OpenWindows Advanced User's Guide

10.5.2 Adjusting Your Viewing Environment

You can make many adjustments to your monitor and working environment to create a good viewing environment. A good viewing environment reduces stress on your eyes. Before you calibrate your monitor establish a good viewing environment. Adjustments are either related to your working environment or your monitor. Make the working environment adjustments with your monitor turned off; make the monitor adjustments with your monitor turned on.

See the following white papers provided on line in /usr/openwin/demo/kcms/docs for detailed information on adjusting your viewing environment:

Reducing Eyestrain from Computer Monitors
Video Monitor Adjustments: "Black Level" and "Picture"

10.5.2.1 Adjusting Your Working Environment

Make the following adjustments to your working environment with your monitor turned off:

Minimize reflections
Adjust ambient light
Establish a suitable surround
Establish a comfortable viewing distance

Note -
You do not need to shut down your computer as long as your monitor has its own power switch.

Minimizing Reflections

Your screen has a glass faceplate that reflects--into your eyes--light that originates behind you. Reflections can change your perception of your display at the location where it is reflected. The flatter your monitor's faceplate, the less of a problem reflections are likely to be; a highly curved screen "collects" reflections over a wide angle behind you.

To determine whether your screen has reflections, sit in your normal working position and examine the dark screen for reflections. (The reflections may be distorted by the curvature of the screen.) Try to arrange your environment so that no intense light sources are reflected on your screen. If you cannot move your furniture, either move the light source or block your (reflected) view of the offending object with dark cardboard baffles.

Your monitor's screen may have an integral antiglare coating or treatment to minimize glare. A monitor with this treatment appears to have a very dark screen when it is turned off. You can attach an external antiglare screen to the front of your monitor, but some antiglare screens have such low light transmission that you may find that they reduce the intensity of white to an unacceptably low level.

Adjusting Ambient Light

Not only can you see light that originates behind you, but you can see objects other than light, like your own silhouette. To minimize reflections of objects in front of your screen other than lights, reduce the general light level, or ambient illumination. Overhead fluorescent light is usually the cause of this type of reflection because it is excessively bright. Use a different light source (for example, lamps) if this type of reflection occurs.

Establishing a Suitable Surround

Visual stress is induced if--while watching your screen--your peripheral vision is exposed to a light intensity substantially brighter than the brightest regions of your display. The color science term surround refers to the area perceived by your peripheral vision while you are looking at a display. In addition to disturbing your peripheral vision, a bright surround increases your ambient illumination. Try to establish a visual surround that is darker than the brightest white of your screen.

It is beneficial to have a visual reference to the outside world--such as a window to the outdoors--while working at your computer. If you have a window, make sure you sit so that the window is far enough to your side that it does not impinge your peripheral vision, but not so far behind to reflect in your screen.

Establishing a Comfortable Viewing Distance

If you can see individual pixels on your screen, you are probably sitting too close to your screen. Visual recognition skills, particularly reading, develop on the basis of recognizing shapes, not dots. When you look at the letter "V", you should perceive two angled intersecting straight lines, not two jagged vertical elements or a collection of dots.

For minimum stress viewing of your screen, you should work at a sufficient distance so that you cannot see individual pixels on the screen. A sufficient distance is usually at arm's length. Extend your arms in front of you while you are sitting at your workstation. The tips of your fingers should reach the faceplate of your screen. The arm's-length viewing distance minimizes stress due to focusing at short distances for an extended period of time.

If you have trouble making out characters at a viewing distance sufficient to blend pixels into shapes, consider using a larger font for viewing on the screen.

10.5.2.2 Adjusting Your Monitor

Once your working environment is set up properly, let your monitor warm up for at least one hour adjust your monitor's Black Level and Picture.

This icon indicates the Picture (or Contrast) control. It affects the brightness that is reproduced for a full white input signal. Once Black Level is set correctly, Picture should be set for comfortable viewing brightness.

This icon indicates the Black Level (or Brightness) control. This control should be adjusted so that black picture content displays as true black on your monitor. Incorrectly adjusting this control is the most common problem of poor quality picture reproduction on computer monitors, video monitors and television sets.

A monitor is properly adjusted when it meets these conditions:

A black input signal should produce true black to maximize the contrast ratio of the display

A white input signal should produce the desired intensity

10.5.2.3 To Adjust Your Monitor

Follow these steps to properly adjust your monitor.

Turn your monitor's Picture control to minimum to display a black picture.

The minimum setting of the Picture control causes the picture content to disappear entirely. If your monitor's picture cannot be made to vanish, then you will have to arrange to display a picture that is substantially black (for example, by activating a screen-saver).

Turn your monitor's Black Level control to adjust black correctly.

Turn the Black Level control to the balance point or threshold. The threshold is low enough that a black area of the picture emits no light, but high enough that setting the control any higher would cause the area to become a dark gray.

Turn your monitor's Picture control to adjust the brightness level.

Once the black level is set correctly, the Picture control can be adjusted so that a white signal produces the appropriate level of brightness. There is no proper setting of this control; it depends entirely on your preference.

Avoid setting your monitor too bright. Excessive brightness can increase your sensitivity to flicker, reduce the contrast ratio of the picture, and defocus the electron beam of the CRT, resulting in poor sharpness.

Note -
You may need to iterate between the Black Level control and the Picture control a few times to set the combination that both reproduces black correctly and white at the brightness you desire.