Guidelines for the preparation of figures

We’ve created a checklist to help you when submitting figures for your article.

Although we encourage you to submit the highest quality figures possible, we consider a wide variety of formats, sizes, and resolutions, whether for submission and peer review, or after your article has been accepted. We’ve created a table that explains which formats are preferred.

It’s vital that you are aware of how to prepare and submit figures in line with high standards of ethical best practice. We’ve created guidance to help you.

Checklist for submitting figures

• Are all figures included in your submission as separate files or in a single PDF/Word document/LaTeX suite? Separate, original files in their original file format are best.
• Do all figures have an accompanying legend that describes the content and explains any abbreviations or symbols? Include your figure legends as a separate section in your main text file.
• Are all figures cited in the main text of your article? Ensure all figures are numbered in the order in which they appear.
• Are all words or symbols in your figures large enough for easy reading by your audience? Closely follow the preferred resolution guidelines for best presentation.
• Are all figures saved in an acceptable file type? Use the preferred file types for best image quality. If in doubt, submit a PDF for initial review.
• Is each individual figure file less than 10 MB? Remove any unnecessary white space around figures to reduce the file size.
• Were figures created at a size between 80mm and 180mm in width, and between 300dpi and 600dpi? Higher quality figures are more useful to readers and look better.
• Are all figure files named with their appropriate figure number? Use only the figure number in the file name.

How to prepare your figures

Description	Example	Preferred format for submission	Acceptable format for submission	Preferred format after your article has been accepted
File type
Line art: Includes graphs, flowcharts, diagrams, scatter plots, and other text-based figures that are not tables. Important! If a figure includes both line art and images, follow guidelines for line art		EPS,PDF	Any standard file type. When in doubt, submit a PDF	Any standard file type
Images: Images include photographs, drawings, imaging system outputs (such as MRIs or ultrasound), and other graphical representations		EPS, PNG, TIFF	Any standard file type. When in doubt, submit a PDF	Any standard file type
Resolution
Line art: Resolution for line art needs to be higher than for images because each individual line must be more precisely rendered. Tip! Larger fonts make for easier reading		600 dpi	Any, as long as it is legible to the editor and peer reviewers	600 dpi
Images: Although many web-based images often appear at very low resolutions, readers will benefit most from your research if your images offer high-resolution detail		300 dpi	Any, as long as it is legible to the editor and peer reviewers	300 dpi
Image size
Small: Used for small line art and images that will occupy one-quarter of the page		At least 80mm canvas size or 1800 pixels wide	Any, as long as it is legible to the editor and peer reviewers	At least 80mm canvas size or 1800 pixels wide. Smaller or larger images will be modified during composition, which may reduce quality
Large: Used for larger line art and images that occupy a half-page or an entire page. Carefully consider the minimum space necessary for each figure		At least 80mm canvas size or 1800 pixels wide	Any, as long as it is legible to the editor and peer reviewers	At least 80mm canvas size or 1800 pixels wide. Smaller or larger images will be modified during composition, which may reduce quality
File size
Individual files: Individual figures may load slowly or time-out slower systems if they are too large		Less than 10 MB each	Any, but large files may be difficult for editors and reviewers	Any, but large files may be harder to transfer
Complete, zipped package of article files: Submission systems often limit total file size		Less than 500 MB total	Any, but large files may be difficult for editors and reviewers	Any, but large files may be harder to transfer
File name
To facilitate ease of review, name figure files only with the word ‘Figure’ and the appropriate number	Figure_1.tif	One figure per file	All figures in a single PDF, Word document, or as a part of a LaTeX submission	One figure per file
Legends and labelling
Use Arabic numerals, follow the order in which the figures appear in the manuscript, and explain any abbreviations or symbols that appear in the figure	Figure 1. A good figure legend succinctly describes the content and enhances understanding with clear labels.	A separate ‘Figure legend’ section in the manuscript, after the references	Anywhere in the article, clearly indicating which figure it explains	Anywhere in the article, clearly indicating which figure it explains

Ethical guidelines

As stated in our Best Practice Guidelines on Research Integrity and Publishing Ethics, changes to images can create misleading results when research data are collected as images. It may, however, be legitimate and even necessary to edit images. Images are subject to screening, and journals will ask authors to declare where manipulations have been made. Authors may be asked to supply original images and should be able and ready to supply them on request. Failure by authors to address concerns adequately may lead to rejection. You should follow the guidance below when preparing your images:

• Specific features within an image should not be enhanced, obscured, removed, moved, or added.
• Adjustments to brightness or contrast are only acceptable if they apply equally across the entire image and are applied equally to controls, and as long as they do not obscure, eliminate, or misrepresent any information present in the information originally captured. Overexposure and high-contrast images should be avoided. If high contrast is required to visualize a certain band, then it should be declared in the legend, and the unmodified original image must be provided for comparison.
• Excessive manipulations, such as processing to emphasize one region in the image at the expense of others, are inappropriate, as is emphasizing experimental data relative to the control.
• Nonlinear adjustments or deleting portions of a recording must be disclosed in a figure legend.
• Authors are advised to store the original, unadjusted image data for 5 years following publication.
• The presence of artifacts in images, if any, should be mentioned and explained in the figure legend. ‘Artifacts’ includes features introduced while image capturing and processing but which are not a part of the real image.
• In cases where image processing is required for the interpretation of data, details of image processing, including the software and the enhancement technique used, must be declared in the Methods section of the article.
• Constructing figures from different gels, fields, exposures, and experimental series is discouraged. When this is necessary the component parts of composite images should be indicated by dividing lines clearly demarcated in the figure and described in the legend.
• Cropped images should be avoided for gels and blots. Wherever cropped images are shown in figures, a full scan of the entire original gel(s) must be submitted as part of the supplementary material. Gels and blots should not be dropped onto white or any other background.
• Control samples should be run on the same blot or gel for each experiment. Relevant controls must be included in each figure. Where control images are re-used for illustrative purposes, this must be declared in the figure legend.
• Source data should be submitted alongside any images that have been processed. All blots from the original materials should be marked with regard to the figure number, and those elements used should be highlighted in the original materials using a dotted line to encircle the relevant band(s).
• Micrographs should include scale bars, and the level of magnification should be provided. Method of sample preparation, details of stains used, information about the microscope, camera, and any image capturing or editing software used should be provided in the figure legend or the Methods section of the article. If any specific region is marked and magnified, then care should be taken to see that the features in the inset and the magnified panels match and are in the same orientation.
• Images obtained from published sources can be re-used with appropriate consent from the copyright owner and should be stated in the figure legend alongside the citation.
• Signed consent for publication is required from the patient or their guardian for photographs, X-rays, or scans of patients' body parts included as part of the manuscript. Any part of the image that reveals the patient’s identity, e.g. the patient’s name or ID number, should be blurred, masked or cropped out before submission.

Here are examples of the most frequent errors with images, and tips on how to avoid them.

Error	Example	Explanation and tips
Low Resolution		The image appears blurred or pixelated upon zooming in to around 150% magnification. TIP: Check image resolution immediately after capture. Export the final image file as a PDF and then convert it to TIFF to prevent loss of resolution. The final resolution of photographs should be a minimum of 300 dpi.
Image Orientation		The image in figure (b) is the flipped/rotated/inverted version of figure (a). TIP: Ensure that the images in sub-panels are correctly orientated. While magnifying an inset, the orientation should be kept the same. Do not flip or rotate the image.
Image Presentation		Two different images have been joined together and presented as one single image. TIP: Image grouping and splicing must be clearly stated in the figure legend. Clear demarcations must be provided for each image.
Mismatch of cellular sections		For the left panel, the enlarged section corresponds with the region enclosed within the black box; this is not true for the right panel. TIP: Ensure there is no mismatch between the original image and its magnified version.
Magnification panel mismatch		The 40X magnification panel doesn't correspond to the features shown in the 20X magnification panel. TIP: Ensure there is no mismatch between the higher magnification image and its corresponding lower magnification image. The same field should be captured for both lower and higher magnification. If the field varies then this should be explained in the legend.