Which format is best for exporting a Prism graph?

Last modified November 5, 2009

Are you sure you want to export?

If your goal is to send graphs to a colleague who doesn't own Prism, consider sending a Prism file. He or she can then open the file using Prism itself, the free Prism demo (expires in 30 days), or the free Prism viewer (never expires).   

If your goal is to place graphs into a Word document or PowerPoint presentation, you can copy-and-paste or use the one-click send buttons rather than exporting. There are some settings in the Prism Edit/Preferences menu that will affect the result and whether or not you will paste your graph as a Prism object or a picture. Read more about copy and paste settings. Also note this easy-to-bypass bug in PowerPoint 2007

Background color

Within Prism, there is no distinction between having a clear background and a white background. When you paste or export a Prism graph into another program, a clear background will let colors and objects show through, so Clear is not the same as White. The problem is that not all export formats support the concept of transparency, and Prism doesn't support all formats. The .jpg, and .bmp formats simply have no concept of a clear background, so those file formats simply don't allow for the possibility of clear backgrounds. Read more about exporting or copying and pasting with transparent backgrounds.

Prism 5 and later can export graphs and layouts as PDF files. This is built in to the Export command. You don't need to "print" to a pdf file, or install any other software. When exporting several graphs or layouts, you can choose to export all to one PDF file or to create a PDF file for each sheet. Prism's PDF files include vectors and fonts (not bitmaps), so there is no loss of quality.

Prism can also export to the EPS format. These EPS files use vectors and fonts. They don't just put an EPS wrapper around a bitmap file. Prism exports EPS files by encoding fonts with the "Type 42" format. Most newer programs that import EPS files expect fonts to be encoded like this. Some programs that use older technology cannot understand this font format and will not be able to import the EPS files that Prism exports. There is an option to include or not include fonts in the file. If you don't include fonts, the file will be smaller, but the importing computer must have the same fonts for the imported file to look correct. Read more about exporting EPS files to submit to journals.

EMF or WMF (Windows only)
Windows Metafile (.WMF) and Extended metafile (.EMF) files contain vector and font instructions for how to draw the graph. This means you can resize the image (in another program) with no loss of quality.

WMF or EMF? EMF is newer and better in theory, but some programs work better with WMF. If you have problems with one setting, try the other. You can set the default for how Prism copies graphs and layouts to the clipboard in the Preferences dialog.

Your only option is whether to include the page background. Omit the background color if you will apply a fancier (e. g., gradient) background in another program.

Many journals ask you to submit your figures as .TIF files. This is a bit-map format, which means that your graph or layout is turned into a collection of dots. You need to choose resolution, color model, and size.

The resolution is expressed as dots per inch (dpi). Computer screens display images at about 100 dpi. Computer printers generally print at 300-600 dpi, and publications are generally printed at 1200 dpi. Journals typically ask for a file at 1200 dots per inch (dpi), the highest resolution that Prism offers.

Choose between two ways to express colors: RGB (designed for computer monitors or projectors) or CMYK (designed for printing). If you are submitting to a journal, follow their instructions. If in doubt, choose CMYK. You can also choose Monochrome files, which are pure black and white with no grays. If you choose RGB, choose between 256 colors (smaller files) or millions of colors (larger file, but more accurate color rendition).

Typically, graphs and layouts in Prism projects are much larger than publication size. If you ask for a graph at 1200 dpi at the actual size in Prism, you will end up with either a huge file or an out-of-memory error message. Avoid this problem by specifying the publication size. Let’s say your graph is 6 inches wide, but you will publish it with a width of 2 inches. By checking the option to reduce the graph to a width of 2 inches, you will create a file one-ninth as large (one-third the width times one-third the height).

The .JPG format is designed for photographs with gradients of similar colors. It is not a particularly good format for exporting for line art and graphs. Prism offers this choice because some journals insist on it, but we recommend that you use the .TIF or EPS formats when possible. The only advantage of .JPG is that the files are smaller.

Most programs that export to the .JPG format give you a choice of compression. If you compress more, the files will be smaller but the resulting image won’t be as sharp. Prism gives you no choice. It only exports to the .JPG format with the least possible compression, making larger files but sharper images. Any compression would reduce the clarity of your graphs noticeably.

Prism mistakenly offers the option of "monochrome, no grays" when exporting to JPEG, but this option does not work. If you want a monochrome export, use TIFF not JPEG.

Other formats

The .PNG format is great for posting on web sites, but these files have too little resolution for submission to printed journals. There are no options of color depth or resolution.

PICT files are a Mac-only format that is now obsolete. Prism 4 exported PICT files that contained vector and font instructions for how to draw the graph. This means you can resize the image (in another program) with no loss of quality. Apple took away the ability to make this kind of file. Prism 5 can export a PICT file, but this is simply a bitmap with a PICT name. 

Prism Windows can also export to the BMP or PCX format, out these are older formats and there is really no reason to choose them.  

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