Preparing Illustrations and Graphics

Use of Colour

PDF, like postscript, supports colour, therefore colour will be visible on the screen when viewing the proceedings. Authors should not forget however, that the proceedings will also be published in book form which will be in black and white. The printer will render colours in greyscales and patterns and authors should inspect the black and white version of their printed paper to ensure that information is not lost due to the lack of colour.

Fill Patterns

For best results authors should use standard half-tones (NOT custom) and solid colour or grey fills.

Large Files

It can be very frustrating for readers to have their computer blocked whilst certain pages are laboriously painted on the screen and even more annoying for other users when a printer is blocked by a file which takes 30 minutes to print. Proceedings editors therefore have to devote a lot of time to ensure that the published files do not cause such problems. In the following sections some recommendations for authors to diagnose and cure problem files are presented.

Diagnostics

There are no absolute values which we can give to say that a file is too large but in general, any file which is larger than a couple of Megabytes has a high probability of causing problems. Typically, graphics files which have been generated from programs like tracking simulations, where the figure is made up from very large numbers of points or vectors cause problems - the Adobe software is unable to compress the files and therefore when the page is displayed there are millions of elements to paint on the screen. There are two methods which authors can use to check if a file may be a problem: firstly, does the file take a very long time to print ? Secondly, if the PostScript file is displayed (using Ghostview or GhostScript on a PC, for example) does it take a long time to display ? The latter method can also be used to identify one figure from among several that is causing problems.

Remedies

Where the author has access to the software used to produce the figure, investigate if there are parameters which can be adjusted to reduce the number of points which are plotted (averaging, downsampling etc.). Alternatively, reduce the figure to a bitmapped image. This is a method which allows the final view of the figure to be essentially the same but which uses very much less space. There are a number of software packages which are commonly available which allow this kind of manipulation: Adobe Illustrator and Photoshop, for example. On UNIX systems one can use ImageMagic and some institutes which have Adobe Acrobat can use the Gemini plug-in from Iceni Technologies. The figure can be imported to these packages and then saved as a bitmap image in GIF, PNG or JPG formats (the latter is not recommended for line graphics) and then re-inserted into the document.