Screen adjustment - brightness, contrast

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Set your screen correctly
	The correct settings of your computer screen are essential when viewing photos or video on the Internet, playing DVD’s or working with your own digital photos. If you find that photos on the Internet always appear pale and washed-out, or too dark and with too much contrast you definitely need to set your screen correctly. However, the human eye is able to compensate for wide errors and allows you to get used to an odd look so you may not necessarily be aware that your screen is not set correctly. Apart from ensuring that you see what the photographer was intending, this is very important when you check your own digital photos before getting them printed – you may compensate an image for brightness or contrast when in fact it’s your screen that is out of adjustment.
The test image and instructions below can be used to set your screen adjustment by eye. Nothing can replace calibrating the screen using a sensor and a proper calibration program, but this method is better than nothing ! (See: Screen calibration equipment - "Spyder" from around £49.) Most screens have the two adjustments “Brightness” and “Contrast” accessible to the user. ”Brightness” sets the blackness of the black and therefore the tone of dark shadow areas of the image. “Contrast” sets the whiteness of the white and therefore the tone of the highlights and lighter areas.
Note for flat screens and lap-tops. If you have a flat screen (LCD/TFT) this problem of adjustment is further complicated by the angle of vision. These screens are intended to be looked at from a restricted angle – horizontally always head-on, not from the side, and vertically somewhere between right angles to the screen to looking slightly down on the screen. If your line of vision is outside these angles the perceived brightness and contrast will vary enormously. The only way round this is to always sit correctly in the same chair/desk with the screen at the same angle every time. (You can copy the test image onto your desktop to be able to easily check at any time.) Lap-top computers usually have different back-light settings between battery and mains supply – in general you can only get sufficient back-light intensity when on the mains supply.
Using this test image. Let the screen “warm up” for at least 15 minutes without going into “screen-saver” mode. If you have a flat screen set your comfortable and repeatable viewing angle. Avoid working with light shining on the screen (desk lamp or sunlight) and also avoid facing a window or working in near darkness. Wide variations in ambient light will alter your perception of the test image Look at the test image in your browser directly on the web site or open it with the Windows image viewer if saved on disc.

The top part of the test image should show bands of black and near black. Adjust the “Brightness” control until the difference between adjacent bands is just noticeable. The lower part of the test image shows a series of bands from black to white. Look at the pair of bands on the right-hand end, white and near white. Adjust the “Contrast” until the difference between these last two bands is just noticeable. Your screen is now set correctly. You may find that it looks very odd. This is normal, as it will take a few hours of use until your eyes “forget” the old setting. However, once past this initial period you will see a real benefit, both on Internet or video and with your own photos. The rest of the test image can give indications of other screen calibration problems (if the greys are tinted pale pink, green, blue… for example). These factors are a little more technical, but for those who wish to go further, see the page on gamma setting, colour balance and temperature.

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Computer screen adjustment - contrast and brightness

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