Multi-panel figures are used quite often in scientific publications. A multi-panel figure can include bitmap images, diagrams and schematics, data plots etc. Here are 5 tips for preparing multi-panel figures.
1. Many scientific images are bitmap images, such light microscope images, AFM, SEM, and TEM images, protein 3D renderings etc. For these images, generate them at highest resolution (pixel count) possible. Below are some useful information about the how many pixels you need. Choose format like TIFF or PNG to save them. If you use JPEG format, maker sure to save images at the highest JPEG quality.
- At 300 dpi (pixel density for print; 300 dpi is the typical minimum pixel density required by journals), if you want a bitmap image to be as wide as a 8.5-inch wide paper, your bitmap image should have at least 8.5 × 300 = 2,550 pixels in width. For half of the paper width, you need at least 1,275 pixels. For a third of the paper width, you need at least 850 pixels. Since a bitmap image is a part of the multi-panel figure, targeting 1000 pixels for the width is quite reasonable.
2. Data plots generated by Origin or Excel, chemical structures created by ChemDraw, flow charts and schematics made in PowerPoint are all vector graphics. Try to avoid using these graphics as bitmap images.
3. Most researchers use Microsoft PowerPoint for laying out their multi-panel figures. For bitmap images, make sure you import/insert the high-resolution high-quality images. High-res images will be embedded in PowerPoint even if you resize them. For vector graphics, copy the graphics from the original applications (such as Origin or Excel) and paste them in PowerPoint. This method usually keeps them as vector graphics in PowerPoint.
4. For final figure export, I recommend that you use PDF format. High-res images and vector graphics will be embedded in PDF files. The screenshot below shows a PowerPoint slide with a low-res image, a high-res image, and a vector graphic. You can download the PDF file saved from this PowerPoint slide. Once zoom in several times, you can see that PDF format does a great job preserving the high-res image and vector graphic.
5. If you decide to use a bitmap format (such as TIFF) for your final figure export, just make sure your figures have enough pixels as discussed in Tip 1.