Manipulated photos are hard to detect | Science| In-depth reporting on science and technology | DW | 19.07.2017
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Manipulated photos are hard to detect

British scientists have investigated how good people are at detecting altered images. The result? Sobering! Test yourself as to whether or not you can spot the changes.

Have you been hoodwinked by a faked photo at some point? If so, you are not alone.

Minimal changes in photos - a bit brighter here, a bit more focus there - or even unambiguous manipulation, like adding or removing certain objects, is becoming ever easier, thanks to digital tools.

And boy, are these tools used. People fib to make themselves a few inches thinner. Unfortunately, people also change pictures deliberately with malicious and deceptive intent.

The authenticity of images on the internet, social media, billboards, in magazines and even in newspapers is getting more difficult to judge.

Detecting phony photos

Scientist Sophie Nightingale of the British University of Warwick, together with colleagues, examined how good people are at detecting alterations to photos.

For the study , 659 subjects completed an online test. Every participant got to see 10 photos with different motifs - five unaltered and five manipulated ones.

The manipulated photos were altered digitally in different ways: There were physically plausible manipulations, like the addition or subtraction of objects (for example, a waste bin) and use of the airbrush tool (for instance, to remove wrinkles and circles under the eyes).

Scientists also implemented so-called implausible manipulations. These include changes in geometry (like an oblique boat mast) or shadows (different angles).

Of the five manipulated photos every subject got to see, four contained one of the named changes, and one image had all at once.


"We have shown that people's ability to detect manipulated photos of real-world scenes is extremely limited," the study's lead author Nightingale summed up. About a third of the altered images were not detected by test subjects.

Of the unchanged originals, 42 percent were mistakenly identified as manipulated - meaning that success rate wasn't far from the 50 percent wild guessing would bring.

Yet the study didn't provide a clear trend on detection of the implausible changes - such as shadows at unusual angles - versus plausible manipulations, like removing sweat from a face.

As a possible reason for this, the authors cite other studies showing how our brains ignore minor errors in logic as long as the overall image is close enough to people's expectations.

"Considering the prevalence of manipulated images in the media, on social networking sites and in other domains, our findings warrant concern about the extent to which people may be frequently fooled in their daily lives," Nightingale concluded from her study.

Did you click through our picture gallery above to do part of the test on your own? Did you detect the manipulations?

You can also take the original test by the British scientists.

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