Most authors will submit electronic graphics files or photographic images along with their papers. The expanded information on this page is provided to help authors to understand our minimum requirements for electronic graphics files and to assist them in preparing graphics for submission to the Journal.

File Format
Common file types are grouped below according to level of acceptability. File extensions (suffixes) are given with each file type, and should be used in file names. Please do not use spaces or special characters in file names, and limit file names to 32 characters, including any file extension.

Table/Figure (graphs and charts) files

These formats are ACCEPTABLE:

• Separate EPS, PS, WMF, or PDF files containing charts or graphs
• Separate Excel (xls), PowerPoint (ppt), or Word (doc) files (if the figure data are textual) containing data (if any) and a chart or graph. These applications produce images of low resolution (72 dpi) and will be converted to EPS files. Please do not use patterns in making bar graphs and avoid using more than 5 shades of gray (including black and white. Do not use color

These formats are UNACCEPTABLE:

• Hand-drawn (or mouse-drawn) graphs in any format. (Yes, we do get these)
• Graphs or charts of any format that use any color
• Word or any other file types containing figures created in another format

Images

These formats are ACCEPTABLE:

• Separate file of minimum 300 dpi at 4 by 6 inches. We accept TIFF, GIF, PSD, and JPEG files (see JPEG requirements below), but we prefer TIFF files saved in RGB color format
• JPEGs of well over 300 dpi resolution at over 4 by 6 inches
• Slides or glossy photographs

These formats are UNACCEPTABLE:

• JPEGs (jpg) or GIFs (gif) of typically low (72 dpi) resolution, unless very large (around 14 by 21 inches)

Resolution
Resolution is commonly expressed as pixels per inch (ppi), dots per inch (dpi), or dots or pixels per centimeter. The higher the resolution, the better the image at the same image size and the better it will look when printed at larger sizes. Some graphics applications can save files at high resolutions. We cannot use images of low resolution (less than 300 dpi) unless the image size is large (around 14 by 21 inches at 72 dpi). Images made from line art should be of very high resolution: at least 1200 dpi regardless of size. Most Web images have a resolution of only 72 dpi, but the original image may be available in higher resolution, so check with the source.

Image Size
Digital image quality also depends on the dimensions of the image, commonly expressed in inches or centimeters of width and height. These dimensions can be set manually in some graphics applications. Doubling the size of an existing image cuts its resolution in half; reducing an existing image will increase its resolution.

• If you are converting a slide to an electronic file, please be sure that its image size is increased from the original, or that resolution is set very high.
• Digital cameras allow you to choose the quality level of images they produce. If you use a digital camera to produce an image, always use the highest level of quality available. This typically will produce a usable large, low-resolution image.

File Size
Do not confuse image size with file size. File size is measured in megabytes (M), and is larger for bigger or higher-resolution images. Image file sizes can often range from 10M to 100M, but you should keep your file size below 20M if possible. If you are sending a large or high-resolution image to us as an e-mail attachment, please consider first compressing it to below 5M with a compression or stuffing utility such as WinZip or StuffIt. While we can receive a file of any size, some internet service providers limit the size of attached files to as little as 2M to 5M.

Revised 7/24/2003