So someone emails you a picture of your husband swinging his arms around some other woman, what would you do? Would you immediately get enraged, call your husband and give him a piece of your mind? Or would you investigate the picture first? After all it could be a prank played on you by your best friend and may be not at the professional level, but these days almost everyone knows how to edit the pictures using Photoshop, GIMP or other alternatives. One way to examine the JPEG pictures for being edited is to use the freeware JPEGSnoop. This software can guess which camera was used for taking a picture and which software was used to edit it.
You can download the JPEGSnoop software from sourceForge website. It is a portable software, so it does not require any installation. You can launch JPEGSnoop, load a picture and it will go to work right away. It works only with JPEG pictures, therefore you cannot load any other type of pictures in it.
As soon as a picture is loaded, it starts to analyze the picture, matches the collected information with its own database and presents a long list of data to you. You can go through the whole data which contains the picture EXIF data, the model of camera used, the software used to edit the picture and other useful information. Or you can skip to the end where you can find the final assessment telling you whether the picture has been edited or not.
In case of a random picture taken by me using my Android smartphone camera, it gives the assessment as “Class 2 – Image has high probability of being processed/edited” even though it was not edited at all. I tried taking pictures using different quality settings, different ISO speeds and other variations, but it always shows the same message. On the other hand, for some pictures downloaded from the internet, it displays the assessment as “Class 1 – Image is processed/edited” because the picture was obviously edited using some image editing software.
Conclusion: JPEGSnoop can show you whether a picture has been edited and if it is edited, then which software was possibly used to edit it. This is useful when you come across pictures that you suspect to be fake but cannot say for sure.
You can download JPEGSnoop from http://sourceforge.net/projects/jpegsnoop/.