How to determine if a digital photograph has been manipulated

I am frequently tasked with providing an expert opinion on whether photographs have been digitally manipulated or not. A simple examination can often reveal some limited information, but to get more accurate results, we need to look beyond a simple visual examination.

Looking at a photograph, there are things to look out for when determining if it’s been digitally manipulated. If the photograph is one of a series taken in burst mode, there may be inconsistencies between the set, such as light/tone variations, or pixel aspect ratio. In saying this, though, this isn’t conclusive, and a more in-depth analysis is needed.

All photos taken digitally contain metadata known as EXIF data. This contains information such as the time and date it was taken, what model of camera it was taken on, geo-locations, and more. Photos downloaded from the internet, however, usually don’t have any useful EXIF data.

One useful way when trying to ascertain whether an image has been manipulated is error level analysis. Error level analysis shows the difference in quality, as represented by brightness. Areas which are very bright have been edited most recently, with the duller parts indicated the photo has been resaved multiple times. Each time JPEG photos are saved, they lose more and more of their quality.

Adobe Photoshop can also be used to interrogate pixel aspect ratios, as well as zooming in to any particular areas of interest within the photograph. Aspect ratio describes how the width of a pixel compares to the height, and allows you to make color, focus and size calculations.

Another useful piece of software is JPEG Snoop. It grades photos from class 1 (definitely manipulated) to class 4 (uncertain if edited/original). While it can’t tell if a photo is definitely the original, it can tell if it’s been edited. It uses an internal database that compares an image against numerous compression signatures. If the compression signature matches that of a piece of photo editing software, we can determine if it’s been manipulated or not.

Photo Credit: Halay Alex/Shutterstock

Aran Pitter is a Director at Data Recovery Specialists