global human spaceflight infrastructurefrom which science can only benefit — an international Moon base being theobvious next step.Ian CrawfordSchool of Earth Sciences, Birkbeck College, Malet Street, London WC1E 7HX, UK

Illustration: databasepictures tell a true story Sir — Julio M. Ottino in his Commentary “Is a picture worth 1,000 words?” (Nature421, 474–476; 2003) divides images intotwo categories: those that convey data and those that illustrate scientific ideas. He defends the practice of image manipulation as sometimes being anecessary part of the process of discovery,yet expresses concern about the blurring of the line between fantasy and reality inscientific illustration.

It may be that the two categories are notthat distinct. The European Space Agency’sprogramme Innovative Technologies fromScience Fiction for Space Applicationsassumes that even the most fantasticillustrations may be a useful stimulus toscience. On the other hand, images thatpurport to convey factual data may convey something else entirely. Manyobservers, for example, were convincedthat they could see little human beings in the sperm images produced by thesixteenth-century microscopist Antoni van Leeuwenhoek, and they recorded this observation as fact, presumablyinfluenced by their beliefs.

Today, we can and should capture not just an image but informationdocumenting the process of image creationitself, from the original unmodified data to the final web-ready or journal-readyartwork. If questions arise about theinterpretation of an image, we need to beable to go back to the raw data or, if this isimpossible, at least to have a full record ofwhat was done to it, and why. For example,in performing video-enhanced contrastmicroscopy, one always subtracts a digitalbackground ‘mottle’ image from the livevideo stream to obtain the mottle-freevideo frames that are recorded, andviewers need to be informed thatbackground subtraction has been carriedout. Similar arguments relate to the pointspread functions used in preparing thedeconvolved fluorescence imagesmentioned in the article.

Of course, as in the days of pen-and-inkillustration, scientists should still considerthe purpose served by each image in theirpublications, and should make theseobjectives clear to their readers. Scientiststoday have the additional responsibility of

recording the processes by which imagesare created, so that these can be accuratelyreplicated. Currently, such information is usually held only in the laboratory from which the image came, if it isrecorded at all.

The BioImage Database Project(http://www.bioimage.org), part of ORIEL (Online Research InformationEnvironment for the Life Sciences;http://www.oriel.org), will be a searchabledatabase of multidimensional images ofbiological specimens. From its outset, wehave felt it essential to acquire not justhigh-quality source images, but also thevarious images derived from them, anddetailed metadata documenting theprocess of their creation. We believe thatthis approach addresses many of the issuesraised by Ottino, and should be far morewidely adopted.Chris Catton, David Shotton Image Bioinformatics Laboratory, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK

Illustration: images failto portray dynamic skies Sir — An example of the visual deceptionpractised by scientific illustrators seekinggreater impact — as described by Julio M.Ottino in his Commentary (Nature 421,474; 2003) — is the increasingly prevalentpractice of adding foreground stars andbackground galaxies to images generatedfrom numerical simulations of galacticcollisions. Examples appear in NationalGeographic 203, 2, 2003; and on the Gadget website at www.mpa-garching.mpg.de/gadget. Another is one of mysimulations, published unadulterated on the cover of Nature on 9 March 1989, which was later “improved” by the image-makers at NASA’s Space Telescope ScienceInstitute (http://hubblesite.org/newscenter/archive/2001/22/video/c) —without my consent.

Although one may agree thatsuperimposed stars and galaxies add a bitof visual interest to the blankness ofcyberspace, it is disturbing that theseadditions are entirely static. In reality,foreground stars hurtle past like snowflakesin a blizzard, and even background galaxieschange noticeably over the hundreds ofmillions of years that are represented in thecomputer simulations. Static foregroundstars and background galaxies underminethe basic idea of a dynamic Universe thatthese images and animations presumablyattempt to convey. Joshua E. Barnes Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA

Swift publication wouldreward good reviewersSir — I completely agree with T. Clausenand O. B. Nielsen, who say in Corres-pondence (Nature 421, 689; 2003) thatpeer-reviewing needs to be adequatelyrewarded for the system to work efficiently.However, their proposed remedies, such asmandatory inclusion of reviews in CVs, donot seem promising, not least because thisis already routinely done and does notseem to change the general picture.

While toiling on my considerablebacklog of manuscripts to review, I cameup with a scheme that might stand a better chance of improving the situation:diligent reviewing could be rewarded byspeeding up publication of the reviewer’sown research.

Currently, most of the prominentjournals impose a strict deadline (typicallybetween 7 and 14 days) on reviewers, yetthe level of compliance is dismally low, asany author waiting for longer than twomonths for reviews of a submittedmanuscript can testify.

My suggestion is that a researcher whomeets the deadline for a particular journalwith satisfactory reviews on, say, sixconsecutive occasions within a two-yearperiod is guaranteed by the journal that his or her next submission will be givenprivileged status and reviewed within that same deadline. If the journal’s editorcannot receive reviews of a privilegedsubmission before the deadline, thejournal would have to make a decisionbased on the other referees’ comments or, if none had been received, accept thepaper as it stands.

A possible variant is for journals thatreject many submissions without review to guarantee to review a privilegedsubmission (again, within the deadline).This is unlikely to burden these high-profile journals with piles of junk, becausean individual writing six or more usefulreviews for one of them within a limitedtime span is, by definition, a highlycompetent researcher.

Of course, a crucial aspect is the notionof a ‘useful’ review: to earn a privilegedsubmission, reviews would have to be ofhigh quality, as judged by the journal’seditors, rather than one-liners. I believethat such direct feedback between aresearcher’s own publications andreviewing activity could seriously improvethe peer-review system.

Feedback loops do wonders inbiological systems; they just might workfor science, too. Eugene V. Koonin National Center for Biotechnology Information,National Library of Medicine, National Institutes ofHealth, Bethesda, Maryland 20894, USA

correspondence

374 NATURE | VOL 422 | 27 MARCH 2003 | www.nature.com/nature© 2003 Nature Publishing Group