Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I'm not really sure if this question belongs here, however I didn't find it fitting well into photography nor stackapps.

I'm looking for a software I've seen some long time ago on Discovery channel. There was a series about some pictures found on Internet. Presenter was analyzing these images to proof whether they were real or not. I can recall analysis of pictures like:

  • Videos with some really incredible basketball tricks and shots:

    enter image description here

  • this video

As far as I can remember, he was using this software on Mac OS X system. I remember one feature he frequently used: ability to analyze light incident angle.

I would also love suggestions on similar apps (open-source ones preferably, but other are also welcome).

share|improve this question

closed as off-topic by random Jun 3 at 17:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions seeking product, service, or learning material recommendations are off-topic because they become outdated quickly and attract opinion-based answers. Instead, describe your situation and the specific problem you're trying to solve. Share your research. Here are a few suggestions on how to properly ask this type of question." – random
If this question can be reworded to fit the rules in the help center, please edit the question.

add comment

1 Answer

up vote 2 down vote accepted

There's one neat trick that you can do in almost any image editing software (I used Photoshop). I've read about an automated implementation in a paper once, but I forgot where I found it.

For an interesting read, check this: H.T. Sencar and N. Memon - Overview of State-of-the-Art in Image Forensics

Copying and pasting from different (JPEG) sources, rescaling and then re-saving the file in JPEG (but also lossless compression) often results in visible differences between block artefacts. This is no guarantee that an image was faked, but in many cases you can identify it that way. Go ahead and change the midtones:

enter image description here

Then you are likely to see these differences:

enter image description here enter image description here

share|improve this answer
Won't that only work if both the original image and the final doctored image are jpegs? –  BlueRaja May 8 '11 at 19:19
In that case, at least the sources would need to be JPEGs. But most of available photographs are in JPEG (and not in PNG or TIFF) anyway I guess. –  slhck May 8 '11 at 19:22
add comment

Not the answer you're looking for? Browse other questions tagged or ask your own question.