You probably know that digital images can provide a lot more information than just what they’re showing in a picture, but do you know how to get to it? You don’t have to be a detective to use one of the many online tools for looking past the surface of a picture. In this two-part episode I’ll be looking at five sites for getting the details behind a picture: two this week and three next week. (I was going to do all five in one article but the word count was getting out of hand.)

Photos: What Can You Know?

Digital images show what you were pointing your camera at when you took a picture. But when you think about it there’s a lot behind that information as well: the date and time, the kind of camera you used, any special settings you used to get the kind of image with which you ended up, and so on. Online tools can also examine the colors in the image, use AI to try to describe what’s in the image (with extremely varying levels of success), and try to find any altered data in the image.

Let’s get into the guts of a picture my husband took a few years ago, using these sites.

Please note: I am not a digital forensics specialist, so some of the options these tools offer are new to me. I’ll provide links to relevant, more expert information in that case, but if I miss anything in my explanations, let me know and I’ll add more resources to the article.

FotoForensics: http://fotoforensics.com/

First thing you should know is: don’t load any images with sexual content to this tool because you will get banned. So if you got an.. Ahem.. an interesting picture via text message and want to get more details about it, don’t upload it here. (There are also some general technical restrictions on what can be uploaded; see the FAQ for more details.)

My husband’s picture is not at all salacious so I uploaded it without fear. FotoForensics has a tutorial to help explain the results you get, but let’s quickly look at your options. The first result is just a digest of information about the picture.

Cool, but what about the rest of the data?

ELA – ELA stands for Error Level Analysis and shows you the image in such a way that you can look for variables in the edges of images or in the brightness of different parts of the picture, giving you clues into whether or not it’s been manipulated. Infosec Institute has a great deep dive into ELA and how it can be used here. Here’s what my husband’s picture looks like ELA’d:

Hidden Pixels – Pretty much what you’d expect; looks for hidden pixels in a picture. How can a picture contain hidden pixels? First you need to learn about steganography, the art of hiding things in other things – like, pictures in other pictures, or data in pictures. Then you can read about hidden pixels in a blog post from the founder of FotoForensics. I get the impression that hidden pixels are not as relevatory as steganography, but can provide information on whether the photo was altered and even possibly what program was used to alter it.

JPEG % – Estimates the JPEG compression levels for the image. I took this picture right from a picture dump from my husband’s phone, so I wasn’t surprised to see the compression level estimated to be 95% (the higher the number, the better.) Coding Horror has a breakdown of JPEG compression levels and some thoughts.

Metadata – This you probably know about. Metadata contains information about the picture that you can’t determine just from looking at the picture. I’m going to get the Metadata for this picture, then change the zoom level for the browser window so you can see how much metadata is available in this image. You ready?

I had to drop my page zoom down to 33% to get all that in. And it’s a lot. It shows what hardware my husband used to take the picture, the date, whether the flash was used, and a ton of other technical data, then it gets down to the longitude and latitude of where the picture was taken along with a Google Map!

(And if you’re thinking of all the images you’ve uploaded to Facebook, Twitter, etc., let me tell you that many social media sites strip this kind of metadata. How-To Geek has a good overview.)

Source –  I’m not sure what this is for, but it shows what the original image you uploaded looks like while you can play with another. For example, here’s the source image while I’ve rotated and changed the colors on another copy.

Looking at this site, you may have concentrated on the metadata, but unfortunately FotoForensics makes that a little hard to view as it’s not really formatted for a casual glance. Jeffrey’s can help you out with that.

Jeffrey’s Image Metadata Viewer: http://exif.regex.info/exif.cgi

This tool is just for reviewing metadata, but I’m including it here for two reasons. The first is because this tool supports tons of filetypes while FotoForensics only supports JPEG, PNG, and WebP files. The second is because the metadata is in a much easier to read format than offered by FotoForensics. Here’s how it sees my picture:

As you can see, the important parts of the metadata are much easier to read than they are with FotoForensics. (All the metadata is in a tabled list at the bottom of the page.) This tool doesn’t do nearly as much as FotoForensics, but it provides nicely-formatted metadata very quickly.

This week we only looked at two sites but FotoForensics has so many offerings it’s almost worth a deep dive itself. Later this week we’ll take a look at three more sites which can provide you with photo information — and one that can help you keep up with photos and videos.