How to... Create image files of maps for a Web site

The information given here is intended as a guide to creating image (GIF) files of DMAP maps for incorporating into HTML pages. It is assumed that you are already familiar with creating HTML pages for Web sites and incorporating inline images into the pages.

GIF or JPEG ?

There are two commonly-used file formats for Web page images: GIF and JPEG (JPG). For photographic images, the JPEG format is very good, but for images like distribution maps, the GIF format is better. The reason for this is that the file compression method used in JPEG images results in blurred or fuzzy edges to map symbols and other objects on maps. GIF files use an entirely different method of compression which preserves the edges of features on maps, giving a sharper and clearer image quality.

Producing GIF images from DMAP

There are various ways of doing this, depending on which version of DMAP you are using:

DMAP Version 7.1 or later

Simply use the File|Save As or File|Save All menu items in DMAP and select the GIF option.

DMAP Versions 6.0 to 7.0

Upgrade to the latest version of DMAP, or:

In DMAP, save the maps as BMP files.
Convert the BMP files to GIF files using commercial image editing software (for example Paint Shop Pro, Corel PHOTO-PAINT, Microsoft Photo Editor, Adobe Photoshop, etc.)

DMAP Versions 1.0 to 5.6

Upgrade to the latest version of DMAP.

Tips & Hints

Maps are best displayed at exactly the same dimensions (in pixels) they have been saved as. This avoids the resampling of the image by the Browser software which often results in rather degraded quality images.
In DMAP, experiment with different combinations of image width and symbol size to achieve maps of the best possible appearance.
Map titles are usually best done as text on the Web page rather than as part of the image.

If you have any comments or queries about these procedures, Contact Alan Morton

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