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Adapting Video for VI Learners

Video controls

Why worry about where controls are sited?

Ideally, students need to have control over both the video image, and the video recorder transport. Correct adjustment of image controls can make an important difference to how well the video being viewed can be understood: if problems arise, then a VI student should ideally be able to pause and review immediately. For the visually impaired student such refinement can make a more marked difference between 'seeing' and 'understanding'.

In practice, whether this ideal can be achieved depends firstly on the situation the video is being viewed in. Clearly a single student in a large group watching a video collectively cannot expect to stop and start the action at will. However, in smaller groups analysing the video individual control might be acceptable, while for private preview or followup study such control is vital. In either case there should be no reason why a separate monitor should not be provided, thus allowing image optimisation even where tape transport control would be disruptive.

Optimum access also depends on where the controls are situated. Lets assume that students are reviewing material privately, and therefore will need to operate both tape recorder and screen. The best arrangement is not to have students use the on-set buttons and sliders, but for them to be provided with remote controllers - even when the monitor in question is close by. Remotes are cheap, and can be laid on the desk in front of the student, easily to hand. They are robust, and often clearer than the miniature, flap hidden set controls.

Which controls will be needed, and when?

Students will need control of image, transport, or both when they have:

  • reduced ability to see fine details
  • problems with sensitivity to glare
  • reduced colour vision or complete absence of colour perception
  • narrowness of the visual field
  • problems with contrast sensitivity (which may be exacerbated by the lower levels of viewing illumination in some teaching settings)

Seeing details

Image contrast needs to be adjusted carefully, and may need readjustment mid programme. An individual smaller monitor can often provides a clearer picture with better contrast than a large screen. Scanning for fine detail often means pausing the tape, and searching back and forth for a particular frame.

Sensitivity to glare

It may be necessary to adjust the brightness controls and compensate by adjusting the overall contrast.

Colour vision

Colour contrast on video (and OHP acetates) needs to be fairly high, especially for those students with colour perceptual problems or any central retinal condition. When teachers or video producers use colour to highlight specific important issues on their acetate or video, they run the risk that subtle differences may be lost on a VI student and with them, explanatory power. Teachers and developers should accompany their colour coding with careful explanation and other cues to understanding. When a student hears these cues, they may well want to review the video passage (transport controls), and might also want to adjust colour balance for material which is on the margins of their perception (screen controls).

Narrowness of field and other field defects

Good contrast control is needed - and brightness may also have to be adjusted as sensitivity to light (photophobia) is very common with field defects. As with subtleties lost due to colour, students with visual field problems will want to review complex sections of tape a number of times (hopefully helped in their search by good audio and other supplementary cueing). Thus, again, it will help if both image and transport controls are to hand.

Contrast Sensitivity

Students will want to adjust their image contrast to be as high as possible without compromising colour definition, and may have to do this mid programme for difficult material.

 
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