[constantinum]

For photo editing and manipulation 1) https://www.gimp.org/

2) https://www.digikam.org/

3) https://www.darktable.org/

Vector based editing tool

1) https://inkscape.org/

Desktop publishing

https://www.scribus.net/

[coffeebeqn]

Fairly well known on HN by now but Krita is also excellent lightweight and simple image editor and painting app like Photoshop was 20 years ago https://krita.org/en/