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This question already has an answer here:

How do I know my image is altered or not?
Is there a tool or a method to know all the related stuff to the photo from Metadata or something else?

P.S:
Sometimes using a Hex Editor like Hiew will give you more info than Photoshop or exiv2 tool.

EDIT:
Why I can See EXTA info with the hex editor like Camera type or Author and can not see them with exiff tools ?

marked as duplicate by TFuto, mattdm, Dan Wolfgang, Philip Kendall, John Cavan Sep 10 '14 at 14:01

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Welcome to photo.stackexchange.com! Your question seems to be addressing several topics, and in general, they seem to be rather broad. E.g. an image can be simply binary-compared to the original if you have two versions. And what do you mean by "related stuff"? If you are trying to extract EXIF-related data, exiftool is your friend. But in general, please provide more information or your question will get quickly flagged for removal. – TFuto Sep 10 '14 at 10:14
  • The title change is quite a different question. Is "How do I know my image is altered or not?" meant to still be part of it? (These are unrelated.) – mattdm Sep 10 '14 at 12:42
  • @TFuto: maybe titles are different but the goal is the same. – M. Abdelhafid Sep 10 '14 at 13:24
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    Okay. In that case: the goal is still unclear. The metadata, by itself, will not tell you if the image has been altered. (It can't. And it can be altered itself, so even if it could... it couldn't.) – mattdm Sep 10 '14 at 13:36
  • As commented, the goal is determine alteration and it's not really what the title change indicated. In that event, it's a duplicate. – John Cavan Sep 10 '14 at 14:02
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There is often proprietary information in the EXIF maker notes that many metadata utilities can not read. ExifTool (http://exiftool.com) is one of the better utilities, but it still can not read everything. Use the -u option to also extract some of the unknown information.

Regarding your question about detecting an altered image: It is often possible to tell if image metadata has been altered, but is it never possible to prove that it was not. One good way to tell if the metadata may have been altered is to look at the binary structure with the ExifTool -htmlDump feature, and to compare this to a known original image from the camera. Often, metadata editors will structure the EXIF differently from the camera, this may show up in the -htmlDump output.

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Full applications may not show all the metadata in a image. Reasons may include that particular information is not relevant to the app's purpose, it was not designed to handle some metadata tags, and displaying everything would be too much clutter.

Surely none of this is surprising!?

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It is not clear to me what you mean with "exiff tools", as you talk previously about photoshop and exiv2, while there is a tool called "exif tool". the latter would probably be the most comprehensive, for viewing and editing.

Camera Makers include so called "maker notes" in the EXIF header, which are in a proprietary, undocumented format. Most tools won't be able to interpret (all) of these data, that's why you might see more with a hex editor or the manufacturers own software.

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