

PS.: I've also tried scale-size-keepaspect - but not the result I want either.

GEGL cannot interact with multiple Gimp layers in Gimp 2.10. The scale command is correct but there is no way to do that yet.

My image has one layer only. It's just a jpg.
But ok to know that it's not possible yet.
Thanks for your answer.

yeah it can't resize Gimp's canvas as that is outside of GEGL. It could be possible in the future.

That's really a pity, isn't it?

GEGL is about a specific bitmap. When you scale an image you have to scale layers (and their mask, and the channels), but also paths. And layers that are not the size of the image need their offsets to be changed.

GIMP uses GEGL, but GIMP isn't all GEGL.

GEGL in theory can have its own virtual equal of Layer Groups, Mask and Channels. But they will all be represented in Gimp as one layer.

However in the future Gimp's team will likely make it where GEGL can apply effects to multiple layers in once in Gimp. btw, accroding to archive.org GEGL Originally stood for Gimp's E Graphics Library. I guess the E can be "eternal" who knows? The bottom line is that means it was designated for Gimp.

Yes, but not to replace it. The engine isn't the car.