Free Image editor try ImageJ

https://imagej.nih.gov/ij/download.html

For schematic ??? Try Eagle (PCB tool)

https://learn.sparkfun.com/tutorials/using-eagle-schematic

Hello,

if you want to use vector graphics, try Inkscape. Inkscape has a devoted, friendly community and it is able to read files of many formats including *.cdr, *.ps, *.eps and even *.pdf images and documents. (free at https://inkscape.org/)

If you want to edit bitmap graphics, i.e. pictures taken by your camera, you can try Gimp. Although Gimp is not as good as Corel Photo-Paint and Adobe Photoshop, it is published under GNU license (https://www.gimp.org/).

If you want to draw some schemes, diagrams or GUIs, you should try Pencil software. It is also free and available at https://pencil.evolus.vn/

Hello,

For vector based graphics, Inkscape is good (https://inkscape.org/da/download/). If you will use Latex afterwards, you can try TikzEdt (http://www.tikzedt.org/), it is a little bit complicated but it will give you good figures in Latex.

Regards,

Ahmed