2006.11.25 13:59 "Re: [Tiff] Windows HD Photo - any interest?", by Sachin Garg

On 11/25/06, Andrey Kiselev <dron@ak4719.spb.edu> wrote:

On Sat, Nov 25, 2006 at 08:53:20AM +1100, Brad Hards wrote:

But the codec implementation supplied with this Kit is effectively non-free. It is not compatible neither with libtiff license terms nor with other popular free software licenses. I hope that it is possible to use documentation to do independent implementation:

I would also like to see an independent implementation (and I think there might be enough information to do one given the Bitstream specification in the DPK), however I'm not sure why you think the current codec is incompatible with the libtiff license terms. Certainly I would agree it might not be compatible with the GPL, but my reading of the libtiff license says that as long as the codec is generally released (i.e. no licensing fees) then it could be incorporated into libtiff.

This is not to say I am sure - I think it is ambiguous.

"1. You may review these Materials only (a) as a reference to assist You in planning and designing Your product, service or technology ("Product") to interface with a Microsoft product, specification, service or technology ("Microsoft Product") as described in these Materials; and (b) to provide feedback on these Materials to Microsoft. All other rights are retained by Microsoft; this Agreement does not give You rights under any Microsoft patents."

I don't think that any of this says that the codec couldn't be used in libtiff. Probably worth a clarification though.

The excerpt I cited here is from documentation license. I cited it to be sure that we can read documentation to implement alternative solution. But the code itself covered by the separate EULA which contains many statements unsuitable for us. Of course we have an option to not integrate codec into libtiff and allow users to link it in form of separate library (as in case of libjpeg and zlib).

Anyway, it is out of scope for libtiff at the moment.

I don't understand this part either. If you consider HD Photo to just be a different version of TIFF, how does it differ from BigTIFF? [This really is a question, not an argument to say that it should be in scope - I'm just trying to understand your thinking].

Well, personally I think that we still not know what benefit we can get with that new format. If their codec really works faster and compress better than other TIFF codecs it is worth to look into this problem. Also there are no files in such format "in the wild" and I can't predict when they start arriving, so why bother? Finally, I do not like the fact that this new format is not TIFF, and tag numbers will be assigned by MS and if we will decide to implement complete support for that format we need one more tag namespace, and that needs a lot of work. The most important tasks for libtiff development are BigTIFF and proper custom IFD support, we even do not have a time to complete these ones.

Anyway, that should not stop discussion.

This format has native support in Vista and MS will be doing its best to increase its use, so it will almost surely be important.

>From what I understand of the license, it should be possible to include the HDPhoto support in libtiff. Getting a reply from their team is a good idea.

You seem to be reading the old version of the license when it was released just for evaluation, MS released the actual license terms later and the latest version of DPK has even more liberal terms.

Info on latest license: http://www.c10n.info/archives/458

Info on previous license: http://blogs.msdn.com/billcrow/archive/2006/06/30/651898.aspx

Complete new license: http://www.microsoft.com/downloads/details.aspx?FamilyID=285eeffd-d86c-48c3-ab93-3abd5ee7f1ce&displaylang=en

In short, all software implementations are royalty free (only implementation in hardware needs an explicit license). Distribution in source form is not allowed if it causes GPL style licenses where users are required to further disclose code, and libtiff's license should not allow its users to modify DPK's code (if DPK code is distributed in libtiff).

And the DPK can be used only to support HD Photo format (libtiff can't just add the codec support, it will need to generate a valid HDPhoto format file), but this probably isn't an issue.

Unless I have missed something, I think it should be possible to include its support in libtiff, else libjpeg style approach can ofcourse be used. (I am not a lawyer)

Sachin Garg [India]
www.sachingarg.com | www.c10n.info