41. How It Works: Screens

By: Dustin Sklavos
From: NotebookReview

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.