How to spot problematic pictures in a publication? A few professors from the National Taiwan University were caught manipulating experimental data in their publications on several prestigious journals this year. They were accused of using the same image in different experiments, and the papers were either retracted by the authors, or removed by the journals.

This kind of plagiarism is not very rare in biology. What are some key points to spot plagiarized scientific pictures?
i once saw a presentation by a journal editor about what they do to check on modified, altered data. 

as you can guess, they ask for the raw data, and check imagies with photoshop. 

a very easy way to spot altered pictures is to blow up contrast and brightness, which tends to highlights cropped and modified areas.

obviously people are getting smarter at that too, but if the goal is to deceive, i think at some point it will be difficult to tell what's fake and what's not.