You could use an alternative program like GIMP. GIMP is usually packaged with Ubuntu full. GIMP does take some getting used to. For features that GIMP lacks, I'm pretty sure you could find extensions for it that does what you want it to do.
Try running it on Crossover, which is basically Wine but proprietary.
And then there's always VMs. Boot up a Windows VM and do what you need to do. But then, you aren't exactly running Photoshop on Ubuntu. But then again, you can get your work done fast enough.
I don't know if there is a lite version for Windows (except the ones that are put out by modders) but you can get Windows 10 Home for free from Microsoft's Official site if you can get access to some Windows machine using the Media Creation Tool. You can read more about how to create installation media for another computer on there. You won't be asked for an activation key. It'll have that Activation watermark and there are some restrictions on customizing your desktop, but if you are running it under a VM, I don't think that's going to be a problem. You'll get the "Your Windows is expiring" popups often enough, but they are just annoying at most and do nothing.
Saji89 thank you for the link I will look into it.
– user280052 May 22 '14 at 11:35