Choosing a new (laptop) monitor – what do we have to know? (Part 2)
Last week we introduced you to the first steps you have to make before buying a new monitor. We touched upon setting your goals, choosing a resolution and screen size, and what the difference between them are. You also learned about the main matrix types – what their advantages and disadvantages are, and which one will suit you best depending on the things you will be doing.
At the end, we promised a second part that will cover questions like “What backlight should we choose?”, “What is pulse-width modulation and how do we protect our health?” and “What finish should we choose?” A promise is a promise, and the in the article you are now reading we will do our best to answer these and even more questions that could be of help.
Choosing the backlight
The third step in our journey to the desired monitor is also very important as two things depend on it – color richness and working comfort, the latter of which greatly reflects on your health. In order for an image to be visible, the matrix is illuminated (except for the organic matrix – OLED that we mentioned at the beginning – it emits its own light) by a special source whose specifications and work mode define the aforementioned color and work comfort.
The backlight is in the basis of color quality, color space coverage (and hence – the adequacy of the monitor for serious color-centric work) and last but not least – less eyesight strain. When combined with FRC technology, pulse-width modulation offers stunning colors. But let us discuss the health-related aspects of it.
Color space coverage should not be mistaken for color depth (the number of colors a matrix can actually reproduce). The spectrum of colors visible to the human eye can be graphically displayed with the so-called CIE diagram. One part of these colors (the ones in the now standard sRGB color space) are used on the Web. It is desirable that the monitors we are going to use for surfing the Internet or watching movies cover them as best as possible. If there is a missing color, it will have to be replaced with the closest option possible, which is, in fact, a wrong color.
If we are going to use the monitor for creating and publishing images, this color space has to be covered completely. Even more than that, if you are into photography, advertisement, or prepress, you should be looking for a monitor that covers almost 100% of the wider Adobe RGB color space.
What role does the backlight play here?
Every pixel usually has three subpixels for the three main colors – red, green, and blue (RGB). Light from the backlight goes through the filters of the subpixels and enters the human eye. Depending on the brightness of each subpixel, the resulting mix of the three main colors creates the corresponding visible color. So to have a specific color there needs to be something passing through those filters. Let’s make an analogy with some delicious cooked rice and vegetables, where the pot is the monitor and the slotted spoon is the matrix. Let’s say you suddenly decide you want rice with chicken. No matter how much you stir the spoon, you won’t be able to find any chicken because there wasn’t any in the first place (users of a backlight known as WLED are in a similar position).
In our case the backlight, unlike the sun, can’t offer the full spectrum of light – the one that when put through a prism dissolves into all the colors of the rainbow. But we don’t need all the colors. We only need light with peaks in the areas of the three main colors – red, green, and blue. What is the current state of technology and which backlight is best for you? If you are buying a monitor for accounting, or your kids want to play more action games, you should skip this part and go straight to the pulse-width modulation (PWM) section since it bears some importance when your eyesight is concerned.
LED (Light-emitting diode)
We will begin with what’s most common – namely light-emitting diodes. The semiconductor elements in question are usually arranged on a strip, and their light is diffused and directed to the matrix. To lower the thickness of the panel, the backlight is placed on the sides, and the light stream is redirected and distributed evenly along the whole surface of the display. Depending on the brand and model of the screen, there can be differences in the precision of light coverage of the backlight in different areas of the screen in terms of brightness and color temperature.
If the monitor is for gaming, in most cases potential issues are not of significance. For professional work, a compromise can be made with a quality matrix that has an uneven backlight, priced only twice as much as a good gaming-grade monitor (instead of five times, let’s say), which would drive the user to choose one model over another. In this respect, our goal here is to show you the necessary graphics and images in every review.
For exact colors, white balance and broad color space coverage we need 3 diodes with the three main colors – red, green, and blue (RGB LED). The cheaper alternative is the so-called “white” diode – White LED (WLED). We put the word “white” in quotation marks because they actually emit blue instead of white light. We can’t help but remember the anecdote about the kid who asks its mother:
– Mum, what is this fruit?
– Blue plum.
– But why is it red?
– Because it’s green.
“White” LEDs are blue with a yellow phosphorus coating whose spectrum characteristics are constantly being enhanced by manufacturers. It is those spectrum characteristics that dictate image quality. Even with all the improvements they still have a significant peak in the blue area, while red and green are lacking.
The GB LED is a relatively new type of backlighting. As you might have guessed from the abbreviation, it consists of green and blue diodes with red phosphorus coating. They are even suitable for professional work.
CCFL (cold-cathode fluorescent lamps)
The second backlight type we would like to cover is fluorescent lamps with cold cathode – CCFL, that is now losing popularity. Similar to energy saving lamps, they are thin glass tubes filled with gas and have a phosphorus coating on the inside. They are more expensive to make, consume more electricity, have shorter life-spans than diodes, and their performance changes more quickly. However, high-quality models have much better spectral characteristics and continue to be used in high-end monitors. The similar could be said for their life-spans. Mass-produced LED backlit monitors have a minimum life of 15-20 thousand hours (according to manufacturers) and elite CCFL monitors have a life expectancy of 30 thousand hours (or 5 years, whichever comes first).
If you see CCFL in the monitor specifications, it would mean that it is either a really old consumer model, if combined with a TN matrix, an old professional model – combined with H-IPS, or a new monitor with very exact color reproduction, where CCFL backlights still “hold the line” against LED diodes (you will recognize it by the price).
The range of colors visible to the human eye can be displayed with a CIE Uniform Chromaticity Diagram. With the help of a CIE 1976 Uniform Chromaticity Diagram you can get an idea of the color gamut coverage and color accuracy of your device. On the inside of the black triangle are placed the standard colors used by digital TV and the Internet – rec. 709/sRGB, and the wider Adobe RGB color gamut is reserved for high quality camera and images meant for printing. The limits of the human visions are marked as well. The colors inside the black triangle are used practically everywhere by millions of users, so their correct rendering is crucial. The yellow triangle – Display1 illustrates the capabilities (color gamut coverage) of a specific display in the marketplace (same goes for Display2 and Display3).
Pulse Width Modulation of light emitted from LED and CCFL
Pulse Width modulation (PWM) is an easy way to control monitor brightness. When you lower the brightness, the light intensity of the backlight is not lowered, but instead turned off and on by the electronics with a frequency indistinguishable by the human eye.
In these light impulses the light/no-light time ratio varies, while brightness remains unchanged, which is harmful to your eyes. If there is PWM, it is better to have a high frequency of around 20000 times per second instead of, say, 200. This is noticeable at different brightness reduction levels for different monitors. It is more expressed in LED than in CCFL backlight due to the former’s lower afterglow and higher nominal diode brightness. Brightness of about 200 cd/m2 is enough for games and movies in a well-lit room, so don’t be too proud if you have bought your child a monitor at a “good” price and double the 200 cd/m2 maximum brightness, and you find them working in a room with lighting turned off and a darkened display.
We’re showing you the waveforms of 4 displays. The first one doesn’t emit pulse-width modulation, which provides the option to work for extended periods of time. The second is a classic PWM. Its aggressive pulsations with low frequency put extra pressure on the eyes and brain. The third also emits PWM, but it has extremely high frequency, which is considered to be less harmful. The fourth one doesn’t flicker unless the brightness is <25% so it is eye-friendly on practically every normal usage mode.
There are many ways to analyze PWM in every display. Below we will show you an easy method of examining an aspect of great importance to your health when choosing a monitor. In the first image, there is a display with black screen and a vertical white line.
Just like the car headlights from the second picture, if the monitor is moved quickly in front of your eyes and the process is photographed, there should be a blurry image as in picture number three.
This is a real photo of a working CCFL backlit monitor with brightness close to the maximum (90%).
The fourth picture is a photograph of a display taken in the same way, but this time of a fast laptop screen with an LED backlit TN matrix and high brightness. At the moment of taking the photograph, the screen brightness is lowered to 40%, but the brightness of the diodes remains the same, they just light on and off like a strobe light in the disco, only many times a second so that your brain can not interpret what your eyes are seeing.
In those two photos, we have chosen the two extremes of the case. In the first, the backlight shows no visible flickering and from this perspective, it does not stress and damage your eyes. In the second case, the light is not just flickering – it goes off completely for a period of time longer than it was lit (the dark lines between the light ones; from their number the “blinks” can easily be calculated, in this case about 200 per second). Combined with the flickering of pixels in monitors with FRC (over 80% of units currently sold), there can occur problems that doctors are already talking about, and manufacturers are quietly searching for a remedy.
Wave a small stick, a pen or pencil, as fast as you can, 5-6 cm in front of the screen, imitating windscreen wipers. If there is a blurry object before you – everything is fine. If you see several pens in the form of a fan as a result of the strobe effect of the impulse backlight, there is a problem. Increase the lighting in the room to levels that allow for an increase of the monitor brightness until this effect is gone. And keep in mind that this lighting should be with traditional incandescent or halogen lamps if possible, instead of fluorescent ones.
A peek into the details
The final step is to look at the details. Some of them you will not find in the description of the product or the advertisements, and you will have to look for them in reviews. Even though there are a lot of details, we think everyone will look for at least three that can definitely sway the opinion to one model over the others.
The finish is usually one of three types – matte, glossy, and semi-glossy. Glossy finish offers more attractive colors, but under certain conditions it can become a mirror which drives some people to criticize that option. Matte finish disperses light that falls onto it, but it too has its disadvantages. Higher grade monitors have high-tech coatings such as a compound that absorbs light and at the same time polarizes the emitted light, thus improving image quality.
Ergonomics, possible positions
If the monitor you have chosen can turn to portrait mode, this is a sign it belongs to the higher end. Particularly important is how the screen looks at the lowest possible position to the desk. When working for a long time with a monitor bigger than 22-inches, it is very comfortable if the lower edge of the monitor can not only lay on the desk, but can also be tilted like laptop screens (like the pictured 27-inch monitor).
This way we can avoid having our heads tilted up for long hours, which sometimes leads to pain.
Whether it’s the power unit or, in monitors with higher power demands, the built-in fan, noise is always a nuisance. That goes double for people who normally work in silence. After we’ve prepared our working environment for proper acoustic analysis, we’ll be able to weigh in more significantly on this issue.
Warranty and reliability
In the computer world, time runs at a faster clip and this leads to a quicker onset of obsolescence. In this sense, the difference between one and five years of warranty (there are monitors like this) is more than important. The first period passes quite quickly, while the second one covers nearly the whole usage span. Also, the enthusiasm of a person who goes shopping in the “big store” some twenty kilometers across the city is certainly not the same as that of someone having to go the same distance because something broke. Things get even more complicated when we have to wait for the authorized warranty service to say whether five “dead” pixels means the whole monitor is “dead” or still “alive”.
In this respect, the types of damaged pixels and the maximum number of allowed defects are standardized with ISO 13406-2. It’s not a bad idea to check what class of this standard your chosen monitor has, and what the policies of the manufacturer are in case of a malfunction (and if anyone will give a higher class rating if they can’t cover the quality).
|Class||Type 1||Type 2||Type 3||Cluster with more than one Type 1 or Type 2 errors||Cluster of Type 3 errors|
There is definitely a difference in build quality and toughness of the housing in different brands and models.
The useful on-screen display (OSD) menus and fast access to options like switching between Adobe RGB and sRGB in high-end monitors are premises for higher quality work.
A quick look at the number and types of ports can tell us a lot about the class of the monitor and can also be helpful for future operation with the monitor.
Calibration and profiling
When colors are of a big importance, calibration and profiling (as well as their respective results) are crucial. There are monitors made with somewhat inaccurate factory settings, that produce amazing color accuracy after profiling with a calibration device. It is also important if the profile is saved in the operating system or in an LUT (look-up-table) on the monitor itself. The latter means the monitor can be hardware calibrated.
Additional functions like Picture in Picture (PIP) or Picture by Picture (PBP) that show a second image on the screen from another source can be really useful for users who are not computer maniacs (which is why they haven’t typically heard of said features), but the computer is still their main working tool.
Energy consumption and heat
Relatively few users are interested in knowing the energy consumption of their monitors. But they should be! For example, noting the difference between LED and CCFL for 5 years of exploitation can be useful when buying your next monitor (this rule isn’t true for elite professional monitors, because the goals there are different, and everything that can be done, has been done). The same can be said of heat. A fireplace is a good thing, but try looking at one for a few hours in the middle of summer.
At the end of this section, we can only give one advice.
We don’t want to reinvent the wheel by explaining that in a regulated market, a monitor that costs $100 is worth a $100, and a $2000 one, worth $2000. We did not mention, for example, one of the VA family members – UV²A, which has a fourth yellow subpixel and impressive colors (just look at how this word has lost its meaning because of constant overuse) that is used in an 80-inch monitor for the low price of about $10,000.
When choosing a monitor, keep in mind that with the arrival of cheaper varieties of high-end matrices you can buy a much better model than one from a few months ago at a relatively low price, even lower than the older-tech ones. Both monitors could be next to each other, one click away.
Dear reader, with this article we tried to prepare a quick guide on choosing the best monitor for different users. The supply is huge, the uses are different and so are people’s resources and needs.
There were a lot of terms and abbreviations mentioned, and we intentionally did not mention any particular company or brand. Behind the names and abbreviations, there are serious companies with strong histories and positions in the modern high-tech market engineering and manufacturing. Out of respect for our readers, and in order to be objective, we did not mention their names. This way, each and every one of you can make a smart choice, and we are ready to help with consultation or through our reviews, constantly expanding the number of tests and giving our marks on every new device with regard to some of the main and most useful specifications.