How to restore old yellowed photo

[Stephen Liu]

[attachment=10411 Wrote:Krikor pid='36184' dateline='1696061928'][attachment=10411]I took a look at:
https://youtu.be/ylIyA6wQGcY?si=IImHxA4w4hBsMPD2 (video), whose tutorial can be found at https://www.alexburkephoto.com/blog/2019...r-negative -film

Also in this other video
https://youtu.be/LXuwnt5ba8M?si=5KMVN9-Bl3byqOhT

But in these techniques (PS) there is a feature that I didn't understand well: when applying curves you use ALT+click, which doesn't work in Gimp.

So the best results I obtained were those that follow the approach mentioned by denzjos.
In the image below I used this approach followed by the use of G'MIC - Color Presets - PIXLS.US(31) - Whiter Whites (default)

Thanks.

The best I can do on another photo
steps:
Filters -> Enhance - Sharpen Unsharp Mask.
Colors -> Exposure 
Finally Colors -> Hue-Saturation