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How do I configure my LCD for the best possible color reproduction?
Autor: Johannes Post
06/11/2005, 08:33 CET
It's not quite that easy to find the perfect settings for an LCD monitor. Which is why we want to shed some light on this issue of finding the right picture settings beginning with the adjustment of brightness and contrast and continuing with color calibration using RGB in conjunction with a vignette and calibration by Colorimeter, among other things.
Brightness and contrast
First, brightness and contrast ought to be set properly, which can be done by means of a grey scale picture. The result should look such that preferably all of the nuances shown on the lower picture can be recognized. In case this doesn't work using brightness and contrast, one can additionally set the gamma value, which is possible in the OSD (On Screen Display) of some monitors. If the display does not provide gamma settings, you can still work around this by setting the gamma value in the graphics card's options.
An LCD's value of black can not cope with a CRT's value of black because the backlight of an LCD consistently shines onto the rear side of the panel during operation. The alignment of the LCD's (Liquid Crystal Display) crystals determine how much light emitted from the backlight reaches the filters for red, green and blue and thus how intense the respective parts red, green and blue appear in the actual color tone that the viewer will be seeing.
For black, the panel's crystals are aligned in such a way that there will be no light from the backlight let pass. However, the luminosity is very high and significantly surpasses that of a CRT monitor. And since the backlight is illuminating constantly, a little light always shines through despite correctly aligned crystals. This effect can often be perceived as little lucencies at the border areas of the panel where some light leaks through, and is the explains why the black value of an LCD can't cope with that of a CRT. A CRT monitor just turns off its electron ray and delivers a deep black. But there are some factors that can influence the perceived value of black, which is why one should always mind to have a sufficient amount of lighting in one's working environment. Particularly in the evening of in less lit rooms, it is advisable to always set up an indirect lighting.
Value of black without indirect lighting
Value of black with indirect lighting
Not only does a light positively influence the perceived value of black, but also does it put a lot less strain on your eyes. Generally the brightness should not be set too high because it only stresses the eyes unnecessarily, eventually resulting in symptoms like tears, head aches and so forth.
After setting up brightness and contrast one should - in case the display provides it - adjust the color temperature. Color temperature is specified in Kelvin. For example 6000 Kelvin corresponds to a white sheet of paper at average daylight. The appropriate value is selected depending on whether a colder or warmer white is wanted. Rule of thumb: the lower the value, the warmer the white.
Afterwards one can address adjusting the colors (RGB). If color fidelity is not of major importance to you, you can adjust the colors the way the user likes them best. When the red spectrum is increased (up the value for red) in the display's OSD, the picture impression becomes warmer, whereas an increase of the blue spectrum (up the value for blue) makes the picture comes across somewhat colder. Here you can just "play" with settings for RGB a little until the picture seems ideal.
Then, there are display that provide a 6 axis color control allowing the colors red, green, blue, yellow, cyan and magenta to be used for calibrating the overall color spectrum and facilitating an even more accurate configuration/ adjustment of each color. In order to make the configuration procedure easier, there are some displays that include Screenmanager software. With the help of which settings can be carries out more comfortably than with the display's OSD. In parts, the software solution also holds significantly more options than the OSD.
One can achieve more accuracy in color reproduction by utilizing a vignette during the calibration procedure. While this admittedly does not match professional calibration methods, it can help to come a lot closer to color fidelity than just going by one's intuition. You can purchase a vignette with true colors at a photography store or you can get it online at CIPHO - Chemieverband Imaging and Photo e.V. (chemistry organization known in Germany). With the help of the color consistent print/ photo you can optimize the picture of the LCD until it matches the original as much as possible. This might require some time and effort, but the result is mostly nothing short of amazing!
Picture of a color-consistent vignette
In order to make the color calibration meet professional standards, there is the possibility to ensure color fidelity by means of a Colorimeter (instrument to physically measure colors). How to use a Colorimeter in detail for calibrating colors depends on the respective device. But as it is in any sector, there can be differentiated between instruments for the semi professional user costing about 100.00 Euro and for the professional user where instruments start from 1,000.00 Euro.