Don't Know Which HDTV To Buy? Try Our HDTV Selector Tool

Picture Quality On KDL40W2000 LCD

by Colin Tang
5 March 2007

Clouding...like.no.other

Mura
Some uneven uniformity is seen on the right side of the TV on no AV input. There is clouding on the left side but that is obscured by camera flare. You may need to adjust your monitor's brightness to see this.

 

Mura
An example of clouding in Batman Begins . You may need to adjust your monitor's screen brightness.

We have been aware of various backlight and screen uniformity issues before we got the Sony, but we weren't quite prepared to see this. The clouding presented itself when we started to calibrate the display in low ambient light. In some areas, there are some irregular patterns of increased brightness that resembles like, you guessed it, clouds. In others, the clouds adopted a more wispy like appearance.

A full treatment on the nature of clouding will not be possible in this review, so watch out for our later article discussing this and other backlight issues that are currently affecting LCD panels. Sufffice to say, there are several possible reasons; NONE of them are officially supported by Sony.

  1. Lack of homogeneity in control circuit adjustments
  2. Misalignment of LCD matrix during manufacturing
  3. Impurities in the matrix
  4. Thermal induced stress
  5. Panel assembly induced stress

The closest thing to describing the clouding phenomenon appears to be 'mura', a Japanese term used to describe a low-contrast and non-uniform region that is typically larger than a single pixel. This is not a new problem to the LCD industry. Earlier LCD panels for widespread use in the computer industry have exhibited this although I suspect the screen size and bright ambient light conditions have helped to mask it a little. This, however, is no longer possible with >40 inch TVs in typical dim viewing conditions. These conditions highlight the screen imperfections and may become noticeable to the user.

During our calibration, we noticed the following

  1. Light pressure on the screen causes the characteristic of clouding to change temporarily with the clouds intensifiying around the pressure point.
  2. Turning the brightness control up may alleviate it a little, although this is clear undesirable if you want deep blacks.
  3. Turning the backlight down gives the greatest improvement at the expense of lowering overall screen brightness. Again not the ideal solution.

The appreciation of this issue relies of course on various factors such as your knowledge on this matter, what picture quality constitutes, your TV settings, how much you like this TV and how the ticket price of this beauty distorts all of the above. With this out of the way...phew...we'll move on to bigger and better things.

Torture Test

Stuck/dead pixels Passed
Backlight test Clouding :)
Overscanning (HDMI, Component) 2-3 percent but correctable for 1080 source using Full Pixel mapping
Blacker than black Passed
Black level Very good
Black level retention Stable
Primary chromaticity Poor
Scaling Fair
Video deinterlacing Fair, no jaggies reduction
Viewing angle 120
Motion blur Mild
Digital noise Hardly any visible at 8 feet with NR off
Sharpness Defeatable edge enhancement

As usual, the vivid `eye blazing'' settings out of the box was too bright with garish colours and bluish whites. Unusually, there was no siginificant red push as one would expect from these settings. We then proceeded with calibration (turning most unnecessary enhancements off was the mainstay), producing the results above.

Black Level

The black level on this display, when set to power saving off and 0 backlight, is quite satisfying. LCDs reputation for poor blacks is fast becoming history. While it can't match the subjective black level of the best plasmas, it came pretty close. Black retention test patterns were stable. This may be of some interest to some readers: despite sharing the same S-PVA panel as Samsung LE40F71BX, it had only a slight red tinge in the blacks at extreme viewing angles.

With the backlight and brightness controls, you have some flexibility in determining your black level. Please note that the decreasing the backlight to achieve lower black luminance can reduce the peak brightness of the LCD, a traditional strength of such panels. For us the threshold was with the above settings. Your limit will of course depend on personal preference and ambient light conditions. If you are having problems with clouding, from our observation you can diminish its impact by adjusting the power saving, light sensor and backlight settings.

Dynamic Contrast Ratio

The Sony excels in this department, thanks to its excellent peak brightness and low blacks. Our post calibration dynamic contrast ratio was the highest among our recent panels and the benefit of this is really obvious in real time programmes. We would have preferred using static ANSI ratios but measurements can be tricky if you don't have a dark lab. Calibrated dynamic contrast ratios (I stress calibrated) is a rough guide on the dynamic range and capability of the display.

Greyscale

Gamma CCT
Greyscale graph at gamma 2.3
The dotted blue line shows 6500K at 0 to 100 IRE.

Bearing in mind the earier limitation with the greyscale settings in the service menu (meaning you can't change RGB gain and drive from the user menu), we proceeded to adjust the values starting from Warm 2 colour temperature and a target gamma of 2.2 (Medium).Warm 2 came closest to D65 standard. We experienced some red clipping during this process and and so went on to a lower `gamma' setting at 2.3 (Low). The Sony's greyscale was well behaved at this point. There is some mild posterization in the lower end of the smooth grayscale ramp but this is not unexpected.

Update: There is no significant magenta tinge on Warm 2 as previously stated. This was due to a mild sensor drift in our equipment, which was corrected in our repeat greyscale calibration.

The adjacent graph shows the relationship of color temperature of a shade of grey under different intensities (white being the brightest grey and black the darkest). It's fairly close to the dotted 6500K temperature after 35 IRE. Below that sensor error can cause inaccurate readings.

Colour

CIE
The black triangle represents HD 709 colourspace. The white represents Sony KDL40W2000 Buy this for £759.98 at Dixons
Use code '5TV' for £40.00 discount

This my pet peeve with current LCDs on the market, and the Sony is like many others in this respect. The enhanced colour gamut does not allow fine control of the primary colout points. The only colour saturation control only allows you to make the white triangle bigger or smaller. So if you study the graph above for example, trying to bring the green down will adversely desaturate the blue and red colours. Turning it up will of course give you your Saturday cartoon colours.

So in essence, if your movie is encoded in HD 709 and you decode it with the current non-standard matrix you will get inaccurate representation of green and cyan colours. To be fair, in the real world you are less likely to notice this problem. After all, colour accuracy comes third after contrast ratio and colour saturation. Also, we are probably more tolerant of green errors compared to red push that is so prevalent in digital displays. Currently, though, my preference for colour accuracy is with plasma displays.

Motion

There is some mild motion blurring on this display and this may be evident to some viewers in fast action movies or sports. We got used to it after a while, and we believe most viewers will do the same.

Detail and Sharpness

Overscan
Not ideal since this is a 4:3 picture but overscanning is present with full pixel off.

 

Overscan
Display area in Normal mode. Note the unusual banding due to lack of 1:1 mapping for 1 pixel black and white lines. 1920x1080i source played on our Toshiba HDE1.

 

The same conditions as above with full pixel turned on. This applies on HDMI and component.

Best detail on the Sony W2000 is seen when full pixel is on. Without it, not only your picture is cropped from overscanning, but you can lose small detail from your source through unnecessary scaling. The point is 1080 source should be displayed as 1080 without any scaling. During our testing there was no night and day difference with normal programme film and video material. But in the HTPC world, it's a completely different matter. Users can usually detect loss of detail and sharp edges because of the `blurring' effect from scaling. The extent of this problem will of course depend on the internal scaling algorithm in displays.

Viewing Angles

The W2000 model matches the Samsung LE40F1BX in viewing angle and ties for best in class off axis viewing. Colours, blacks and contrast ratios are reasonably maintained at 120 degrees and not at the quoted 178 degree.

Video Artifacts

Depending on source quality, the Sony is generally free from noise riddled images on a wide range of materials. The occasional twitter and jaggies slips through the deinterlacing process but the picture quality is not excessively degraded.

Scaling quality is fair by current standards. There is a tendency towards softness at the edges but jaggies are filtered quite well. There is no significant ringing on most material (with sharpness at 0) but this really depends on the pre-processing at source. You can change the sharpness control to counter any edge enhancement found to some extent.

High Definition

Despite some issues with the Sony, the out-of-lab performance for this model is in a word, sublime. This is really a case of the sum of components being greater than its parts; lab measurement often don't tell the whole story. On a calibrated set, the HD film material was amazingly sharp and detailed, without being too artificial. Bright scenes were given first rate treatment, given its natural strength in contrast ratio and peak brightness. The dark scenes have satisfying blacks with minimal loss in shadow detail. You don't feel that you're missing too much here at any point. We preferred the colour pallette of our Panasonic Plasma PH9 (the most noticeable effect with the Sony is in the green foliage having too much blue), but we are probably talking about personal preference here. Some users may rate the increased brightness, resolution and clarity of this LCD above any current consumer level plasmas.

 
Batmobile...
 
Gabby Logan...
 
King Kong...
 
Serenity...

With HD sports video broadcast, the same benefits are transferred over. Motion smearing may be an issue to some viewers but this was not excessive. In the end, I still prefer to watch football or rugby on a good plasma screen, but if this LCD is any indication this could change at some point.

Standard Definition

SD is a bit of a mixed bag. For all the Bravia Engine advertised benefits, it cannot tame the poorest SD material. For this you may have to look at external video processors. With analogue source (I don't know why we bothered), blurring and ghosting was readily apparent, with the occasional dot crawl coming through.With the digital tuners you trade the above artifacts for macroblocking and mosquito noise but I will stress here that this is mostly bit-rate (and therefore channel) dependent. With a bit of experimentation you can see which channels consistently underperform on this respect and avoid them. Personally, I've had good viewing experiences with Channel 4. You can also use Noise Reduction, MPEG NR, sharpness and wide colour space controls to improve picture quality with poor bit rate source. For most of the part, the Sony delivered an above average performance on digital SD broadcast.

Update: I noticed an issue with the wide colourspace and live colour on for SD football broadcast yesterday March 09, 2007. Somehow, in all the excitement of the goals-galore Newcastle UEFA match yesterday, I noticed a flickering grid like green discoloration on the pitch. The problem went away with switching the colourspace back to normal. Has anyone seen this effect?

With DVDs, the Bravia Engine does a whole lot better or needs to work less if you will. In short I was impressed by what I saw. The images were so smooth and detailed that a casual viewer may easily mistake it for a HD source if viewed from afar. A quick look at a comparable scene produced by our Toshiba HDE1 revealed no significant difference. The Sony does an excellent job of representing the DVD color fidelity, blacks and detail on a large HD screen.

HTPC

We had some problems with the DVI/HDMI interface at 1920x1080 hooked up to our ATI Radeon card. It gave us an `interlaced' combed picture. Scouring the internet, we discovered that this is a recognized problem and solution involves changing the card. VGA users may overcome the limitation of 1360x768 resolution by using Powerstrip, a software which can allow 1920x1080 1:1 mapping.

Sony KDL40W2000 Settings

The following settings are optimized for HD broadcast and HD DVD performance via HDMI input. There are several reasons why they won’t work for you, as they can all affect `final’ picture quality.

1) Personal preference
2) Ambient light
3) Source material
4) Players
5) Intramodel variation

So here goes...

  • Picture Mode Custom
  • Backlight Min
  • Contrast Max
  • Brightness 42
  • Colour 55-60
  • Color Temperature Warm 2
  • Sharpness 0
  • Noise reduction Off
  • Black corrector Off
  • Advanced contrast enhancer Off
  • Gamma (Low for daytime viewing, Off for night-time)
  • Clear White Off
  • Colourspace Normal
  • MPEG noise reduction Off
  • Power Saving Off
  • Full pixel On

Please note that these settings were applied after service menu greyscale calibration. There is a slight difference in image contrast depth without the service menu settings but the overall picture was still very good. I can’t give out service menu settings, so please don’t ask. If you are wondering why my settings are making the images too dark or too yellow, then that's because you are probably watching at showroom settings. Give it some time, you might like it after a while.

With SD broadcast, the above settings will not apply directly. You can improve the picture by setting colourspace to Wide, adding a touch of sharpening and applying MPEG NR and general NR as you see fit.

These settings are not gospel, so don't let it change your life. In the end, just do whatever you want to get `your' best picture. Enjoy :)

Back To: KDL40W2000 Review
 

Discuss this article at our new HDTVTest forum