- Copyright © 2016, SEPM (Society for Sedimentary Geology)
Geology is a very visual science, so figures are the heart and soul of most papers published in the Journal of Sedimentary Research (JSR). The problem is how to present your work in the very best light: You want the very best resolution possible, but AllenTrack limits your figure size! The key to solving this conundrum is to plan carefully and set the dimensions to fit the JSR standards. Making a larger file does not improve quality and may delay publication.
JSR has three standard sizes for figures (whether figures are maps, stratigraphic columns, photos, etc.). Since all figures must fit into one of these standard sizes (Table 1), you should plan your figures accordingly. Once you have the dimensions, you then need to set the resolution (pixels or dots per inch, ppi or dpi) to make a file of reasonable size that fits the required figure dimensions.
Photographs and Other Images
For example, take a photomicrograph of an entire thin section. Since it is a composite image (at least on my microscope), it is huge in size. How huge? To check, take your favorite graphics program (Photoshop for this author) and select Image: Image Size (Fig. 1). In this case (Fig. 1), it shows a file size of 58.7 megabytes with the dimensions 47.85 cm × 30.73 cm and 300 ppi. When saved as a JPEG (i.e., jpg; a nice choice to get a smaller size), the actual file is 9.3 megabytes, still too large. Many cameras produce an even larger image (e.g., 194 cm × 131 cm at 72 ppi; a 13 MB JPEG). These are too large for publication, but how small can you make your image and still show the beautiful detail?
The first step is to change the dimensions under image size to one of the standard JSR figure sizes (Table 1). For a single photomicrograph, single-column width of 8.8 cm works well; a composite figure of multiple photomicrographs will usually be two columns wide. Be sure to fix the aspect ratio so your image is not distorted, thus changing the width will automatically set the height. Once you set the column width, then set the image resolution (e.g., ppi or dpi). You can change the dimensions and resolution freely as long as the resulting file size is the same as, or smaller than, your original. If the file size goes up, then the graphics program is making up data to fill in new detail, which never looks good!
Using a photomicrograph of a cave pearl for example (Fig. 2A–D), the minimum resolution for JSR is 200 dpi. At 600 dpi, the image is nice and sharp (Fig. 2A), but so is the same image at only 300 dpi (Fig. 2B) and even at 200 dpi (Fig. 2C). The higher resolution doesn't translate to better resolution in printing, but it does make a larger file size, which may delay publication. Going down to 100 dpi (Fig. 2D), produces a fuzzy image, not suitable for publication. In general, you want the smallest file that still produces a quality image. When making a full page of photomicrographs (12.5 cm by 23.2 cm), 200 dpi resolution gives a JPEG file size of 0.9 MB; using 300 dpi resolution enlarges the JPEG file size to 3.7 MB, a bit large.
Many of the figures in JSR are not photographs and don't start life in Photoshop or equivalent software. For example, drafting lines and labeling stratigraphic correlation diagrams are much easier with a drafting program, such as Adobe Illustrator. For publication, however, all files must end up as JPEGs (jpg, preferred), PDFs, Postscript files, or TIFFs. This means exporting or saving (“save as”) your file to the new format. When you do so, keep in mind the size restraints discussed above. You want to size the figure and adjust to fit yourself; you do NOT want the printer to do this for you. Adjusting the final size of JPEGs is easier (see above).
Another consideration is the font size and the line weight. Many figures are drafted very large, suitable for printing as a poster. Thin lines that show up well when printed on a poster are not as clear when printed to fit the much smaller journal page. It is the same with fonts. JSR recommends that the smallest lettering print be at least 1 mm high (about 6 point font without reduction). If you aren't sure, print a copy using the JSR sizes (Table 1) and check that all text is readable. If the lines and fonts don't print well on a standard laser printer, they won't look good in JSR either. You cannot depend on readers zooming in to see that tiny font, as printer limitations mean that the resolution isn't there.
For clear figures in JSR, be sure your JPEG (jpg) files are sized to match the journal figure dimensions (Table 1) and have a resolution of 200–300 dpi or ppi. Smaller files will be fuzzy and lose detail; larger files may delay publication and lead to extra charges during production.