A Guide to LCDs

[originel]

This information started in another thread post, and I decided to make a new thread at the request of others. I hope that it is helpful to you. If anyone finds any errors or would like to expand, please feel free to do so!

There is a basic relationship in LCD monitors that is often overlooked. Simply stated, image quality is inversely proportional to the refresh rate of a monitor. In other words, the faster the refresh rate, the poorer the image quality. I am, of course, generalizing and there are plenty of exceptions.

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| 6-bit versus 8-bit panels |
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Lets start with color representation. There are lots of ways to represent colors in a numerical format. The common is to use rgb method. This is defined as a 32-bit number like so: 00RRGGBB where the first 8 bits are 0's (unused), the next 8 bits are for red, the next 8 bits are for green, and the last 8 bits are for blue. This is called 24-bit color (note: windows calls it 32-bit color because values are stored in 32-bit integers). You set this value in color quality section of the display properties in windows. Note: you can actually use true 32-bit color, although windows and most consumer level graphics cards/monitors don't support it. YOu need some high end unix stuff from someone like SGI for that.

So, how does this relate to LCD's? LCD's also use a numerical format to represent numbers, although their naming convention is different. There are two types of displays available, 6-bit displays and 8-bit displays. This refers to the number of bits per color. In other words, an 8-bit panel corrosponds to 24-bit color directly and 6-bit color refers to something not available in windows (although it's close to 16-bit color). What this means is that even though you may set the color depth to 24-bit (it reads 32-bit remember), you are not seeing that bit-depth. Now how much of an impact does this have? 8-bit displays can display a total of 16.7 million colors. 6-bit displays can only display 262 thousand colors. That's almost 100 times more colors on the 8-bit display.

Now of course showing that few colors is completely unacceptable, so LCD manufacturers employ a little trick called dithering. It works by tricking you into seeing a color that isn't really there (it's rather clever actually). If it has to display a non native color, it takes two adjacent pixels and sets them to values just to either side of the desired value. The result is that the eye thinks it sees the proper color, even though it really doesn't. Printed media that uses only 4 colors of ink but places two colors right next to each other works the same way essentially (think magazines and newspapers). However, even using this method it can still only "display" 16.2 million colors. As a side note: you can tell if a panel is an 8-bit or a 6-bit panel by checking if it can display 16.2 million colors or 16.7 million colors. Newegg reports all panels in this manner. Ok...now why is this bad? Depending on how sensitive your eyes are, you can see the dithering taking place. I usually see it as a sort of "banding" usually, and the colors don't quite look as good. It's like the old refresh of CRT monitors...some people are perfectly happy with 60hz, and some can't stand 75hz. In any case, the fact is that the images you are seeing on a 6-bit panel are not completely accurate. In an 8-bit panel, images look very rich in color without having to use any extra features such as increasing the contrast too much or using something like digital vibrance in the nvidia drivers. Color representation is pretty much perfect on an 8-bit panel (except in really dark shades due to bleed-through of the backlight, which all TFT panels have).

So why are 6-bit panels so common? They are a lot cheaper to make, and they have faster response times. This is why we saw a jump in refresh times from the 18ms range to the 8ms range almost overnight when the 6-bit panels were first introduced. And of course consider that companies have been stressing response times for years since they were so much of a problem at first, that pretty much everyone viewed response time as the only criteria in selecting an LCD. Companies capitalized on this, and that's why most panels today are 6-bit panels unfortunately.

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| Common Parameters |
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There are many different parameters that characterize an LCD. The order of importance varies from person to person and their needs, and ultimately you have to decide for yourself which parameters are most important.

Dot Pitch - the size of the individual pixels. The larger this is, the more blocky images look

Image Brightness, aka Black level - typically they mean the maximum brightness, measured
in candellas. You don't always want more. The problem with LCDs is that the back light stays on all the time, and an LCD filter is used to block the light to make black. These filters are never perfect and so a little light leaks through (called bleed-through). The brighter a display is, the greater the potential for bleed-through. So you need to take that into consideration.

Contrast ratio is the difference between pure white and pure black - This helps define the dynamic range of the monitor, but there are better methods.

Delta E (or delta tracking) - the short of it is that it compares the expected color to the displayed color...you want this as close to 0 as possible across all values

Contrast Stability - how steady is the contrast across multiple brightness values

Spacial uniformity - how uniform is the brightness between pixels. Usually the edges are darker than the center.

Related to the delta e (and i forget the term) is how the recorded versus expected values across all three colors plot. Some colors may be more off than others. If you set each color to the same value from 0 to 255 you should get a black/gray/white color. However, not all colors are the same and so they will have a slight tint to them. You want the graph of the brightness of all the colors to lie directly on top of each other. This goes back to delta e...the bigger the delta e, the bigger the problem of color alignment.

That's all I can think of off of the top of my head. There are other intersting parameters out there. also note: you can't get most of the values from the manufacturer, you have to get them from a 3rd party test site (like anandtech or tom's hardware).

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| Overdrive |
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There is a technology called overdrive. Basically, the way an LCD works is that you have a white backlight, and then you have color LCD filters on top of it. The filters are engaged by applying an analog voltage to it. The higher the voltage, the bigger the change in the filter. Now one side effect is that the higher the voltage, the faster the filter responds (thus the faster the refresh rate). A technique was developed at viewsonic first and is now available with many manufacturers that essentially "overshoots", i.e. it sets the voltage higher than the desired value and then backs it off as the color approaches the correct value. It works quite well, but if it is not implemented correctly you can get incorrect color values.

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| Recommendations |
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Ultimately you need to find an LCD with characteristics that match your personal needs. A graphic artist needs a display that is vastly different than a gamer. In my opinion, Viewsonic makes very good LCDs. I have the VP930b which is overall a very good display. It has very good color representation, although suffers from bleed-through, especially in the four corners resulting in a slight X shape. It only affects very dark colors though, and so it's livable. I did a significant amount of research for a monitor and settled on this one because it is a good general purpose monitor. It doesn't have any standout qualities (other than that it is an 8-bit panel), but it also doesn't have any weak areas.

A friend of mine has the Viewsonic VX922 is a cheaper 6-bit panel and is excellent for gaming, although I wouldn't recommend it if you do any sort of graphics work as it is a 6-bit panel and doesn't have very good color representation IMO. I used to have an Apple Cinema display where I worked and they have very good image quality, but have a slower refresh rate and are not suited for gamers. The colors were just gorgeous, but suffered from visible ghosting.



Finally, make sure that you use a DVI connection whenever possible. As much as I've tried, I've never been able to get the color balance as good on a VGA connection as I have on a DVI connection when identical monitors in a dual monitor configuration.

[Whir]

Also, not imperative to a purchase plan, but I'd like to state that as of yet, there is no industry standard for contrast ratio measurements. One manufacturer can say their panel does 800:1, while another can say 1,200:1 and they could be the same panel

[GroundZero3]

stickey for you

[originel]

Also, not imperative to a purchase plan, but I'd like to state that as of yet, there is no industry standard for contrast ratio measurements. One manufacturer can say their panel does 800:1, while another can say 1,200:1 and they could be the same panel

That's a very good point. Response measurements are also a good area. LCD's have a different response time depending on which color your changing too, and there are two methods that only show you the change between two preset colors, which is pretty useless since they don't say much about real response times. FYI, there is no such thing as a sub 10ms display right now.

Thanks GZ.

[tony_j15]

to expand, most companies measure the response time that it takes for a pixel to change from white to black, which is much simpler than changing from a burnt orange to dark green for example. Along with this, some only report the half time for the change. IOW, when going from black to white they count from black to neutral grey which can give a response time of 8ms. This is actually the same as a 16ms panel doing the full color change.

Did I get that right?

[camaro]

TFT Technology Breakdown and Model/Panel Index
LCD Panel Technology Type and Characteristics

TN film (Twisted Nematic)
- low manufacturing/retail costs
- restrictive viewing angles
- fast pixel response times
- dead pixels display white. Stuck pixels display RGB colors
- lower contrast levels means blacks are not as dark as VA based panels
- lower color reproduction

IPS (In Plane Switching)
- improved viewing angles over TN
- very good color reproduction
- slower pixel response times than TN
- dead pixels display black
- lower contrast levels means blacks are not as dark as VA based panels

Super-IPS (S-IPS)
- same as IPS except ...
- likely best color reproduction of all TFT
- less expensive to produce than IPS
- improved pixel response


VA (Vertical Alignment) Technologies

MVA (Multidomain Vertical Alignment)
- compromise between TN and IPS technologies
- superior color reproduction over TN but not as good as IPS
- very good viewing angles but less than IPS
- higher contrast than TN or S-IPS means very good blacks
- dead pixels are black
- slower pixel response than TN or IPS
- details can be lost when directly viewing dark areas

Premium-MVA (P-MVA)
- same as MVA except ...
- "overdrive" technology increases pixel response but still slower than TN
- may have slightly degraded color reproduction due to "overdrive" process

PVA (Patterned VA)
- same as MVA except ...
- larger viewing angles
- higher contrast levels means darkest blacks

Super-PVA (S-PVA)
- same as PVA except ...
- “Magic Speed” (the Samsung equivalent to Overdrive) improves pixel response
- slightly improved color reproduction
- slightly improved viewing angles



Purchasing Considerations

TN Gamers
Considered a "gamers" panel due to it's fast pixel response times which reduces trailing images know as "ghosting". However, this advantage has been reduced by new technologies to accelerate pixel response times in other panel types. Colors and contrast tend to be weak and blacks are not truly dark. Viewing angles are significantly limited. However, monitors based on this technology tend to be inexpensive.

IPS / S-IPS Graphics Work or Web Browsing
Considered to have the best color reproduction of all panel types, these panels are well suited for graphics work or web browsing. Pixel response time is also good but slower than the TN "gamers" panel. Contast and blacks are also less dark than VA panels but viewing angles are excellent.

MVA / P-MVA / PVA / S-PVA Compromise for All-Around Use
These panels are a compromise between the fast pixel response times of the TN panel and the excellent color reproduction of the IPS panels. Contrast and blacks are best of all the panel types. Viewing angles are similar but slightly inferior to IPS.


Model/Panel Index


Acer
Acer AL1951Cs - 19" TN Film
Acer AL1916ws - 19" WS TN Film
Acer AL2016ws - 20" WS Chunghwa Picture Tubes TN Film
Acer AL2032wa - 20" WS AU Optronics P-MVA (M201EW01 V0) OR LG.Philips S-IPS (LM201W01)

BenQ
BenQ FP202W - 20" WS Chunghwa Picture Tubes TN Film

Dell
Dell 1905FP - 19" Samsung PVA (LTM190E4-L02) or AU Optronics P-MVA (M190EN03 V0)
Dell 1907FP - 19" TN Film
Dell 2001FP - 20" LG.Philips S-IPS (LM201U04)
Dell 2005FPW - 20" WS LG.Philips S-IPS (LM201W01)
Dell 2007WFP - 20" WS LG.Philips S-IPS (LM201W01)
Dell 2007FP - 20" LG.Philips S-IPS (LM201U04)
Dell 2405FPW - 24" WS Samsung PVA (LTM240M1-L01)
Dell 2407WFP - 24" WS Samsung S-PVA (LM201W01)
Dell 3007WFP - 30" WS LG.Philips S-IPS (LM300W01)

Gateway
Gateway FPD2185W - 21" WS Samsung S-PVA (LTM210M2)

HP
HP F2105 - 21" WS Samsung S-PVA (LTM210M2)

Hyundai
Hyundai L90D+ - 19" Samsung TN (LTM190EX-L01)

NEC
NEC LCD20WGX2 - 20" LG.Philips AS-IPS (LM201W01)

Sceptre X20G Naga II 16ms 20" P-MVA
Sceptre X20G Naga II - 20" WS P-MVA

Samsung
Samsung 930B - 19" Samsung TN Film
Samsung 940B - 19" Samsung TN Film
Samsung 940T - 19" Samsung PVA (LTM190E4)
Samsung 940MW - 19"WS Samsung TN Film (LTM190M2)
Samsung 204B - 20" Samsung TN Film (LTM201UX)
Samsung 215TW - 21" WS Samsung S-PVA (LTM210M2)
Samsung 244T - 24" WS Samsung S-PVA (LTM240M2)

ViewSonic
ViewSonic VA1912W - 19" WS Chi Mei Optoelectronics TN Film (M190A1)
ViewSonic VP912B - 19" AU Optronics TN Film (M190EN04 V1)
Viewsonic VX922 - 19" AU Optronics TN Film (M190EN04)
Viewsonic VX924 - 19" AU Optronics TN Film (M190EN04 V5)
ViewSonic VP920 - 19" TN Film
ViewSonic VP930 - 19" AU Optronics P-MVA (M190EG01 V0)
ViewSonic VA1912W - 19" WS Chi Mei Optoelectronics TN Film (M190A1)
ViewSonic VA2012WB - 20" WS Chunghwa Picture Tubes TN Film
ViewSonic VX2025WM - 20" WS AU Optronics P-MVA (M201EW01 V0)

[mrniceguy]

is there any relationship between all of these standards and lcd hdtvs? I plan on buying one to use with the computer and as a tv.

[Whir]

None at all. LCD projection TVs and projectors use a completely different setup. Response time and contrast are still valid of course, but the display mechanics are totally different.

[mrniceguy]

great, more headaches, I have severe trust issues with manufacturers

[-FMA]

How does a CRT compare to the 6bit and 8bit LCDs?

Right now I'm using an old CRT. It's VGA with the DVI connector for the graphics card.

I don't really know anything about displays. Does the fact that I'm using an adaptor mean that it's only displaying as good as VGA? Getting a DVI monitor would improve this right?

How would my setup right now compare to 6bit and 8bit? If it's anything like 6bit then I'll probably get that because my current display is fine for the graphics I make and I need something good for gaming. 8bit wouldn't be as good for gaming, but it would be better for the colors.

Any suggestions on what might work best?

Thanks,

-FMA

[originel]

What is your current CRT?

Does the fact that I'm using an adaptor mean that it's only displaying as good as VGA

Correct

Getting a DVI monitor would improve this right?

From a purely theoretical standpoint yes, however read below for some caveats

How would my setup right now compare to 6bit and 8bit?

Your current setup will be better than LCDs in some ways, worse in others.

CRT's have the unique advantage over all TFT LCDs in that they display a true black. When you switch from a CRT to a TFT LCD, you will be annoyed in games for a while because the blacks and dark shades will look really terrible. You get used to it, and if you spend some more time configuring your brightness and contrast correctly in the game settings, then it is bearable. However no TFT LCD will ever have the accurate black levels of your current CRT due to the bleed-through described above. When I first switched, it really bugged me for about a month...but now I don't notice it. Also note that I have an 8-bit panel with the better color fidelity than 6-bits...so it will be even worse if you get a 6-bit panel. Remember, CRT monitors ALWAYS have better color than a TFT LCD panel.

CRTs may not be as accurate colorwise though due to the VGA connection and the way that CRTs work. Note that LCDs using a VGA connector and/or are 6-bit panels are not any better, only 8-bit panels using a DVI connection. From what it sounds like, color accuracy isn't important to you anyways though.

Also, just because a panel is not 8-bit doesn't automatically make it bad for games. I cannot notice any ghosting on my 8-bit panel, which is the only advantage that a 6-bit panel has over an 8-bit panel (aside from price). However, this varies from person to person. Since your used to CRTs, what refresh rate do you start to notice flickering at? I would say that if you're fine using 72-75Hz refresh, then you wouldn't notice any ghosting on an 8-bit panel.

[-FMA]

What is your current CRT?
Correct
From a purely theoretical standpoint yes, however read below for some caveats

Your current setup will be better than LCDs in some ways, worse in others.

CRT's have the unique advantage over all TFT LCDs in that they display a true black. When you switch from a CRT to a TFT LCD, you will be annoyed in games for a while because the blacks and dark shades will look really terrible. You get used to it, and if you spend some more time configuring your brightness and contrast correctly in the game settings, then it is bearable. However no TFT LCD will ever have the accurate black levels of your current CRT due to the bleed-through described above. When I first switched, it really bugged me for about a month...but now I don't notice it. Also note that I have an 8-bit panel with the better color fidelity than 6-bits...so it will be even worse if you get a 6-bit panel. Remember, CRT monitors ALWAYS have better color than a TFT LCD panel.

Hmm alright. Thanks!

CRTs may not be as accurate colorwise though due to the VGA connection and the way that CRTs work. Note that LCDs using a VGA connector and/or are 6-bit panels are not any better, only 8-bit panels using a DVI connection. From what it sounds like, color accuracy isn't important to you anyways though.

Well, it is, but not so much, as I'm colorblind Color shading doesn't mean a whole lot to me, and if they're slightly off, I wouldn't even notice.

Also, just because a panel is not 8-bit doesn't automatically make it bad for games. I cannot notice any ghosting on my 8-bit panel, which is the only advantage that a 6-bit panel has over an 8-bit panel (aside from price). However, this varies from person to person. Since your used to CRTs, what refresh rate do you start to notice flickering at? I would say that if you're fine using 72-75Hz refresh, then you wouldn't notice any ghosting on an 8-bit panel.

Hmm. Alright. I don't really feel like spending a whole lot on a LCD, I just wanted something to be able to bring to LAN parties and not have to deal with my CRT. I also wanted to use it for graphic design, that's important too.

Knowing this, I might just get a cheap 6bit LCD and use it just for gaming. And use my CRT for graphic design.

I'd want a 19", and I'd probably pay $250. Would you suggest I do otherwise?

Thanks a lot,

-FMA

[originel]

There are basically two price points in LCDs right now: $200+/- for cheap 19" panels and $300+/- for good 19" panels. Note that you can get 6-bit or 8-bit color depth in both price points. After some searching it looks like 8-bit panels are roughly the same price as 6-bit panels for similar quality (similar quality meaning the quality of a specific 6-bit panel compared with other 6-bit panels falls at some point, and the point where each panel falls relative to other similar panels is the same, not the image quality. Confused?).

So really 6-bit v 8-bit is not about price, it's about preference.

Ultimately the things I recommend looking for are a DVI connection (this is critical IMO) and a name brand with good user ratings. Viewsonic is my favorite, but NEC, Samsung and Dell also make good quality panels with BenQ and LG making decent budget-priced panels.

[StealthyV]

I have the 19" Hyundai L90D+ (8bit) and I am very happy with it. NewEgg had a fantastic deal on this monitor about a year ago, pricing it around $265, when all other LCD monitors of same size were well above $350. I recommend this monitor to everyone who games and everyone who is looking for an extra-sharp display. It has an adjustable base, with weak speakers built-in...perfect for a backup if you have more than one computer plugged into your monitor (think, KVM switch).

review at TomsHardware

~Branson

*just re-read the review...it's actually a glowing review...if you take the time to click through the pages. Looking back at this review, I really don't think I read it before I purchased the monitor, but it's an investment I'm not sore for making.

[originel]

That monitor isn't made anymore...and looking at it's measurements it doesn't look that great. It's response time is uniformly worse than mine, and mine is an 8-bit panel. In fact, I would stay away from this monitor if you're a gamer...there are much better out there. You're probably just not sensitive to refresh rate. Even Tom's hardware didn't have a "glowing" review as you stated...there were several caveats, especially in video playback. Plus it's just a 6-bit LCD, not an 8-bit like you said.

[StealthyV]

actually if you look at the product specifications page, you'll see "16.7 million colors", which makes it clear it's an 8bit panel; a 6bit panel would only display 262 thousand colors.

I have the refresh rate set at 75 Hertz, as 60 Hertz is too flickery for me.

Regardless, there will always be a "superior" product available (except when a monopoly controls the marketplace) and that's just something you have to accept, especially when building your own computer. I'm very happy with the performance of this monitor and still would recommend it.

Also, as for its 'not being produced' anymore, I haven't found anything online confirming this...even their product website still lists it. The only 19" Hyundai Imagequest monitor I see discontinued is the N91S, which is not my model number. But, I'm not interested in straying off-topic.

It's important for every buyer to research the options, then make the best decision for their situation. This monitor has performed well since I bought it over a year ago, and therefore, I maintain zero reservations in recommending its use by others.

I appreciate the dialogue on this topic, and especially the detailed explanation above about the differences between the 6bit and 8bit panels, and how that affects the age-old "how quick is YOUR monitors' response time?"

The original reason I responded was to recommend the Hyundai L90D+ LCD panel and to offer a "review" for consideration, for those who might be interested. I consider Toms Hardware to be a good source of information, and their only gripe was the narrow viewing angle if you're watching DVD's with your friends. Most people have a seperate DVD player and television anyway, so I don't see this as a problem.

Thanks for putting together such a detailed (original) post.

~Branson

[originel]

actually if you look at the product specifications page, you'll see "16.7 million colors", which makes it clear it's an 8bit panel; a 6bit panel would only display 262 thousand colors.

Note exactly, a 6-bit panel shows as displaying 16.2 million colors due to how it does dithering (read my first post). However, it turns out that Tom's Hardware has a typo...they said 16.2 million, hence my 6-bit comment, but the Hyundai site said 16.7, so I assume the mistake is THG's.

Regardless, there will always be a "superior" product available (except when a monopoly controls the marketplace) and that's just something you have to accept, especially when building your own computer. I'm very happy with the performance of this monitor and still would recommend it.

That's certainly your opinion...but I simply cannot recommend it to gamers because there are "superior" products available for less money.

Also, as for its 'not being produced' anymore, I haven't found anything online confirming this...even their product website still lists it. The only 19" Hyundai Imagequest monitor I see discontinued is the N91S, which is not my model number. But, I'm not interested in straying off-topic.

Try and find it on newegg. I mean this literally too. I tried for about 10 minutes and I couldn't find it...possibly because of a hole in my search patterns. This monitor looks like it might be good for people with a low sensitivity to refresh rate or non-gamers.

This monitor has performed well since I bought it over a year ago, and therefore, I maintain zero reservations in recommending its use by others.

Keep in mind that any decent monitor will perform well over time, which means that it's not a good criteria for recommending a monitor. Just because something performs well doesn't mean something else won't perform better (for cheaper).

I consider Toms Hardware to be a good source of information, and their only gripe was the narrow viewing angle if you're watching DVD's with your friends.

Something to keep in mind about THG and why they aren't that great...they tend to be really relative in their declarations. They said the Hyundai was great because it was the best of the group...but they didn't do a comparison with a broad range of monitors in that article. What THG IS useful for is getting performance ratings...you should take their measurements and compare them with their measurements of other monitors. When you do this...the Hyundai looks much less enticing. As for their comments...the person reviewing probably had a high tolerance for refresh rate. This is something that can never be corrected for either, which is why going with the actual measurements is important. Check the measurements for your monitor and compare it with mine. Yes THG loved yours, but look at the difference in contrast stability and latency between ours. The only area where mine is worse is in spatial uniformity...which I have previously stated as the drawback. Suffice to say, this paints a very different picture compared with the opinions expressed in the THG article. And ultimately I think my monitor is the best in it's immediate price range (at the time), but it still has several flaws that keep it from being anything but perfect, so while it has performed well for me, that doesn't mean there can't be something better.

---------------------

This brings up a good point. Using the opinions of others is pretty useless. The best way to shop for anything is to completely ignore any commentary and just look at the numbers. It's a lot harder to fake numbers when measured properly, whereas opinions are just that, opinions. This even includes my opinions expressed about monitors...just look at the measurements for the true story.

[truckpuller]

So from what i read here that the response times are bogus that they give in the spec's for LCD's. This link is too a viewsonic advertising a 2ms response time on a 19" panel.
http://www.newegg.com/Product/Produc...82E16824116375

Iam in the market right now for a new LCD monitor and have been looking around right now im using a Mitsubishi Diamondpoint sb70 17" crt which has a antiglare antistatic coating which is coming off why i dont know and NEC doesnt know.
What about the HannsG monitors in your opinion like this one
http://www.officedepot.com/ddSKU.do?...Ne=5&An=browse

Hope link works
Bye the way great article Original

[carl33p]

Google some reviews on the model you are looking for.

But the HannsG are the cheapest LCDS on the net. Ive seen the 19" going for 150$ after-rebate.(Might have even seen it for 100$ a little while back) So dont expect all that much.

[originel]

The actual response time for the viewsonic is around 12-15ms for most transitions. It's a good gaming LCD, although the color isn't as good since it's a 6-bit.

That HannsG looks pretty crappy. According to the specs, it's very dim, and it's refresh is probably not that great either since the budget manufacturers tend to skew the specs more.