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A competition I want to participate in demands that they want unedited photos. The submission should not even have basic edits like brightness, saturation, white balance etc

They claim they'll check this using meta data, is it possible that they'll know if one has edited the photo?

I think some people might edit and submit and will get an unfair advantage...

Prabhat
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    Impossible. A RAW image must be edited to save it as a recognisable picture, so anyone shooting RAW must have edited in order to submit. – Tetsujin May 17 '21 at 16:58
  • @Tetsujin Couldn’t the competition require out of camera jpegs? – Eric S May 17 '21 at 17:11
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    Sure - but a) how would you be able to tell the difference? b) most devices that shoot to jpg have already made several computing decisions as to how to render the jpg, from simple sharpness, white balance etc right up to full HDR & out of focus blur enhancement. Where do you stop? – Tetsujin May 17 '21 at 17:15
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    I got this requirement removed from a competition I used to be a judge for every couple of years. I shot an image in raw+jpeg and edited the raw image 4 ways, then cloned the original exif data to all 5 images (script took less than 10 minutes to write) and challenged the organizers to tell me which was the original out of camera version. They could not come to a consensus, so the requirement was removed. They did maintain a rule against "compositing and hyperrealistic editing" which accomplishes the goal of judging the photography skills instead of the photoshop skills. – LightBender May 17 '21 at 20:07
  • If you have a bit of time, you can circumvent it this way at least with a Canon camera: 1) shoot the image "raw", 2) download the CR2 to your PC and open with Canon's DPP application 3) tweak tone curves to your liking, 4) export these settings from DPP as camera settings to your camera, 5) shoot again with JPEG output. – xenoid May 17 '21 at 20:53
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    There's really no such thing as an "unmanipulated" or "unedited" photo. I've never looked at a photograph and thought I was looking at the real world instead. The information coming off a camera's sensor has to be processed to look anything like what our eyes expect to see of a scene that we just photographed. With "straight out of camera" JPEGs, we've either allowed the makers of the particular camera we're using to make all of the decisions regarding processing, or we've modified them slightly as much as the camera allows before shooting. – Michael C May 18 '21 at 00:39
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    Ideally, the camera would sign the files with a cryptographically secure hash. As of 2011, Canon and Nikon were not secure. A nice thing about this is you could exhibit a chain of edits that got from the camera photo to what you supply, so the contest could specify some acceptable editing. They could then ask the prizewinner to prove the submitted photo had no more editing than allowed. – Ross Millikan May 18 '21 at 02:15
  • Some contests reserve the right to request the (provisional) winner submit a copy of the raw file before being named the winner. – Michael C May 18 '21 at 03:14
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    Does this answer your question? How to detect if a photo's metadata has been changed? – Michael C May 18 '21 at 03:27
  • Also related: Is there a way to check whether the image has been modified with Exiftool? and How can I tell if a photo is real or faked? and How to identify photoshop-edited files – Michael C May 18 '21 at 03:29
  • Another question that deals with ill-informed contest requirements: How do I make my image comply with the requirements of this photography competition? – Michael C May 18 '21 at 03:47
  • Some more background in the answers to How to convert JPEG to RAW in Photoshop or similar? – Chris H May 18 '21 at 07:58
  • @Tetsujin Well, one could ask for submissions of (the various) RAW formats. Not that that would constitute any safeguard against manipulation: Since the data is uncompressed it may be both simpler and less detectable. – Peter - Reinstate Monica May 18 '21 at 12:54
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    @Peter-ReinstateMonica ..& what would you open it in to see what it ought to look like? Can't be in anything not by the manufacturer of the camera, otherwise you get a misinterpretation. See https://photo.stackexchange.com/questions/96952/why-does-the-histogram-of-an-image-depends-on-the-software-that-opened-it/96953#96953 for my opinion of using the 'wrong' app to open it ;)) – Tetsujin May 18 '21 at 13:35
  • @Tetsujin, technically, jamming the rgb values from the raw straight and undemosaiced into a jpeg encoder, maybe with a very simple integer multiplication applied (might be just a binary shift), might yield a recognisable picture. Very likely not an aesthetic picture. :) A RAW is at its lowest level an array of brightness values, so is the framebuffer of a computer graphics card. Possibly with different word lengths - which can be dealt with with truncating, shifting, padding. Whether you would call this editing is not a trivial question I think. – rackandboneman May 19 '21 at 04:41
  • @rackandboneman - none of this would prove the picture delivered was the one shot, because all that wizardry was responsible for making the jpg they delivered up, & if none of that can be reproduced in any other RAW app. Who knows what may or may not have been tweaked, or what the file looked like to the entrant. Simply opening in the correct app from the camera manufacturer & saving as jpg will already include a whole lot of processing defined by the photographer at the moment of shooting, plus a lot of automatic work by the camera itself. None of that would be visible in any 3rd party app. – Tetsujin May 19 '21 at 08:56
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    This is like telling you to shoot film but you're not allowed to use a darkroom for anything. – J... May 19 '21 at 10:36
  • Is cropping allowed? – Acccumulation May 19 '21 at 20:48
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    @J... No, you're allowed to use a darkroom, but you aren't allowed to manipulate the enlarger, development time, etc. Also, when you take the picture, you're not allowed to manipulate the focus, f-stop, etc. You can only use the original values for them. What do you mean you don't know what "original values" mean? – Acccumulation May 19 '21 at 20:51
  • @LightBender : but they were judges, trying to decide with their own eyes, not forensic experts. There are many ways algorithms can detect things like that. – vsz May 20 '21 at 10:24
  • @Tetsujin There's no single way any raw file ought to look. Even the manufacturer's default in-camera processing engine is applying one of near countless legitimate ways to interpret the data in a raw image file. All viewable images derived from a raw file have been interpreted. Every. Single. One. Of. Them. (Unless you are viewing direct sensor output that will look like a giant blob of near-black nothingness on your screen). – Michael C Jul 12 '21 at 15:59
  • @MichaelC - did you look at my linked question, as to why I hate Adobe's interpretation of RAW, compared to Nikon's? If you're taking RAW+JPG, then that's how it 'ought' to look, the same as the camera's interpretation. Anything else is just accepting that your start point is four paces to the left of what you thought you were going to get. – Tetsujin Jul 12 '21 at 16:03
  • @Tetsujin I strongly disagree. Most camera's allow us to alter the default raw conversion routines. This allows the in-camera produced JPEG to more closely adhere to the photographer's intentions, rather than the camera's default programming. At a minimum you can change contrast and WB presets (e.g. sunny, cloudy, fluorescent, etc.). Many cameras allow one to adjust highlights, shadows, white point, black point, Color temperature and WB correction, etc. Some top tier models even allow HSL adjustments in-camera. Many allow preloading custom processing instructions (Picture Control). – Michael C Jul 12 '21 at 16:19
  • @MichaelC - yes, & once you've done that, you want your RAW interpreter to know what you did & start from there, not just from a guesswork baseline. – Tetsujin Jul 12 '21 at 16:27
  • Insisting that the camera's JPEG engine is always the "correct" interpretation is akin to shooting Polaroid instant film instead of exposing film that has to be developed after it comes out of the camera. What you seem to be saying is that it was not legitimate when Ansell Adams was exposing his film based on how he planned to develop it and print it, rather than using the "standard" exposure and development recommendations for that film, and then only printing a straight contact print.. – Michael C Jul 12 '21 at 16:28
  • @Tetsujin Or, like Adams, one knows when one shoots a scene that they are going to apply processing steps that are more complex than what the camera's internal routine allows, so they don't even worry about in-camera settings for things like CT, WB correction, contrast, etc. because they already know how they're going to process the raw files afterward. I shoot night football at our home stadium without applying most of the processing steps in-camera because I know I'll batch apply a "recipe" I've already created for the lights in that stadium as soon as I import them to DPP 4. – Michael C Jul 12 '21 at 16:33
  • I also shoot using the "Neutral" Picture Style because the "flat" preview image gives "blinkies" and a histogram that more accurately show me when I'm getting close to blowing the highlights (in the raw data). I change that to "Standard" Picture Style automatically upon import into Canon's DPP 4. When I shoot, my purpose is not to produce an image in-camera that is closest to what I want to end up with. My purpose is to capture raw data in a way that gives me a raw file that allows me to end up with a final result closest to what I wanted when I took the shot. – Michael C Jul 12 '21 at 16:42
  • It matters not to me what the in-camera JPEG preview looks like when I'm saving raw data. I usually know before I take the shot most of what I'm going to do in raw conversion that the camera's routine is not capable of doing. Adams called this "pre-visualization". Shooting film for many years before digital came along forced me to learn how to do pre-visualization. – Michael C Jul 12 '21 at 16:43
  • So for someone who's been doing this for decades, you know what to aim for. For everyone else there's the disappointment of "I'm sure it didn't look that bad when I took it." – Tetsujin Jul 12 '21 at 18:20

4 Answers4

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Being slightly harsh, competition rules like that show that the organisers don't really understand how modern cameras work. A very high level and simplified view of how a camera makes a image (JPEG):

  • Light hits the sensor. Every pixel on the sensor produces an electrical reading which corresponds to the amount of light hitting it.
  • The camera converts those readings into an image. At this point, the camera makes a whole load of decisions around white balance, brightness, saturation and a number of other things. There are no "default" decisions here, the camera chooses - and on just about every camera, you have control over those decisions, whether they're "basic" decisions like white balance, or "complicated" decisions like adding a filter.
  • The camera might or might not write any of those decisions in the metadata, or they might just write "auto" for all the settings. In any case, you can delete the metadata, or replace it with other metadata - there's no way to reliably detect from metadata whether an image has been edited.
Philip Kendall
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    "Competition rules like that show that the organizers don't really understand how modern cameras work." This. If underexposing film when shooting and then pushing development was OK in the film days, why isn't the digital reverse equivalent (exposing to the right, then pulling exposure back in post) OK in the digital age? Or underexposing slightly to protect highlights and then pushing the mids and crushing the blacks? These are both legitimate techniques in various situations to get an end result image that actually looks more like what the eye might have seen when the scene was shot. – Michael C May 18 '21 at 03:20
  • Just to throw in some keywords to google for the Interested: The first bulletpoint here results in the known RAW "image" format. As someone already said, a RAW "picture" is simply not viewable in that form. The second bulletpoint is where that RAW image is converted into something actually viewable like a JPEG. However: Photoshop & co can also do the cameras job of turning a RAW image into a JPEG. And with the right values you can even get the absolutely exact same image (JPEG) from both tools. – Hobbamok May 18 '21 at 08:27
  • Also: that metadata is just that: data. And not even encrypted in any way or anything. Anyone who wants can believably edit it to their liking. Depending on the competence of the Jury it takes anywhere from 5 minutes to 20 to fool them. As always: if someone really wants to cheat they will. – Hobbamok May 18 '21 at 08:29
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    I know you provided a high-level description but I feel the need to add: "Every pixel on the sensor produces a non-linear, not entirely deterministic electrical reading which corresponds to the amount of light hitting it which is algorithmically smoothed and corrected to produce a numerical value corresponding to a preceived brightness..." – Peter - Reinstate Monica May 18 '21 at 14:06
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    I think this answer has pedantically over-analyzed the pragmatic rules which were laid out. In other words "Submit your photos as they were taken by the camera; jpeg format assumed." – MonkeyZeus May 19 '21 at 12:22
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    @MonkeyZeus Am I allowed to change white balance in camera? Am I allowed to up the saturation in camera? Particularly for a static scene like a landscape, what's then the difference between that and editing it out of the camera? – Philip Kendall May 19 '21 at 12:31
  • It's a photography competition, not a post-processing competition. The difference is that you knew to make adjustments in that moment which showcases your photography skills. If you were photographing an animal then it shows that you knew exactly what you were doing in that exact moment instead of settling for a sub-par shot and fixing it later. Imagine how boring it would be to watch an archery competition where the archer is allowed to remove and re-insert the arrow after taking their shot. – MonkeyZeus May 19 '21 at 12:39
  • If you're saying that your camera has the option to make these adjustments after taking the picture then I guess you're at an ethical crossroad. If the exif data doesn't reveal this edit then you're good as far as competition rules are concerned. If this feature is widely available on cameras then it's reasonable to expect that most other participants will use it as needed. In a perfect situation everyone would be required to use the same exact equipment. – MonkeyZeus May 19 '21 at 12:49
  • If you disagree with my sentiments then I would love to hear how you would choose to regulate such a competition. – MonkeyZeus May 19 '21 at 12:51
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    It may be interesting to note that I had a project to see what we could extract from EXIF metadata. The result? Not much—many sources don’t bother to write any to begin with, a lot of processing software doesn’t bother to preserve it, and even when these things do, they’re done only kinda-sorta to any kind of standard, so good luck guessing what it means. Plus all of it is extremely prone to corruption. We abandoned that project. – KRyan May 20 '21 at 03:59
  • @MonkeyZeus It's not "widely" available on most cameras, but there are more than a few that offer in-camera raw editing and conversion to JPEG. For example, Canon's 1-Series, later 5-Series, and the last of the two cameras in the 7-Series (EF) include the capability. The x0D, x00D, and x000D series (which are the vast majority of the total number of EF/EF-S mount bodies Canon has sold over the years) do not offer it. – Michael C Jul 12 '21 at 16:10
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Submissions for these types of contests, and even some news agencies, require photos to be submitted as straight-from-camera JPEG files, not as exports of RAW images. This is usually enough to satisfy the submission requirements.

Most of the time, people trying to skirt such rules by faking EXIF data, tend to make a mistake somewhere, that is a tell-tale clue of manipulation. Often those clues are discrepancies in the various time/date stamps in the EXIF data and/or the filesystem metadata. Sometimes there are extra EXIF fields modified or added by their manipulation tool, that they weren't aware of.

To the point that even straight-out-of-camera JPEGs are manipulated by "decisions" in the camera's RAW processing algorithms, that ignores intent: a CPU or camera has no intent or goal; it is merely a complex machine following its programming. Only a person has intent, so implicit in the requirements for your contest are "no intentional edits" to be made.

But in a strict sense, there is no technical way to be absolutely sure an image wasn't manipulated. Because at some point along the way, we're out of the realm of technology, and into the realm of trust.

For smaller competitions, the stakes aren't worth it to ensure a high degree of trust. That is, the contest generally trusts (but attempts to verify) submissions were made according to the rules. But they're not going to employ expensive time-consuming techniques to try to disprove the trust. They will use simple, point-and-click -style tools to pass a "good enough" test. That's all they can do. As the stakes of the contest increase (such as substantial monetary rewards, etc.), the techniques and tools to spot alterations can be more sophisticated and more expensive.

For some news agencies, they actually extend the trust even quicker that submitters don't alter their images. This is because the photojournalists have a reputation to stake (as do the news agencies themselves), coupled with contractual submission agreements. Those agreements are backed with the possibility of termination or severance of relationship if undisclosed manipulations were made. See What are the editing restrictions for sports/photo journalism?

For other purposes where image integrity is absolutely important, knowing that technological means cannot guarantee image integrity, the trust is placed in processes and procedures ensuring the chain of custody, file handling, etc., is maintained, so that the opportunity to alter the image is reduced or eliminated. Things such as file checksumming, append-only data stores (i.e., blockchains), can certainly help, but they are not guaranteed to ensure unmanipulated data if there is no knowledge of the chain of custody of the data before those tools were employed.

scottbb
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  • "append-only data stores (i.e., blockchains)" you mean e.g. (example) not i.e. (that is). – Nobody May 18 '21 at 09:12
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    There is no reason to put "decisions" in scare-quotes when talking about in-camera JPEG rendering; every camera more expensive than a child's toy will have a number of settings which explicitly allow the photographer to affect that rendering process. Changing the white balance on a dial on the camera is exactly equivalent to changing it in a post-processing program like Lightroom. – IMSoP May 18 '21 at 09:29
  • @IMSoP Disagreed, because the camera is not making "decisions", it's a human making "decisions" to set the dial. The camera has no intention or will of its own. It is merely following a script, a set of rules. It is making no artistic judgement or preferences. Those are human choices, intentions. – scottbb May 18 '21 at 13:55
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    @scottbb No, you missed my point, I'm saying that even straight from the camera the human has made decisions about how to "develop" the raw sensor data into an image, so asking for an image with "no intentional edits" is meaningless. An image with white balance tweaked in Lightroom is significantly less "manipulated" than one where the photographer selected "simulate tilt shift" in the camera's menu, but both images have been manipulated by a computer based on the artistic decisions of a human. – IMSoP May 18 '21 at 14:22
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    @IMSoP For the most part I don't disagree with you then. But there is a meaningful distinction between intentionally editing after seeing what was taken, vs. deciding to accept what is produced before pressing the shutter button. Yes, the "I'm taking what I get regardless" is pretty well deliberate and informed by settings beforehand. But there's still a difference between the two, and that difference is what the spirit of such contests are about. – scottbb May 18 '21 at 14:32
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An additional thing to take into account is the code that creates the jpeg has an identifiable signature. The way Photoshop writes the jpeg will be different than the way Corel will write it. Exiftool, for example, has a JPEGDigest tag, which is defined as:

an MD5 digest of the JPEG quantization tables is combined with the component sub-sampling values to generate the value of this tag. The result is compared to known values in an attempt to deduce the originating software based only on the JPEG image data.

JpegSnoop goes into more details on it's Identifying Edited Photos.

StarGeek
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By looking at the exif data, it's possible to know if the image has been developed in lightroom, or comes straight form the camera as a jpeg. This can also be faked.

Now, if you take a picture, then look at the result on the camera LCD, you can check the exposure, histogram, white balance, etc. They you can adjust settings and take another picture. Technically, it is not edited, but the result would be the same as if it was. You could also use bracketing.

I think this rule somewhat gives an advantage to photos of subjects that won't go away, like landscape or portraits, since these subjects allow several attempts. If the intent of the rule was to make the photos more spontaneous and candid, it may achieve the opposite.

bobflux
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