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The essential 10 video tips
By Dr. Raymond Soneira   -      From: ,DisplayMate Technologies Corp. (www.displaymate.com)
Editorial content partner

DisplayMate Technologies Corp.



Copyright © 1990-2004 by DisplayMate Technologies Corporation. All Rights Reserved. This article, or any part thereof, may not be copied, reproduced, mirrored, distributed or incorporated into any other work without the prior written permission of DisplayMate Technologies Corporation.


POSTED: 09/08/04

Essential information on selecting and using video displays and video adapters

1. How picky are you? 

No video display is perfect, including the best and most expensive displays, so be prepared to accept some compromises in image and picture quality. If you tend to notice imperfections right away, then you'll have to spend more money to prevent the mental anguish that results from owning a display that doesn't meet your expectations. Remember, you may be looking at that display for several thousand hours! Every single major computer magazine in the USA uses DisplayMate to test and evaluate displays. DisplayMate is also used by a rapidly increasing number of publications in over 50 countries. You can gain similar insight into display performance and capabilities by taking along a copy of DisplayMate when you go display shopping.

2. Know what bothers you the most 

Different people are bothered by different image-quality imperfections. It's important to identify the ones that bother you and then prioritize them. The most common problems that bug people include color misregistration, fuzzy image, moiré patterns in the image, geometric distortion, tilted image, flicker, glare and screen reflections. Using magazine reviews and recommendations, identify the models that perform well in your top categories. Look for displays with controls that can adjust the imperfections that bug you the most: for example, look for convergence controls if color misregistration is at the top of your list.

3. The more controls on your display the better 

Displays are now coming with more and more end-user accessible controls that allow you to adjust and correct problems in the image. Besides the mandatory brightness, contrast, size and position controls, you may find focus, convergence, tilt, pincushion, keystone, moiré, color temperature, RGB color drive and cutoff, and manual degaussing controls. Advanced controls found on only a few displays include dynamic focus, dynamic convergence, color purity, pincushion phase and pincushion balance. LCD displays may also have a backlight control as well as pixel clock and tracking. They're all very useful. The more controls you have, the better the image and picture quality on your display will be. Don't worry if you don't know how to adjust some of the more obscure controls, DisplayMate can show you how.

4. The more controls on your graphics video board the better 

Controls on the graphics video board can be used to correct some problems in the display's image. For example, as demonstrated within DisplayMate, certain combinations of video-board and display-control adjustments may be able to reduce or eliminate certain forms of geometric distortion. Controls that are especially helpful in a video board are vertical and horizontal size, vertical and horizontal position, horizontal scanning frequency and vertical refresh rate. Many boards now also include brightness, contrast and color temperature controls. Some of the video-board controls may only be accessible using obscure DOS or command line utilities that came on the video-board's drivers disk, so look over the list of files carefully. In other cases, the controls are only accessible through supplementary utilities available from the manufacturer's website.

5. Watch out for sample-to-sample variations 

There is generally a significant sample-to-sample variation between displays of the same make and model, even among the best brands. All displays are actually delicate precision instruments. They are affected by variations in components, assembly and factory calibration. They are also particularly affected by how much they bounce around during shipment and handling. If you're buying from a store rather than mail order, then checkout the actual display you're getting with DisplayMate before you pay for it and take it home. If you're buying mail order, then try to get an exchange capability in case there is a problem.

6. Carefully set all the controls on your display and video board 

Many users don't know how to adjust some of the controls on their display or graphics video board. If you don't take the time to properly set every control, then they'll actually make matters worse rather than better. DisplayMate includes specialized test patterns to precisely adjust every one of the controls to its optimum value. Detailed online information and instructions explain what to look for and what to do. For example, setting the brightness and contrast controls is straightforward, but requires four separate test patterns in DisplayMate to do it accurately. The payoff is obtaining an optimum grayscale with optimum contrast.

7. Take advantage of inherent image-quality trade-offs 

Most of the display's image parameters are interdependent. Changing one control will often directly or indirectly affect another. While this is a complication, it's also an opportunity, because some things can be improved at the expense of others, based on your own preferences. For example, the higher you set the refresh rate, the lower the image flicker, but the fuzzier the image is likely to appear due to limitations in video bandwidth. Setting the refresh rate to the highest values allowed by your display and video board is not likely to be the best visual compromise setting. DisplayMate tells you which are the important trade-offs and provides test patterns that let you decide what the best overall visual compromises are. There are hundreds of suggestions on improving image quality.

8. Make sure you get a sharp video board 

Image quality and image sharpness vary significantly among graphics video-board brands and models. Try out different boards with the same display to compare the differences.

9. Use video-board controls for improved color accuracy 

The color-matching controls found on most high-end displays can only adjust the white-point or color temperature. To perform detailed color matching or to correct color-tracking errors you need a graphics video board that lets you adjust the RGB color transfer functions, sometimes incorrectly referred to as the gamma correction curves. This can be accomplished by downloading new RGB tables into to the board's hardware RAMDAC, or alternatively performed in software by the Windows® driver. Check for these capabilities. If you need them but don't understand the terminology or how to calibrate the colors and grayscale, DisplayMate explains how and leads you through the calibration procedures in a detailed step-by-step fashion.

10. Keep the display in good tune 

Many users will set the controls as best as they can when the display and graphics video board are first installed, and then forget about them. Displays drift as they warm up, they'll drift a bit during the day, and they'll age over a period of weeks and months. Environmental factors such as room lighting are also important, and can vary because of changing sun light. How often you need to adjust the display controls depends upon how stable your hardware is, the nature of your application, and how discriminating you are. Once you become aware of image-quality issues, you'll become sensitized to them. Things that you glossed over or tolerated before will no longer be acceptable.


Disclaimer: This article originally appeared in a content partner publication. ICIA/InfoComm reserves the right to modify articles for concerns regarding grammar, style and format.


   

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InfoComm - The essential 10 video tips