Display Check

Use the Lagado Display Check to see if your computer display is set correctly for the web. This is an easy test to perform. It helps you know if web pages appear on your display as the author intended.

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Can you see the numbers 1 to 16?

When you look at the test strip above you should be able to read the numbers from 1 to 16.

If you can read all the numbers - your display passes. It should be fine for the web.

What if some numbers don't show?

If some numbers can't be discerned, probably 1 or 16, you may need to adjust your display or your computer software to correct the problem. Alternatively you might need to change the location of your display or the lighting in the room. If none of these help you may have a faulty display.

Lighting

Computer displays are expected to be used to view the web in rooms with normal lighting. You don't require dim lighting for normal web use. You should make sure that the lighting is not too bright. For example, try to avoid bright light, from a window or artificial light, that falls directly on the screen of your display. If the light is too bright you will most likely not be able to read number 1 in the display check.

Display Adjustments

There are currently two main types of computer displays (also known as monitors) widely used for web display. The older type known as CRT is heavy and quite large behind the screen. The newer type known as LCD is lighter and takes a lot less space on your desk. The LCD type is used for portable computers and most new desktop computers.

The controls available for adjusting displays can vary quite a lot between models. The following suggestions will help with a large selection of displays but you may need to adapt them for your display.

Adjusting a LCD display (most new displays)

If your LCD display has a contrast control this may have a significant effect on whether it can pass the display check. If high numbers can't be read on the display check - reduce the contrast. If low numbers can't be read on the display check - increase the contrast.

The brightness control on an LCD display usually adjusts the strength of the backlight. This has little effect on the display check. You can set this wherever it is comfortable for your eyes.

Adjusting a CRT display (older displays)

Most CRT displays will have brightness and contrast controls. If these controls are set too low on a CRT display you will not be able to read low numbers on the display check.

Adjust the contrast control as high as it will go without becoming uncomfortable for your eyes.

Adjust the brightness control from its lowest setting gradually increasing until you can just read the number 1 on the display check. Don't increase it any further.

Software Adjustments

There are a range of possible adjustments. Some computer systems may provide display adjustments in software. You may be able to change contrast and brightness this way if your display doesn't have those controls.

Another setting which may need to be adjusted is gamma. If the display gamma is not set correctly for the web then the display check may fail.

The best accuracy can be achieved with colour management. When you calibrate your web display system properly for colour management it will pass the display check and provide even better accuracy. Colour management is important for high quality colour matches across a range of media and is typically used in professional publishing.

How to adjust these settings using software will vary from system to system. Your computer system user manual might be a good place to look. Also see the references section below, especially relevant for adjustments are those on monitor calibration.

How the display check works

The display check is a strip containing 16 squares of grey. The greys are arranged to have steps of uniform lightness from black to white. Each square contains its number using the grey of the next lighter square.

This use of numbers to identify contrasts is simpler for users than comparing adjacent squares.

The uniform lightness steps are calculated with allowance for sRGB typical viewing flare of 5%. A gamma value of 2.2 is applied to match the sRGB target display gamma.

While the lightness contrasts are reasonably large this is intended to make the test easier to use and more decisive. It will show gross problems in display calibration.

References

A Standard Default Color Space for the Internet - sRGB by Stokes, Anderson, Chandrasekar & Motta
Frequently Asked Questions about Color by Charles Poynton
Frequently Asked Questions about Gamma by Charles Poynton
The rehabilitation of gamma by Charles Poynton
Making fine prints in your digital darkroom: Monitor calibration and gamma by Norman Koran
The Monitor calibration and Gamma assessment page by Photoscientia

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