artwork guide

The aim of this guide is to help you prepare your electronic artwork for submission to IUCr journals. By following the recommendations in this guide, you will be helping us to achieve the highest possible standards of reproduction.
 
  1. General points to consider
  2. Preferred file formats
  3. Figure sizing
  4. Composite images
  5. Fonts, labelling
  6. Number formats
  7. Colour
  8. Cropping
  9. Notes on particular types of figures
  10. General guide to digital images
  11. Checklist
  12. Useful resources
  13. FAQs

1. General points to consider

All figures should be submitted electronically via the submission system. Figures should be numbered sequentially in the order in which they are referred to in the text. Captions to figures should be provided separately in the manuscript file. Please submit one file per figure.

Please aim to keep lettering on figures to a minimum, and ensure you use SI units (e.g. K) throughout.

Only those figures that are necessary to illustrate the techniques or results described will be published; any others will be deposited.

For any figures that have been published previously, please ensure you obtain permission from the copyright holder prior to submitting your article to us. Please also forward a copy of the permission letter to the IUCr.


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2. Preferred file formats


The IUCr recommends that only the following file formats are used for electronic artwork submission:
  • EPS (Encapsulated PostScript, .eps), PS (PostScript, .ps)
  • TIFF (Tagged Image File Format, .tif)
  • HPGL (Hewlett Packard Graphics Language, .hpg)
We recommend that you do not use the following file formats, because they may result in lower standards of reproduction:
  • JPEG (Joint Photographic Expert Group Image File, .jpg)
  • GIF (Graphic Image File, .gif)
  • PDF (Portable Document File, .pdf)
  • MS Office (Word, Excel, PowerPoint) (.doc, .rtf, .xls, .ppt)

EPS, PS (resolution independent unless there is an embedded bitmap/halftone)

Line weights should be between 0.35 and 1.5pt at final size. Please ensure that fonts are embedded. For embedded images, please follow the guidelines for TIFF below.

TIFF

Colour images should have a resolution of at least 400 d.p.i. (dots per inch) at final size.

Monochrome images (black line art on a white background) and greyscale images should have a minimum resolution of 600 d.p.i.

TIFF files should generally be compressed. TIFF supports several lossless compression schemes (such as LZW and zip) ensuring that file sizes are kept to a minimum for easy file transfer. Compression schemes that are lossy (such as JPEG compression) should be avoided.

HPGL (resolution independent)

This is a resolution-independent format, used mainly for simple plots such as packing and ellipsoid plots.

The following two figures demonstrate the standard of final reproduction achieved from different resolutions and file formats.

Compare the EPS file (left) with the TIFF files (centre) and the JPEG file (right). The EPS and 600 d.p.i. TIFF files are suitable for printing in the journal, whereas the lower resolution TIFF and JPEG files are not. The JPEG also shows `lossiness' (i.e. loss of image data).

Only the 600 d.p.i TIFF file (left) will produce a satisfactory result when printed; the other two files are too low resolution.

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3. Figure sizing

A journal page has a two-column design, and most figures will be sized to fit a single-column width (8.85 cm) when published. In exceptional circumstances, figures will be sized to fit either part-page width (12 cm) or full-page width (18 cm).

Submitted artwork should be single-column width or larger (at the resolutions given in Section 2).


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4. Composite images

Where a figure is made up of several parts, please provide a single composite figure with the individual parts labelled (a), (b), (c) etc. Vertical and horizontal arrangements are acceptable. Please consider the overall width and height of a journal page (approximately 18 x 24 cm) before laying out a composite figure. Composite figures should be no larger than one journal page; if more space is needed, please create a new figure.

The following illustration shows a possible way of combining three related figures as one, with the individual parts arranged vertically.

Please prepare and submit one combined figure (right) rather than three individual figures (left).


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5. Fonts, labelling

Please use only the following standard fonts in your artwork:

  • Arial
  • Courier
  • Helvetica
  • Symbol
  • Times or Times New Roman

Any non-standard fonts will be converted during the production process, which may lead to problems such as missing symbols or overlapping characters.

Labelling should generally be roman (upright) and consistent with the text of your article. At the final published size, the labelling on the figure should be approximately 8pt.


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6. Number formats

Use scientific (exponential) notation where appropriate. Do not use E notation e.g. 6.28E+08 should be written as 6.28 × 108. Where scientific notation is used for data labels in figures, please put the multiplier in the axis label and not next to the interval (tick) marks, as this improves the clarity of presentation. See the example below.

Left: a clearly presented figure, with the axis multiplier included in the axis label. Right: interval (tick) marks labelled unclearly, E notation used when it should not be, and multipliers next to interval (tick) marks.

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7. Colour

7.1. Use of colour in figures

As colour printing is very expensive, please only use colour in your figures where absolutely necessary. Colour figures may be converted to greyscale for print publication if it is judged that colour reproduction is not strictly necessary. Even if your article is published in colour, please bear in mind that it may be photocopied or printed on a black and white printer. You may also wish to consider how your figures may look to someone who is colourblind, and there are useful tools available for this at http://jfly.iam.u-tokyo.ac.jp/html/color_blind/ and http://colorfilter.wickline.org. Figure captions too should be colour independent, i.e. they should not mention specific colours used for differentiating parts of a figure.

The following figure shows a colour bar chart and its greyscale equivalent. In the top half of the figure, the colours chosen do not appear distinct when the figure is converted to greyscale. To help the reader distinguish between the bars, either choose a different set of colours (lower half of figure) or add appropriate labelling.

The colours used in the colour bar chart (top left) do not appear distinct when converted to greyscale (top right). A more appropriate choice of colours for conversion to greyscale is shown in the lower-left bar chart.


It is important that you choose colours that will display clearly in greyscale. Light yellow, light green and light blue in particular display poorly in greyscale. The figure below illustrates how light yellow can virtually disappear in greyscale.

This figure shows how light yellow virtually disappears in greyscale.


Please also consider using different-shaped symbols as well as, or instead of, different colours to distinguish between different sets of data. In the following example, the symbol in red is also a different shape to the black symbol, which makes it distinct in both colour and greyscale reproduction.


As the red-coloured symbol in the colour figure (left) is a different shape to the black symbol, it is still distinct when converted to greyscale (right).

7.2. Colour spaces

For best colour reproduction, you need to take account of the colour space that you are using to create your diagram and the colour space that will be used during production of the journal.

RGB stands for Red Green and Blue, which refers to the red, green and blue pixels that are used to display colours on a computer monitor. The four-colour printing process, however, uses cyan, magenta, yellow and black (CMYK) inks.

The CMYK colour space contains a smaller range of colours than RGB, and conversion of RGB to CMYK often has an effect on the colours in the final image. If accurate reproduction of your colour image in print is important, then please supply the file in CMYK format.

The following figure illustrates the difference between the two colour spaces, RGB and CMYK.


A comparison of the RGB and CMYK colour spaces, demonstrating the smaller range of colours available in the CMYK colour space.

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8. Cropping

Images should be cropped to remove any extraneous white space around the area of interest. Please do not draw a box around figures. In addition, images should not include a description of the figure, e.g. Fig. 1, or the figure caption.

An example of how a figure should be cropped before submission. The red border is the area that should be cropped (encompassing the box around the figure, the `Figure 1' label, and extraneous white space around the figure).

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9. Notes on particular types of figures

9.1. Chemical schemes

Chemical schemes should be complete, showing all species present in the structure, including counter-ions and solvent molecules in their correct proportions. Charges on ionic species should be included. The relative or absolute stereochemistry should be shown and should be consistent with the ellipsoid plot. Hydrogen bonding should not normally be indicated.

As a guide to the final scheme size, benzene rings should generally have a width of 5-8 mm on the final version (schemes will be sized to fit a single-column width, i.e. 8.85 cm). Labelling should be roman and approximately 8pt. Compound labels, e.g. (I), (II) etc., should be shown under the relevant structures. Avoid the use of colour, and arrange the scheme to take the least amount of vertical space. See the following example:


An example of a suitably drawn scheme.

For IUPAC recommendations on graphical representation standards for chemical schemes, click here.

9.2. Ellipsoid plots

Ellipsoid plots should generally be provided on a white background. Atom-site labels should not contain parentheses [e.g. C1 and not C(1)] and should match labels used in the atom-site lists and text. The labels should not overlap or touch ellipsoids or bonds.

As a guide to the final figure size, an in-plane carbon–carbon bond should generally measure about 1.0-1.5 cm on the final version (ellipsoid plots will usually be sized to fit a single-column width). Labelling should be roman and approximately 8pt. The ellipsoid probability should be stated in the figure caption.


Ellipsoid plot.

9.3. Packing diagrams

Packing diagrams should show the cell-axis directions (labelled a, b, c) and the cell origin (labelled O), but should normally exclude H-atom sites unless these are involved in hydrogen bonding.


Packing diagram.

9.4. Stereoviews

Please submit left and right views as a single figure. Atom labelling should be on both left and right views in stereo perspective.


Please submit one single figure rather than left and right views as separate files.

9.5. Enhanced figures

IUCr journals offer authors the chance to prepare enhanced figures (interactive visualizations of crystal and molecular structures). More information on enhanced figures can be found by clicking here.


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10. Digital manipulation of images

Images submitted with manuscripts should correctly represent the original data. We encourage authors to make only minimal alterations to their images using digital graphics programs (for example, to add labelling).


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11. Checklist

  • Artwork files are in the correct format – EPS, PS, TIFF, HPGL
  • Images are of sufficiently high resolution (at least 400 d.p.i. for colour images, 600 d.p.i. for monochrome and greyscale images)
  • Images are an appropriate size
  • Lettering on images is in a standard font, and does not vary too much in size
  • Colour has been used only where absolutely necessary
  • CMYK colour if accurate colour reproduction is essential
  • Colour figures will display satisfactorily when greyscale
  • Copyright permission has been obtained for any previously published figures


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12. Useful resources

  • ImageMagick – A suite of tools for converting between different graphics formats, as well as editing and creating images.
  • GhostScript – A tool for viewing, manipulating and converting PostScript, EPS and PDF files.
  • jpeg2ps – A tool for converting jpg files to PostScript.
  • Colorblind web page filter – A tool for viewing web pages through the eyes of someone who is colourblind.
  • Vischeck – A tool for simulating colourblind vision for both image files and web pages.
  • Guide on colour blindness – Description of how to make figures and presentations that are friendly to color blind people.
  • IUPAC recommendations – Recommendations on graphical representation standards for chemical schemes.
  • Online greyscale converter – Converts colour images to greyscale.

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13. FAQs

Despite having followed these guidelines, the figures in my proof appear to be of poor quality. Why is this?

For the purposes of proofing out an article, figures are `downsampled' (to reduce the amount of image information they contain). This results in a reduction in the overall file size, which makes it easier and quicker to download the proof (although of course there is a reduction in the image quality). The final files used for publishing print versions of the journals include the non-downsampled figures.


How should I submit my figures and figure captions?

Include the figure captions at the end of your manuscript. For initial submission, the figures should ideally be one per page with identifying text, e.g. Fig. 1, placed below the figure. The identifying text should not be part of the Figure itself, but part of the document. On acceptance, you will be asked to upload the source files for your figures.


Why has my table been converted to a figure?

Where a table requires any additional formatting, such as shading, it will be published as a figure.

Data in tabular form will usually be published as a table (left), but when there is additional formatting, publication as a figure (right) may be necessary.



If you cannot find an answer to your artwork question on this page, then please contact support@iucr.org.



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