May
14

Digital photography experts confirm the integrity of Paul Hansen’s image files

posted on May 14th 2013 in Photography with 0 Comments

It’s just a matter of time before the World Press Photo organization remove the award for Paul Hansen“, predicted yesterday the technology blog Extreme Tech.

In an article that blends information and opinion, the publication abounds in accusations against Swedish photojournalist Paul Hansen, awarded the World Press Photo to the snapshot of the year, about his alleged excessive photo manipulation. And says that he made the award-winning image through a mixture of three different photos. This is based on technical analysis conducted by Neal Krawetz in The Hacker Factor Blog. A footnote on page announces that Extreme Blog article has been updated this morning to “soften slightly the claim that the image is a mixture of three different images.

Given the accusations against photographer winner from the very announcement of recognition, of which recently echoed the German weekly Der Spiegel, World Press Photo has today decided to commission two independent experts “a forensic investigation of the image”, whose results be announced “as available” basis.

Yes, the organization advocates in an email that everything happens with the “full cooperation Hansen”. In fact, World Press Photo clarifies that the study seeks to “limit further speculation” and photographer Swedish “explained in detail how processed the image.” Therefore, the jury “has no reason to doubt their claims.”

World Press Photo has submitted the image files for a forensic analysis. The purpose of the investigation into the authenticity and editing history of the picture is to curtail any further speculation about the integrity of the image and to establish that it is not a composite (read the whole news by World Press Photo here).

Paul Hansen has previously described in detail how he processed the image file and World Press Photo has not had any reason to question his explanation. He has now again fully cooperated in the investigation carried out by independent experts. After examining the RAW file and the JPEG image entered in the competition, these are the experts’ conclusions:

“We have reviewed the RAW image, as supplied by World Press Photo, and the resulting published JPEG image. It is clear that the published photo was retouched with respect to both global and local color and tone. Beyond this, however, we find no evidence of significant photo manipulation or compositing. Furthermore, the analysis purporting photo manipulation is deeply flawed, as described briefly below.”

1. XMP Analysis. The XMP analysis reflects an incomplete understanding of the Photoshop metadata and also paraphrases the contents in a misleading way. The referenced block of metadata merely indicates that the file was adjusted in the Adobe Photoshop Camera Raw module on multiple occasions before it was opened in Photoshop and then saved out as a JPEG. In fact, this metadata does not track whether multiple files were composited.

2. Error Level Analysis. The forensic analysis of the JPEG compression as performed by error level analysis (ELA) does not provide a quantitative or reliable analysis of photo manipulation. This analysis frequently mis-identifies authentic photos as altered and fails to identify altered images, and as such is not a reliable forensic tool.

3. Shadow Analysis. The shadow analysis is flawed in its logic and conclusions. It is true that linear constraints that connect points on an object with their corresponding points on the shadow should intersect at a single point (assuming the presence of a single light source). The location of this intersection point, however, cannot be used to reason about the elevation of the light in the scene. The intersection point is simply the projection of the light source into the image plane. This projected location can be anywhere in the image (including below the ground plane) depending on where the photographer is oriented relative to the sun.

Dr. Hany Farid, Professor of Computer Science at Dartmouth College and co-founder and CTO of Fourandsix Technologies & Kevin Connor, CEO of Fourandsix Technologies:

“When I compare the RAW file with the prizewinning version I can indeed see that there has been a fair amount of post-production, in the sense that some areas have been made lighter and others darker. But regarding the positions of each pixel, all of them are exactly in the same place in the JPEG (the prizewinning image) as they are in the RAW file. I would therefore rule out any question of a composite image.”

Eduard de Kam, digital photography expert NIDF (Nederlands Instituut voor Digitale Fotografie):

World Press Photo is the leading international contest in photojournalism. The contest entry rules state that the content of the images must not be altered. Only retouching which conforms to currently accepted standards in the industry is allowed. The jury will consider what they deem acceptable in each category during the judging and they can request original, untouched files or scans from the photographers to examine. In case there is doubt after the judging has been completed, there is a procedure for re-examining the files which could ultimately lead to the disqualification of the work and withdrawal of the award.

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