How is manipulation detected?
In the manipulation review workflow, a contest picture and its original version are loaded as separate layers in Adobe Photoshop.
The two images are subsequently resized and aligned to match each other. Switching between the contest picture and original image, differences between the two images become evident.
Further use of Photoshop blending modes exposes any differences between the two images, giving a clear visual representation of any details that are different. The histograms of the contest picture and original image are compared to see if there are large differences and if the contest picture contains significantly less information due to darkening or lightening.
In certain cases, the RAW file is lightened or darkened to inspect the amount and type of information contained within the RAW file. This information is then compared with the contest picture to see if the information from the RAW file matches the contest image.
The images are examined at a scale of 100%, meaning each pixel of the image corresponds to one pixel of the screen. Viewing the images at this scale allows details to be seen that would otherwise be overlooked if the images were scaled down to fit the computer screen.
Who conducts the manipulation review?
For 2017 the manipulation review will be conducted by two independent forensic analysts retained by the World Press Photo Foundation: Eduard de Kam, who is a co-owner of the Nederlands Instituut Digitale Fotografie, a center of digital photography expertise in the Netherlands; and Peter Lipton, who is an expert on photographic post-production, and a freelance photo editor and photographer. Professor Hany Farid (Department of Computer Science, Dartmouth University, USA, and the leading authority on digital forensics and image analysis) is available to the Foundation for technical advice on particular cases when required.
How is the decision to exclude a contest entry made?
For all work remaining in the second last round of the contest, entrants are contacted during the judging period and required to provide file(s) as recorded by the camera for their entry. If entrants can not or do not provide these files, their entry will be ineligible for the final round and a possible award.
After following the above workflow, the analysts present a technical report to the jury identifying which, if any, pictures have had content altered, noting the details of the alterations.
Entrants whose work has been identified as having content altered will be contacted for an explanation before the jury makes a final decision. Entrants will have to provide this explanation within 36 hours of being contacted.
After receiving the technical report and any explanation from the photographer, the jury determines which entries are ineligible for an award. This process is detailed in the Judging Procedures Handbook, Section F (viii).