Signature for standalone ICC profiles

[bertran...@bnf.fr]

Dear All,

I've noticed that PRONOM has no entry for ICC standalone Profiles. It was (apparently) a perfect issue for a first signature submission, as there is a most simple signature for all versions of ICC profiles ('acsp' at offset 36, 0x61637370, see specification documents at https://www.color.org/icc_specs2.xalter and http://fileformats.archiveteam.org/wiki/ICC_profile#Identification).

I had a first attempt at producing a signature for v. 2 (there are three major versions: v. 2, v. 4 and v. 5 aka "iccMax") but could never succeed in identifying example profiles at https://www.color.org/profiles2.xalter, neither with DROID nor with Roy.

I enclose a screenshot of the input to the Signature development utility, and the signature file produced. I am pretty sure I make an obvious mistake somewhere but I can't figure out where...

In addition, I was wondering how to indicate in the Signature development utility that the format can have several extensions (icc and icm in this case)?

Thank you so much for your help!

Bertrand

[Francesca Mackenzie]

Dear Bertrand,

Thank you for sending this over. I'm struggling to download the sample files but without testing possibly the problem you are having is that there are two BOF sequences. Something you could look at is using the {} to signify the gap in bytes between the 0x02 and the 0x61637370 and submitting the one sequence. So the following: Offset:8; Max offset: 0; Sequence: 02{23}61637370 might work (hard to be sure I'm getting the numbers right without the samples so I'll try and find some!)

[bertran...@bnf.fr]

Hi Francesca,

Thank you for your help. I understand that different sequences are alternative signatures, but in my case, at least the v. 2 should have been identified as it has 0x02 at offset 8, shouldn't it?

I tried again with two different signatures: the one that targets v. 2 with your solution, and the other one that targets all versions of ICC Profile. Strangely, the first one fails normally (no file is identified) but the second one seems to produce warnings in the terminal and even the basic information (like the extension) are not returned (see screenshots).

I also probably lack some knowledge about using a hex editor. Do you recommend a resource for learning the basics?

Kind regards,

Bertrand

[bertran...@bnf.fr]

(I also attach the three icc files I use as examples.)

[Francesca Mackenzie]

I am trying to work out what we are doing differently so I can help! I created the following generic signature (see screenshot attached), then placed it in the .droid6 folder after downloading. I then created a new DROID profile and that identified all three of the samples you sent over.

I then created one specifically for version 2, and that identified just one of the three files you sent over. (as it should- see screenshot.)

I've compared the signatures I've generated to yours and they look identical! (maybe I'm missing something). But I do think you are getting it right! How are you loading the signatures into DROID? Sometimes there are problems when you use the install signature file option. Instead you could try placing it in your .droid6 folder under your user name, selecting the new signature and then creating a new profile. Maybe you are doing this already.

You asked for resources and though I think you are using everything correctly if you do want to look at materials for another time we do have a starter pack (PRONOM_Research/Resources/PRONOM Starter Guide (1).pdf at main · digital-preservation/PRONOM_Research (github.com)) as well as the DROID user manual (cdn.nationalarchives.gov.uk/documents/information-management/droid-user-guide.pdf).

[bertran...@bnf.fr]

Thank you Francesca, I could finally get this to work with Roy / Siegfried!

And thank you too for the starter pack, I've read quite a few blog posts but hadn't come across it yet.

Should I suggest a new entry in PRONOM?

[Francesca Mackenzie]

Yay! I'm glad you got it working. 

This looks perfect for a new entry into PRONOM or even 3-4 entries if you think that it is important to be able to identify the different variants? You could suggest it here, but also you can use the templates on the PRONOM GitHub (https://github.com/digital-preservation/PRONOM_Research/issues) under issues if you wish, or the PRONOM Mailbox pro...@nationalarchives.gov.uk

[bertran...@bnf.fr]

https://github.com/digital-preservation/PRONOM_Research/issues/50

\o/

[Tyler Thorsted]

Just a note here, the version number in the XML is important to change each time you make a change to the XML. DROID loads the signature into a profile based on the version number so if another is loaded it will behave oddly. 

Tyler Thorsted

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