Programming Web Graphics with Perl and GNU Softwar

Using the Gimp for Day-to-Day Web Projects

The Gimp does not have many of the features needed by a professional service bureau for doing sophisticated graphics destined for print media. Not with Version 1.0, anyway. It is not a Photoshop-killer, nor is it necessarily the one tool best suited for all image manipulation tasks. But when it comes to creating web graphics (or any image meant to be viewed on the screen, for that matter), it can be considered the most important tool in your toolbox.

Image Formats

Because of the Gimp’s plug-in architecture, support for many image file formats has always been available. It is also relatively easy to contribute new plug-ins as new formats come along. File format handlers are registered in the Procedural Database as two entries: a load procedure and a save procedure. For example, there are the file_gif_load and file_gif_save procedures that handle the loading and saving of all GIF format images.

The Gimp supports each of the major web graphics formats very well. Each of the formats (GIF, JPEG, and PNG) deserve a few comments, however.

GIF

Probably the number one most frequently asked question on the Gimp mailing lists is “Why can’t I save such-and-such a file as a GIF?” The answer is usually, “You can’t save an RGB image directly in the GIF format; convert it to Indexed mode.” The Indexed menu option in the Image menu will allow you to convert the image to Indexed mode. In Indexed mode, each pixel in the image is represented as an index to ...