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Illustrations and figures

General guidelines | File format | Figure types

Line drawings and diagrams

Information represented in diagrammatic form is best submitted in a vector format as this allows a better reproduction of line and text elements, especially when printed.

  • Supported vector file formats are PDF, EPS, Microsoft Word (DOC) and PowerPoint (PPT)
  • Most graphics/statistical software can save PDF and EPS files. Please refer to the software documentation.
  • On Mac OS X, the operating system also allows you to print to a PDF file from any application.
  • On Windows, in order to print to PDF, users need either the full version of Adobe Acrobat or a free alternative, for example: doPDF, PDFcreator, or primoPDF.
  • Where a diagram contains graphical or photographic elements, these should be included within the vector file.
  • If your figure contains a key, please include this within the figure. This will ensure accurate reproduction of colour and/or hatching between figure and explanation.

In the final PDF, figures will appear as either single (85mm) or double column (176mm). Please ensure that, when scaled to the appropriate width:

  • Lines are at least 0.5 pt in width
  • Label text is sized to ensure legibility (not smaller than 8pt)
  • Images have a resolution of at least 300 dpi

Charts and graphs

Charts and graphs are best submitted as vector figures, as these permits a sharper reproduction of line and text elements.

  • Supported vector file formats are PDF, EPS, Microsoft Word (DOC) and PowerPoint (PPT)
  • When submitting a graph or chart produced in Microsoft Excel, it is recommend to either save the chart as a PDF or copy the chart into a new Microsoft Word file and save according to the instructions for DOC files.
  • If a figure contains a key, it should be included within the figure. This will ensure accurate reproduction of colour and hatching between figure and explanation.
  • Figure titles should not be included within the image file.
  • Authors should avoid using hatching or patterns and instead use shading or colors as these are more suitable for high-resolution printing.
  • Axis labels must be legible at final figure sizes.

Large plot graphs

Complex plot graphs (such as those that result from Systems Biology visualizations) may have a very large file size and should be rasterized (converted from vector to bitmap format). This can be done using a graphics program such as Adobe Photoshop, before the submission to BioMed Central in order to reduce the file size greatly.

Photographs/scans/medical x-rays

Where possible, the original raw or JPEG files of photographs for gels or microscopy pictures (untreated, unaltered images) should be included.

Figures that contain only photographic data are best submitted in a bitmap format such as JPEG, TIFF or PNG.

  • Many photographic images are captured as JPEG images, in which case they should be submitted as JPEGs. When capturing the image, be sure to use the maximum quality setting for JPEG quality, to avoid visible artefacts.
  • The maximum effective resolution and quality of an image is determined when the original image is created (when the photograph is taken in the case of digital photography, or when an image is scanned). Increasing the resolution subsequent to this, whilst maintaining the same image size, is not advisable as it does not improve the quality of the image: the effective resolution remains the same.
  • Similarly, resaving with higher quality JPEG compression settings will not compensate if the image was originally captured with low quality JPEG compression.
  • Final resolution of photographs should be a minimum of 300 dpi, when scaled to single (85mm) or double column (176mm) width.
  • Photographs should be provided with a scale bar if appropriate.

If the photograph needs to include text, arrows or other explanatory elements, these can be added in a graphics program, or these elements can be overlaid in Microsoft Word or PowerPoint, and the figure submitted in that format instead.

  • Copy the photographic image into a new file in the chosen editing program.
  • Add all explanatory elements.
  • Once the image has been edited, save and submit the final file as EPS, PDF, DOC or PPT depending on the program that was used to add the text. Do not reconvert to TIFF, JPEG or PNG as this will result in loss of quality.

If photographs, X-rays or scans of patients' body parts are included as part of the manuscript, written and signed consent of the patient (or the patient's guardian, where under 18) must be sent or faxed to the Editors, and indicated in the manuscript.

Medical X-rays

Medical X-rays should be treated like photographs with the following additional guideline.

  • If it is necessary to obscure a patient identity in a photograph or X-ray, please do not use an overlay. Instead, edit the image itself using a graphics program, such as Adobe Photoshop.

Micrographs

Micrographs should be treated like photographs with the following additional guidelines.

  • Details of the magnification should be given.
  • Details of any stains used and the method of preparation of the sample should be given in the figure legend or in the Methods section.
  • Detailed information about the microscope used should be included in the figure legend or in the Methods section.
  • The type of camera, photographic software and details of any subsequent image manipulation should be given in the article text.

Screenshots

  • Screenshots are best saved as TIFF or PNG. Avoid JPEG as the compression will needlessly reduce the quality of the screenshot image.
  • Screenshots should be submitted at the same resolution at which they are captured (e.g. 1024x768) - there is no benefit to resaving them at a higher resolution.
  • Similarly, do not convert screenshots to EPS format as this result in a larger file size with no increase in quality.

Genetic information and sequence alignments

Figures that present either amino-acid or nucleotide sequences should be treated like line drawings and diagrams. In the case of large, multiple sequence alignments additional care should be taken to ensure legibility of text.

  • Courier is the preferred monospace font.
  • Ensure that all text is legible at BioMed Central's standard figure widths.
  • Figures should not exceed one page in size.
  • If all information cannot be presented legibly in a single figure, please submit this data as an additional file.

3D atomic structures

Figures that contain stereoscopic images such as protein structures should be prepared according to the following guidelines.

  • Figures should be prepared so that the center of each stereo pair is separated by 60 mm or less.
  • Figures should be accompanied by details of the necessary distance between the stereo pairs.
  • Images should be submitted at the size they should appear in the final print version.

Chemical reaction schemes

Chemical reaction scheme, unlike other figures, should be included within the text and given their own sequential numbering.

  • Schemes should ideally fill a single column width (85 mm).
  • If necessary, sparing use may be made of double column schemes (176 mm).
  • Captions and atom labels should use a sans serif font (such as Arial or Helvetica) at 8 pt.
  • Schemes should be accompanied by a separate legend.
  • Recommended file formats - CDX (ChemDraw), TGF (Isis/Draw).

Electrophoretic gels and blots

Each gel and blot included in a figure or additional data file should display appropriate positive and negative controls in addition to molecular size markers and loading controls. Gel or blot images must not be electronically enhanced or manipulated. Any adjustments have to ensure that the final image is still a true representation of the original data.

Linear adjustment of the color, contrast or brightness are permitted, but they must be applied to the entire image, not just parts of it. If gel or blots images have been cropped in order to improve the clarity of a figure, the cropping must be explained in the figure legend; any important bands must be included in the cropped figure. The complete gels and blots should be provided as additional data files and referred to from the legend of the corresponding figure in the main text. If lanes are displayed together in an image that were not adjacent in the original gel, the lanes must be separated clearly by lines and a note must be added to the figure legend. If previously characterized antibodies were used, a reference must be included in the article. If less well known reagents were used, antibody specificity and its reactivity in the actual assay should be included in the article.

If quantitative comparisons between samples shown on different gels or blots have to be made, this must be made explicit in the figure legends.