When starting to prepare your figures, make sure that you always use the same name for your experimental groups. Choose a short but specific and precise name for each group and use this name throughout the whole scientific manuscript. Choose the proper name for your controls. Do you have more than one control group? If so, how do they differ? Identify the different groups, ideally including information on the most relevant features for your scientific question (for example: genotype, sex, age, treatment).
Always show the control group first (in graphs this is left) and afterwards the remaining groups in a logical order. Keep this order for all graphs and related images. Define a color scheme so each group is always shown in the same color. If you are comparing only a few groups, it is best to use black, white and grey only. If you have more groups, you can either work with colors or with patterns. Even if you have to work with many groups, keep the color scheme as simple as possible and not too colorful as this is irritating for the readers eyes.
Graphs
Each graph needs to have an x-axis and y-axis title that also contains the unit of measurement. Just “distance moved” is not precise enough, it needs to state “distance moved [m]”. Most graphs should also have a graph title. If you show a group of graphs that would all have the same title it is probably better to show this title only once.
Within a figure or even a whole scientific manuscript, you should try to keep the general design and formatting of graphs identical. Graph title, x- and y-axis: capitalized? Font size? Bold? Distance of title from x/y-axis? Thickness of any lines? The same applies to groups and colors as mentioned above. For any letters or text used in a figure use a sans-serif typeface as this is easiest to read, even when letters are quite small. This is often a requirement by the journal mentioned in the Authors guide. The most commonly used sans-serif typefaces are Arial or Calibri.
Photographic Images
In general, the same rules apply here as described above. Additionally, don’t forget the scale bar! An expert in your field might be able to identify the relative size of objects in your image, but someone not familiar with your research topic will probably be ‘lost in space’.
When showing fluorescent images, please be aware that the human eye is able to see the color green best, while red and specifically blue are harder to distinguish when the rest of the image is black. If you don’t have good scientific reasons not to do so, you are doing the reader a great favor to show the most important labeling in green. If this is not the original color of the used dye/antibody, you can mention the change in color for illustration in the figure legend.
When preparing images, please make sure, that you don’t manipulate your images improperly. As image fraud is a very sensitive topic with today’s image manipulation options, please check which changes are acceptable and where fraud starts. The well-written publication by Johnson, 2012 can also help preventing unintended fraud.
Figures usually contain a group of elements, like graphs, pictures, images and so on, each called a panel. Assemble all panels of a figure in a logical order and label them with letters A to … . If you need to use capitalized or lowercase letters often depends on the journal you are submitting the scientific manuscript to, so check the Authors guide of the chosen journal for requirements (see above). When later writing the text to the figures, you should be able to describe the panels of a figure in consecutive order from A to B to C to D and not have to jump from A to D and back to B. When arranging the panels of a figure, place them quite tight next to each other. Empty space is lost space and depending on the journal you submit to the publication fee might even depend on the length of your article.
If your manuscript contains less than four figures, you should consider to submit the manuscript as Short Communication / Brief Report that many journals offer. Such a shorter version of an original article is mostly limited regarding both the number of figures and word count. Check the journal’s requirements for details. However, if you are preparing the manuscript as part of your PhD thesis, check with your PhD program if such a shorter article version is fully recognized; it may be counted only as a half publication.
Figure Legends
The layout and length of a figure legend might depend again on the journal, so check the Authors guide as described above. All figures of your manuscript should be consecutively ordered. Each figure needs a unique, short, but meaningful title stating what is shown in the figure. The body of the figure legend should provide sufficient detail allowing to understand what is shown in each panel. Also mention the group size (n), what the graphs display (mean + or ± SEM or SD?), the applied statistical test and explain any symbols you use (for example, * for statistical significance of p<0.05). If you show scale bars in images and the size is not shown in the image, mention it here in the legend. You need also to explain any abbreviations you used in the figure.
In summary, the figure legend should provide all information that is needed to understand the figure without reading the main text in the results section. Some scientists additionally mention the overall result(s) of the figure but this is not mandatory and up to you.
As you now already started to write text, you should decide from the beginning on, if you write in American English or British English. This might again depend on the journal, but in most cases, it is up to you. Once you decided on one style, stick to it throughout the manuscript.
Today’s conclusion about figures and figure legends:
I:
Standardize as much as possible
II:
Provide all information needed to make figures self-explanatory
