Easily Distracted

I was really puzzled… and in fact, I’m still puzzled, but at least it works now.

Update: I’m a bit less puzzled now. I wasn’t using the correct version of EXIF.py (see comments). This post has been updated to correct any information. I also updated the CODE style because posting python code when whitespace is ignored is a little confusing. ^.^

I’m now using EXIF.py for loading EXIF information from photos for my little project, PhotoFile. Today, I wanted the image orientation information. Looking in the source of EXIF.py, you’ll find:


EXIF_TAGS={
...
0x0112: ('Orientation',
{1: 'Horizontal (normal)',
2: 'Mirrored horizontal',
3: 'Rotated 180',
4: 'Mirrored vertical',
5: 'Mirrored horizontal then rotated 90 CCW',
6: 'Rotated 90 CW',
7: 'Mirrored horizontal then rotated 90 CW',
8: 'Rotated 90 CCW'}),
...
0x9003: ('DateTimeOriginal', ),
...
}


So, I tried:


image = open("photo.jpg", "rb")
tags = EXIF.process_file(image)


To correct the above, I’m a little lazy with composition, so it’s easier to just post some output from a python session:


>$ python
>>> import EXIF
>>> p = open("photo.jpg", "rb")
>>> tags = EXIF.process_file(p)
>>> for key in tags.keys():
... if "orientation" in str(key).lower() or \
... "datetime" in str(key).lower(): print key, ": ", tags[key]
...
EXIF DateTimeOriginal : 2006:03:19 14:22:40
Image DateTime : 2006:03:19 14:22:40
EXIF DateTimeDigitized : 2006:03:19 14:22:40
Image Orientation : Rotated 90 CCW


There is indeed no “Orientation” tag but there is an “Image Orientation” tag. The string “Image Orientation” appears nowhere in the source, and I couldn’t find any documentation on it. It looks like the tag keys are set by reading them from the EXIF information within the file appending the key to the classification (as pointed out by Shirley – see comments), but even the EXIF spec lists the tag as “Orientation”. If anybody knows why this is the case wants to clarify further, please post in the comments.

Conclusion

So if you’re using EXIF.py and want access to the image’s orientation, use “Image Orientation” for the key.

Did a bit of IRC channel ping-pong today. Went over to #f-spot to ask a user-related question about f-spot, and got pulled in by curiosity on a totally unrelated topic: opening a folder with the default file-manager. Initiated some discussion on #mono and discovered this was, in fact, not trivial – which seemed odd. But I’ve never personally written any C#, or much desktop code at all, for that matter. So I started playing around with various suggestions from the good folks in #mono, and writing my very first C# application.

(Yeah, basically a one-liner. You gotta start somewhere! ^_^) Anyway, for something so simple, there seemed to be a lot of uncertainty and discussion about it (even from the man, himself! – He claims his memory is fading…), so I figure it’s worth documenting. More info can be seen here under Process.

On FreeDesktop systems it will use xdg-open, if not, it will try to use gnome-open or kfmclient to open the files.

Not sure if this will work on Windows. The file:// prefix is required.

Update: According to ccoish, this will work on Windows.

Passing this info back to #f-spot resulted in a patch to allow you to open the folder containing your photo. Thanks, Gabriel! Open source is cool.

Not sure if I’ll look at C#/Mono much more, was kinda gonna do the Python thing for a while… but this was a fun distraction.