Artists can freely manipulate images at will, but there are very strict limitations on "scientific" data. scientific misconduct
Photo manipulation

Compared to other forms of scientific misconduct, image fraud (manipulation of images to distort their meaning) is of particular interest since it can frequently be detected by external parties. In 2006, the Journal of Cell Biology gained publicity for instituting tests to detect photo manipulation in papers that were being considered for publication.[23] This was in response to the increased usage of programs such as Adobe Photoshop by scientists, which facilitate photo manipulation. Since then more publishers, including the Nature Publishing Group, have instituted similar tests and require authors to minimize and specify the extent of photo manipulation when a manuscript is submitted for publication. However, there is little evidence to indicate that such tests are applied rigorously. One Nature paper published in 2009[24] has subsequently been reported to contain around 20 separate instances[25] of image fraud.

Although the type of manipulation that is allowed can depend greatly on the type of experiment that is presented and also differ from one journal to another, in general the following manipulations are not allowed:[citation needed]

splicing together different images to represent a single experiment
changing brightness and contrast of only a part of the image
any change that conceals information, even when it is considered to be aspecific, which includes:
changing brightness and contrast to leave only the most intense signal
using clone tools to hide information
showing only a very small part of the photograph so that additional information is not visible

Image manipulations are typically done on visually repetitive images such as those of western blots, histologies or data visualisations like graphs.

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