In previous parts of this series on tidying up the chaos that is your (or at least is my) digital photo collection, we reorganised our photo folders and de-duplicated our photo files. Things are going well – we have lovely, date-ordered folders and all of our duplicate photos have been zapped. But we’re not there yet. Dig into the folders, and you’ll still see those annoying, meaningless photo file names generated by digital cameras – DSC1634.jpg? P76376.jpg? Not helpful, when you want to sort those folders in OS X Finder or Windows’ File Explorer. So, we’re heading on a path to automatically rename all of our photo files based on the date the photos were taken. But before we do that, we need to talk EXIF.

Did you know that every time you take a digital photo, your camera adds some descriptive data (or metadata) to each file? Like the date and time, camera make and model and a host of other technical data that the pros care about, but you may not. That data, often known as EXIF data (Exchangeable Image File Format) is what we’ll use to rename our files – but before we do that, we need to check for any files that may not have EXIF data (data can sometimes be removed by image editing software), and if we spot any, restore it.

To give you an example, like most couples, back in 2004 my wife and I had our wedding day professionally photographed and we received the digital files on a few DVDs. For whatever reason, whether it was lost in the editing process or not, those files arrived without any date and time EXIF data. As you can see from the screenshot below, there’s an EXIF entry for the date the photo was “digitized”, (the 6 Sep 2004) but that’s a few days later than the wedding itself (which was 27 Aug 2004), so pretty useless for renaming purposes.

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To view EXIF data on a PC, simply right click on a photo and select Properties, then go to the Details tab. On a Mac, open the file in Preview then go to Tools > Show Inspector.

If you’re in a similar position, and you have some of your photos missing EXIF data, or have the wrong date and time – maybe they’re scanned photos from physical originals, or your camera’s clock was incorrectly set – then worry not! You can edit EXIF data using an app. On Windows, you may want to check out a free app such as Exifpilot, which allows batch editing of EXIF metadata. As we’re using OS X in this series, we’ll be using an app called File Multi Tool 5 which is available from the Mac App store.

File Multi Tool 5 allows you to perform a host of editing options on your digital photo files. You can reset File Creation and Last Modified dates, manually set EXIF timestamps to a specific date and time, sync File Creation and Last Modified dates, sync EXIF timestamps with  File Creation and Last Modified dates, remove File Creation and Last Modified dates and a whole lot more.

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Using the app is very simple. Open it up, and as we have no EXIF timestamp at all, and the File Creation and Last Modified dates are of no use to us for synchronisation purposes, we’ll have to set the date manually. In the Action dropdown, select Set EXIF timestamp, and a handy calendar and clock appear.

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Set the time and date to what you want to appear in your photos’ EXIF data, and then drag and drop the files and folders you wish to receive the new timestamp on to the panel as indicated. The app works with both local and network files – try it out with a test file first.

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As you can see in the screenshot above, the file we selected apparently was shot on the 17 Aug 2010 – a  full six years after I actually got married (as no EXIF data exists, the File Modified date has been pulled in). I’ve set the time and date correctly, and then just need to hit Perform Changes to set the EXIF data. After a couple of seconds, the timestamp is changed.

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Just to be sure, let’s check it in Preview.

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As you can see, the Date Time Digitized field has been joined by a Date Time Original field, which is our shooting date.  Go ahead and make any changes you need to to clean up your EXIF data.

Okay, now that your EXIF data is correct, you may want to take the extra step to synchronise your File Creation and File Modification dates with the EXIF timestamp. Your File Creation date can often be different to the shooting date as it can be set when you import your files from the camera on to the computer – if you’ve left the files on your camera for a few days, well, there’s the issue. At this point, I want to baseline all of my images with the correct File Creation dates – and as operating systems tend to use the last modified date as a sort filter, I’d like to reset this too.

We’ll do this in two hops, again using File Multi Tool 5. Firstly, in the Action drop down, select Copy EXIF timestamp to creation date.

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As you can see, you’re given the option to change just the date, just the time or both. I’m changing both. Again, drag and drop your photo folder on to the panel and hit Perform Changes.

Depending on how messed up your File Creation dates have been historically (and mine look pretty horrible), you may receive the following message which states that Inconsistent File Dates have been detected – all this means is that the File Modification date is currently set to a time before the new File Creation date your setting, which of course is illogical – a file can’t be modified before it has been created. So to resolve this, the app changes both File Creation and File Modification date to the EXIF timestamp.

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Depending on the size of you collection, this may take a little time to complete – especially if your collection is stored on the network rather than locally. Once done, we can move on to the final preparation step we need to take ahead of renaming our files – that is to reset our Last Modified dates, which will be synchronised with the File Creation date. This is a purely optional step for those that wish to fully reset their photo collections.

To perform this step, in the File Multi Tool 5 dropdown,  select Copy creation date to modification date. Add your photos folder and allow the app to synchronise the dates.

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The result? You now have your photo EXIF metadata corrected, where required, your File Creation dates accurately reflect when you took each photo and you’ve reset the File modification date to match the File creation date. Not the most glamorous tech project in the world, but handy behind-the-scenes tweaking which will make automated file renaming, which I’ll cover in the final part of the series, a whole lot easier.