bugGNU Octave - Bugs: bug #47706, imfinfo: exif tags missing...


bug #47706: imfinfo: exif tags missing ISOSpeedRatings and PhotographicSensitivity values

Submitter:  Carnë Draug <carandraug>
Submitted:  Fri 15 Apr 2016 12:03:18 PM UTC
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Fri 15 Apr 2016 05:32:59 PM UTC, comment #1: 

I have dig a bit deeper on this issue and it seems that GM has the same issue. Using a test image with exif version 2.3 http://dev.exiv2.org/projects/exiv2/repository/raw/testdata/trunk/1153/DSC01769.JPG and querying it with GM utilities, we can see that GM still calls it "ISO Speed Ratings" instead of "PhotographicSensitivity":

$ gm identify -verbose DSC01769.JPG | grep -iE 'exif|iso|sensitivity'
  Profile-EXIF: 44455 bytes
    Exif Offset: 364
    ISO Speed Ratings: 100
    Exif Version: 0230
    Exif Image Width: 6000
    Exif Image Length: 4000

Carnë Draug <carandraug>
Project Member
Fri 15 Apr 2016 12:03:18 PM UTC, original submission:  

I'm not sure of what's happening here but the end point is that Matlab is naming an exif tag as `ISOSpeedRatings` which does not appear under Octave. See http://stackoverflow.com/questions/36644018/how-to-read-iso-speed-of-an-image-in-octave/36646300#36646300

What Octave does is an hardcoded list of EXIF tags and tehn looks for them within the very large of graphicsmagick tags http://hg.savannah.gnu.org/hgweb/octave/file/1dda942a2514/libinterp/dldfcn/__magick_read__.cc#l1981

This may be fixed by replacing the search for that specific list of tags by using all tags that start by "Exif:" and then remove all the ones we don't want.

But that is dependent on what GM does which I don't know.  Would be nice to have the problematic image for testing (I have asked on the SO question for it).

Carnë Draug <carandraug>
Project Member


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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-04-15 carandraug Summaryimfinfo: issues with exif tag names imfinfo: exif tags missing ISOSpeedRatings and PhotographicSensitivity values

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