How Important Are Makernotes in JPEG Files?

[gcoupe]

I notice that, when I edit the metadata of JPEGs, Microsoft's Photo Gallery will merrily corrupt Canon Makernotes, while Picasa will remove them altogether.

My question is, should I be concerned about this, or just shrug my shoulders and accept it?

My feeling is that, perhaps, if I were dealing with RAW files, then I should want everything to be preserved, but because they are JPEGs, I should be prepared to live with the fact that Microsoft and Google ain't never going to get it right...

I would value the perspectives of others on this issue.

Thanks.

[Phil Harvey]

It is a personal preference.  It sounds like you don't use the makernote information, so it probably isn't very important for you.

But for me they are very important (although I am a bit biased).  When I am looking at my pictures I like to be able to tell what the camera settings were for a picture.  This helps me to determine why a particular shot was either good or bad, and lets me learn from my successes or failures.  For example, if a subject was focused poorly I can check the focus mode and the active AF points.  With my camera I can also tell how long the shutter button was half pressed, so I can tell if I had time to recompose the image after focusing.  Or if the image was just blurry I can check to see if the shake reduction was enabled.  As well, my camera stores the level sensor information, which I can use to level an image afterward if necessary if there were no obvious horizontal or vertical lines in the image.  Plus, there is a ton of other useful information and an equal amount of stuff that hasn't even been decoded yet, so I don't even know what I would be missing if I throw out all of this neat stuff.

- Phil

[gcoupe]

Phil, thanks for your reply. That helps.

I understand completely why the Makernotes information is important to photographers such as yourself, but I think that I'm gradually coming to accept that I need to choose my battles. I am, and will likely remain, just a hobby photographer. If I want to up my game, then I'll move to shooting RAW. In the meantime, I'll just accept that Microsoft and Google really don't give a damn.

[Phil Harvey]

I'm a hobby photographer too.

For anyone who is interested, here are some of my pictures.

- Phil

[jcharmon]

You might find it useful to use different tools for editing metadata, such as ExifToolGUI or GeoSetter, both of which use ExifTool to modify (and preserve) metadata.

You can still use Picasa or MS Photo Gallery to keep track of your photos (without editing the metadata). They will still be able to read your metadata changes. That way you should be able to get the benefit of using familiar tools for organization while keeping maker notes available for future use. And you might even find you prefer the new tools for adding and editing metadata.

[gcoupe]

jcharmon, thanks for your reply.

In fact, the method you propose is what I do. My primary tool is IDimager, and I occasionally use Geosetter to check the metadata. Photo Gallery is used by other family members as an easy to use method to browse the photo collection.

The drawback is that I can't use Picasa or Photo Gallery for face recognition, since they would write out XMP metadata into the photos.

There's also a lucky break with Photo Gallery. Microsoft has stated that their photo tools follow the principle of "the truth is in the file", i.e. they will write out metadata to the file wherever possible. Photo Gallery will do reverse geocoding on photos that have GPS coordinates in their Exif. In previous versions, Photo Gallery would write out the text strings into the IPTC Extension LocationCreated fields, and in so doing, corrupt the Makernotes of those images. The current version no longer does that, except under very specific conditions, which is a good thing. See here for more info.

[jcharmon]

"The drawback is that I can't use Picasa or Photo Gallery for face recognition, since they would write out XMP metadata into the photos."

I believe Picasa stores face recognition information in its own database, not in the .jpg file, unless they've changed something. You may want to check AVPic Face XMP Tagger - http://www.anvo-it.de/wiki/avpicfacexmptagger:main - which was created to write Picasa face information to XMP. It should be safe since it uses ExifTool to write the information.

[gcoupe]

Yes, Picasa has changed with version 3.9. It writes out XMP metadata into the JPG using the proposed Face Region standard of the Metadata Working Group.

Andreas Vogel's AVPic Face XMP tagger uses the Microsoft-proprietary Person Tag, which is all very well, but I prefer cross-industry solutions.

[pb]

Interesting.  Me, I don't want that kind of data in the jpeg.  So, while this is not exactly a Picasa forum, do you know whether Picasa has a way to not use the jpeg for that info?  ...Other than, of course, disabling face recognition?

--peter

[pb]

In a possible answer to my own question, Picasa 3.9.0 build 136.04,0 (win xp 32 bit) has a check box at tools > options > name tags that is marked "store name tags in photo".  So, apparently, assuming name tags (and their location) are the only things being stored (not, for example, the parameters that define an individual's face to Picasa), storing that data in the jpeg is optional, and appears to be off by default.

--peter

[gcoupe]

Correct - however, the name tag definition includes the region in the photo where the face is, so it's the complete definition that's being stored if you check that option, not just the name of the person.