Since I'm getting more interested in photography and understanding cameras and techniques, I find myself wanting to know the details under which a photo was taken. Modern digital cameras encode a lot of such data -- shutter speed, lens focal length, etc. -- into the image file, generally called “Exif Data” (“Exif” stands for “exchangeable image file format”).
So, I wrote a little online Exif viewer to view whatever data might be encoded. Here's a screenshot using the viewer on a picture from a recent post:
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That's just the summary -- you can see the full data using the tool itself.
The amount of data encoded in the image is quite variable. Many times there's just about nothing, as the data is stripped somewhere along the way. Here's a version of the previous picture with most data missing. It's missing because it's a smaller version that's meant for web display, and for such use the data just makes the file bigger and slower to download.
Here's one with GPS location data encoded, which I think is quite cool. In the summary area is a link to a Google Map of the location, and below that is an embedded Google Maps pane. With either, you can switch between Satellite and Map, and zoom, etc. For some reason, though, the satellite imagery available to the embedded pane is of a much lower quality, at least for Kyoto Japan, so with this picture it's best to follow the map link in the summary.
My Tech-Related Photography Posts
- Digital Image Color Spaces
- Online Exif (Image Data) Viewer
- Adobe Lightroom 1.x Resources
- Jeffrey's Lightroom Configuration Manager
- Adobe Lightroom Custom Metadata-Viewer Presets
- Jeffrey's Autofocus Test Chart
- Photoshop CS2 Calendar-Template-Building Script
- A Qualitative Analysis of NEF Compression
- NEF, Color Space Settings, and Embedded JPGs
- Tripod Stability Tests, Part I
- Timing a Transcend 80x 4GB Compact Flash card
with a Nikon D200 - Digital Camera “White Balance”
- Maximum Aperture of the Nikon 18-200mm
Throughout its Zoom Range
more...
You can also check images on your local hard drive -- images directly from a camera generally have the most information. Give it a try!
If you're using Firefox or Safari, you have the added benefit that you can install an Exif-viewer button on your button-bar toolbar. Once you've done that, later, when you're viewing a page with an image you want to check out, just click the button and you'll be whisked to a new tab showing the image's data. I find this really useful. It doesn't work in IE, though, sorry.
I use the viewer a lot on images I see in the Digital Photography Review Samples and Galleries forum. Lots of nice pictures in there. Many have their Exif data stripped, but many do not.
Finally, I should note that my viewer makes use of Phil Harvey's most excellent Image::ExifTool library. Thanks Phil!
There is a camera which hash GPS integrated into it. No more manual geocoding.
http://personaltechpipeline.com/news/57702442
Built-in GPS is cool, but at this stage I don’t think I’d like it built in unless I knew it was at least as good/accurate/fast as the current crop off GPS handhelds.
My Nikon D200 can be hooked directly to a GPS unit and automatically encode pictures with the appropriate data…. but I don’t use it that way. (To have something teathered to the camera would be fairly awkard, I think).
As for manual geoencoding, I don’t do that, either.
What I do: I have my GPS unit keep a track updated every second or so. When I get home, I correlate the data from the track with the pictures (via the picture timestamp). While I’m updating the Exif data with the GPS stuff, I also add my name and copyright and human-readable location info (e.g. Kyoto Japan).
The downsides of what I do is that I must be sure that the camera clock is set correctly (the GPS clock will always be correct when its talking to the satellite), and that I must remember to bring my GPS unit, and remember to turn the tracking on, and must be sure that I download the track before its memory fills. I’d certainly like not to have these downsides, but I think it’ll be a while before a built-in GPS unit will be good enough yet small enough to add to a full-size SLR to make it a real value…..
Was just reading one of your posts in the Digital Photography Review forums :
http://forums.dpreview.com/forums/read.asp?forum=1018&message=16751765
and was wondering how you planned to deal with the timezone info. I have a Nokia 3650 camera phone (which takes pretty decent pictures) that does not save EXIF data. It does however create a modification date in UTC , which I can then inject into the EXIF data with ExifTool. But how to indicate the time zone? I will most likely leave the time in UTC, and set TimeZoneOffset to EST (-5), which is the time zone where most of my pictures “live”….Tom
Hi Jeffrey,
Your EXIF tool is fantastic. But I do have a question about how you’re obtaining a timezone offset. I suspect it’s via the XMP headers which I assume are simply set by whatever Adobe program I happen to be using. And set to be the same as the timezone offset of the machine on which the photo was processed. Am I totally off base?
Ted
The viewer’s timezone stuff is sort of random, because timezone data within the Exif data is random. The Exif standard does not provide for timezones, which is just an amazing oversight as far as I’m concerned. When I asked a member of the committee about it, he asked “why would you need timezone information? Could you give an example where it’d be useful”. Arrrrgh.
Some programs do insert timezone info in the data in various ways. Adobe Photoshop assumes all images are in the machine-local timezone, and so adds that timezone (turning data that’s vague into data that’s perhaps wrong).
Until there’s clear direction as to what should be done, my online viewer remains sort of random WRT timezone stuff. I should at least update the output to indicate that timezone stuff is random, though….
How do you merge the GPS data? I’ve been thinking of coming up with something like this but it seems like I’d end up manually merging all the data in, which is more work than I want to do at this point. If there were some way to automade adding the GPS info I’d be all for it though.
Rahim, I wrote my own little script to do it, but I know that there are scripts and apps out there that will do it. Try
a search and you’ll find some.
Tethering recently got less awkward. I’m finally considering it:
http://www.dawntech.hk/di-GPS/n2.htm
Moose’s blurb:
http://www.moosepeterson.com/moosenews/archives/2007/06/23/coolest-tool-ever-062307/
And Bjørn’s review:
http://www.naturfotograf.com/GPS_review.html
Thanks for the great information, dww. That unit looks quite nice, and it seems to be a great solution for many. I think I’ll still opt for the untethered approach because it offers much more flexibility at little cost (at least, little cost to me… YMMV). I’m at the point of probably soon replacing my Garmin GPSmap 60cs because of it’s old GPS antenna not being as fast or sensitive as the newer models. I’d probably just get the newer “60csx” model except for the worthless barometric altimeter. So, what to get…..? Now, if Nikon built the GPS into the camera….
—Jeffrey