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 Re: طلب بخصوص التقنيات المستخدمة في المنبر (Re: حاتم إبراهيم)
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visualexpert.com/FAQ/Part6/cfaqPart6.html#p6.3
6.5 Does color affect eyestrain?
The short answer is that poor color usage can increase chances of eyestrain. In order to explain why, I must step back and explain the causes of eyestrain.
The major origin of eyestrain is eye muscle fatigue. The eye has two sets of muscles, ciliary and oculomotor, that play a major role in perception. Just like any muscles, the ciliary and oculomotor muscles tire if overworked. When this occurs, eyestrain can result.
The oculomotor muscles around the eye control direction of gaze. When focusing on an image, the oculomotor muscles turn the eyes inward so that they point, or "verge," on the focal object, and its image falls on the fovea in both eyes. If you sit in the dark there is no visual input so the muscles relax to a resting state. Resting vergence is 20-25 feet for most people, although there is wide individual variation. At this distance the muscles are completely relaxed.
If you view a screen which is much nearer (40-60 cm distance is normal for computers), then the vergence muscles must work to turn the eyes toward the nearer point and eventually there is fatigue. The closer the distance, the more the muscles work and the faster they fatigue.
The ciliary muscles change the lens thickness when a viewer accommodates to bring the image into sharp focus. The ciliary muscles' resting state brings objects at about 20 feet in focus, so accommodating to nearer objects causes muscle stress in the ciliary as well as in the oculomotor muscles. A recent study shows that people have huge accommodative error when trying to focus on a CRT screen; they tend to focus somewhere between the screen distance and the resting accommodation. (However, research results suggest the vergence stress is far more important than accommodative stress in causing eyestrain.)
Any factor which causes someone to read at a shorter viewing distance will promote eye muscle fatigue and therefore eyestrain. This is exactly what occurs when legibility is low, as when reading in dim light. The reader brings the material closer to the eyes which effectively increases the font size. Low achromatic contrast also decreases legibility and causes shorter viewing distance.
So the answer to the question of color and eyestrain is this: if the designer chooses colors which produce insufficient achromatic contrast, legibility will be low. The user will move toward the screen to increase font size. The ciliary and oculomotor muscles will work harder and make eyestrain more likely.
writer2001.com/colwebcontrast.htm
randomterrain.com/web-design-readability-and-backgrounds.html
(عدل بواسطة حاتم إبراهيم on 08-29-2014, 05:41 AM)
(عدل بواسطة حاتم إبراهيم on 08-29-2014, 05:43 AM)
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| العنوان |
الكاتب |
Date |
| طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-26-14, 07:36 PM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | أيمن محمود | 08-26-14, 10:45 PM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | قصي محمد عبدالله | 08-26-14, 11:01 PM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | mustafa mudathir | 08-27-14, 01:23 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-27-14, 07:53 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | هاشم احمد ادم | 08-27-14, 08:29 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-27-14, 11:37 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | هاشم احمد ادم | 08-28-14, 02:15 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-28-14, 07:40 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-29-14, 05:49 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-29-14, 06:03 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | بدرالدين فرو | 08-31-14, 00:53 AM |
| Re: طلب بخصوص التقنيات المستخدمة في المنبر | حاتم إبراهيم | 08-31-14, 10:15 AM |
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