
GIMP can use 3rd-party Photoshop filters on Linux, too.
Back in 2001, I wrote a piece of software called
pspi, for PhotoShop Plug-in Interface. It's a GIMP plug-in that runs Photoshop plug-ins. (Just the "filter" kind of Photoshop plug-ins so far.)
Photoshop filters can be found for free on the net, and on the cover CDs of various magazines. Many of them are just crap, or offer functionality already included with the GIMP. But some can be real gems. I am not a graphic artist and don't have any huge collection of them myself.
Until now
pspi has only worked for GIMP on Windows, as Photoshop plug-ins are Win32 DLLs. (Well, on the Mac they are that platform's shared libraries, presumably.)
When I wrote
pspi I had in mind that it might well be possible to use it on Linux, too. It would then use Wine for the Win32 emulation necessary to load the Photoshop plug-in DLLs and run the code in them. I didn't have the inspiration or time to work on this myself, though. Now I hear that Mukund has actually done it! He says making
pspi build on Linux and adapting it to load the PS plug-in through Wine was not hard at all. See screenshot above. Mukund, you rock. Kudos to the Wine developers, too, of course.
One problem with
pspi is that in order to be able to build it from sources, one needs headers from the Photoshop 6 SDK. This SDK used to be downloadable for free from Adobe, but was pulled long ago. Only people with the PS6 SDK can build pspi. It is not legal to redistribute the SDK.
The current Photoshop SDK is much harder to get. It's expensive and requires case-by-case approval from Adobe. It is said to have a license that prohibits using it when developing products that potentially could compete with Photoshop. I haven't seen it myself so I don't know.
I have been told that the PS6 SDK was also bundled with the PS6 product. Buying a legal copy of Photoshop 6, if one can find it (used?) somewhere, seems currently to be the only way to get the SDK. It probably depends on your local legislation whether software can be freely resold by one end-user to another despite what a shrinkwrap license might say. I downloaded my copy of the PS6 SDK back when it was still available from Adobe's site.
Presumably it would be perfectly legal to distribute a Linux binary of
pspi built against legally acquired PS6 SDK headers.
Don't ask me for such binaries, I haven't built pspi myself for Linux yet.
The
pspi source code is currently GPL, but I am willing to change the license to for instance a MIT-style license. In fact, GPL probably doesn't really make sense for software whose express purpose is to dynamically link to proprietary shared libraries?