Free Software Foundation advice on use of the GPL for Art

[irrevenant]

I've received an email response from the Free Software Foundation to some questions about the suitability of the GPL for game content. I've posted their reply here in the music forum since music was a particular concern, but most of the email applies equally to the other game conent.

[Taurus]

Irrevenant wrote:
* Is it legally permissable to distribute GPL software with non-GPL-compatible game data (graphics, music files etc.)

If the "content" does not contain any code -- so that it only has maps, sound, graphics, and so on -- then you can release such content for a GPLed game engine under a proprietary license. If the content includes code -- like enemy AI, event scripting, and the like -- then the answer depends on how the engine and the code interact. It would be like releasing a plug-in for a GPLed appliation; see <http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins> for more information about that.

So does this mean that if you have the artist's permission to use a piece of his artwork for your campaign, you can legally use it without having to liscence it under the GPL - i.e. giving everyone permission to do whattever they like with the images.

[scott]

Yes and no. There is a local policy that an entire campaign has to be under the GPL, but there is no reason the policy couldn't be changed.

[irrevenant]

There's no legal impediment to using non-GPL licences for the art, though there is currently a policy against it.

But actually, the GPL isn't too bad a fit for artwork after all. It only has one significant disadvantage: You have to make the source code (GIMP/Photoshop files) available, and this could be awkward to administer.

OTOH, that limitation is also a strength: It would be very useful if everyone had access to Jetryl and Jormungandr's working files (for example). We could use them to learn from, to base derivative artworks off, etc.

The only problem might be if people are incorporating textures in their artworks that are licenced incompatibly with the GPL.

[lwa]

But actually, the GPL isn't too bad a fit for artwork after all. It only has one significant disadvantage: You have to make the source code (GIMP/Photoshop files) available, and this could be awkward to administer.

Art is not the compiled version of artist's drafts, is it ?

[irrevenant]

Art is not the compiled version of artist's drafts, is it?

[Edit: Initial reply snipped due to being misleading and wrong]

The definition of 'compiled' is actually irrelevant. The important thing is that the GPL explicitly states "The source code for a work means the preferred form of the work for making modifications to it."

For art created in The GIMP or Photoshop, the preferred form for making modifications is the GIMP/Photoshop format file.

[turin]

I think saying that the .xcf file is the source for the image in the same way that the C++ code is the source for the binary is misleading. However, I'll have to re-read the GPL to see if it is necessary to interpret it that (IMHO incorrect) way...

[scott]

Does photoshop compile the layers? It just flattens them. Compiling converts human readable code to machine readable instructions, while image editing writes directly to binary files. If you edit a binary executable with a hex editor then save it, did you compile? Not really. But, I think the term compiling used in place of image flattening was meant to be used analogously, not literally. The requirement is preferred form, which would be xcf/psd even for a 1-layer image (if the output form is jpg for example).

[Jetrel]

#1 thing that makes uploading "source" files for graphics quite a bad idea:

I'd have to have gigabytes of server space. Those photoshop files of mine are bigger than a wesnoth distribution, and I mean each portrait file.

My current wesnoth work files directory, minus all the old portraits I've thrown away, exceeds a gigabyte.

[turin]

Well, IIRC, we don't need to distribute the source files to meet GPL requirements, we just have to put something in the images/ directory that says "if you want the source files, email whatever@something.blah"...

[Kestenvarn]

The photoshop file for the single map I'm working on is over 50 megs.

[Taurus]

My real concern about this whole issue is about approaching outside artists to use their artwork - i.e. the artwork isn't drawn spicifically for BFW. It's hard enough to get their permission to use it - let alone supply the "source code". And what if the artwork was a reproduction from an oil painting.....?

[scott]

I have done some digging around the debian message boards. From what I can tell they may require images to be submitted under the GPL, thus the topic comes up.

I am almost positive at this point that png files distributed alone satisfy the requirements of the GPL. This is because the analogy between software and images breaks down at a critical point (after all, if the analogy didn't break down then they would be the same thing instead of an analogy).

You can't say working files are source code because, in digital imaging, the binary is the source code. When you edit an image you edit the binary code directly. I used to write programs in hex for the apple //e directly into the system ram... it's the same thing. When you do that, that's all there is. There is no source. The source is the binary file. Therefore, when you distribute the binary file, you distribute the source code. If you (as the originator) delete your software source code, you cannot modify the binary. If you delete intermediate/working image files, you still have 100% ability to modify the image in any way. This is how we know that intermediate rendering instructions are not the image "source code".


Now for some proof by contradiction. Here is a situation. You create a 3-D model in 3DMax, render and export it to .png, which is picked up and modified in Photoshop (with layers), then re-exported to .jpg. The general opinion was that you have to make available both the 3D model file and the psd. Ok, that makes sense under the source/binary analogy. If you want to edit the image, you have to be able to edit the original 3D model and re-render your modifications. If you want to modify the pre-loss rendering, you need the photoshop file, especially if that's the receiver's preferred form for editing. Now, the 3D source is quite a different thing from a digital image. It's a set of instructions for creating an image, but unlike software the instructions are NOT the image. In software, the code is the same thing as the binary, except they are in a different language. The spirit is to let you modify the software binary, but you can only do it if you have the software in human-readable code. Now for the image, the spirit is to let you modify the image -- which is why it makes intuitive sense to include the 3D model -- but when the source and the binary are the same thing I belive your requirements stop there by technicality.

Abstractly, in the analogy mindset, you are being asked to provide one method (out of many) to recreate the image from scratch. Furthermore, it has to be the method you used. When you produce a software binary, the source code is the only way to reproduce the binary, since they are the same thing (translated into different languages). When you consider an image, the workflow from 3D model to rendering is somewhat irrelevant. You have the ability to make any pixel to be any of 2^32 values regardless of how the pixel got to be that way originally. Should this change based on the context, or should the legal standard be context independent? Here's the contradiction: what is my requirement for including the 3D source if I release a digital photo under the GPL?

My conclusion is that either the combined source/binary (i.e. the image) is sufficient or that it is not possible for images to be legally released under the GPL. When the legal standard is clear and simple, it is not an undue burden. The requirements for what part of the image-producing workflow need to be made available are so variable and context dependent that trying to define a legal "standard" for images is unclear and burdensome. We are feeling the effects of a license that is supposed to liberate both parties.

Now, we have been releasing images under the GPL for quite some time. I suggest we continue as we have. The spirit of the GPL is to preserve copyrights while transmitting significant freedoms, which is what we are doing. As for the letter of the law? Who knows?

Edit: It's not really a proof by contradiction. If, by chance, it even qualifies as a proof, I realize that's a technical term that I used flippantly (sorry!).

[Jetrel]

I used to write programs in hex for the apple //e directly into the system ram...

I you. That's just so cool.

[irrevenant]

I think saying that the .xcf file is the source for the image in the same way that the C++ code is the source for the binary is misleading.

[Something similar]

I'm sorry, you're both right. Trying to draw analogies between "compiling art" vs "compiling software" was misleading, wrong and irrelevant.

"Source code" is defined in the GPL itself : "The source code for a work means the preferred form of the work for making modifications to it.".

This definition is pretty clear, but the email from the FSF guy confirms that, eg. for GIMP art, this would be the .xcf file.

#1 thing that makes uploading "source" files for graphics quite a bad idea: I'd have to have gigabytes of server space. Those photoshop files of mine are bigger than a wesnoth distribution, and I mean each portrait file.

As Turin noted, the GPL doesn't require that the source be available for download - you just have to supply it on request for a minimum of 3 years, and include an offer to this effect with the artwork.

Wesnoth basically has two options:
(1) Continue to use the GPL for art and comply with the source-availability requirement. Responsibility for this can rest either with the original artists or the Wesnoth project. In the latter case, the project would need to hold a repository of source (which needn't be made available online).
(2) Have all contributing artists relicence their art under different licence. (eg. cc-by-sa looks much like the GPL without the source provision).

My real concern about this whole issue is about approaching outside artists to use their artwork - i.e. the artwork isn't drawn specifically for BFW. It's hard enough to get their permission to use it - let alone supply the "source code".

Yes, the more rights that you ask people to share on their work, the fewer artists are likely to contribute. OTOH, accepting work only on a Free basis has resulted in the skilled, generous Wesnoth art community that we have today. And that ability and willingness to tweak each others' work has been invaluable.