Captions and image descriptions serve different purposes. Captions make spoken information and important sounds readable. Image descriptions communicate relevant visual information to people who cannot see the image or can see it only partially.
Begin with the information
First decide what the post needs to communicate. A photograph of a new shopfront may show the entrance and its location. A graphic containing opening hours carries text that needs to be fully accessible. The appropriate description depends on the purpose, not simply on which objects appear.
For a complex chart, a long list of colours may achieve little. Provide the main finding and important values in ordinary text too. Someone unable to see the chart should still be able to understand the relationship it describes.
The W3C image description decision tree distinguishes images by function and information. Apply that principle to the post instead of demanding the same description length for every photograph.
Review captions editorially
Automatic captions can provide a starting point, but they need checking. Names, technical terms, negatives and numbers can change meaning when transcribed incorrectly. Compare the visible text with the audio and check whether changes of speaker remain understandable.
Include important sounds when they affect understanding. A signal tone may matter in a demonstration; incidental background noise does not always need a detailed description. The W3C explanation of captions describes this role.
Consider timing and placement. Captions should not change so quickly that reading becomes difficult, and they should not cover important visual details. Inspect the actual mobile crop because platform controls may obscure additional areas.
Describe what would otherwise be missing
An image description need not include every decorative detail. For a product photograph, shape, arrangement or the action shown may matter. If colour determines a choice, include it; if it merely decorates the background, it may be unnecessary.
Avoid interpretations that cannot be observed. “Satisfied customer” asserts an internal state. A factual description can instead identify what the person visibly does, if the person is relevant to the image's purpose at all.
Do not use descriptions as hidden collections of search terms. That interferes with their actual purpose and can make the post difficult to understand. Ask whether someone could recover the intended information from the text alone.
Test the whole post
Read text on a small screen. Tiny lettering in graphics, low contrast and long lines can create obstacles even when a description exists. Important information should not live exclusively inside a difficult-to-read image.
Watch a video without sound, then listen without looking at the images. These simple checks do not replace a comprehensive accessibility review. They do often reveal information communicated through only one sensory route.
If the format lacks a suitable description facility, provide the essential explanation in the accompanying text or on an accessible linked page. The link label should explain what readers will find. Supplementary information is particularly important when an action or choice would otherwise remain unclear.
Include these checks in approval. Corrections are easier before text and images have been fully exported. Keep editable caption files and descriptions with the source material so later changes do not reach only one of several versions. That makes accessibility part of ordinary content maintenance rather than a separate task that disappears after the first publication.
