What are the ethical limits for the application of Photoshop?

I have been intrigued by some of the image forensic analysis work of Dr. Neal Krawetz as documented in his blog the Hacker Factor.  He applies a variety of tools to try to uncover manipulation in digital images and has several posting dissecting various still photos and videos.  One of the tools he applies is something called the Error Level Analyzer.  The original author of this tool (P. Ringwood) previously had posted the source and binary a few years back (at which time I downloaded this).  A website now exists where you can post your images and have them analyzed using this tool.

My personal interest has been out of curiosity of many images I see posted on Flickr or submitted in various photo contests that I believed to be doctored in a misleading manner. Some of these more popular or winning images to me look like some blatant manipulation has been involved that crosses my personal ethical line of what should be modified without disclosure.  However, trying to prove such manipulation can be difficult.  There is also a debate that I have with myself and others as to what should be considered ethically acceptable versus what crosses the line. One of my concerns is that more blatant modifications will result cheapening the field of photography, and turn it into more of a field for those with the best graphics artists skills. The other is the undermining of the hard work by a photographer to capture a unique image in an honest manner.  Consumers and viewers of such art may become more jaded and question more and more geniune work from that in which the capture was "cheated" and not necessarily know the difference.

My interpretation as to what is OK with the intent to reflect the realism of a scene would consist of edits that follow these guidelines:

Some readers of this article may view this as a long list of liberties. But overall my goal is to maintain the realism of the scene at the time of the original capture with the edits in line with adjusting for deficiencies in the technical limitations of the camera and/or related equipment. Any serious photographer I am aware will find the above list to be necessary work as part of producing high quality images.  In addition, if you shoot in the camera raw format, some of this is necessary as part of the conversion to tiff, psd, jpeg, png, etc anyway.  The difference is the post-processing is being down during the raw conversion by the user in software manually versus the conversion being done in the camera by its firmware as controlled by one of the picture profile settings. 

To be clear on my views of what I think crosses the ethical barrier for non abstract or impressionist types of images without disclosure, I would treat the following as crossing the line:

To aggregavate matters, I do find it a bit frustrating that some requests for photo submissions make blanket statements such as: "No photoshop", without in my view an understanding of the distinction between these two different class of edits described above.  Perhaps it would be hard to judge or referee such a distinction, so as a result a zero tolerance policy is stated instead?

Morning fly out (unedited)Anyway, now that I have gotten that off my chest, I thought I would perform an experiment on one of my one photographs to see if I could use the Error level analyzer tool previous referenced to determine if doctoring of the image could be detected. As shown to the right, I started with an image that I captured on one of my bird photography outings. I liked the lighting on the birds as it was difficult to get this opportunity with them flying somewhat toward me and into a sunrise. But my framing at the time of capture was leading a little to much to the right. Shooting birds in flight can be tricky while still maintaining focus lock as you only have seconds to get it right. Unfortunately this resulted in a slight clipping of the end of one of the Sandhill Cranes legs and wingtips as shown to the right. 

Rather than throw the photo out, I liked the image enough that I applied some photoshop work to restore the clipped portion and extend some space to the left and above to better balance the composition.  You can see the results of my handy work here in this next version. Morning fly out (fixed)This required a bit of finesse involving cloning a foot and some wing tips from one of the other birds and applying it to the left-most bird.  This should also give the reader an idea of the types of things that are easily possible for those skilled in the art.

To me, this level of manipulation I have shown here is a gray area.  I believe it would be OK to reference such a result for documentary purposes (i.e. for a book or magazine documenting the migration of Sandhill Cranes). But I don't believe it would be proper to submit such an image to a photo contest or some other judged artistic competition without at least disclosing such edits, since the fundamental skill in winning the contest should be based on your photographic skills, and not your Photoshop skills. If it was a Photoshop contest, then the circumstances would be different. 

After attempting to analyze the results using the error analyzer tool, it was not that obvious that the edits could be detected on the bird itself.  The background area to the left and top that I expanded by cloning the immediately adjacent area is an obvious give away using this tool.

Original unedited ELA result:  Original ELA output

Edited (doctored) ELA result:  Edited ELA output

According to the ELA website, this tool is supposed to work by introducing a small amount of noise and then highlighting the pixel areas that that already have reached some error minima. Theortically false introduced content will have less error on the borders where the changes have been made. But based on this algorithm it is not clear how effective it is at detecting this type of manipulation.  Based on the edited ELA result, I do notice the rear foot does have a small amount of increased illumination, but then again, I knew to look there. It is interesting to note the feet of the right-most bird also exhibits some of this increased illumination, although I did not edit that area of the image (honest :^). Perhaps one weakness with a tool like ELA is that its algorithms may be better at catching manipulated JPEG compressed image content versus those maintained in raw.  A raw file will have more bits of precision per pixel, and thus less likely to saturate its numerical range. 

So at this point, I have not reached any conclusions on a more robust means for detecting such edits through a tool like ELA.  As an example, there is a particular image I note on Flickr titled "Capocotta Beach" that I am curious about. The artistic aspects of this image appeals to me, but the seagull looks suspicious. The lighting on it seems unnatural for what I would expect to exhibit more backlighting characteristics (Apologies to the author if I am wrong.) Using the ELA website to examine it does show a little unusual highlighting around the beak, but it hard for my untrained eye to know the difference of this from similar randomness in the ELA output on the sand of the beach. I have not posted it out of respect for the owners copyright, but you can go through the exercise yourself by viewing the image at the large size in source form in your browser, and then cut-and-paste the jpg reference as a link to the ELA website to perform the analysis.