Transforming Images

One way to increase images’ accessibility is to provide Alternative Text (“alt” text) and Long Descriptions (“longdesc”) for them. “Alt” text provides a short description that gives the learner a general idea of what is depicted. If the “alt” text suggests something of importance or interest, learners can read or listen to the long description (“longdesc”) for more detail.

	Guidelines for text equivalents from the W3C
	Further resources at CAST’s Bobby site
	Article on Web Accessiblility

The long description comprehensively describes the substantive image content germane to the learning task. Learners accessing the long description should be able to obtain all of the key information available to a student who uses the visual form of the image. When composing a long description it is essential to keep the learning goal in mind and include only enough information to serve that purpose. Extraneous detail or vague descriptions can obscure the core content of the image.

Cross-media transformations cannot retain all the characteristics of the source medium. When transforming a complex image into text, certain nuances of the image may be lost. For example, it is very difficult to reproduce in text the subtlety of visual details that can be suggested but not explicitly portrayed in an image. Further, a chart that summarizes complex information may become ungainly when transformed into continuous text.

However, thoughtfully-constructed descriptions that keep the primary learning goal and the learners' needs in mind can minimize this loss.