Serene Life

by garik

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Take the 2-minute tour ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

The Canon 5D MkIII introduced a new featured that lets you rate images by using a dedicated rear button. I am interested in finding out where in the EXIF data that this rating is stored. I wasn't aware of any metadata field that ratings were typically stored in, so I'm not sure what they would be using.

You can read about the feature on page 255 of the manual. The manual notes that:

With Windows Vista and Windows 7, you can see each files rating as part of the file information display or in the provided image viewer.

share|improve this question

3 Answers 3

up vote 2 down vote accepted
+200

Sadly I don't have a 5DmkIII but I've managed to figure it out with a bit of detective work.

The answer is that it's stored in an XMP header as the <xmp:Rating> value.

I started by hunting down a Canon 5DmkIII group on Flickr and found this thread. Click on one of those photos then go to the metadata page and you'll see one of the values listed is Rating (in this case with a value of 3). I'm certain that value hasn't come from post-processing because the metadata also shows it was processed in Lightroom 4. I use a 5DmkII and Lightroom 4, and rate all my photos before uploading to Flickr, and yet my photos don't have a Rating value on their metadata page.

Unfortunately all the photos I checked in that group have download disabled, so I headed over to dpreview.com's gallery of 5DmkIII test shots where I found this test image:

If you click that to go through to dpreview.com you'll see one of the tags on the photo is pre-production. Seeing that, and knowing dpreview.com's usual approach, it's pretty certain this image is straight out of camera.

So, I got the URL of the original image and posted it into Jeffrey's Exif Viewer. And there it is, right in the XMP section:

<?xpacket begin='' id='W5M0MpCehiHzreSzNTczkc9d'?>
<x:xmpmeta xmlns:x="adobe:ns:meta/">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about="" xmlns:xmp="http://ns.adobe.com/xap/1.0/">
<xmp:Rating>0</xmp:Rating>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta> 
<?xpacket end='w'?>

Also note there's no Software value in the metadata anywhere: a further indication that this is straight from camera.

Finally, just to be absolutely sure, I took a straight-from-camera JPEG from my 5DmkII and ran that past Jeffrey's Exif Viewer. Sure enough, no rating value.

share|improve this answer
    
Just found this blog post too that concludes that Canon are now adding XMP headers in camera: metadatamadness.blogspot.co.uk/2010/03/… –  Mark Whitaker Apr 17 '12 at 18:07
1  
I think I've got about as far as I can now without actually going out and buying a 5DmkIII. ;) –  Mark Whitaker Apr 17 '12 at 18:09
1  
If you go out and buy a 5DMkIII to lay this question to rest, I will award bounty points equal to all of the rep that I have to you. –  dpollitt Apr 19 '12 at 20:45

I assume the rating is included in the EXIF data. I wrote a PHP parser a while back that actually opened .JPGs exported from Lightroom as text, and read the rating as part of a batch export script.

There's some info on the addresses here: http://www.exiv2.org/tags.html

Tag(hex)    Tag(dec)
0x4746      18246      Exif.Image.Rating
0x4749      18249      Exif.Image.RatingPercent
share|improve this answer
2  
Note that the linked page is actually the list of tags that the 'exiv2' program (which I like and use a lot) understands; although that page says the tags are "defined in the Exif 2.2 standard" the Exif standard doesn't include the Rating or RatingPercent tags, and the exiv2 page only says those 2 Rating tags are "used by Windows" so they may not be universally supported if that's what the 5D MkIII uses. –  drewbenn Mar 21 '12 at 23:11
    
@drewbenn: Good points! I would presume those tags are indeed used though, since the manual explicitly states that Windows Vista and Windows 7 can read the rating information. –  jrista Mar 21 '12 at 23:31

According to this the Ratings and RatingPercent tags are not part of EXIF 2.3 specifications but can co-exists with EXIF tags. I figured out from my machine that Windows 7 uses this but I do not have a 5D Mark III to test if it uses the same tag.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.