How to detect if changes were made to JPG file


I need a help of Adobe Photoshop guru who is able to inspect JPG file using all available tools in Photoshop and determine if there were any changes made to the originally generated and saved document in JPG format. I agree to pay for it if required.

Thank you in advance
Sydney NSW Australia

Just to clarify…

You have two separate photos and want to know if one has been altered by comparing the original to the other one? Right? Or do you just have one jpeg that you want someone to look at to see if it’s been retouched, faked or whatever?

For what it’s worth, in case it matters to what you’re after, jpeg is a lossy compression algorithm, which means that data of lesser importance is thrown away each time the photo is saved. In other words, each time the file is opened and re-saved (not simply closed but re-saved) all the pixels get juggled around, reconfigured and changed. This makes it more difficult to detect tampering since a jpeg file’s pixel data is never identical to the original — there are always visible compression artifacts.

Do you have the original available? If yes, it’s easy to see the differences. If not, one can still do some forensic analysis. Typical mistakes include copy pasting elements, or textures, and getting shadows or colors slightly wrong in the modified area.

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