W3C home > Mailing lists > Public > semantic-web@w3.org > February 2005

[Image] How to identify images in an RDF context

From: Karl Dubost <karl@w3.org>
Date: Wed, 9 Feb 2005 16:46:43 -0500
Message-Id: <bf33b8a5470ccd68cc02335c63a2ff08@w3.org>
To: semantic-web@w3.org

I would like to have information about images. I have read a lot of 
things about cataloging and creating images database in RDF, though 
"nothing ready to use" for now ;) but something is still not solved in 
my head.

I'm taking a photograph with my digital camera. This image is 
transfered to my computer with a JPEG format and contains already a 
certain number of data like EXIF data.

1. I can extract the EXIF data of this image and put in an RDF file 
outside of the image, (not inside the image [see below])
2. I can create more information, description, etc. That I add to this 


a. Is the good strategy one RDF file for one image? or an EXIF file? 
and an geo file? and a description file?

b. How do I identify the image ? a urn (which kind?) or an http uri?
	<http://example.org/photo/2005/02/06/foo.jpg> even if the image is not 

c. Images are between 1 and 3 Mo each, I keep them on DVDs or external 
hard drive.
	Can I use the previous identifier?

d. I have many versions of the same image.
	* Original Image (2000 x 3000 px)
	* Thumbnail	(75 x 75 px)
	* small version (400 x 600 px)
	* cropped version
	* published version in different context (different HTML pages, web 
	* Sampling (different images or part of the images associated with 
All these versions share one part or all parts of the information which 
is about the image. How do I define the model to identify it and gives 
information about it?

e. Is it better to have a large RDF file with information of all 
images? Or a small individual RDF file for each image?

* RDF inside or outside the image.

RDFPic recommends to put metadata inside the comment zone of JPEG. XMP 
does it in the binary. In both case, I don't think it's always a good 
idea, for privacy reason. Many softwares do not propose to wipe 
metadata before publication on the Web. Problems will arise with cell 
phones and GPS information.

You may have information you don't want to publish on the Web. Personal 
comments on the image, geo-localization of the image.

Scenario: Someone is at a party at your place and likes very much your 
painting or you computer. Cool. He takes a picture of it and send it on 
his moblog, which displays the GPS information, then the latitude and 
longitude with a comment "We are having so much fun at Peter's place. 
He will write something about it on his weblog".

Well no problems :))) Peter is leaving for holidays in Africa for one 
month. Some people have noticed that. It's time for robbery !!! We know 
the stuff inside, we know that Peter is not there. Let's go.

That's one of the many possible cases and danger of information 
contained in an image directly accessible to everyone. ;)

Karl Dubost - http://www.w3.org/People/karl/
W3C Conformance Manager
*** Be Strict To Be Cool ***

Received on Wednesday, 9 February 2005 23:38:41 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:47:00 UTC