Photo authtication.

[george_bowers1]

I have an extremely unique digital photo that I would like to have

professionally analyzed to agree that it has not been edited. Before

I realized what I had, I erased it from my scan disc. My previous

post is related to this same photo. Does anyone know of a company

that performs this service?

 

Thanks for your help

[bobatkins]

Can't be done. There's no way to tell if a digital photo has been edited, the time and date changed, the file size changed or any other modifications made (assuming that any digital editing of the image is done properly).

 

Canon do have an image verification system, but it's HARDWARE based and the image needs to have been shot with a Canon DSLR which supports image verification and is used with the image verification accessory (DVK-E2)

 

So if you have a photograph of aliens, nobody is going to believe you, sorry!

[kelly_flanigan1]

Here is a quote from Kitty West's book in 1955; Guide to Retouching negatives and prints" :<BR><BR>><i>The goal of a retoucher, or better still, the guiding motto, should be: <b>retouching must be executed in such a manner that the picture never reveals or allows the observer to guess that the corrections were made.</b> Only then is the retoucher's artistry successful. </i><BR><BR><BR>These words apply to todays retouching too; mostly all done with Photoshop. Unless you have a hardware rig like Bob mentioned; you might never tell.

[mike_elek]

What do you mean, "I erased it from my scan disc." -- ??? What did you erase? The program or the image?

[gsbhasin]

Is it a spouse caught in a compromising position?

[mark_houlder2]

it depends what you mean by edited - if you mean the contents of the file changed in any at all (including resizing, converting to a different file format etc) then it's quite simple - for instance you could checksum it; but i presume you DON'T mean something so straightforward. in that case, other than looking for tell-tale tags left in the image file (some editors insert tags like "created by the GIMP © GNU Foundation" or whatever), which would be a bit of a 'schoolboy error' anyway, there's not much you can do that i know of.

[brian_ristuccia1]

There's no trivial way to do what you want. Even a watermarking or signing system like the one used in Canon's high end DSLR's cannot prevent or reliably detect doctored photos. In that case, one could still shoot a scene, retouch it, have a slide made of the retouched photo, project the slide, and shoot a second photo of the projection screen. The second shot will show as unmodified when checked with the camera vendor's software even though it's been doctored.

[arnold_theisen1]

I'm not sure whether this answers the question or not, but I recently scanned a group of slides and then edited them in Photoshop Elements 2. I could see distinct differences in the histogram between unedited scans and edited scans. After editing there are gaps in the histogram where pixels are missing. The original images have solid histograms with no gaps. Seems like this might be one way to tell if an image has been edited.

[bobatkins]

Only if it's been edited badly. If someone wants to edit an image so that the editing can't be detected, they won't make trival errors that result in such obvious changes as stretched histograms or additional data in the file headers.

[george_bowers1]

Thanks for all of your responses. I am not very photo edit savvy. Photos that I edit consist of basically changing contrast, brightness and cropping. Photo is not an alien, not a compromising position, but a photo that was taken with a resulting image that will never be duplicated by anyone. I will probably post it on e-bay in the upcoming months. Should get more than the grilled cheese sandwich. Maybe even more than the ghost and cane.

 

Thanks again for all of your responses.

[Sanford]

Let's see it!