Fibonacci Ratio - Aurea Ratio

[Krikor]

Hello everybody,

Some image editors have a feature that makes it possible to visualize either the Fibonacci graph or the Aurea ratio grid.

In Gimp that I remember, there is something similar when I select the Scale tool and in the 'Guide' field there is the option 'Rule of thirds'.

In G'MIC there is 'Testing - Reptorian - Fibonacci', but it didn't seem practical to superimpose the image and look for better adjustments.

Does anyone know of a way to use GIMP and take advantage of these features (Fibonacci Grid and Golden Ratio)?

Taking advantage of the post, would anyone know if Inkscape would also have something similar to this feature?

Grateful.

[denzjos]

Maybe this script : fibonacci.scm : https://gimpbook.com/scripts/

[rich2005]

A couple of oldies here: Just tried again and they do work.

https://www.gimp-forum.net/Thread-Dynami...9#pid14969

Edit: ..and from above that Ofnuts golden spiral plugin applied over an image.

   

Edit: Inkscape ? For version 1.3.x it is Extensions -> Document -> Guides Creator and in the Guides preset drop-down there is Golden Ratio and Rule-of-third.

[sallyanne]

   
Also with rectangle & ellipse select in the tool options it gives you options of these.

[PixLab]

For a golden rectangle, just input in the aspect ratio 1.618:1, and you will have the full area of the golden ratio
It could do both, sure the golden ratio because the golden rectangle is based on the golden ratio, but also the Fibonacci sequence as the ratio of two consecutive Fibonacci numbers tends to the golden ratio as n increases (the later is not from me but is what Wikipedia said)

   

[Krikor]

Hello,
denzjos, rick2005, Sally and PixLab, All of your posts were very useful and helped me understand a little more about how to use GIMP for this purpose.

Here are some observations I made while playing around with this subject a little:

1- The script suggested by denzjos in post #2 definitely has a serious problem with the spiral it generates.
Namely, the spiral must form a quarter circle in each square that it circles. Which is clearly not the case with what is produced with this script.

   

Sally and PixLab remembered the option found in the rectangle select tool, but there is an important observation to understand in this case:
If your image is already in golden proportions (1:1.618 or 1.618:1) the GIMP Rectangle Select tool will work perfectly;
But if your image has any other aspect ratio, this tool does not correctly find the grid for that image's golden ratio.

   

The golden-rule.scm script, made available by rich2005, can generate the grid with the area ratio for your image, whether it is with or without the golden ratio aspect (1:1.618 or 1.618:1).

In the second image I posted, you can see the Ofnuts golden-spiral-0.0.py plugin in action.
Note that the generated path exceeds the height of the image (3239 x 4856).
I believe this occurs because the plugin expects the image to have the golden ratio, so considering the width to be 3239 px, the plugin considers the image height to be 5240 px.

PixLab, in your image, although the Rectangle select tool has the aspect ratio set at 1.618:1, you selected the Diagonal lines option.
I believe that the Golden sections option should be selected.

Thank you all!