How It Works: Screens

by Dustin Sklavos

As the "How it Works" series gets on in the years, it may be helpful to look back at one of its predecessors; in this case, the Notebook Screen Guide I wrote in 2005. While yes, laptops continue to have screens and many traits have managed to stay the same, there have been advances and changes in the market that definitely precipitate a new guide. Since "How it Works" is in full swing right now, it seems fairly obvious that screens should get their due here. After all, we're examining every facet of your notebook to understand how it all comes together, right?

It's easy to underestimate the importance of the screen. Performance characteristics of computers in general often take precedence in peoples' minds; no one goes up to their friends and says "I just got this sweet 15.4 inch screen laptop" when they could say "I just got this sweet Centrino 2 laptop." But the screen is important, especially with your laptop. The screen is the most important part of you interact with your computer, and a bad screen can ruin the experience while a great screen can make it that much more enjoyable. I found on my own desktop that moving to a 21" widescreen made using it more pleasant, and when I made the jump from a 24" LG to a 27" Dell screen, everything became that much better. Being able to use that 24" as a secondary monitor also dramatically improved video editing and even just basic efficiency. Frankly, my computer is a place I really don't mind spending a whole lot of time.

Likewise, a bad screen can ruin your day and make you want to use your laptop less. While the screen on my HP dv2500t isn't going to win any prizes, it's still a good enough screen that it doesn't factor in to whether or not I want to use the laptop itself, and the backlighting even on the lowest setting is still quite manageable. Likewise, I used to have an Asus A8Jm that was a remarkably powerful laptop with such an abysmal screen that it made using the computer a chore. What good is a gaming quality GPU when a game with subtle shadowing like Doom 3 is rendered virtually impossible to see by dismal viewing angles?

So, today I'm going to talk to you about your laptop screen.

How It Works: Screens

Laptop screens may be one of the simplest things to get into while dodging the irritating technical stuff. The vast majority of information is readily available on these, so this guide is going to wind up largely being a "screen decoder ring."

First of all, in order to understand the screen, you're basically looking at these qualities: resolution, aspect ratio, screen size, backlighting, and finish. Before I get into these qualities, a little briefing may be in order as to how the screen itself is designed.

Building A Laptop Screen

Basically, the modern laptop screen is a fixed series of "little windows" called pixels. The pixels themselves each have three subpixels - red, blue, and green. These subpixels are basically tinted shutters. To get a picture on the screen, these subpixels shutter the light from the backlight and together produce the different colors displayed on the screen itself.

While desktop panels are typically one of three types - TN, *VA (PVA and MVA), and IPS - laptop panels are almost universally TN panels. It's important to note that desktop screens are not all created equal, and that TN panels are by far the cheapest (read: least expensive and lowest quality) of the three. They sport mediocre viewing angles and in the case of larger panels, this results in a profoundly non-uniform perception of the coloring of the image.

In laptops, this is pretty much the way of the world, but because laptop screens are smaller they're at least better suited to this panel type. Unfortunately, TN panels also produce generally poor color accuracy. TN panels have 6-bit color per subpixel, totalling an effective eighteen bits of color or a maximum of around 200,000 colors. They then use dithering to simulate the remaining 24-bit color gamut which has been standard for as long as I can remember. This ultimately makes TN panels - and by extension, laptops - less than ideal for doing color sensitive work like video editing and photo manipulation. Try not to take this too seriously, though: the dithering is generally pretty good and you largely wouldn't notice this if I never mentioned it to you. (On desktop screens, this is another matter entirely.)

Another aspect briefly worth mentioning is "response time." Since the image on the screen is created by the subpixels moving to filter light through, motion in the image itself can ghost or blur a little bit. This is where TN panels excel; ghosting is minimal on these compared to the other panel types. Thus, motion appears quite fluid on typical notebook screens, and the response time isn't really an issue.

Resolution and Aspect Ratio

These are going into a section together because they're inextricably tied to one another. Resolution is expressed in X times Y; X is the number of pixels wide the screen is and Y is the number of pixels tall.

Aspect ratio is a profoundly important thing for the modern consumer to know and be aware of. I can't tell you how many times hairs have stood up on the back of my neck in restaurants because someone is running the HDTV at standard aspect, causing the image to appear stretched and squished. This is something easily controlled but no one has been educated about it, so let me spell it out for you.

Aspect ratio is expressed in a similar way to resolution - X:Y, where X is the number of units wide and Y is the number of units tall. Alternatively, it may be expressed as X:1, where X is a decimal value. A screen that is 1.33:1 is 1.33 times as wide as it is tall. You follow?

So here are the aspect ratios in rotation right now:

4:3 (1.33:1) - This is the aspect ratio of standard definition. Your old TV is going to produce a picture three units tall and four units wide. While screens are seldom produced in this aspect anymore, a common resolution in standard is 1024x768.

16:9 (1.77:1) - This is the aspect ratio of HDTVs. It's substantially wider than it is tall, and while this aspect ratio was more or less nonexistent in the laptop market a year ago, it's becoming increasingly popular with the manufacturers as 16:9 panels are cheaper to produce than the next type, which is currently the most common. 16:9 laptop screens are commonly either 1366x768 or 1920x1080; 1680x945 is an awkward half step that has materialized as well in 18.4" screens.

16:10 (1.66:1) - This is the most common computer aspect ratio. While it may be a matter of preference, I personally find this aspect to be the most productive for computing. As humans we read left to right, down a page, so an aspect slightly taller than 16:9 - which is more ideal for movie watching - is typically more practical.

5:4 (1.25:1) - This is a bizarre aspect that used to be quite common but is becoming increasingly rarefied. This aspect only appears with the resolution 1280x1024, a resolution which was common on desktops but rare in notebooks and is now all but extinct.

The only aspect ratios you need to worry about in modern laptops are 16:9 and, more importantly, 16:10. Naturally, in an effort to make things even more confusing, manufacturers seldom refer to these by their resolution, but instead with odd abbreviations. Here's your decoder ring.

16:10 screens come in the following resolutions:
WXGA - 1280x800
WXGA+ - 1440x900
WSXGA+ - 1680x1050
WUXGA - 1920x1200

16:9 screens thankfully eschew these conventions, instead simply stating their resolutions. This is, however, where high definition entertainment and resolution cross paths:
1280x720 (720p)
1366x768 (erroneously referred to as 720p)
1600x900 (odd half step)
1680x945 (odd half step)
1920x1080 (1080p)

Okay, before I go on I just want to point something out: high definition resolutions are often referred to with an i or p at the end; these stand for interlaced and progressive respectively. What you need to know is this: progressive is better than interlaced, and all computer screens are progressive.

Going back to the resolutions themselves, there are a couple of key points to make here. First, the higher the resolution, the more information can be displayed on the screen because there are more pixels. Second, when in gaming, resolution is the single biggest factor in determining the game's performance. A weaker GPU (remember part 5?) is going to have a tougher time pushing higher resolutions, and resolutions above 1440x900 will tax even solid mid-range graphics hardware. Integrated graphics will be lucky to run anything at better than 800x600. Third, the resolution of the screen is NOT the resolution you have to run it at. You can set a lower resolution in Windows or in games, but the trade off is that edges will be slightly blurred. Remember that the number of pixels in the screen hasn't changed, but the number of pixels you've asked it to render has. Rendering 1024x640 pixels on a 1280x800 pixel screen means there's going to be some softening of the edges involved.

I haven't mentioned every single resolution that appears in laptops here, but you should now be able to understand what the resolution is, and using simple math you should be able to calculate the aspect ratio of any given laptop screen.

Now, moving on.

Screen Size

Okay, so how big is the freakin' screen? Screen size is measured in a diagonal line from opposite corners of the screen. It's important to note the relationship between resolution and screen size here, because it directly affects the usability of the screen itself.

Let's say we have a 15.4" screen and a 17" screen, and both have a resolution of 1440x900. The 15.4" screen will be harder to read because the pixels comprising the image are physically smaller. At 14.1" this issue is only exacerbated, so it's really going to depend on how good your eyesight is and what's comfortable for you.

Because the screen is the largest single part of the laptop, the screen size typically defines the size of the entire machine. A 15.4"/15.6" is going to be a standard middle of the road mainstream unit, running at least six pounds and generally closer to seven. 14.1" and smaller are more and more portable, while larger than 15.6" are desktop replacement class and much less portable as a result.

Now, the screen size itself can be a useful tool for determining the aspect ratio of a screen and, to a lesser extent, the resolution. Next to each screen size I'll list the lowest (and often most common) resolution and in parenthesis the other resolutions screens of that size come in.

16:10 screens:
12.1" - 1280x800
13.3" - 1280x800 (1440x900)
14.1" - 1280x800 (1440x900)
15.4" - 1280x800 (1440x900, 1680x1050, 1920x1200)
17.0" - 1440x900 (1680x1050, 1920x1200)

16:9 screens:
11.1" - 1366x768
13.1" - 1366x768 (1600x900)
15.6" - 1366x768
16.0" - 1366x768 (1920x1080)
16.4" - 1600x900 (1920x1080)
18.4" - 1680x945 (1920x1080)

This is still missing some resolutions on the extreme sides - the netbooks and the units charitably called notebooks - but should be a pretty good, clear indicator. I've neglected to include standard aspect screens as they're all but dead in the mobile market and will almost never be seen in the wild.

Backlighting and Viewing Angles

Remember how I mentioned earlier that the screen on your laptop required backlighting? There are two types of backlights on the market: CCFL (cold cathode fluorescent lamp) and LED (light emitting diode).

CCFL is the old tried and true standard, and what most laptops have. It draws more power than LED backlighting does and generally produces a more washed out picture than its counterpart. Additionally, CCFL tends to result in a phenomenon called backlight bleed, where the lamp results in uneven lighting of the image. Since the CCFL is generally in the bottom of the notebook panel, on a pure black screen you may notice the top of the screen is much darker than the bottom. In a particularly bad notebook where the bottom of the screen bezel isn't properly affixed to the screen itself, you may even be able to see the backlight itself. CCFL screens also tend to have poorer viewing angles than their LED counterparts, partially due to this poor quality lighting.

So why is CCFL more common? It's presently cheaper than LED backlighting. When custom ordering a laptop, LED backlighting may cost an extra $100.

LED backlighting provides a much more even lighting of the image, somewhat better viewing angles, and a much brighter and more vibrant picture overall. It also draws notably less power than CCFL backlighting. The industry is transitioning to this at present, as it can also be potentially cheaper to produce than CCFL lighting.

I do want to point out that while CCFL is being presented to you as godawful, it IS the old standby, and a well made CCFL screen can still be very pleasant to look at.

I'm including viewing angles in this section because the lighting method used does affect the viewing angles of the screen. You may note when looking at a laptop from above, below, or the sides that the picture washes out a bit (or a lot). This is the nature of the beast with TN panels, which are most readily identified by their dismal below viewing angles that cause the colors to invert. If a screen has bad viewing angles, it may be impossible to produce an even image from looking at it dead on. Some laptops do have excellent viewing angles, though, but they're typically the more expensive ones.

Surface Finish

The last section here is the finish of the screen itself, of which there are two kinds: glossy and matte.

The glossy finish is vastly more common than matte, which is fortunate or unfortunate depending on how you look at it. A glossy finish on the screen will make it appear brighter and the colors more vibrant, but the trade off is that the finish itself is very reflective. Some manufacturers are even using multiple coats in some instances, which would produce a fantastic image if you couldn't style your hair in it.

The matte finish is the old standby, and a lot of desktop panels still use this. While color may seem a little bit dull compared to the glossy finish, mattes are far less reflective and a lot of more seasoned computer users tend to prefer these in the long run (myself included). These are unfortunately becoming rarefied, but business class notebooks still use these much more often than consumer grade hardware.

This is all a matter of taste, honestly. Glossy or matte isn't a dealbreaker for me on my laptop the way it is on my desktop. The overwhelming majority of screens in retail are going to be glossy, while manufacturers like Lenovo tend to prefer mattes.

Conclusion

This is another one of those articles where I can't give you much of a helpful rundown at the end nor offer recommendations, and this holds true from the last time I talked about screens.

The fact is that screens tend to be very subjective. My girlfriend, for example, has a 1920x1200 resolution screen on her 15.4" Dell. That's way, way too high resolution for me. Text is tiny. But she also has better than 20/20 eyesight while I'm blind as a bat. Likewise, a lot of gamers recommend getting the lowest resolution screen you can for your laptop so the graphics hardware isn't stressed too hard and thus produces a much sharper, cleaner image. And don't get me started on glossy vs. matte. Some people intending to use their laptop as a portable media device may be happy with the influx of 16:9 screens in the marketplace, while stalwarts like me vastly prefer our 16:10 screens. In applications like Adobe After Effects and Premiere Pro, for example, that extra 32 pixels at the bottom of the screen means enough space for one more timeline, while Photoshop users are oftentimes going to want the tallest screen they can get.

So it's going to be a matter of taste for you, but the nice thing is that you can go out into retail and generally see what the screen looks like and get a proper feel for it yourself. If you're thinking of custom buying a laptop from a manufacturer, retail is a great place to see what you'll be getting yourself into. Just don't sell yourself short on the screen. It's how you interact with the computer itself, and if it's a lousy screen, you're not going to want to use the laptop if you can avoid it.

Coming Up: Battery

Next time I'm going to talk about the battery of your laptop and how not all machines are created equal.

 

Informative article but it misses information I wanted most: what about the screens in the top of the line mobile workstations, using not typical LED but RGB LED backlight (the HP Dreamcolor, the Dell 100% Adobe RGB screen). What panel tech do they use to achieve the claimed color fidelity? There's a lot of info lacking in this area and I hoped to see it cleared in this article.
Dragos

 

Nice work man

 

Really great article! The importance of a good screen is definitely underestimated.

One minor gripe though: as I interpret it, the article makes it seem like only CCFL screens exhibit backlight bleeding, which is far from true. Although LED should be better in theory (and often is in practice), backlight bleeding can also be caused by improper assembly of the display itself and its mounting in the laptop. For instance, if excessive pressure is put on some parts of the panel during assembly, it could result in backlight bleeding. And of course, there will never be such a thing as perfectly even backlighting, since itis inherent in this technology. OLED can't come soon enough

It would also be nice to bring up these major quality fluctuations (backlight bleeding, viewing angles), and also the notion of "panel lottery", in an article like this.

And finally, a question. Would glossy screens make backlight bleeding easier to see due to the fact that it oversaturates colors? My experience has generally been that the worst backlight bleeding has been on glossy displays.

 

I just ordered a laptop that is
17" WUXGA "Glare Type" Super Clear Ultra Bright Glossy Screen (1920x1200)
What does WUXGA mean exactly? "Glare Type"? and the rest?
All I understood was 17", Glossy and 1920x1200...
Anyone wanna give me a hand?

 

-> potenty, that line states:
17" - size
WUXGA - the resolution (same as the bracketed numbers)
"Glare type" - glossy
the rest is marketing mumbo jumbo

 

-> pulp
i need to ask you a thing (or two). if it's an informative article on notebook screens... my question is this - in an lcd which colour displayed by the screen would eat less energy? black, as it was in kinescopes (no rays that burn out the colour), or maybe white (if i understood it correctly lcds' subpixels take energy to cover the light from the backlight device thus subtracting their colour from the pixels colour, therefore white, when all the three subpixels "shine" would mean no energy on stoping either subpixel and thus power economy)?

 

Maybe thats why I didnt understand. Many thanks mate.
I wish these companies would get rid of all the mumbo jumbo... Sometimes it gets so annoying... Like the time I got pissed because I found out my 160GB hard drive didnt have 160 GB....

 

other potentially useful facts:

+ bleed caused by light leaking from the backlight and screen not being perfectly aligned in the housing. uneven lighting is the artifact that occurs in CCFLs that do no create equal amounts of light at all points.

+ backlight is only part of the equation for viewing angle. the other is the surface coat. the surface coating can diffract the light emitted, causing wider viewing angles.

+ wider viewing angles = energy that is wasted (it's not a free feature). if you do not share your notebook, then sending information (photons) at widely varying vertical angles is a waste of energy. that translates to lower battery life.

+ ccfl's contain mercury (as do most fluorescent lamps), a hazardous material and toxin, which is now found in excessive levels in larger fish and humans that consume fish.

 

also should mention different types of panels etc...

 

quoted from anandtech:

Table of Contents

1. Criteria
2. Types of Panels
3. Aspect Ratios and Resolutions
4. Technologies
5. "Ghosting"
6. Backlight Uniformity/Leaking
7. Common Misconceptions
8. Color Reproduction
9. Recommendations
10. Specific Problematic LCDs
11. Review Sites
12. Appendix A: Helpful Links
13. Appendix B: Index of Reviews
14. Appendix C: LCD Module Reference

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1. Criteria
----------------------------------------------

* Color Gamut and Color Depth

Colors in computer systems are stored as an array of three elements: Red, Green, and Blue. Typically, each of these is a byte (8 bits) long. This is where you get the 24-bit color mode you're so accustomed to. Or, maybe that is 32-bit color, which is actually Red, Green, Blue, and Alpha, where each is a still a byte, but the alpha simply specifies transparency so you are still really limited to R, G, B in the end.

The color gamut describes the domain of the monitor's reachable area in the color spectrum. The actual gamut can be seen as three values, being the X coordinate, Y coordinate, and Z coordinate (in a CIE xy chromacity diagram). Color depth refers to the granularity of its color gamut, that is, how far apart each of the values are within the (X,Y,Z) area. That means, if you keep the color depth at 8-bit, and increase gamut from 72% to 92% of NTSC (US TV standards), you will lose color precision (colors will be farther apart) but you will have a wider range (maximum-minimum) of colors that you can display. This is why working on photos captured in a 72% space on a 92% LCD is a bad idea. 92% LCDs can not reach the precision of 72% LCDs, given the same color depth.

All LCD monitors can take in the 8 bits (per color component), but not all can actually display them. To display them they employ psychovisual methods of emulation such as dithering (grid patterns, spatial [over area]) and FRC (frame rate control, temporal [over time]). These are used to trick human eyes (and even colorimeters) into viewing a color 1/4~1/2 way between two emulated ones.
* Black Level (brightness of the color black)

Transmissive LCDs (the predominant type used in computer monitors) require a source of light behind the panel to display an image. Most today use cold cathode fluorescent lights (CCFLs), while more expensive ones use LEDs. With either technology, the crystals have a hard time blocking the light. How well they can do this is quantized by the black level. This measures how many nits (candelas per square meter) are emitted when black is displayed. This value is ideally zero nits. A low black level and high white level value will produce a high-contrast display, and that's what you're looking for in terms of colors.
* Response Time

Response time measures how long it takes for one crystal cell to change its state from on to off. Some types of panels are faster than others in this category. The lower value of time (usually milliseconds) means a quicker change. A high response time can cause blurry/streaky effects in motion. A technology called Overdrive (ODC, overdriving circuit) can assist in reducing these effects.

Overdrive is not perfect. It takes advantage of the phenomenon where crystals transition faster when put under a high voltage (and likewise slower under a low voltage). However, it can push this voltage too high, resulting in bright artifacts around moving objects. The opposite can happen with reverse overdrive which droops voltage and can result in dark artifacts.

* Viewing Angle

The viewing angle measurement measures the angle at which you can view an undistorted picture. On TN panels, the colors will invert when viewed at an extreme angle. VAs will generally just wash out, but with little color shift. IPS panels exhibit the fewest abnormal effects when viewed at a different angle (they decrease in brightness just a tad with very little color shift).
* Video Inputs

Many monitors come with both a DVI (Digital Visual Interface) and VGA (Video Graphics Array) interface. DVI will deliver a perfect picture in terms of geometry due to its digital nature. VGA, analog, can sometimes be noisy or blurry. Generally the difference is insignificant with a powerful RAMDAC (digital->analog converter on the video card) and a good analog input on the LCD.

Multimedia LCDs may even feature HDMI (arbitrary-bandwidth digital video and audio interface), component (YPbPr), S-Video, composite (Y/C) inputs. These are typically paired with PIP (picture-in-picture) and/or PBP (picture-by-picture).

Video quality ranking (1 is best):

Digital

1. HDMI (165 MHz+)
2. Dual-link DVI (310 MHz)
3. Single-link DVI (165 MHz)


All digital connections provide the same quality picture. HDMI and dual-link DVI can reach higher resolutions and refresh rates than single-link DVI, which will simply fail at higher bandwidth (resolution * refresh rate).

Analog

1. VGA (~350+ MHz@-3 dB)
2. Component
3. SCART
4. S-Video
5. Composite


Analog connections can carry an infinite resolution and refresh rate but also decrease with quality at higher bandwidth. Thus, the image is never perfect but it can be more than ideal.
* Ergonomics

LCDs can be very flexible with physical adjustments. These may include height adjustment, tilt, swivel, and pivot (portrait/landscape).

It shouldn't come as a surprise all measurements are biased when it comes to manufacturers' specifications.

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2. Types of Panels
----------------------------------------------

The most important thing to consider is the type of panel in the LCD.

(Please note that no guarantees are made regarding the accuracy of the scientific details of these panels.)

* TN (Twisted Nematic): Without Overdrive, this type of panel offers the fastest pixel response time. This does however come at the expensive of viewing angles and color fidelity. Out of all TFT-LCD panels, the TN type has the lowest contrast. It is also a 6-bit color depth panel, meaning dithering or frame rate control (FRC) must be employed to reach close to a full 8-bit depth. Pixels in their active state on a TN are black, while in their inactive, white.

* (P-)MVA ({Premium} Multidomain Vertical Alignment): The liquid crystal (LC) cells on MVA panels are in their active state white, and in inactive black and are separated into four domains. This slightly improves viewing angle over TN-type displays (MVAs provide ~45 degrees). MVA panels also provide a high contrast ratio. Grayscale inversion is minimal on these displays. Response time is the second slowest in the industry without ODCs. MVAs and all derivatives hide details at a perpendicular viewing angle due to their multidomain nature. Cells are never perfectly vertical or horizontal in an MVA, but they can be very close.

* PVA (Patterned-ITO Vertical Alignment): Developed by Samsung, PVA is very similar to MVA. Viewing angles are very similar and inversion is minimal at wide viewing angles. Samsung is not clear on the true color depth of these panels. These panels deliver the slowest response time. Cells are vertical when light is blocked, and horizontal when light is let through.

* S-PVA (Super Patterned-ITO Vertical Alignment): These types of panels deliver a full 8-bit color depth and have a structure split into eight domains. At wide viewing angles, they have less color shift and a lower black level than MVAs. According to Samsung, they have a higher contrast ratio and better response time than MVAs as well.

* S-MVA (Super Multidomain Vertical Alignment): Likely similar to P-MVA from AU Optronics, Chi Mei Optoelectronics has developed the S-MVA type of panel. These also include multidomain, vertically-aligned liquid crystals so that the cells stay in the same shape at different positions, increasing brightness at wide viewing angles. According to CMO, S-MVA improves viewing angles from conventional MVA types to 80 degrees in all angles. Like other types of panels, response time has gradually improved on these as well.

* IPS (In-Plane Switching): The IPS panel was pioneered by Hitachi to fix the problems that plague the VA and TN types. Like TN, most IPSes contain only a single domain, although DD-IPS (dual domain IPS) does exist. This technology sports the least distortion at wide viewing angles. Two transistors per each pixel are needed, so brighter backlighting is crucial and power consumption is higher than competing technologies, but response time benefits greatly from this. Color depth varies. One disadvantage is that a purple-black is now introduced in black colors at different viewing angles.

* S-IPS (Super In-Plane Switching): LG Philips LCD improved on IPS with their S-IPS technology. These offer a lower black level, higher contrast ratio, lower response time, and a wider viewing angle than traditional IPS technology. Color depth on S-IPS panels is 8-bit. The purple-black tinting still applies to wide viewing angles, but orange and red hues are greatly reduced versus other technologies at wider viewing angles.

* AS-IPS (Advanced/Enhanced Super In-Plane Switching): These type of panels are LG Philips LCD's third generation of IPS technology. This is mainly just a wieldy moniker for improvements in the front-end driving electronics, including ODC to reduce response time, and a dynamic contrast ratio technology, raising contrast up to 1600:1. The diagonal viewing angle is also increased to 178 degrees, from 170 on S-IPS panels. AS-IPS panels very often include much brighter backlights than S-IPS types.

* A-MVA (Advanced Multidomain Vertical Alignment): This is a new panel from AU Optronics promising contrast ratio and viewing angle performance comparable to Samsung's 8-domain S-PVA panels. These should be capable of true 8-bit color. Still, it is unknown if ODC will force them to dither.

Still confused? Check out the Matrix of all Matrices.

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3. Aspect Ratios and Resolutions
----------------------------------------------

Aspect ratio is a fraction or rational number (width divided by height). Common aspect ratios are listed below.

* 5:4 (1280x1024 for 17" and 19"): Squarest of all the listed, thus maximum area.
* 4:3 (1600x1200 for 20.1")
* 16:10 (1680x1050 for 20.1", 1920x1200 for 24"): Resolution of most "widescreen" monitors
* 16:9 (1280x720, 1920x1080): True widescreen. No LCD monitors that I know of incorporate this HDTV resolution with a few exceptions (HTPC monitors). 16:10 is the commonly used one for monitors because it's a good compromise between productivity (Word documents anyone?) and movie watching.

As for scaling quality, it first depends on if you tell your graphics card to do it, or your monitor. If you find your monitor's scaling is sub par, you can engage your graphics card's scaler. In addition there are a number of scaling modes, like 1:1 and fixed aspect ratio scaling. Many monitors deliver OK scaling when viewing photos, however text clarity can easily suffer. Games may not look very pleasing at lower resolutions, mainly due to aliasing (jagged edges) and inconsistency.

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4. Technologies
----------------------------------------------

* Overdrive (Response Time Accelerator)

Most commonly called ClearMotiv (ViewSonic), MagicSpeed (Samsung), Over Driving Circuit (LG.Philips LCD), and Response Time Compensation (X-Bit Labs). All of the above technologies bump the voltage to increase the speed of the transition (among other things in the case of ClearMotiv). When it goes too far (an overshoot), there can be noise, especially noticeable in subtle transitions or the dithering of TN panels. Tom's Hardware Guide does however have a rating for this overshoot phenomenon. X-Bit Labs has also cracked down on it in their recent reviews.
* "Widescreen" (16:10 AR)

Usually widescreen means 16:9, but LCD monitor manufacturers use the moniker widescreen to refer to a 16:10 ratio instead, a compromise between desktop real estate and movie watching. While it may sound great at first, there are a lot of things to consider. Is widescreen all it's cracked up to be?

The main problem with widescreen is the resolution itself. As you may know, LCDs can not change their resolution without a loss of quality, and most of the time it's a significant loss of clarity. CRTs can do this much better because they inherently have a Gaussian distribution of the pixels, and in the end it yields much better quality. Think of it like analog zoom vs. digital zoom.

This means in order to get a good image on a widescreen monitor, you must run it at its native resolution, or deal with black bars on the edges. I'd say 50% of today's games still require you to edit a configuration file manually to achieve the widescreen resolution. Fortunately, many people have already done the grunt work for you. Here's a site that will help you configure your game to work with your widescreen LCD: Widescreen Gaming Forum

But, not all games can support widescreen, even through the configuration file. For these, you'll have to settle with a game/DirectX DLL proxy hack (if it exists), or use black bars/scaling.
* X-Brite/OptiClear/HP BrightView/Acer CrystalBrite

These are glossy, contrast-increasing coatings. Note, Samsung's MagicBright/MagicColor and BenQ's SensEye are not necessarily related to these, they are internal panel technologies. Anyhow, many people prefer the higher contrast of these coatings and say they look beautiful. One small note of concern is they could increase reflective glare, but that'll depend on the ambient lighting surrounding you. These types of panels do reduce another type of glare (ambient light emanating among the panel, much like a burning effect). Instead the reflections come right off of it and do not affect transmissivity.

Details: http://www.screentekinc.com/pixelbright-lcds.shtml
* HDCP

High-Bandwidth Digital Content Protection. This will be mandatory for playing Blu-Ray/HD-DVD discs on Vista (or any other OS). You won't need it to boot into Windows though (not even Vista). HDCP can be used through the DVI port or through the HDMI port. It's hardly anything to worry about for computer monitors (very few have it), but you should definitely consider it for multimedia monitors and TVs.
* Hi-FRC (pdf)

This is a new form of FRC (temporal "dithering") developed by Chi Mei Optoelectronics that makes up for the colors lost in conventional FRC (3 tones, (256-3)^3=16.2M). When a color value of 1 is requested, it is remapped to 0.25, 2 to 0.5, 3 to 0.75, and then 4-255 are created by the regular FRC method. The end result is 16.7M colors.

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5. "Ghosting"
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Maybe you've looked at LCDs before, and find the colors great, the viewing angles good, but one thing you are especially worried about with your future purchase is the response time. There's a fundamental problem in explaining how good or bad the level of ghosting is. This may be the only way I can relate it to you: if you've ever used an aperture grille CRT and seen its faint lines but still love it regardless, the same thing will probably happen to you with response time.

Obviously the first week you get it, that's the first thing you're going to look for, because for most gamers it's the obvious disadvantage. So you bring your LCD home, plug it in and play some Battlefield 2 on it, then turn around a bit, and you can see some smearing. At that point, you're probably already thinking of returning it and thinking you'll never be able to live with it. In reality, once you take your focus off scrutinizing the ghosting and start playing your game, you will find it to be an extremely small obstruction, if it is any problem at all. In the end, that's all that matters. It's also worth noting some people may not even be able to see it if they look for it. Unless you have a panel with an atrocious response time like 25 ms. (min), then it will be a minor issue. That said there are some people who may be especially sensitive to it.

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6. Backlight Uniformity/Leaking
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Unfortunately, this can vary a lot per unit. If uniformity is bad, some places on the panel will be slightly brighter than others. This still occurs today, especially in cheaper monitors. However even more expensive ones have their share of duds, such as the VP191b/VP930b, which many users have had leaking issues with, along with some of the Dells. But like I said, this will vary per unit. The majority of the time, this is not a serious problem.

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7. Common Misconceptions
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* An IPS or VA panel is always 8-bit

Just because the crystals themselves have the ability to twist that accurate does not necessarily mean the driving electronics can support it. Don't rely on this. For instance, the Samsung 970P and ViewSonic VP930b use a form of dithering/FRC.
* "16.7 million colors" is a connotation for a dither-free 8-bit panel

You cannot count on this measurement to be true among manufacturers.
* A lower-listed response time on the specifications is always faster

This is very untrue. Manufacturers can measure the response time any way they so desire. Gray to gray, white to black and back to white, only the rise time, only the fall time, or any combination of those. One manufacturer's "20 ms." can be another's "4 ms." Beware. For example, the Samsung 940B is rated as 8 ms., but it reaches 35 ms. most of the time.
* Contrast ratios

Usually the contrast ratios are grossly overrated on spec sheets and there's no telling if they're using the standard ANSI method.
* Viewing angles

This is yet another inflated spec. 160/160 can mean 80/80 up/down and 80/80 left/right or 40/120 up/down and 90/70 left/right. You can't tell. Some manufacturers will list their method as CR>5 or CR>10, this means it maintains a contrast ratio>x at y angle. But there will still be immense distortion on some panels, particularly TN. It does not take that in to account.
* Bigger is better

When you compare a 17" to a 19" which both have a 5:4 1280x1024 resolution, the 19" only has bigger dot pitch. This means your display will be grainier in general, though text will be bigger for the visually-impaired. Unfortunately, manufacturers are mostly only spending R&D on 19"+ panels nowadays, and some are even cheaper than their 17" counterparts.

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8. Color Reproduction
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6-bit LCDs can truly only produce 262,144 colors ((2^6)^3). Thus they must implement a dithering or frame rate control technique to simulate up to 16.7 million colors. These techniques still don't reproduce colors as good as 8-bit panels that don't use the dithering. More primitive forms of dithering can only reach 16.2 million colors (253^3=16,194,277). True 8-bit PVA and IPS panel LCDs can produce 16,777,216 (16.7 million) real colors ((2^8)^3). And to recap: not all PVA and IPS panels are driven by "true" 8-bit electronics, so they could still use dithering! As another precaution, LCDs do tend to have problems reproducing skin/subtle tones vibrantly.

 

nice guide. +rep

 

I agree with the poster that says LED's can have light bleed as well. T500 screen has MUCH more light bleed than my old acer screen.

 

Thanks for good article!

I am trying to figure out two things:

1) it is sometimes possible that you can install a screen with slightly higher resolution than the native one, and the notebook will work with this higher resolution screen? Which factors are to pay attention to then? Specifically, I am considering to try 1280x800 screen on my subnotebook with 1280x768 (intel 915 graphics). Does it have chances to work?

2) is it possible to increase the brightness of the screen by moding the invertor and/or upgdading the bulb to a brighter one (though it is problem itself to learn if the bulb you're going to purchase is any better than the one you have)?

 

and yes 100% led screen can and do bleed light. the thing about the way they usually look is more like bright bars going from bottom to top across the screen if they show the bleeding

 

Very informative and well-written. With the current flood of 16:9 laptops available, it's more important than ever to understand the differences in display resolution, backlighting, etc.

I chose a WXGA+ (1440x900) LED display for my DELL Studio 15 for all the reasons mentioned in this article. I'd be interested to know if there is any hard data showing how much less energy an LED backlit display uses compared to a similar CCFL version? How much difference is there in weight between displays with each type of backlight?

 

Neither the article nor zfactor's anandtech.com C&P mention the latest twist on some newer machines - glass overlays which extend to cover the bezel. For example, HP labels their version the "Infinity" screen.
The advantages: protects the screen from scratches and cosmetically makes the bezel look like part of the screen - all glossy right to the edge.
The big disadvantage: the slightest reflections off the glass are some distance above the screen - causing the eye to jump to a second focal plane. After some time in certain conditions, this can cause tremendous eyestrain for some people.

 

^em,never experienced that

 

I'm not sure if it was mentioned, but I'd talk about dead pixels and LED vs non-LED screens.

 

Very nice.

But I am still wondering if LED is glossy or Matte of both?

 

I'm kind of an idiot so I'm probably butchering this explanation, but I believe the LED refers to the backlighting (so you can see the screen), and the glossy and matte coating refers to the coating above the pixels.

So... facing you it's matte/glossy coating, LCD technology (TN or whatever), and then backlighting (CCFL or LED).

At least I think that's what it is...

 

As Naris has said, it can be both. LED is a type of backlighting of the screen, whereas glossy and matte are types of coating on the screen itself. So you can have CCFL and LED backlit screens with glossy and matte displays.

 

Ok. thankyou

So there are glossy and matte LED screens

 

Great article which gives a great overview of the screens available on laptops today.

 

I'm really not impressed by LED screens. I've had an m1530 w/ LED screen for a few days (before I returned it) and besides the horrible backlight bleeding, it was just way too bright to be useful. My current "eco-bright" screen is so much better and more comfortable to use than the LED one and deserves much more recognition than it actually gets.

Thanks for the very informative article!

 

This is a great article....lot's of great information!

My next lappy is going to have a LED



Cin

 

anyone care to answer my short question (page 1 of the thread, by the end of the page)?

 

my question on page 2 is also left unanswered.

 

1) yes you can easily change the panel to a higher res one AS LONG as the gpu can handle that res. so if it was either originally offered as a option or with say a external monitor it will work at the res you want then get a replacement panel at that res.

2) no. there is little to nothing you can do here. you can replace the bulb but it requires the know how and you have to dissasemble the screen itself. i do not suggest it. and the inverter can not really be modded easily. maybe if you have the know how the voltage can be stepped up that goes to the ccfl bulb but then you stand a chance of shortening the life or possibly blowing it out unless you know the exact specs of the bulb used.

i have swapped inverters a few times and they did make the screen either brighter or dimmer but this was only on one or two occasions.

 

depends some panels "rest" one way or the other. some have the "shutters" (lol) open unless told to close or visa versa some will have them closed normally. but generally either way the main energy drawn is from the ccfl bulb which remains on whether its black white or whatever color.. if you want to save energy turn down the brightness otherwise the difference will be negligable

 

but it will be there... and sometimes it's a matter of seconds when you click the save icon before your lap dies