Your Photos Are Hiding Secrets: How to Read Exif Data
When I’m publishing a photo at one of my sites, I like to tell the story of the shot – where it was, when I took it, and sometimes how I did it. The problem is that I’m often publishing several months after I took the photo, and I can’t always remember those details. As it turns out, the photos themselves can tell me all of that, and more. Today’s digital photographs store Exif data, and it’s invisible to the image, but we can use it to tell us important details. Exif data is metadata – data about the data – that digital devices store within digital images. Let’s take a closer look at what Exif data is and what it can tell us.
What is Exif Data?
Exif data – and we always capitalize it – stands for Exchangeable Image File Format. It lives as a metadata block within the image file. It doesn’t affect the visual content, but it remains attached to the file. When a digital camera or smartphone captures a photo, the firmware generates and embeds the Exif data into the file before saving it.
Exif follows a standardized structure, which is based on the specification for Tagged Image File Format (TIFF) files. That ensures that different devices and different software will be able to read and interpret the data. Devices store the metadata in binary format . Using binary storage makes the data efficient and light, but it still keeps the detailed information about the camera settings, date and time, and, if your camera can do it, GPS coordinates.
The metadata is structured using Exif tags, which are specific fields inside the image header. The tags will tell us things like shutter speed, aperture, ISO, and GPS location. We can extract the data using photo editing software, operating system tools, and certain command-line utilities. However, not all images will have Exif data that you can view, depending on the format of the image. PNG and BMP files don’t support Exif data, but RAW files store even more extensive metadata.
What Information Does Exif Data Contain?
Exif data can contain a lot of information, but what you see depends on the camera and software you use. One thing is what object is capturing the data. Different cameras and phones will capture different data sets. The other main factor is what software you’re using to look at the metadata. At a minimum, if you’re looking at the metadata or Exif information, you should be able to see:
- Shutter speed
- Aperture
- ISO
- Focal length
- Date and time of capture
- Camera and lens model
- Location data (If the device is GPS-capable and location tracking is enabled)
Some of the other data facts you may find include:
- Pixel dimensions
- Resolution (DPI)
- Colorspace (sRGB or Adobe RGB)
- File size
- A thumbnail of the image
- Flash information
- Orientation
- Copyright information fields
How to View Exif Data
There are probably as many different ways to look at the Exif data as there are software programs capable of displaying it. I’ll show you the three I use most often.
GIMP
The Gnu Image Manipulation Program (GIMP) is a photo processing program comparable to Photoshop. It takes about as long to get good with it, too, but it’s a comprehensive program. It’s the only program I have that can do image compression, so I use it mostly for that, but it has some fun filters as well. To find the Exif data, navigate to Image>Metadata>Metadata viewer. These images are a scroll-by-scroll of the Exif data you get with GIMP.
Photoshop
It’s just as easy in Photoshop to see your Exif data as it is in GIMP. Navigate to File>File Info and cruise through the options in the dialog box.
Bridge
Adobe has a product called Bridge that is quite versatile. I use it to preview images before I import them to Lightroom or Photoshop, but most often I use it to search for a particular image. Bridge can view just about any kind of image file, including the raw files that not just any processing software can view. It was in Bridge that I first discovered the metadata and realized how useful it is. There are a couple of ways you can see the Exif data in Bridge.
In Filmstrip view, the selected image is presented in the largest panel, but below that you’ll see a thumbnail and a quick view of the Exif data.
If you want more information, it’s just a couple of clicks away. Up at the top center of the viewing window, select the Metadata option.
Now you have a wider array of metadata to tell you what your image is made up of.
The Benefits of Exif Data
I use Exif data for several different purposes. For one thing, when I was writing the article on Lens Compression, the Exif data helped me identify what the different lens lengths and extensions did to compress the background in the image.
Analyzing my photos
Exif data also helps me look at a great shot that I managed to get and see what about the final image made it so wonderful. Maybe I can try to replicate those settings in a different scene and see what I come up with. It’s helpful to see what worked and what didn’t, because I have specific numbers, rather than just “it’s overexposed, let’s play around and see if we can make it better.” I can see whether it’s overexposed because I had the ISO too high, or if I opened up the aperture too much, or if the shutter stayed open too long, and I didn’t compensate for any of the other factors in the exposure triangle.
Verifying authenticity
There’s another benefit of Exif data that I expect to become more important as we see Artificial Intelligence, and even just good Photoshop skills, making image manipulation more difficult to detect – verifying the authenticity of an image. Because the Exif data is a part of the image file itself, some fields are difficult, if not impossible, to alter, and a casual photo-shooter may not even realize that this data exists. It’s starting to become important information in court cases.
Protecting my copyright
Additionally, I can claim a copyright to all my photos just because I shot them. However, someone else can claim a copyright to my photos as well – except that I can justify my claim with my Exif data. Most of the sites where you see photos shared, like Facebook and Instagram, strip out most of the Exif data in the upload process. I have that Exif data in my original files. That makes it pretty easy for me to prove that the images are my own.
However, with the benefits of Exif data comes the risk of exposure of information that might better be kept private. Location data, for example, could reveal not only the location of the subject, but inevitably also the location of the photographer. (I don’t allow my phone to geo-tag my photos.)
Your Turn
Did you know about Exif data before you read this? If you did, how do you use it? I’m always fascinated to look at the lens zooms of some of the images I take. When I’m shooting mountains or rivers, I usually take several shots at different zooms, but I don’t pay attention to what the zoom length is until I get back home and start processing them.
If you found this article helpful, drop a comment below and let me know. Tell me what else you’d like me to cover – it’s probably something I’d like to learn more about myself!
If you want to go deeper into this topic, here are some links for you:
Exif Data Basics: Understanding the Fundamentals of Image Metadata – PhotoWorkout
What is EXIF Data? The Complete Guide
What is EXIF data? (YouTube video)
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