LCD – For the Novice and the Expert
by Kristopher Kubicki on September 4, 2003 12:13 AM EST- Posted in
- Displays
Testing procedures
Manufacturers often post specifications that bring them the largest advantage. Below is a small cross-section of how some of those specifications are obtained in the lab (and what they mean).Luminescence [cd/m2]: This measurement is the basis for most other measurements concerning displays. Candela per meter squared basically just lets us know how bright the image is.
Contrast Ratio [N/A]: This is a unique measurement in the respect that it has no units. Purists argue that this is one of the most confusing and misleading specifications on an LCD. In any case, the Full Screen Contrast Ratio is obtained by placing the display in a dark room. The screen is turned to black and the luminescence obtained (Lb). The screen is then turned to white and the luminescence obtained (Lw). The ratio is then a measurement of the Lw versus Lb. Manufacturers sometimes skew this number by not taking the luminescence values on center.
Response Time [milliseconds]: This is a very important figure for gamers. LCDs do not rely on refresh rates for screen redraws. Instead, they rely on the time it takes a single pixel to power on and off. This measurement is done by placing the screen in a dark room and turning the screen to black. The time it takes the screen to go from black to white is the “Rising” response time, and the time it takes to go from white back to black is the “Falling” response time. Adding both of these together gives the average/typical response time. The important fact to remember is that even though it takes 16ms for the pixel to completely untwist and then twist, most media do not solely consist of extreme shades of color.
For example, a pixel may be illuminated in a grey fashion (i.e. all sub-pixels are half untwisted). According to a lot of our substrate insiders, the Gray-to-Gray response time is much more important. Due to electrical modulation, the response time from one gray half tone to another gray half tone can be as high as 100ms on a typical VA monitor!
Viewing Angle [degrees]: Viewing angle is a very straightforward measurement that can be done very easily with very little equipment. Because the LCD twists and untwists, the human eye has trouble seeing the crystal at different angles. At extreme angles, usually around 80 degrees from center, the human eye cannot determine if the crystal is twisted or untwisted and thus, the image doesn’t really look like anything. Using a protractor, you can determine the viewing angle of your monitor by rotating it until you cannot see the image anymore – then measuring the angle.
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Anonymous User - Sunday, September 7, 2003 - link
http://www.anandtech.com/showdoc.html?i=1730Its ok from what I hear.
Anonymous User - Saturday, September 6, 2003 - link
Great article - typical AnandTech coverage/information! I have a question though - I would like to get a 17" LCD with DVI and S-Video inputs (for playing console games). The Samsung MP series has VGA and S-Video, but no DVI. Albatron has a one with some nice specs - the L17AT.http://www.albatron.com.tw/english/ia/pro_view.asp...
The only problem is that I have seen no reviews of them. I am a little leery of spending $500+ on a monitor sight unseen. Any suggestions?
KristopherKubicki - Saturday, September 6, 2003 - link
#49, Ill add that into Part II then.#50, perhaps down the line I will try to do that. It would not really fit into part II right now.
Cheers,
Kristopher
artifex - Saturday, September 6, 2003 - link
Also, I'd really like to own an LCD because of the weight and size issues (I want larger than my current 16" viewable CRT, 17 or 19 maybe), but also because of the expected power savings. Would you consider adding a comparison of the power consumption in future roundups?artifex - Saturday, September 6, 2003 - link
I am disgusted to discover that many manufacturers using the 262000 color panels are lying and claiming 16.7 million. I challenge Anandtech to clearly identify these manufacturers in future product reviews, because if they can't tell the truth about this simple spec, how can we trust them on things like warranties?KristopherKubicki - Saturday, September 6, 2003 - link
#47 - Yes, SamsungUSA anyway. Computex is around the corner, maybe we can find out something new there =)Anonymous User - Friday, September 5, 2003 - link
Hi Kristopher, is Samsung still denying/not talking about their X line of 16ms panels?KristopherKubicki - Friday, September 5, 2003 - link
Hi Dan,The Apple 23" monitor is OK, but its more bark than bite (Apple does these amazing things with advertising). I would be very hesitant to judge a monitor by its contrast ratio.
In fact, one monitor we reviewed a few months ago, the Samsung 192T claimed a 500:1 contrast ratio when we recieved. Now, the specifications claim 750:1 even though nothing has changed on the monitor.
In any case, do remember that the Cinematic Displays are expensive as well. Samsung has done some very neat things in the 21 and 23" area, and in my opinion they are better than apples. To further sweeten the deal you wont need a seperate adaptor to convert the signal.
If you use graphics heavily (as in professionally) CRT is still your only option.
As for your question about DVI, there are actually about 3 versions of the technology. However, almost all hardware on the PC uses the DVI-I format. This format is backwards compatible with the other two, so you'll be just fine.
Cheers,
Kristopher
Anonymous User - Friday, September 5, 2003 - link
Hi my old 17" CRT is dying, and I'll need to replace it very soon. I have found that when working in PhotoShop, my old 17" monitor is just to small, and my eyes get quit sore. I think I would like to get and LCD of around 19". I am a PC user and am running Windows 98se.In my research "the Monitor to which all others is compaired" is the Apple 23" Cinem HD Display Having a resolution of 1920 by 1200, 170 viewing angle, brightness of only 200 cd/m2, lowsey 350:1 contrast ratio, and a half decient pixel pitch of 0.258.
Here in Australia coumptor stores aren't at all helpful in showing you their monitors in real world sisutions. So I've only been able to read the technical specs found on the internet. It seems a number of monitors have hit the 700 to 1 mark, and Planar offer a 19" with a pixel pitch of 0.242mm at 1600 x 1200 while most offer a auful 0.290mm at 1280 x 1024.
Going on specifications alone, I think I would like a 19" LCD with 1600 x 1200 resolution, 300 CD/m2 brightness, 700 to 1 contrast ratio, 25ms or less response time, 170 degree horizonal and vertical viewing angle, 0.242 mm pixel pitch, and of course a DVI coennection. I am not a gamer.
Is this reasonable and practical, or is a CRT a better option, and if so which one would best suit the graphics environment?
I recently read something about there being two kinds of DVI, DVI and DVI-D, is this a concern?
Thank You for any help you can give me, my e-mail address is danandrews@optusnet.com.au
Sincerely, Dan Andrews
Anonymous User - Friday, September 5, 2003 - link
What's the deal with all the misleading and irrelevant hypertext links in the article (e.g. "computer", "connection", "solution", etc?)