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Sony KDL40W2000 Bravia Technology

by Colin Tang
5 March 2007

Bravia

The whole Bravia experience for our model is the result of several key technology below:

  • Bravia engine
  • Wide color gamut CCFL backlight
  • Live Colour Creation
  • 1080p capable display
  • Super Patterned Vertical Alignment Panel

The latest panels from Sony are using the S-PVA technology that is also employed by Samsung, but they differ in internal electronics, backlighting and picture processing. With Patterned Vertical Alignment, off-axis viewing angle is possible without significant degradation in contrast ratio, blacks and colour saturation. In S-PVA panels, the matrix of liquid crystal molecules within each sub- pixel is itself divided into discrete segments. The overall viewing angle can be increased considerably by varying the orientation of each segment to refract light over a wider area.

The colour gamut for the Sony W2000 series is increased via the Live Colour Creation Process. This involves non-standard colour decoding through Bravia Engine processing, the WCG CCFL backlighting and selected colour filters (remember that the creation of colours in a LCD uses colour subtraction.) As written previously, the non-standard decoding or physical limitations of the system can create colours of different hue and saturation from the original image.

The Bravia engine is difficult to `quantify' as I cannot find any detailed technical breakdown from Sony's recent press releases. It seems that the engine processes the picture to achieve better detail, lower blacks, richer colours and less digital noise and artifacts. It seems that part of the picture processing is available to user in the advanced settings. I have heard that the Bravia Engine only benefits SD material, but this is from an unconfirmed source. While I look into this, I am delighted that Sony has included many advanced settings for user adjustment as the whole calibration process was much smoother as a result.

Black Corrector

Turning on the Black Corrector enhances the black areas of the picture. Sadly, this is done at the expense of loss of shadow detail, which becomes crushed and muddled due to low end gamma modification. I chose to leave it off and lower my black level through other means.

Advanced Contrast Enhancer

Automatically adjusts backlight and contrast levels to suitable settings based on image brightness. I left it off for critical viewing because of its dynamic nature.

Gamma

Sony is setting unprecedented standards for LCD TVs by including many tweakable picture settings in the user menu. One of the most important is probably gamma. It affects the midtones intensities of all colours including grey but does not affect peak white or black in general. This allows us to control contrast depth (brightness ratio between colours) depending on the ambient light. In general, for dim conditions, you should increase your gamma value (this does not apply here see below), which will have an effect of making the picture more contrasty.

Here gamma on high has a value of 2.0 which is much too bright for most conditions. In addition, while performing calibration we found that we were unable to get an accurate grayscale at the highest intensity (red did not have enough output - clipping). Gamma Medium is roughly 2.2, Low has 2.3 and Off has approximately 2.5. So, looking at it again, you actually need to dial the gamma to low or off for subjective improvement in contrast in dark environment and vice versa in during bright conditions. I would avoid high gamma and probably keep it mainly between low and off mode.

One design glitch is that the service menu grayscale seems to be the same at all inputs. Ideally different gamma's should be calibrated indepently. Given this limitation we can only be content with the above method for switching the gamma depending on viewing conditions.

Clear White

It is probably a `bleaching' agent but I did not see a significant effect with it on. So off it went.

Live Colour Colour Space

Setting a wide colour space with live colour on has a similar effect with dialling up the colour saturation. When measured on the CIE chart, the original triangle/gamut/range becomes larger. Some users may like it that way and I say to each his own. however, I am more concerned with colour accuracy and thus examining flesh tones and green foliage will reveal exaggerated, unrealistic tones.To prevent this I went for the normal but still inaccurate colourspace.

MPEG Noise Reduction

There are two general MPEG artifacts found mainly in SD material; blocking and mosquito noise. There are inherent in low bit rate material. Mosquito noise is a temporal phenomenon and is characterised by edge busyness around moving objects. Your classic example would be your favorite football player with `flies' around him as he runs down the field. Blocking artifacts are large rectangular areas in objects normally seen in high motion sequences at low bitrates. Sony's MPEG noise blurring algorithm is insufficient for good quality artifact suppression. It's high frequency spatial filter robs fine detail to minimise these artifacts. My advice, use it sparingly. Just a note to say that it works on analogue signals as well.

Noise Reduction

Most video noise reduction algorithms use a temporal filter to remove differences in noise over many frames. Using this mode reduces background noise significantly without removing too much detail and is probably recommended for low quality programmes from poor reception or bit-rates. It is most effective with static scenes but it can get complicated when there is motion. We were unable to detect any significant motion blurring normally associated with this mode on regular programmes but have yet to experiment this in sports. If you do have some trouble with motion, try lowering it or turning it off altogether.

Update: We had the opportunity to examine this again with SD football broadcast. It appears that the temporal noise reduction works quite well in 'stabilising' the picture by removing pixel fluctuations commonly seen in digital displays. No detail was significantly lost in this instance. However, football (or any fast motion sequences for that matter) presented a greater problem with a lot of motion smearing and loss of detail. You can see this when switching the mode on/off during panning shots.

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