Nature 439, 891-892(23 February 2006) | doi:10.1038/439891b; Published online 22 February 2006

Not picture-perfect

Nature's new guidelines for digital images encourage openness about the way data are manipulated.

Researchers struggle to amass good data and present them in as clear a fashion as possible. But what do we mean by 'clear' when it comes to images? In days gone by, whether we liked it or not, data acquired at the bench were not much different from what was published. In a biomedical lab, for example, samples that had been radio-labelled and separated on a gel were recorded on X-ray film. Composite figures were assembled, with lettering carefully placed around the mounted film. If a control was forgotten or a gel was uneven, the graduate student or postdoc was sent back into the lab to get it right 'for publication'. If a speck of dust on the film obscured data in the original photograph, another picture was taken. Slicing films to rearrange the order of samples, or to splice in a control group that was actually part of another gel, was not common because it took almost as much skill to do that as to rerun the experiment.

It is doubtful that scientists were more angelic then than now. It is more likely that, when it came to image manipulation, they wouldn't because they couldn't. These constraints led to the accepted standards for publishing quality images: what you got is what you saw. It's not that researchers didn't aspire to perfection — to have obtained images worthy of the admiration of colleagues enhanced your prestige because it proclaimed technical mastery. But the numerous examples of slightly inadequate data continually reminded everyone just how difficult it was not only to perform the perfect experiment, but to acquire the perfect image.

Digital image acquisition and processing tools have removed the physical impediments to perfect images and laid bare the inadequacies of current training practices. Traditions for image handling were not passed down from one generation to the next because there weren't any traditions. Into this vacuum has crept 'beautification' — the digital manipulation of properly acquired data for the purpose of making a figure clearer, more perfect and more consistent with the best images yielded in such experiments. Removing dust from a digitized photo with the erasure tool, cropping bands from gels, and playing with fluorescence micrographs to enhance a particular effect are all attempts to show better results than were actually achieved in that run. In all these cases the data are legitimately acquired but then processed to yield an idealized image.

In Nature's view, beautification is a form of misrepresentation. Slightly dirty images reflect the real world. Accordingly — and after consulting with technical experts — the Nature family of journals has developed a concise guide to appropriate image handling (http://www.nature.com/nature/authors/submissions/images), which will soon be incorporated into Guides for Authors.

In short, any digital technique that isn't applied to the entire image is suspect and needs to be explicated to the reader in the Methods or Supplementary Information. Authors should detail the instrument settings and the software manipulation that was performed on figures in an additional table in Supplementary Information. The fewer manipulations, the easier it will be for authors, referees and readers. Any changes made to misrepresent the data in the original image (such as boosting the contrast to eliminate backgrounds, making a collage of cells in a micrograph to show more cells in a visual field, or removing possibly informative bands in narrowly cropped gels) are of course strictly off limits.

In short, any digital technique that isn't applied to the entire image is suspect and needs to be explicated to the reader.

We should conspire to end the fetish of the perfect image. Let's all get a little more 'real'. Nature is happy to work with others to aid the promulgation of image standards that we can all live with. The responsibilities of the institutes that train students, of the investigators who use their labour, and of the journals that publish the data can be better defined. Finding ways to regain our trust in scientific images is a goal on which we can all agree.

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