Samsung XL20
Simon Baker, 2 December 2007

 

 

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Samsung are well known for their popular SyncMaster monitor range, with many models being held in high regard by reviewers and users alike. The model here for review at the moment is part of another range they are marketing, and is being aimed at colour enthusiasts and professional graphics work. The XL20 is a 20" (4:3 aspect) screen featuring an  impressive spec and most noteably, an LED backlight unit. We have also seen the annoucement recently of a 24" and 30" version of this screen, with the XL24 and XL30 expected to be released over the next couple of months.

The LED backlight unit offers an enhanced colour gamut stretching even beyond that of modern W-CCFL backighting. While CCFL's are limited to around 92% of the NTSC colour space on modern displays, LED units like this can offer a gamut covering 114% of the NTSC space. This corresponds to a complete coverage of the Adobe RGB natural colour space as well.  Further to the LED backlighting used here, the XL20 features an AU Optronics AMVA panel, the first of this technology we have tested here in fact. Professional colour enhancement is realized using the Samung designed Color DNA chip (FPGA), enabling high-speed 14-bit image reproduction, extremely expressive gradiation and exact colours. The 8-bit input is converted to 10-bit data by the monitor's LUT (Look Up Table), before being subject to 14-bit data processing to help express further detail. The screen is packaged with Samsung's Natural Color Expert software and a Samsung branded X-rite i1 (Eye-One) Display 2 colorimeter. This is the same hardware device which X-rite provide with their calibration package and that LaCie provide with theirs. We already known this to be an excellent high end hardware calibration tool, and later we will take a look at how effective their bundled software package is.

The rest of the monitor spec and features as listed as follows:

Size

20"

Colour Depth

16.7M from a palette of 1 billion, 114% NTSC gamut

Resolution

1600 x 1200

Viewing Angles

178 / 178

Response Time

8ms G2G

Panel Technology

AMVA

Contrast Ratio

600:1

Interfaces

DVI-D and DVI-I

Brightness

250 cd/m2

Colour

Black bezel and stand

Special Features

LED backlighting technology, 2x USB hub, packaged X-rite i1 Display 2 colorimeter and calibration hood. Height, pivot, tilt and rotate functionality

 
Above: Front and back views of the XL20. Click for larger versions


Above: OSD operational buttons.

The Samsung XL20 is entirely in a black colour (the bezel is actually a very dark blue, but it looks practically black), with a fairly thin bezel and discrete OSD operational buttons. The side view of the screen shows that the display is quite thick, which is due to the use of an LED backlight unit. One thing unfortunately missing from the back of the screen design is a cable tie, which is something Samsung have done on quite a few of their screens as of late (Pebble range for example).


Above: OSD quick access to 'color mode', and the 'color tone' menu accessible through the menu system

The OSD itself is fairly easy to use, with all the usual options as well as modes for gamma and colour tone (a range of cool and warm settings). The buttons also give quick access to 'color mode' settings, contrast, brightness and source selections. When using Color Modes other than the 'custom' setting, a light up indication appears beneath the OSD selection buttons telling you which mode you are using (e.g "Cal." is displayed when using the calibration preset mode).


Above: full height adjustment shown from minimum to maximum

The stand is height adjustable, allowing you to easily position the screen at a comfortable height for working. The above images show the extreme variations available in this adjustment, from as low as it will go, to a full height extension. The fluidity of the mechanism is very good.

The stand also allows you to rotate the screen from landscape to portait mode. This is also a very smooth and easy to use mechanism and can be handy for certain work such as reading webpages or writing documents. At least at this size screen this feature is practical, as I feel it is pretty pointless on anything much larger in practice.

The screen features a good tilt function, affording a nice range of movement and the possibility to position the screen comfortably at any angle.





Above: interface options shown and small internal fan visible on back. Click for larger images

The back of the screen features a DVI-I and DVI-D interface, along with the usual power socket you would expect. There is no D-sub (VGA) connection here, a sign that this is a high end device and is best used with a pure digital end to end connection. You can use an analogue output if need be, with the use of a conversion cable and the DVI-I interface, which accepts both analogue and digital signals. The monitor features a built in power supply, and there is no need for an external power brick, just the normal kettle lead. Also evident on the back of the screen if you look closely is a tiny internal fan, present to help keep the LED backlight unit cool, and dissipate heat. This runs silently.

Overall the build quality of the screen was very good, and materials were of a high standard. Because of the range of ergonomic adjustments, the screen was a little wobbly if you nudge your desk, but nothing to worry about really.

 



Colour Quality and Accuracy

The Samsung XL20 utilises an 8-bit AMVA panel, capable of producing a true 16.7 million colours from a palette or 1 billion (14-bit data processing internally). The colour capabilities of the XL20 are further enhanced by the use of an LED backlight unit, which offers a colour gamut covering 114% of the NTSC colour space, considerably more than the usual 72% coverage from standard CCFL backlighting. Obviously this screen is very much aimed at colour critical work, and the included detachable hood allows you to appreciate professional image quality further, with its high style design makes it more than a tool for eliminating ambient light interference. Plush inner fabric effectively removes reflection as well.

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user. I restored my graphics card to default settings and set it to its standard profile. The XL20 was tested at default factory settings out of the box using the LaCie Blue Eye Pro and their accompanying software suite.

Default settings of the screen were 70 brightness, 80 contrast. Gamma mode was set to '0', color mode was set to 'custom' and RGB values were all at a default of 50.


Samsung XL20 - Default Settings

 

Default Settings

luminance (cd/m2)

186

Black Point (cd/m2)

0.34

Contrast Ratio

547:1

Out of the box, the Samsung XL20 performed quite admirably. Firstly, you can tell by the CIE digram on the left hand side that the gamut of the screen stretches clearly outside of the sRGB colour space, something which standard backlighting cannot offer, and only recently exceeded with W-CCFL backlighting which is used in some modern screens. This is particularly evident in green shades, and in practice, greens did feel richer and more varied. Gamma was recorded at a value of 2.0, a little way out from the desired level of 2.2, being the default for computer monitors, and the standard for the Windows operating system and the Internet-standard sRGB colour space. Colour temperature was pretty much spot on, even at factory settings, being very close (<0.5% difference) to the 6500k colour temperature of 'daylight' we aim for. Luminance was a little high, as is common for many screens, and was recorded at 186 cd/m2. With black depth measured at 0.34 cd/m2, this provided a static contrast ratio of 547:1, pretty close to the specified 600:1 from the manufacturer.

The graph on the right shows the DeltaE (dE94) values for colours tested by the LaCie Blue Eye Pro. As a reminder, the lower these bars down the Y-axis, the better, in terms of colour accuracy. For reference, LaCie describe the DeltaE readings as:

  • If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer.

  • If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable.

  • If DeltaE < 1, the color fidelity is excellent.

The XL20 showed pretty decent colour accuracy out of the box, with an average dE of only 1.6. There is a slight difference between the requested and displayed colour, but overall the colours felt even and rich in practice. This is a good performance as one would hope from a screen of this price and specification.

 


Natural Color Expert


Above: Samsung branded X-rite i1 Display 2 Device. Click for larger image

The XL20 comes packaged with a Samsung branded version of the X-rite Eye-One Display 2 device, the same which X-rite / Gretag provide with their software which we tested recently, and the same provided with the LaCie Blue Eye packages. Coupled with this high end device is Samsung's Natural Color Expert software suite. Since this is provided with the monitor, I wanted to test its effectiveness in calibrating the screen, and see what features the software had to offer.

Installation of the software was quick and easy, and on loading the package up, you are presented with the above screen. This allows you to select between several modes:

  • Calibration - you can define the target brightness and black point levels along with the white point (colour temperature) and gamma levels for the RGB channels.

  • Emulation - Using the Emulation tab, you can create a new profile that contains your selected settings, apply an existing profile, or apply a stereotype of a system profile. Different from a profile created from the Calibration tab, you can also change the R, G, and B color gamma. Of course, you cannot use a gamma value beyond the range of gamma values that can be expressed by your monitor.

  • Uniformity - Using the Uniformity tab, you can improve the uniformity of your monitor.

  • Miscellaneous - Allows you access to load saved ICC profiles, set a calibraiton reminder frequency, restore defaults and run a measurement report on the screen.

I first ran the measurement process which flashed between RGB colours and a white and black shade. This process took quite a long time, about 5 minutes in total, and certainly longer than the test and report feature of the LaCie Blue Eye Pro software (~30 seconds). The test feature confirmed that luminance was at 187 cd/m2, and black depth was 0.33 cd/m2, which was pretty much what we had found from LaCie's software. A CIE digram was shown, but lacked any reference triangles for sRGB, NTSC etc. DeltaE values were also not recorded.

Following the calibration process you are asked to place the colorimeter in the centre of the screen. At no point are you asked to alter the OSD settings for brightness, contrast or RGB values. Instead, the process is entirely automated and adjusts the values at a LUT level and written into the monitor itself, creating an ICC profile as it goes. This process took a long time though, around 15 minutes total!

At the end you are presented with a calibrated results screen showing how successful the process was. Luminance was adjusted pretty well to 121 cd/m2, but black depth remained at only 0.33 cd/m2, no real improvement from default settings. This gave a static contrast ratio of 367:1 which was quite a way off the specified 600:1 from the manufacturer. Gamma was levelled to 2.2 for all channels, but colour temperature was now a little out, being changed from 6504k before, to 6447k after calibration. DeltaE was now listed at a value of 0.345, which presumably is an average value. You are asked if you want to save the created profile, and you are given the chance to name it as you see fit.

I loaded up LaCie's software to run a test and report on the calibration results from this process:


Samsung XL20 - Natural Color Expert Calibration Results



 

Natural Color Expert Calibrated Settings

luminance (cd/m2)

119

Black Point (cd/m2)

0.33

Contrast Ratio

360:1

Testing the results with LaCie's software showed a positive change in the monitors colour rendering capabilities and set-up from the default values. Gamma was now corrected from 2.0 to 2.2 and luminance was now also recorded at a value of 119 cd/m2, not far off the desired 120 cd/m2. Black depth remained unchanged at 0.33 cd/m2, giving a usable contrast ratio of only 360:1. This was the only real disappointment with the screens colour performance, with black depth being quite poor, especially considering the use of a *VA based panel.

Colour accuracy was improved with the Natural Color Expert calibration process, with dE now improved on average from 1.6 to 0.7. LaCie would consider colour fidelity to be excellent overall. Maximum deltaE was also improved from 3.2 to 2.0, with only a slight difference now detectable between the requested and displayed colour. Overall, Samsung's NCE software seems to have done a good job in setting up the screen more accurately, but the process did feel a little long to be honest. Upon saving the results, the monitor is entered into the 'calibration' option through the Color Mode menu, where the results are written into the monitors LUT and not reliant on whether NCE is running or not.  Switching back to the 'custom' Color Mode allowed you to quickly see what the screen looked like before the NCE calibration.

I ran through LaCie's software package again to see if further correction was possible:

 


Final Calibration


Samsung XL20 - LaCie Calibrated Results


 

LaCie Calibrated Settings

luminance (cd/m2)

120

Black Point (cd/m2)

0.27

Contrast Ratio

444:1

I restored the screen to default values and discarded the profile created during the NCE process. During the calibration process with LaCie's software suite, the brightness setting was altered to 45, contrast remained at 80 and the RGB values were changed to 48, 43 and 50 respectively. This calibration process does allow you to alter the OSD settings to help achieve the most accurate results possible, something which NCE did not offer. However, it should be noted that this adjustment only forms part of our calibration process, and the majority of the changes occur at a LUT level, as an automatic process altered by our colorimeter. Gamma was corrected nicely to 2.2 and luminance was also corrected to the desired 120 cd/m2. With black depth now recorded at a slightly improved 0.27 cd/m2, contrast ratio was 444:1, still a little way off the specified 600:1 from the manufacturer.

Colour accuracy was improved quite considerably, with an average dE of only 0.4 (colour fidelity is excellent) and a maximum of only 0.8. Overall I was pleased with the results here, and the AMVA panel showed some very good colour rendering capabilities. LaCie's software offers a little extra in the way of calibration accuracy, and obvious offers the test and report features we have shown here, which are very useful to help quantify your results. I tested the screen with colour gradients which showed no issues with colour banding at all.



Extended Gamut

One problem the enhanced-gamut monitors are bringing about is how to make them correctly reproduce images prepared for older, sRGB, monitors. Widespread graphics file formats encode colour not with some absolute values (e.g. with CIE diagram coordinates), but with some relative units. It means such files are going to be displayed differently on monitors with different colour gamuts. So, a picture prepared for an ordinary sRGB monitor is going to have extremely saturated colors on the screen of monitors such as the XL20. It can be said that its colour gamut is forcibly stretched out from its native sRGB (72% NTSC) to the XL20ís colour gamut (114% NTSC).

There are two ways to solve this problem. First, an ICC profile is created after calibration and each program that has colour management options can learn the monitorís colour gamut from it and correct images appropriately. Second, the XL20 monitor can emulate any colour gamut smaller than the monitorís own gamut. This is offered by the 'Color Mode' option, accessible through the 'mode' OSD selection button. When you press that button, a menu with five modes opens up:

  • Custom: the user has access to all of the monitorís settings and the colour gamut is not limited at all

  • sRGB: the monitor emulates the sRGB colour gamut and the user-defined settings are blocked

  • AdobeRGB: the monitor emulates the AdobeRGB gamut and the user-defined settings are blocked

  • Emulation: the emulation set up in the corresponding mode of the Natural Color Expert utility is enabled. The monitor offers full-featured hardware calibration with the results being written into the monitorís rather than the graphics cardís LUT and this mode will work irrespectively of the software you use

  • Calibration: the monitorís calibration results are enabled. Like with the emulation, the results are written into the monitorís LUT and do not depend on whether Natural Color Expert is running or not

By switching to the sRGB Color Mode setting you could immediately tell that the colour range was reduced, and after using the XL20 for a long period of time, it felt strange reverting back to this level of colour. Testing the screen with the LaCie probe again allowed me to see that (as shown above), the monitors gamut was now simulating the sRGB colour space, and was considerably reduced from the gamut tested before. It is a nice feature to offer this emulation of smaller colour spaces, and this could well be useful to colour enthusiast work.

 


Viewing Angles


Viewing angles of the Samsung XL20 were very good, with the image being clearly visible even from extreme angles. The AMVA panel technology shows none of the major contrast shift vertically that you can see from TN Film based models, and therefore does not show the characteristic blackening of the image when you look from below. There was a slight contrast shift detectable as you move away from a central field of view, and some slight pink tinting when you get further away. This was only very slight though, and quite hard to detect in normal use. S-IPS is often used in other colour enthusiast orientated screens, and can offer slightly wider viewing angles, and does not show the slight constrast shift when you move from a central view, which is inherant to VA panel technologies.

 


Panel Uniformity


In our usual testing process I viewed an all black screen in a darkened room, which allowed me to test the uniformity of the panel and to examine whether any backlight bleed was evident. There was no detectable leakage from the backlighting, and the uniformity remained very consistent. The top half was perhaps ever so slightly brighter than the bottom, but hard to capture with a camera.

The Natural Color Expert software offers another handy feature here as well, that being an option to help improve screen uniformity. You can choose whether to use a 9 point or 15 point reference grid, and are asked to place the colorimeter over each part of this grid in turn. Brightness is measured by the device, and at the end, the brightness uniformity across the screen as a whole is automatically adjusted. That is the theory at least. It was difficult to detect much in the way of change, but then uniformity was pretty good from the outset anyway.

 


Office and Windows Use

I found the Samsung XL20 to be pretty good in Windows and office use, with it's tight pixel pitch of 0.255mm being well suited to viewing text. The DVI interface obviously offered a nice end to end digital connection, and resulted in clear text and a very good picture quality. I found it a little hard to get used to using a 4:3 aspect screen againn however, and the lack of a WS format meant it was not easy to do any side by side working. The preset colour modes did not offer any 'text' option, something which is often quite useful for office work when you are working in low light conditions, and want to reduce the monitor brightness somewhat. All in all, I personally prefer a WS format screen for normal work, but I can't really hold that against the XL20 as it isn't marketed in this way! The rotate adjustment might prove handy for some users, and is at least functional at this screen size.

 


Responsiveness and Gaming


 

The Samsung XL20 was tested using the chase test in PixPerAn, a good bit of software for trying to quantify differences in real terms responsiveness between monitors. As a reminder, a series of pictures are taken on the highest shutter speed and compared. The images above show the best case example on the left hand side, and the worst case example on the right hand side. This should only be used as a rough guide to comparative responsiveness but is handy as a way of keeping a constant test of each screen.

As you can see from the above images, the 8ms G2G rated AU Optronics AMVA panel performed very well here. In the best case image on the left, it was very comparable with the 8ms G2G rated S-MVA (from CMO) panel from the Viewsonic VX2435WM, showing that the 8ms G2G generation of VA panels are all quite comparable. The performance remained a little behind the very well regarded NEC 20WGX2, which features a 6ms G2G AS-IPS panel from LG.Philips. I was impressed by the responsiveness of the XL20 in these tests, something which you perhaps wouldn't expect from a high end professional screen such as this. If you are a graphics or photo worker, and need the high end colour capabilities from your screen, but also want to do a bit of gaming, this may well be a good choice.

This response time is made possible through the application of RTC (Response Time Compensation) technologies, which can sometimes lead to some overshoot and artefacts. In this case, there was no obvious sign of any such issues, and the RTC impulse seemed to be well controlled. Motion blur was detectable in games if you knew what to look for, but there was no sign of ghosting or trailing of the images in practice. To elminate motion blur you would need to consider screens with additional measures for handling this, such as MPA, BFI or 120Hz technology.

  

As usual I tested the screen in clone mode with a CRT to determine the level of input lag. This is something which can put off some gamers and is a delay between graphics card and monitor output. By hooking up a CRT you can show that  the LCD lags behind somewhat, which can affect users in some situations where they rely on the screen image being as fast as their inputs (e.g. fast FPS shooting games). Often, input lag is very low and probably wouldn't represent too much of a problem in real terms.

 

The above graph shows the average input lag across several screens tested at TFT Central, and also average input lag as recorded from other sources on some popular and well established models. As you can see, the input lag of the XL20 was quite high, with an average of 34.4ms delay between the images. Maximum input lag was also 41ms. Obviously this screen isn't really aimed at the gaming market, but an input lag of this degree could prove off-putting to some buyers. In other uses, obviously there is no problem at all.

 


Movies and Video

When considering whether a display is well suited for movies, you need to consider a few things:

  • HDCP support over a digital interface is vital for viewing HDCP encrypted content. Unfortunately the XL20 does not offer this support over it's DVI interfaces, which could cause a problem in the future.

  • HDMI interfaces are becoming more common on modern screens, but the XL20 features only a DVI-I and DVI-D interface. Connection of external devices could be tricky, and it was also a pity not to see a dedicated D-sub interface, which is often used for connecting games consoles.

  • Viewing angles must be wide if you intend to have more than one person watching the video. Thankfully the AMVA technology is strong in this regard and perfectly well suited to viewing the screen from a variety of angles, or with several other viewers.

  • Black depth must be good to allow darker scenes to be rendered correctly, and for detail to be distinguishable. The 0.33 cd/m2 black depth is quite average here, and not as good as we have seen from some PVA, or even TN Film based panels. In practice, it didn't prove too much of an issue anyway.

  • Movie noise must be kept to a minimum, otherwise artefacts and twinkling in large colour masses can be noticeable. MVA panel technologies are considered to be good in this regard, and the AMVA panel in the XL20 performed well. There was no real issue with noise when sitting at a sensible viewing distance.

  • Widescreen format monitors are obviously much more suited to viewing movies than a 4:3 or 5:4 aspect screen. The XL20 is of course 4:3 aspect, with its 1600 x 1200 resolution, and so this results in large black borders being used when watching DVD's or any other WS content. The Samsung XL20 can show movies and video quite well really, but if this is going to be a primary use for you from your screen I'd suggest a WS format display would be far more suitable. The forthcoming Samsung XL24 and XL30 are both WS aspect and may well be more suited.

  • The wide colour gamut helped make colours look vivid and bright in movie playback, and you could compare this improvement quite easily by switching to the limited sRGB mode. If colours appear saturated then you also have the option to switching to a different emulated colour space.

 


Conclusion

The Samsung XL20 is an impressive screen. There's no doubting that it's performance and features are high end, and it is capable of offering not only some excellent performance in its target area, colour work, but also in other areas as well. I was impressed by the colour rending capabilities of the LED backlight unit here, and the inclusion of a decent hardware colorimeter was a nice touch. Obviously a screen like this comes at a cost, and with current retail prices of around £790 GBP / $1700 USD, it is clearly a more expensive option than some other screens in the market. However, for colour critcal work, it is a good option, and pleasingly, it wasn't let down in other areas such as responsiveness. The only thing which was a little disappointing was the black depth of the screen, and the contrast ratio was recorded at lower than even the 600:1 quoted spec.

If you can afford the high price tag, or are looking for a colour enthusiast screen for work, the XL20 is a good option. It will be interesting to see how the XL24 and XL30 compare when they hit the market, although the price point is surely going to be even higher.
 

Pros

Cons

Excellent colour accuracy and extra wide colour gamut

High price tag puts it out of reach of most average users

Good responsiveness, despite being a colour enthusiast orientated screen

Disappointing black depth and low contrast ratio

Good range of ergonomic adjustments and useful packaged colorimeter

Natural Color Expert software is very slow!

 

 

 

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