There is an emphasis on the need to combine energy savings with good visual quality when lighting. Lighting that is visually appealing, comfortable, and energy-efficient is ideal.
Visual quality is defined as the combination of visual efficiency and visual comfort. The capacity to complete tasks that require vision is measured by visual efficiency. It is possible to quantify visual efficiency. For example, people can be tested to see how often they make proofreading errors under different lighting settings. Visual comfort is linked to how easy it is to see the work, and the same characteristics as visual efficiency influence it. Being a matter of feelings and perceptions, visual comfort is highly subjective, and it's determined by a nebulous criterion known as "visual comfort likelihood."
The illumination intensity on the region of interest, illumination homogeneity, shadow generation, background lighting, glare from the light source, veiling reflections, and color rendering are the essential aspects of visual quality.
- The intensity of illumination, expressed in lux or foot-candles, significantly impacts visual efficiency and comfort. There can be an illustration of how the impacts could clash. High levels of brightness, in this instance, improve task performance while also making people feel uncomfortable. The size and contrast of the details examined, the viewer's age and other factors influence appropriate lighting levels.
- Although the effect cannot be assessed precisely, task lighting homogeneity is significant for visual comfort. A related factor is shadows. Although shadows are required for visual efficiency within the material being viewed, excessive covering shadows in the viewing region degrade visual quality. Discussions can be held of how shadows form and are affected by light sources, the viewing area, and the viewer.
- Background lighting refers to light that is visible outside of the work's immediate area, such as what you see out of the corner of your eye or when you look up from the task. The question is how much pleasing contrast between the task's brightness ("luminance") and the background. There is also a discussion of how backdrop lighting influences visual efficiency and comfort and its aesthetic impact.
- The glare of light sources can significantly negatively impact visual comfort. The size of the light source, its position in the visual field, the duration of exposure, background brightness, and the viewer's age all influence the experience of glare.
- The most under-appreciated issue in lighting design is veiling reflections. Veiling reflections waste energy while reducing visual efficiency by lowering contrast, and they can induce discomfort by making vision more challenging. These impacts can be described and demonstrated by avoiding veiling reflections, mainly through proper light source positioning.
- Color is responsible for a significant portion of the information and pleasure humans get from their vision. There can be a discussion of how the human eye perceives color, the color properties of sunshine and various types of lamps, the relationship between color vision and illumination level, and how to adjust for color vision impairment. The "color rendering index" is a scale that measures how well light sources render colors.