The World Wide Web Consortium (or W3) has noted that there has to be enough contrast between text and its background if it is to be readable to people with moderately low vision (particularly those who do not have assist contrast-enhancing technology).
For those with color deficiencies, luminance contrast can greatly affect how the learner experiences the video. Hue, saturation, and legibility are pivotal in helping vision-impaired learners to understand what is on-screen. W3 recommends that the contrast be calculated so the usage of color is not a key factor in the video. This ensures the learner(s) has adequate contrast between images, text, and the background. It makes the learning process easier for disabled people to obtain and retain information.
From the beginning, the text needs to be large with wider character strokes, allowing for an easier read at lower contrast. This gives editors or animators the chance to use a wide range of colors for large text. Usually, 18-point text or 14-point bold text is recommended as the best font size when it comes to the required lower contrast ratio. The exact ideal size will depend largely on the audience you are hoping to reach.
Additionally, people with vision impairments tend to have difficulty reading text that is indistinguishable from its background. The minimum contrast criterion (1.4.3) applies to video text, including animated and stagnate text and interactive text is shown when a pointer is hovering over an object or when an object has keyboard focus.
This ratio is optimal for those suffering from color deficiency or complete color blindness trying to read the text. Under any of these circumstances, the text must provide sufficient contrast between it and the background in order to become section 508 compliant with your eLearning content.
When it comes to on-screen images, people with cognitive disabilities need color combinations or hues that have low contrast. Writers, editors, and animators can use color contrast tools to adjust the foreground and background colors in the video.
Finally, scaling images and text can be problematic for the visually-impaired, as both tend to distort and pixelate. Changing foreground and background contrast and color combinations of images can be an aid or hinder the situation. The creator can supply high-quality resolution images and text and backgrounds for visually-impaired learners to understand the lesson or training.