By-the-way, perhaps you can explain wat you want to do? Photoshop has evolved into such a do-it-all and so much more tool that you can't assume you want to work with a Photo. You might want to paint colormaps in 3D. Or work on Video. A lot of things can be done. Ditto with Dogwaffle, where 3D in the GPU is reality and fast.

 

Tell us a bit about your needs. There is a free version Photoshop 2 you can find that is old but might cover your needs. Not my recommendation, but still worth mentioning. Likewise, there are free trial or home learning editions of many other tools that, amongst other things, let you work on images.

 

Do you do digital painting? DO you need particle brushes for foliage effects? Do you want pigment lifting (or even know what that means?). There are many aspects to imaging and painting.

Do you like to work with filters?

Do you like to code your own filters (e.g. with Lua scripting)?