Samsung SyncMaster XL24 and XL30 Monitors Review

Samsung SyncMaster XL20 caused a sensation back in the days, because Samsung was the first to introduce a monitor with LED backlighting and remarkable color gamut at an affordable price. It used to be the only solution like that for a while, but it couldn’t go on like that forever. Today we are going to discuss two more representatives of the same family.

by Oleg Artamonov
10/31/2008 | 10:45 AM

The SyncMaster XL20 stirred the monitor market up as Samsung became the first company to introduce a model with LED-based backlight and extended color gamut at an affordable price. Before the release, the XL20 was rumored to cost about $2000 whereas the other LED-based monitor, the NEC SpectraView Reference 2180WG-LED, cost three times as much. Moreover, the XL20 has got cheaper since the announcement and can now be got for less than $1000 here, in Moscow. The mentioned NEC is still far more expensive.

 

The SyncMaster XL20 used to sell alone for quite a while as Samsung did not offer any other model with LED backlight. But keeping ahead of its competitors, the company has now introduced a 24-inch XL24 and a 30-inch XL30. The retail prices of these models won’t be as affordable as that of the XL20, yet they do not seem outrageous considering the larger screen and the lack of competition.

But can it be that the low prices are the result of some simplifications that may affect the declared advantages of these monitors? And what do you get from the extended color gamut anyway? Is it worth the difference in price from the cheaper monitors that use fluorescent lamps as the backlight?

We can answer these questions today as we’ve got Samsung’s SyncMaster XL24 and XL30 here, in our test lab.

Extended Color Gamut: Highs and Lows

If you want to know what color gamut is, why it is rather small with most of existing monitors, and how it can be enhanced, you can refer to the appropriate section of our article called Contemporary LCD Monitor Parameters: Objective and Subjective Analysis.

Theoretically, a larger color gamut is always an indisputable advantage as it enables the monitor to display colors that a monitor with a smaller color gamut can never show. Do not confuse color gamut with the amount of colors a monitor can display, which is usually 16.2 or 16.7 million colors. These are two complementary things. A color gamut is the range of colors the monitor can display while the amount of colors is how many gradations this range is split into in order to display medium hues or halftones. These two parameters are not directly interrelated. Theoretically, it is possible to make a monitor with four colors and a huge color gamut. Such a monitor would only display pure green, pure blue, pure red or pure white – without any halftones – but these four colors would be indeed very pure.

Thus, you can have a purer, more saturated color on an extended-gamut monitor even if you have a prehistoric graphics card with 16-bit color representation or are an inveterate user of Windows 3.11 for Workgroups. A color gamut is a hardware property of a monitor that does not depend on what system the monitor is connected to.

So, the two mentioned parameters do not affect each other, yet they should be discussed both together in some situations. It is obvious that the number of colors determines the difference between two adjacent colors. The more colors the monitor can display, the smaller this difference is. The entire space of colors the monitor can reproduce is split into 16.7 million dots, each specific color being as accurate as one of these dots.

And when this space – the color gamut – gets larger, but the number of dots remains the same, the difference between the adjacent dots grows bigger. So, although an extended-gamut monitor can show more colors in a physical sense, it does so less accurately. This lack of color precision can be observed by means of smooth color gradients: they appear to be banded, each band corresponding to one color dot.

In fact, you can see this effect even with the 24-bit color representation that is standard today (graphics cards work with 32-bit color representation but there are only 24 bits that describe color proper, the other 8 bits being employed for auxiliary purposes; in fact, these extra 8 bits were introduced only because graphics cards find it easier to process 4-byte numbers than 3-byte ones). Try to stretch a gradient from red to black to full screen and you will see it to be striped, not smooth, even on a best of LCD monitors (bad monitors will even add wide and irregular bands of their own).

The banding of color gradients is going to be a little more conspicuous on extended-gamut monitors if we use the same 24-bit color format.

The only solution is to increase the color precision to 30 bits so that each color component was represented by 10 bits. This would increase the total number of colors, reduce the size of each color dot, and solve any gradients-related problems.

Alas, even though graphics cards have supported the transfer of 30-bit color via the DVI interface for long already (ATI’s cards have offered this support since the X1000 series, for example), this is not a widespread feature as yet. Only few monitors, such as the expensive NEC SpectraView Reference 2180WG LED, support a 30-bit interface, and there is not much support on the software side, either.

Although the lack of colors on extended-gamut monitors is not a serious problem, especially for home users, it is a problem anyway. After all, we are talking about professional monitors that can be used for prepress and onscreen proofing, i.e. when even minor defects in color reproduction can have serious consequences.

Next goes a more serious problem. Working with color and software, the graphics card and monitor both operate not with physical measurement units but with some formal numbers, from 0 to 255 for each of the basic colors. For example, {0; 255; 0} is not green, it is just a set of numbers. It will become green if we assume that this set corresponds to the monitor’s showing a green subpixel.

So, the problem is that a green subpixel has different color on an ordinary monitor and on an extended-gamut monitor. It is greener on the latter. That is, it is purer, more saturated. If you put two such monitors next to each other and display the color {0; 255; 0} on both, you will see a pure green on the extended-gamut monitor and a green with a noticeable yellowish hue on the ordinary monitor.

The transformation of a formal value (a number) into a physical value (a specific color perceived by the eye) is performed by the monitor’s LCD matrix. But the matrixes are different whereas software is mostly oriented at one and the same standard called sRGB.

As a result, monitors with an extended color gamut – which is extended relative to the standard sRGB gamut – will distort colors when displaying sRGB-oriented pictures prepared in sRGB-oriented software that does not know anything about non-sRGB monitors. The monitor will just stretch the sRGB-oriented picture out to fit its own gamut. Not only the pure colors, but also halftones will shift. The only exception is white and gray which are going to look correctly on any monitor unless the monitor is set up badly.

The most typical model of an extended-gamut monitor is the one that uses lamps with improved phosphors. Such monitors differ from ordinary sRGB monitors with a more saturated green. Thus, all the halftones will be somewhat shifted on them in the direction indicated by the white arrows in the diagram above (the black triangle is the standard sRGB gamut, and the white triangle is the effective gamut of the extended-gamut monitor sRGB-oriented images will be stretched out on).

People who have some basic knowledge of any measurement tools may argue that every measurement tool works like a monitor: it shows some formal units as physical properties. An ordinary weighing scale shows not the weight of something but the angle of the arrow. But we know that the angle depends on the weight, so we can write numbers denoting kilograms, not degrees, below the arrow.

Can this procedure be applied to monitors so that image-processing software could correct the picture for the current monitor’s color gamut? Yes, it can. This procedure is known as hardware calibration.

Hardware Monitor Calibration

Strictly speaking, the most accurate definition would sound like “a hardware calibration of an image reproduction system consisting of software, graphics card and monitor” but the phrase is too long and, on the practical level, the monitor is the only component of the three to be imperfect. The graphics card and software do not bring about any distortions by default. Thus, it is quite reasonable to shorten the phrase to just “monitor calibration.”

Why hardware calibration? Because the monitor is calibrated using a special device called calibrator. It is a sensor you can hang on the monitor’s screen for measuring color and brightness.

In the process of calibration the software included with the calibrator outputs fields of different colors under it. It is usually white, black, sometimes a few levels of gray, and a sequence of black to red, green and blue with a certain step. The calibrator identifies what color is actually being shown and thus allows to calculate the correction that would adjust the monitor’s characteristics to your requirements.

It is logical that we use an individual device for that. Without the calibrator we can only send a certain signal to the monitor but cannot get any feedback about the monitor’s reaction, i.e. what color it displays.

The calibration process is simple from the end-user’s point of view: you just hang the calibrator on the screen, launch the included software and answer a few questions regarding the desired parameters of the monitor. The whole process is automatic and takes 10-15 minutes. Then you can take the calibrator away until you need to calibrate the monitor anew, for example if the monitor’s settings or the ambient lighting change.

Calibration can be used for three purposes. I will discuss them in order of ascending complexity.

Measuring Color Gamut

Measuring the gamut is as simple as measuring what colors the monitor displays as pure red, pure green and pure blue. In other words, you get the coordinates of the vertices of the color gamut triangle. This information is written into an ICC file that can be used as the monitor’s profile by every application.

This solves the problem described at the end of the previous section: if the application knows the monitor’s color gamut and knows what gamut the given picture is optimized for, it can correct the picture in such a way that its colors looked like the author of the picture intended. If greens are stretched out on the extended-gamut monitor by 10% relative to the sRGB gamut, they must be shrunk by 10% when displaying an sRGB-optimized picture so that the colors looked like they should, i.e. without any tonal shift towards greens. This approach helps use the advantages of extended-gamut monitors for processing images and also work normally with ordinary sRGB-optimized pictures.

There are multiple difficulties, though. First, not all programs, even image-processing programs, can use data about the monitor’s color gamut. Of course, professional suites like Adobe Photoshop have no problems, but simpler programs, like image viewers, are deficient in this respect.

Second, the monitor’s profile alone is not enough. It is also necessary to know what color gamut the specific picture is optimized for to decide if it needs any correction. This technology exists in theory: JPEG and TIFF file formats can embed ICC profiles that report the native color gamut of the picture. However, most images do not have such a profile while most programs cannot use it.


Setting monitor profile in XnView manager

Well, some progress in this area could be observed recently. For example, Firefox 3.0, even though not a specialized program for viewing images, supports color management using ICC profiles. Many cameras allow not only embed a color profile into JPEG files but also save pictures in the AdobeRGB gamut that ensures a better reproduction of greens and is a better match for extended-gamut monitors. Cameras’ matrixes can make pictures with a large color gamut easily. Pictures are reduced to sRGB in them only for the sake of compatibility with sRGB monitors.


Setting color space on Canon EOS-350D

So, we are steadily progressing to problem-free operation of monitors with different color gamuts by means of ICC profiles. However, you need to be careful as yet when selecting and setting up the software you want to use with extended-gamut monitors if you want colors to display properly.

Finding White Balance

There is no universal white in nature. Our brain identifies a certain color as white depending on the ambient lighting. The windows of houses look yellow to us from the evening twilight. And the evening twilight looks blue if you look out of the window.

So, for your monitor not to look bluish or reddish, you must set up the balance of blue and red depending on the lighting in your room. The process is called color temperature setup.

It may seem trivial, but most of LCD monitors do not offer a color temperature setting as such. They only offer three independent sliders for red, green and blue, suggesting that you select the optimal correlation between them manually.

A calibrator can solve this problem automatically. You just tell it what color temperature you want to have on the screen, and it will measure the current temperature of white, calculate everything and introduce appropriate changes into the graphics card’s settings. Some models, for example the senior versions of ColorVision Spyder, offer a setup mode in which the calibrator helps position the monitor’s RGB sliders manually by showing you the current balance of these colors and prompting you to decrease or increase the level of a specific color to get the desired result.

Gamma Curve Correction

In each test of any LCD monitor in our reviews you can see one or more diagrams of the so-called gamma curves. These curves show the dependence of the digital signal from the graphics card and the effective brightness of the pixel set by that signal. Ideally, the curve must comply with the equation y=x^γ where γ=2.2. This ideal curve is colored black in the diagram.

In the ideal case, the curves for red, blue and green must coincide with the theoretical curve, merging into a single line in the diagram. It means the monitor is set up perfectly. Alas, there are very few such monitors in reality.

A more frequent case is illustrated by the diagram above: green and red are more or less the same as the theoretical curve but blue sags below them. It means that if you try to display a blue halftone on the screen, it will be darker than you could expect basing on the standard gamma of 2.2. A halftone (including a gray), which is a mix of the three basic colors, will prove to be shifted into the area of reds and greens due to the same lack of blue.

This resembles the color gamut problem described above: applications take it for granted that the monitor meets certain standard requirements (sRGB color space, gamma value of 2.2) but it is not so in reality. The method of solving the problem is somewhat different. A large color gamut should not be corrected. It just must be accounted for when displaying images. Inaccuracies of the gamma curves are, on the contrary, undesired, and it is better to correct them right away on the level of the graphics card or monitor. And applications must still assume that the monitor has a gamma of 2.2.

Gamma curves are corrected with a calibrator. A sequence of halftones, from darkest to lightest, is displayed under the calibrator’s sensor. For each halftone the necessary correction is calculated. Thus, the gamma curve is verified and corrected in a certain number of points. A correction table is created basing on the results of the measurement. The table is loaded into the graphics card and the graphics subsystem gets a guaranteed gamma of 2.2 and neat curves. User’s applications don’t have to do anything. The data is obtained and loaded into the graphics card by the calibrator’s software. Of course, the table must be loaded into the graphics card anew after each reboot, so the calibrator’s software must be installed in the system permanently although the calibration process proper can be performed only once every few weeks or even months.

In fact, monitor’s gamma curves can be corrected without a calibrator, but this is a tedious and daunting task and the result may prove to be not very accurate.

As I wrote above, the correction table is loaded into the graphics card. This is the most frequent case, but some professional monitors allow to load the correction table into themselves. This approach improves calibration accuracy and, accordingly, the color accuracy of the monitor, and you don’t have to run the software for loading the table into the graphics card on each reboot. Once loaded, the table will be stored in the monitor until the next calibration.

Natural Color Expert and Calibration of XL Series Monitors

The SyncMaster XL24 and XL30 allow to load the calibration data right into themselves.

The calibration software must be able to use this opportunity, of course. Fortunately, an X-Rite Eye-One Display 2 calibrator is included with the monitors. This model should be familiar to people who professionally work with color. The calibrator comes with Natural Color Expert software.

The Eye-One is a small device that can be hung on the monitor’s screen (you could see a photo with the calibrator in action earlier in this article). It is secured in place with the USB cord that is thrown above the monitor as well as with multiple suction cups placed in two rings on the screen-facing surface of the calibrator. The suction cups cannot hold the calibrator without the USB cord. Their purpose is to ensure tight contact between the calibrator and the matrix.

In the center of the calibrator there is a photo-sensor (a few sensors, to be exact, each behind a filter of certain color). The calibrator has a strip of soft porous rubber around its perimeter that prevents stray ambient light to get to the sensors.

Natural Color Expert software replaces the native software of X-Rite calibrators and is meant for Samsung’s XL series monitors only. You won’t be able to use the calibrator on other monitors with this software.

When you start the calibration process, the program displays black, red, blue, green and white squares under the calibrator. There is no progress indicator – you can only see the petals of the flower moving next to the Reading Monitor caption in the bottom right corner of the screen. The whole process takes a few minutes only. When it is complete, you can remove the calibrator from the screen.

Alas, this description makes it clear that the calibrator performs only two out of the three functions discussed in the previous section of the article. It corrects color temperature and measures the color gamut. Although the Eye-One is a full-featured calibrator with its native software (i1 Match) and can determine and correct the shape of the gamma curves, Natural Color Expert does not offer such functionality, perhaps due to a licensing agreement with X-Rite that allows to sell this rather expensive tool together with monitors at a low extra charge.

So what is the purpose of writing correction tables into the monitor then? And what is the purpose of using a calibrator with cut-down functionality?

Talking about the extended-gamut monitors in the previous section, I mentioned ICC profiles and how they can be used with user’s applications for such monitors to work properly. The XL series monitors offer another opportunity. They can emulate any color gamut smaller than their own one.

The first mode of NCE is called Calibration. It allows to change any basic setting of the monitor save for color gamut. You can calibrate the monitor for specific brightness or set a desired value of color temperature or gamma. You can even calibrate a few monitors in such a way that their colors were identical. If you just select the same settings in the onscreen menus, there would be difference due to the variation of parameters between different samples of the same monitor. The calibrator helps minimize this difference.

When the calibration is over, you see a window with the results of the measurements: the coordinates of the vertices of the color gamut triangle, color temperature and the deflection of white from the desired level (in Delta E units), brightness and level of black (the contrast ratio is the ratio of white to black or 121/0.11=1100:1 here). When you click the Save button, an ICC file is created in the folder C:\Windows\system32\spool\drivers\color. This file is bound in the system to the current monitor. Any program that supports color management can use this file to get valid information about the monitor in order to correct images accordingly.

What if the application you use cannot use ICC profiles? You can switch into the Emulation mode then.

There seem to be no difference from the Calibration mode but look at the top of the screenshot: there is now a string with the path to the ICC file. This is not a file for saving the results of measuring the monitor’s parameters into. Instead, NCE will set the monitor up according to the parameters of that file.

You can also specify the target parameters without any profile: just type in the coordinates of the vertices of the color gamut triangle into the appropriate fields.

Suppose you use an application that only works correctly with sRGB monitors. In this case you just load a standard sRGB profile into the Emulation mode and launch the calibration process.

After that NCE will ask if you want to write the result into the monitor. If you answer yes, you will have your extended-gamut monitor provide hardware emulation of the standard sRGB color gamut that can be evoked with a press of a button.

The XL series monitors offer five emulation modes:

Interestingly, although the sRGB and AdobeRGB modes are set up at the factory, you can reset them with the calibrator to correct certain flaws or the deviation of the monitor’s parameters that may occur with use. To do this you must load a standard sRGB or AdobeRGB ICC profile on the Emulation tab of Natural Color Expert. When the calibration is over, the program will suggest that you save the result into the appropriate mode of the monitor.

From a practical point of view, the Custom mode gives you access to all the monitor’s settings that you can change whenever you want but it is the least accurate mode in terms of color reproduction. sRGB, AdobeRGB and Emulation allow you to emulate two standard and one custom mode with a limited color gamut if images cannot or should not be corrected on the software level for displaying on the extended-gamut monitor. The Calibration mode helps achieve the most accurate color reproduction in applications that can work with the monitor’s color gamut and can correct images according to it.

The last tab in Natural Color Expert is where you can manage your ICC profiles. You can also measure the current parameters of the monitor (without creating a profile or changing any settings), enable a scheduled warning about the need for recalibration and reset the settings of the sRGB and AdobeRGB modes to their factory defaults (if you changed them as I described above).

So, here is the summary of what Natural Color Expert can and cannot do together with the Eye-One Display 2 calibrator and SyncMaster XL20 monitor:

Is the last item important? It depends on how neatly the gamma curves are set up originally and if they need any correction. You will see this shortly.

Samsung SyncMaster XL24

The XL series had begun with the 20-inch XL20 and it is only after a long while that Samsung complemented it with larger models, starting with the 24-inch XL24.

The monitor is based on a widescreen S-PVA matrix with a native resolution of 1920x1200 pixels. It features LED-based backlight and a color gamut of 123% NTSC (for comparison, regular desktop monitors and notebooks have a color gamut of about 75% NTSC and 45% NTSC, respectively). The monitor is declared to have a maximum brightness of 250 nits, a contrast ratio of 1000:1, a response time of 8 milliseconds (GtG) and viewing angles of 178 degrees both vertically and horizontally.

The XL24 features the traditional exterior design of Samsung’s professional models. It is just larger than usual. The case is matte black. The metallized dots in the bottom left corner make up the word LED.

Included with the monitor is a detachable sun visor. It is metallic and painted matte black on the outside and trimmed with black velvet on the inside. In short, it is very top quality.

The kit also includes an X-Rite Eye-One Display 2 calibrator I mentioned above together with Natural Color Expert software, a DVI cable, a power cord, and a user manual.

When I wrote about the monitor’s dimensions I meant its thickness, of course. The XL24 is not slim as you can see. The high heat dissipation of the LED backlight is the main reason. It is less economical than fluorescent lamps and requires more cooling.

You may wonder how it can be if LED backlight helps save power in notebooks. This is a different case. Desktop monitors use triads of red-green-blue LEDs, which are not economical but ensure the larger color gamut. Notebooks use white LEDs which are economical but provide no advantages in terms of color gamut.

Therefore the XL24 has to use a fan to cool the backlight. The fan is located at the monitor’s back panel, near the connectors, and is rather quiet. It won’t be audible in an office environment. You may hear its soft hiss at home only if you’ve got a quiet system case.

The monitor’s stand allows to tilt the screen and adjust its height (from 120 to 220 millimeters from the desk to the bottom edge of the matrix). You can also turn the screen around and pivot it into portrait mode. The default stand can be replaced with a VESA-compatible mount if necessary.

The monitor has two DVI connectors: a digital DVI-D and a universal DVI-I. You can connect your graphics card’s analog output to the latter via an adapter (I wouldn’t recommend such connection for a 24-inch monitor, though). The input of the integrated USB hub can be seen nearby.

The four USB ports are placed in pairs on the side panel. The ports are too close to each other in each pair, so you can only plug cables or very thin flash drives into them simultaneously. That’s not a big problem, though. I guess even two USB ports would suffice for most situations.

The control buttons are placed in a row in the bottom right of the front panel. Their labels are white and visible even in semidarkness. The buttons provide quick access (bypassing the main menu) to selecting a color gamut (the Mode button; I described the available modes in the previous section), to the Brightness and Contrast settings, to choosing an input, and to the automatic adjustment at analog connection.

The Power button is highlighted in white at work. Below it, on the band that seemed opaque, the name of the current color gamut mode is displayed. If this illumination distracts you, you can turn it off in the monitor’s menu.

The onscreen menu is Samsung’s standard one. It has not been changed for the professional XL24. It is handy and logical. Why should it have been changed?

Well, the values of different parameters are usually expressed in physical units in professional monitors. For example, color temperature is expressed in degrees Kelvin. The photo above shows you the color temperature menu of the XL24. There are names, but not specific numbers. What does this Warm1 mean? 6000K or 5400K? More or less? You just don’t know it.

Of course, this is not a problem if the kit includes a calibrator you can set any color temperature with, yet I’d prefer to see specific numbers here.

The manual color temperature setup is not good, either. You are supposed to choose the balance of red, green and blue “by eye.” For comparison, NEC’s professional monitors from the UXi series allow to set color temperature up in degrees Kelvin whereas the ColorVision Spyder3Elite has a special mode for setting the balance accurately using the monitor’s own setup options. Alas, the XL24 and the Eye-one Display 2 offer neither of the two opportunities.

As for special menu options, I can only note the option of disabling the indicator LEDs on the front panel.

The monitor has 70% brightness and 80% contrast by default. I achieved a 100nit white by reducing both to 60%. Of course, Brightness and Contrast can only be regulated in the menu in the Custom mode. In the other modes they are set up during calibration in Natural Color Expert. The monitor regulates its brightness by means of pulse-width modulation of the power of the LED backlight at a frequency of about 1.4kHz.

Color gradients are reproduced without flaws.

Of course, the most interesting test with XL series monitors is the measurement of their color gamut. I performed most of the tests with a ColorVision Spyder Pro calibrator, but measured the color gamut with the Eye-One Display 2 included with the monitor. ColorVision calibrators lower than Spyder 3 do not identify the coordinates of green on extended-gamma monitors correctly.

The result is impressive indeed. The picture shows you the two standard color gamuts, sRGB and AdobeRGB, and the color gamut of the SyncMaster XL24 as measured in the Custom mode.

The XL24 is obviously far superior to sRGB and larger than AdobeRGB in greens and reds. An ordinary monitor with fluorescent lamps is somewhat smaller than sRGB and AdobeRGB in reds, so if you put it next to the XL24, you will see the latter display a deep and pure red whereas the ordinary monitor will have a parasitic orange huge in its red.

Although the diagram suggests a bigger difference in reproduction of greens, it is actually red that strikes the eye, so good this color is on the XL24. Of course, if you take a closer look, you also notice that the ordinary monitor’s green has a yellowish hue in comparison with the XL24. Moreover, the XL24 is better at displaying turquoise and yellow-orange hues.

To check out the monitor’s ability to emulate other color gamuts, I switched it into sRGB mode. As you can see, the result is perfect: the white (the measured gamut of the monitor) and black (the standard sRGB color space) triangles just coincide. Take note that the XL24 will produce a somewhat different picture in this mode than monitors with fluorescent lamps do because their color gamut does not exactly coincide with sRGB in reds and greens. Well, you can use the Emulation mode to calibrate the XL24 in such a way that it corresponded to a specific monitor in terms of color gamut.

The XL24 also provides a coinciding color gamut in the AdobeRGB mode.

 

The monitor’s white brightness is very uniform: an average deflection of 1.4% with a maximum of 6.1%. This is three to four times better than with most other monitors. I guess this model is set up individually at the factory for uniform brightness (NEC’s professional monitors also feature such technology). This supposition is confirmed by the fact that black brightness, which cannot be set up at the factory in the same way, is worse: an average deflection of 4.6% with a maximum of 26.4%. You can easily see the brighter spots of the backlight on the black screen.

The gamma curves are good as regular monitors go, but not quite good for a professional model. The value of gamma is somewhat too high and the curves lie lower than the theoretical one as the consequence. The resulting image is darker and has more contrast than it should.

The monitor is set up better in the AdobeRGB mode. The curves rise up, nearly coinciding with the theoretical curve. Anyway, the blue curve differs somewhat from the ideal one.

The gamma curves setup in the sRGB mode is better than in Custom but worse than in AdobeRGB mode.

I ran the calibration procedure for this mode in the Emulation section of Natural Color Expert:

Just as you could expect, Natural Color Expert makes no attempt to correct the shape of the gamma curves. The diagram didn’t change almost. Calibration with the calibrator’s native software gives better results, but the correction table is written into the graphics card rather than into the monitor then.

The monitor offers 12 color temperature presets in the Custom mode plus a manual setting but these presets are called something like Cool3 rather than specific numeric values. Color temperature is fixed in the sRGB and AdobeRGB modes. In the Calibration and Emulation modes it is specified in Natural Color Expert, so I didn’t include them into the table below.

Alas, the setup quality is far from perfect. Such a big difference between the temperatures of different grays is too much for a professional monitor. For comparison, this difference varies from tens to hundreds degrees in the NEC MultiSync LCD2190UXi. Here, the difference can be as big as 2000K and more. The sRGB mode delivers a temperature of about 6500K which is appropriate for the namesake standard. The AdobeRGB mode is colder for some reason although it should produce 6500K as well (illuminant D65, to be exact). The temperature proved to be about 7000K in reality. This can be corrected by means of calibration, though.

One of the common problems of monitors with LED backlight is about the uniformity of color temperature. The problem is caused by the use of multiple LED triads. If the parameters of the LEDs in different triads differ a little, the triads will produce somewhat different light.

To check out if this problem concerns the SyncMaster XL24 I measured the color temperature of white in 25 points of the screen.

So, the difference amounts to about 400K. In other words, not only different levels of gray but also different points of the screen differ in temperature. This problem can be solved by culling LEDs that meet specific requirements or by setting up each monitor individually like it is done to achieve uniform brightness of white.

The maximum brightness is about 200 nits, and the contrast ratio is 400:1. These values are measured with a ColorVision Spyder Pro calibrator which produces somewhat understated results. The level of brightness matches the requirements of the namesake standards in the sRGB and AdobeRGB modes but the contrast ratio does not. The level of black is as high as 2.77 nits in the AdobeRGB mode whereas the AdobeRGB standard demands it to be about 0.56 nits. Both parameters – brightness and contrast ratio – can be set up during the calibration of the monitor in the Emulation mode, but it would be better to have them set up correctly right at the factory.

Although the XL24 is based on a PVA matrix which is inherently slow, it is equipped with response time compensation. As a result, its speed proves to be good enough for games, let alone for work. The response time average is only 6.7 milliseconds (GtG) with a maximum of 16.5 milliseconds.

There are RTC-provoked artifacts, too. They show up as light or dark edges around moving objects. The average value of the RTC miss is 9.0% with a maximum of 42.9%. The artifacts won’t be too annoying, yet you can notice them if you want to.

I’ll give you a summary of the XL24 in the Conclusion. Right now let’s proceed to the 30-inch XL30 model.

SyncMaster XL30

Taking its start from the small 20-incher, Samsung then made its series of LED-backlight monitors complete in terms of diagonal length by introducing not only the XL24 but also the 30-inch XL30.

Excepting the screen size and resolution, its parameters are similar to those of the XL24. The XL30 is based on a 30-inch S-PVA matrix with a color gamut of 123% NTSC, a native resolution of 2560x1600 pixels, a maximum brightness of 200 nits, a contrast ratio of 1000:1, a response time of 6 milliseconds (GtG) and viewing angles of 178 degrees in every direction.

The high resolution imposes limitations on the graphics card and cable which must support dual-link DVI. Otherwise you won’t be able to get more than 1920x1200. This shouldn’t be a problem, though. An appropriate cable is included with the monitor or can be bought in nearly every computer shop. And dual-link DVI output has been provided by every graphics card for at least three generations. Basing on my personal experience I wouldn’t recommend you to use a very cheap card, though. Even if it formally supports dual-link DVI, there are may be image quality problems in practice.

You will not be able to connect the XL30 at its native resolution to integrated graphics cores or notebooks. They have only one DVI channel and do not support resolutions above 1920x1200.

Well, interpolation in the XL30 is set up in such a way that there is an absolutely sharp image at 1280x800: every line just has double thickness. So, you can work with this monitor and single-link DVI cards more or less normally if you want.

The SyncMaster Xl30 is large and heavy for an LCD monitor. It weighs as much as 14 kilos. The exterior design is identical to the XL24. The case color is matte black.

Like with the XL24, the case is thick as it has to accommodate the LED-based backlight and its cooling. Comparing the XL series monitors with Samsung’s ordinary monitors following a similar exterior design (for example, SyncMaster 215TW or 225BW), the XL series has an additional insert between the front and panel panels of the case that makes the monitor thicker.

The stand allows to tilt the screen and adjust its height from 90 to 170 millimeters. You can also turn it around the vertical axis and pivot the screen into portrait mode. The stand can be replaced with a standard VESA mount (that is rated for a weight of no less than 15 kilos).

The monitor is equipped with a DVI-D connector. It doesn’t support analog connection at all. There is a USB hub near the video input. It provides four USB ports, two of which are located at the back panel.

The XL30 needs a cooling fan which is hidden deep within the case. You can only see numerous vent grids from the outside.

The remaining USB ports can be found on the side of the back panel. You can use them for flash drives even though without much convenience – you can only find these ports blindly or by looking behind the monitor.

30-inch monitors – and the XL30 is no exception – offer very simple controls. There is no onscreen menu proper. The only setting you can change is brightness. I guess the reason is the low performance of current processors that would not be able to process information at 5.5Gbps in real time considering the user-defined settings.

Well, the XL30 differs somewhat from other 30-inch monitors. It offers a Mode button that selects a color gamut emulation mode. The current mode is shown on the panel under the buttons. The selection of modes is the same as with the XL24: without calibration, with calibration plus maximum color gamut, and three emulation modes.

The monitor’s brightness is regulated by means of pulse-width modulation of the backlight LEDs at a frequency of 1.4kHz.

Included with the monitor are a sun visor trimmed with black velvet on the inside, an X-Rite Eye-One Display 2 calibrator, and Natural Color Expert software.

The monitor’s color gamut is larger than sRGB and AdobeRGB except that the very edge of the latter goes beyond the monitor’s gamut. Like with the XL24, the difference in the reproduction of red strikes the eye. Red is far purer and saturated on the XL30 than on ordinary monitors with fluorescent backlight.

The XL30 has no problems emulating the standard color gamuts. The diagram above shows that its sRGB mode coincides with the sRGB precisely. The two triangles merge into one. Take note that the XL30’s sRGB mode will differ somewhat from real monitors just because real monitors do not exactly match the sRGB space. But you can calibrate your XL30 with Natural Color Expert for any color gamut, including the gamut of a specific monitor with fluorescent backlight.

 

The brightness uniformity is similar to that of the XL24. These monitors seem to be set up individually at the factory for uniform white brightness but this process is technically unfeasible for black. As a result, the average nonuniformity of white brightness is 3.4% with a maximum of 10.7%. On black, the average and maximum are 6.2% and 23.8%, respectively.

The gamma curves are not exactly neat in the Custom and Calibrated modes. They coincide with the theoretical curve at the beginning of the diagram but then go lower than necessary, making the appropriate halftones darker than they should be.

It is much better in the AdobeRGB mode: the monitor’s gamma curves almost coincide with the theoretical one. Interestingly, AdobeRGB was the neatest mode on the SyncMaster XL24, too.

The monitor doesn’t provide a color temperature setting in the menu, so I just measured color temperature in the Custom, sRGB and AdobeRGB modes at the default settings (although you can use Natural Color Expert to calibrate the monitor for any temperature you want). The temperature dispersion between the levels of gray is quite acceptable, except that the darkest tone is suddenly warmer in the sRGB mode.

The color temperature setup is not perfect in terms of absolute numbers, either. It must be 6500K in sRGB and AdobeRGB modes, but proves to be 500K and 1000K higher, respectively. This drawback can be corrected with calibration in Natural Color Expert, though.

Alas, the positive impressions from the neater color temperature setup in comparison with the SyncMaster XL24 are spoiled by the results of the uniformity test: different pixels may vary by almost 900K in color temperature. There is a reddish warm smudge in the bottom right of the screen.

The level of brightness is normal in the custom mode (notwithstanding the lack of a contrast setting, you can reduce the monitor’s brightness to a comfortable level for standard ambient lighting) as well as in the sRGB and AdobeRGB modes. To remind you, these standards describe not only color gamut but also brightness of the monitor: 80 nits for sRGB and 160 nits for AdobeRGB.

Notwithstanding the same specified response time, the XL30 proves to be almost twice as slow as the XL24. Its response time average is 12.4 milliseconds (GtG) with a maximum of 26.8 milliseconds. The monitor is going to satisfy gamers, at least not very demanding gamers, yet it is not very fast. Popular inexpensive 5ms monitors based on TN matrixes have about the same real speed.

The average level of RTC errors is 8.8%, similar to the XL24, but the distribution of errors is different. A large part of halftone transitions are performed without any errors at all. RTC-provoked artifacts are negligible on light halftones, but a dark-gray object moving on a black background may acquire a visible light trail. This effect is only noticeable in games, though.

Conclusion

LCD monitors with LED-based backlight are ambiguous products as yet. Although I have discussed only products from Samsung, the market of relatively inexpensive LED-backlight models is limited to them actually (the ViewSonic VLED221wm is based on a TN matrix whereas the NEC SpectraView Reference 2180WG-LED is too expensive).

So, such monitors do provide an impressive color gamut. I have never seen any other monitor that would deliver such pure and saturated green and red. Monitors with ordinary fluorescent lamps (a color gamut of about 75% NTSC) are far inferior. Monitors with lamps with improved phosphors (97% NTSC) are more or less comparable to LED-backlight monitors in reproducing green but far inferior in reproducing red.

The difference is obvious to the eye if you just put two monitors, one with ordinary and another with LED backlight, next to each other. For you to imagine this difference without having a LED-backlight monitor, take a notebook (a color gamut of 45% NTSC) and a desktop monitor (75% NTSC) and display the same picture with vivid pure colors on both: a LED-backlight monitor is as superior to a fluorescent one as a fluorescent monitor is to a notebook.

Furthermore, the reproduction of turquoise and yellow is improved, too. This should be appreciated by polygraphists who don’t like the pale yellow of ordinary monitors.

However, you should keep it in mind that pure, vivid colors do not mean high color accuracy. Yes, LED-backlight monitors can display colors that are not available on monitors with fluorescent lamps but this is no guarantee of color accuracy. I found a number of problems during my tests, some of which are fundamental and some are SyncMaster XL specific.

First of all, the Natural Color Expert software included with the monitor cannot do one important thing, despite the included Eye-One Display 2 calibrator. It cannot correct the shape of the gamma curves, i.e. the accuracy of halftones. Yes, the calibrator makes it easier to work with the monitor as you can quickly set up its color temperature, brightness, contrast and color gamut to meet any requirements but the option of gamma curve correction would be good because the XL monitors I tested had not been set up ideally at the factory.

Second, one of the biggest problems with LED-based monitors is that color temperature varies on them not only between different levels of gray but also between different pixels of the screen due to the variation in the parameters of LEDs in different triads. Each triad highlights its own zone of the screen, so if the triad’s blue LED is somewhat brighter, the screen is colder. If the red LED is brighter, the screen is warmer. This problem can be corrected by per-pixel calibration of each individual monitor at the factory (this method is currently used to solve the problem of nonuniform white brightness) or by culling or setting up the triads individually. Both methods will increase the manufacturing cost of the monitor, of course. So, my recommendation is that you should scrutinize the monitor’s screen when shopping to avoid buying a poor sample.

Third, the stretching out of the 24-bit color representation to a larger color gamut lowers color accuracy somewhat. This is a general problem, not limited to the XL series. The inaccuracy is small, but you must be aware of it.

Fourth, you must know that most images are oriented at sRGB monitors and get distorted on non-sRGB monitors without color correction. Therefore it is necessary to use applications that support color management and to install a correct ICC profile of the monitor in the system. This problem is solved perfectly with the XL series, though. The included calibrator allows to create such a profile whenever you want it. Besides, the monitor supports hardware emulation of three color gamuts, two of which are standard and one is custom.

Generally speaking, the choice between Samsung’s SyncMaster XL20/XL24/XL30 and professional models with fluorescent backlight (produced by NEC or EIZO, for example) should be based on your personal requirements. If you need highest color accuracy within the ordinary sRGB color gamut, the XL series won’t be the best option. But if you are ready to compromise somewhat in order to be able to work within the AdobeRGB or even larger gamut, you should certainly consider the SyncMaster XL series.

Some people also think about purchasing an XL series monitor for home nonprofessional use as their price is quite affordable. In this case the XL series won’t disappoint you. It delivers vivid, lush colors, a good response time (quite enough for playing games), and hardware emulation of the standard color gamuts, which is very handy for home use because not all applications can work normally with non-sRGB monitors as yet.