Forensics

[cambshiregordon]

A newbie here, enjoying this awesome program and the excellent video tutorials.  There is an adage that 'the photo never lies' but after seeing only some of the editing techniques I wonder if, to that adage, we should add ' ...unless it is a digital photo'. 

 

I have tried searching "forensics" as I was wondering if the various photo editing techniques are detectable from the finished image.  I hasten to add that I have not bought this programme with any intention of committing a crime or hiding / manipulating evidence!

 

I am just curious as to whether a pixel altered photo (AP or otherwise) is detectable in some way by scanning the resulting image.  Would for instance entering an AP edited photo be acceptable in a photographic competition.

 

Sorry if this topic has been addressed in previous posts - if is has perhaps someone could direct me thereto? 

 

Thank you for a first-rate piece of software.

 

cambshiregordon

 

[MattP]

Hi cambshiregordon,

 

With respect to whether AP-edited images would be allowed in a photography competition, that's totally down to the terms of the specific competition... I submitted edited photos to a camera club and won, but the club were happy for their members to 'enhance' their photos however they saw fit - it was the end result that mattered in that club - whereas other clubs may have a strict 'as shot' policy.

 

There are often tell-tales in any manipulated image - often the absence of noise or indeed noise being too regular, other artefacts seen around compositing/blending with non-linear gamma, things like that... but most of them can be minimised to the point where it's very hard to tell... but if someone was desperate to tell, they probably could...

 

Thanks,

Matt

[anon1]

 

There are often tell-tales in any manipulated image - often the absence of noise or indeed noise being too regular, other artefacts seen around compositing/blending with non-linear gamma, things like that... but most of them can be minimised to the point where it's very hard to tell... but if someone was desperate to tell, they probably could...

 

Thanks,

Matt

 

1. http://www.armscontrolwonk.com/archive/1201635/mh17-anniversary/

one example 

 

cheers  :)

[Peter Werner]

Images have been retouched and manipulated before the digital age (see here for a few famous politically motivated examples). Stars used to have their own retouchers they worked with for their portraits. It's just gotten a whole lot easier to do. In fact, the accessibility of Photoshop and similar tools has lead people to finally distrust the images they see, whereas in former days, only a select few people were privy to knowledge about the extent that images could be manipulated.

 

Most of the time, recognizing edits it's as simple as applying an extreme curves adjustment. Most manipulated images fall right apart. Sometimes just looking at an image on an uncalibrated monitor is enough, which is why extreme curves are a good way to check if your own edits hold up. Other techniques include analyzing the grain structure or looking for repeated patterns (usually more subtle than this famous example however) or looking for strange glows or edge artifacts that are the result of sloppy masking. More often than one would think, it's as easy as looking at the EXIF metadata and seeing which software was used to write the file.

 

There have also been various automated ways, programs and scientific papers with various approaches to detecting manipulated images, some using machine learning, others looking for small repeated patterns that might be the results of using the clone stamp and so on.

[anon1]

machine learning

buzzword_count++;  :)

[cambshiregordon]

Thank you to those members who responded so quickly to my first post and for supplying some examples.

 

Whilst aware that photos pre the digital age can be and have been manipulated, I was curious as to whether the sophistication of digital photography and post-editing software would make it easier to 'forge' an image and more importantly for it then be undetectable.

 

Thank you also for the heads-up regarding 'terms and conditions' when entering photographic competitions.

 

cambshiregordon

[R C-R]

This is a very thought provoking topic. For example:

 

• I wonder how some of Affinity's tools like the inpainting brush would stack up vs. Adobe's (the obvious choice) regarding detection of alterations with world class forensic software? Some things probably would not make any difference but I can imagine that some of the forensic stuff has been "tuned" to detect the use of PS's toolset.

 

• Given sufficient talent, money, & other resources (& a strong enough motivation), perhaps there are those using this same forensic software to tweak their alterations to be as undetectable as possible by it, or failing that to introduce the kinds of artifacts that would obscure things enough that it would be hard to say anything definitive about their most likely cause. IOW, a digital arms race of a sort.

 

• Even without that, sometimes the line between "enhancement" & "alteration" is blurry enough that the motivation remains unclear, at least for evidentiary purposes.

 

• The chain of custody & source of evidence could become a problem or something to exploit, depending on one's goals. If a digital photo was taken with a DSLR but only a JPEG version of a RAW image is known to exist, should it be considered the "original"? Some high tech cameras don't even create a conventional photo, but instead use techniques to create one from high resolution line scans built up over seconds or from time of arrival & incident angle data from specialized sensors. Without access to the raw data & knowledge of how it is gathered & used, the whole concept of an original image begins to get a bit murky.

 

Anyway, thanks to the OP for starting the topic & to those who contributed links.

[John Rostron]

The original poster used the word 'Forensics', which set me thinking. What is the current state of the admissibility of digital images as forensic evidence? I would guess there is variability across states. I would be interested in UK law in particular.

[cambshiregordon]

By way of a little background detail, I am a septuagenarian who recently bought AP.   Looking at my digital images, I realise that my digital camera skills were lacking on many occasions, so I bought AP to do some simple (?) enhancements.  The accompanying video tutorials I find to be instructive, fascinating and illuminating.  I had no idea of the extent to which digital photos could be -- what its the word to use here -- manipulated? enhanced? doctored? improved?  

 

I am no computer geek and like John Rostron (post no8), I too began to think about forensics and evidence.  John, I am no lawyer and certainly not in any position to advise on the UK law on this topic.   My guess is that ask two lawyers the same question and you will get three answers!  Hopefully there is a photographer who is conversant with UK law on this topic who will make a post.

 

cambshiregordon