Writing articles, webpages or documents can often be more enjoyable or informative when you include graphics, such as images or graphs. Some texts just work better, when there is a visual element to it that further explains what you are trying to say.
But an image loses value when someone with low- or impaired vision accesses your document or webpage through a screen reader and the screen reader tells them that there is an image but does not describe what the image shows.
Alternative text or image descriptions
For all images on the internet and in digital documents, there are usually one of two types of text attached to it. The short text you sometimes see when an image does not load is called an alternative text (alt text). The alt text is usually just the filename, e.g. dog.jpg, or a very short description of what the image is supposed to show. This provides little to no information for someone who cannot see the image with their own eyes.
Image descriptions are meant to explain what the image is, in a way that provides a similar effect to seeing the image. Writing “A photograph of a dog” might be enough to assess that there is a photo of a dog, but it does not allow the user of the screen reader to fully appreciate the meaning or effect of the image.
Take notice of the little things
When you see an image (e.g. the image of the dog), you obtain much more information than just “A photograph of a dog”. Look at the photograph and consider all the things you see. Some details are more important for understanding the image implies, than others.
Image descriptions are meant to convey some of the same feeling that you get from looking at the image, but in words. Trying to capture the essence of the image is important. Try to take in the surroundings as well as the focus. For example, if the dog in this image was lying in a parking lot or sitting in a kennel, it might give off a very different meaning. Which is why you might be tempted to simply write:
“Photograph of a happy dog lying in a daisy-filled lawn.”
Writing good descriptions
If in doubt, always ask yourself: What text would I use if I could not use an image? In the case of our dog-picture, an example of a good image description could be:
“Photograph of a smiling golden retriever lying in a green daisy-filled lawn and wearing a leash.“
A description rich in detail is superior to the standard simple descriptions, but high-detail can be redundant for some images. Always consider if the information has value or if it is decorative and does not add to the text it accompanies.
Consider going with something like this, if you want users with screen readers to gain the maximum effect of the image:
“Photograph of a smiling golden retriever, lying in a grassy, daisy-filled lawn. There is an out-of-focus metal fence in the background. The dog is wearing a leash that is lying on the dog’s front paws and the sun is shining.”
It comes down to whether you go all out and aim for the richly detailed descriptions or if you stick with writing simple, but informative, descriptions. Either way you are making an important difference in including people with disabilities and creating a more accessible world for everyone.