CRT or LCD – which one is better?
By Alex Galante
Posted January 16, 2003, with the author's permission.
It seems to be an argument discussed in nearly every computer trade magazine at some point in time. What are we to make of all this information being thrown at us about the different technologies? Since we here at Loop Enterprise have to answer many questions and concerns on this issue daily, we put together this e-mail to inform you about the two technologies, and how they perform the job they are designed to do. The information in this e-mail will bring up some points which you should be aware of when purchasing your next monitor.
I will approach this article with the frame of mind that image quality and colour accuracy is a very important factor in the selection process. So lets break down of the two technologies in an attempt to put the difference between the two into perspective.
LCD
As little as 5 years ago LCD screens were not pleasant to use even in their most common application on laptop computers. The evolution of LCD technology over the past few years tightened the dot pitch, pixel response time, colour range, and brightness of LCD screens. Today we have LCD monitors which look bright, sharp and colourful, a main reason why they are becoming more widely offered by many companies. They are small in size and offer a small footprint. They consume less energy than CRT monitors. Their main weaknesses are related to colour accuracy, image quality, viewing angle, and pricing.
CRT
Some say that CRT technology is old and has not evolved much in the past years. Nothing could be further from the truth. While the basic principal of how CRT tubes work has remained the same for years, the image quality has improved significantly on CRT monitors over the past few years. Introduction of flat tubes, super fine dot pitch, higher resolutions and higher refresh rates have done wonders for the CRT monitor's image quality. The fact that the technology is mature means great value in terms of price and product reliability. CRT tube colour accuracy is 2-3 times better then that of an LCD screen. Maximum resolutions also tend to be higher then those offered by LCD screen. The main weakness everyone points to is size and weight, power consumption and refresh rate flicker.
Let's take a look at some of the recent claims made by both the LCD and CRT camps. Note that since the LCD is the challenger to the CRT technology, it is the LCD technology camp making more claims directed at dethroning the CRT.
LCD is better because it's smaller and lighter
If the comparison is done directly on a weight scale, and lighter is better then LCD wins. LCD monitors area also thinner then CRT monitors. Since most users will lift their monitor once or twice a year it's not the ultimate deciding factor as size reduction has little to do with image quality.
LCD offers the same viewable size
You see these claims often. 15" LCD is the same as 17"(16" viewable) CRT, or 17"LCD is the same as 19"(18" Viewable) CRT, etc. Well, the numbers should tell you this is not so. Not only do you get this extra 1" in viewable size on the CRT, but the CRT is able to display a higher resolution image. A quality 17" or 18" LCD will do 1280x1024 where as a quality 19"(18" Viewable) CRT will display 1600x1200 resolution comfortably. A 30% desktop area increase over the LCD. This resolution difference is true all the way up in the direct viewable size comparison chart between LCD and CRT.
CRT monitors have annoying flicker
Due to the physical difference between LCD and CRT technologies it is true that CRT monitors can flicker. However, if you are currently using a monitor which flickers, it's time to put that Commodore 64, 286XT and Apple II on a quick retirement plan. Today's graphic cards are able to provide high resolution and high refresh rate signal to the CRT monitors. And CRT monitors are able to refresh images well in excess of 80Hz at resolutions as high or higher then 1880x1440.
Why do my LCD resolutions look strange?
LCD screens have a fixed resolution. Let's say you have one that's 1024x768. If you try to display 800x600, you will experience an effect called pixel multiplication. In this case the pixels are not able to scale down evenly to the lower resolution, 2 pixels end up representing one. Also the higher dot pitch of LCD monitors in the range of .28-.31dpi further amplifies this effect. It makes the image and fonts appear deformed, and is a source of many technical phone calls. If you buy an LCD screen that is designed to work at 1024x768 resolution, you have to use it at that resolution to have a clear undistorted image. CRTs can display any resolution up to their maximum allowable resolution without this strange effect.
LCDs look bright and lively, just like CRTs
LCDs today do in fact look bright. LCD panel is really a light filter. It needs a back light source projected at the rear of the LCD panel to actually make it appear like an image. It is the intensity of this light that has improved providing high brightness levels on today's LCDs. What about Colour? How does LCD stand up to CRT? The truth is that current LCD models can't hold their own when it comes to colour range they are able to display. Many LCD screens found on the market today are 18-bit, with six bits per pixel for RGB colour interpretation. That means they have a maximum colour range of 262,144 colours, instead of the 16.7 million with eight bits per pixel, 24-bit which CRTs are able to display. It is also true that CRT monitors are at least 2 to 3 times more accurate when it comes to displaying colour then LCD screens even when both are displaying 24bit colour and both are measured and calibrated with a colorimeter. CRT is able to maintain colour uniformity across the screen 2 to 3 times better then an LCD as well. The brightness in the LCD we just talked about above comes at a price. It may make the colours appear "washed out". When LCD screen is measured with a colorimeter and calibrated for colour the brightness in many cases must be reduced by half to display acceptable colour range.
LCD screens have better image geometry
LCD screens are flat and therefore, from the start did not have to overcome some of the challenges CRT had to overcome to be flat. LCD screens certainly display geometrically correct images. However, today's flat CRT monitors also display images with equal accuracy. CRTs of today also provide many "tweaking" menu options to have full control over the CRT image properties to ensure this accuracy.
So by now you may think that LCD has some short comings. You are not the only one. Keep these in mind when purchasing your next monitor !
Check out these links for further info:
www.macworld.com/2001/06/features/color.html
www.macworld.com/2000/07/features/flatpanelside.html
Alex Galante is a Corporate
Account Manager at Loop Enterprise
Inc.
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