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Toshiba 40ZF355D Calibration

by David Mackenzie
11 June 2008

Greyscale

The default "Warm" Colour Temperature presented a greyscale closest to the D65 standard out of all three presets. It should do a reasonable job of pleasing users who are interested in semi-accurate reproduction, but not interested in entering the service menu to make further refinements:

Pre-calibration CCT
Pre-calibration CCT with [Colour Temperature] "Warm"
Pre-calibration RGB
Pre-calibration RGB tracking and delta errors (dEs)

Nevertheless, experienced tweakers will still notice that the [Warm] mode emphasises red, and delta errors are relatively high. Of course, by entering service mode and adjusting the RGB [CUT] and [DRV] controls, things can be refined that little bit more:

CCT after greyscale calibration
CCT after greyscale calibration
RGB tracking after calibration
RGB tracking and delta errors (dEs) after greyscale calibration

After calibration, delta errors remained below the acceptable threshold of 4 from 30% stimulus onwards. However, the RGB tracking chart shows that the lower Greys remained slightly blue-tinted, even after calibration. Correcting this introduced a far more objectionable excess of blue in brighter tones, so we left it as is.

Colour

Similar to Sony and Samsung's implementations of the SPVA panel, Toshiba also boast a "Wide Colour Gamut" in their promotional material. Unsurprisingly, this meant that out-of-the-box colours verged towards neon, which can at first be quite addictive, but grew old quickly, especially with photorealistic content. The below CIE chart demonstrates the extent of the widened gamut:

Pre-calibration CIE chart
CIE chart after Greyscale calibration, with [3D Colour management] off

Fortunately, Toshiba offers a user-accessible colour management system. Using this, it was possible to bring the gamut much closer to Rec.709 standard, for more accurate viewing. Curiously, the exception to the otherwise excellent results was the Cyan secondary colour, which remained firmly in its widened position. Fortunately, this should have little impact on the TV's real world performance. More noticably, it proved quite difficult to get accurate results from Red, so we made do with lowering its saturation slightly.

Post-calibration CIE chart
CIE chart with reference to HD Rec. 709 after calibration with HD source

Benchmark Test Results

Dead pixels None
Screen uniformity Clouding reducible to negligible levels
Overscanning on HDMI 0% with [Display Area] set to "Exact Scan" or "PC"
Blacker than black Passed
Black level Excellent
Black level retention Stable if [Active Backlight Control] off
Primary chromaticity Very good (after calibration)
Scaling Very good
Video mode deinterlacing Excellent
Film mode deinterlacing Excellent, 3:2 (60hz) and 2:2 (50hz) passed
Viewing angle Good for an LCD TV (90°)
Motion resolution 450 with [Active Vision M100] on, 250-300 otherwise
Digital noise reduction Effective
Sharpness Defeatable edge enhancement
1080p/24 capability (PS3) Accepts 1080p/24 video signal; no telecine judder
Input lag 30ms slower than a PC monitor

Power Consumption

Default 252 watts
Calibrated 118 watts
Standby 2 watts

Black Level

We measured the Toshiba 40ZF355D HDTV's calibrated black level at a satisfyingly deep 0.06 cd/m2. This is an excellent result, and is what we've come to expect from the excellent SPVA LCD panels. Such a result is achievable only with a superb quality LCD panel and sufficient user control provided by the television's on-screen displays. The 40ZF355D has both, and is up at the top with the best LCD TVs as a result.

Screen/ Backlight Uniformity

The Toshiba 40ZF355D review sample we received showed very slight "flashlights" in the top-left and top-right corners of the screen in its out-of-the-box state. These were very minor to begin with, so it wasn't surprising that they disappeared entirely after calibration. This was better than our expectations, as we've seen large-screen SPVA panels with unacceptable amounts of unevenness in the past.

Connecting a PC to one of the HDMI inputs confirmed the quality of this individual panel.  White windows stayed white across the screen's surface with little fluctuation. In the past, we've seen panels where one side of the screen appears more green or red tinted than the other. Thankfully, this was not present here.

Static Resolution

Whilst in the [Exact Scan] or [PC] Aspect Ratio modes, the Toshiba 40ZF355D LCD television resolved the full 1920x1080 pixels from our test patterns. Again, there is no permanent feature for 1:1 mapping, so owners of this TV will need to familiarise themselves with the habit of selecting these modes manually.

Motion Resolution

With the [Active Vision M100] system disabled, the Toshiba 40ZF355D HDTV managed around 250-300 lines of motion resolution. This is fairly standard for LCD panels being driven without the help of a 100hz MCFI algorithm. Enabling the 100hz system, however, didn't boost the results as much as we'd hoped. On the FPD Benchmark Software Blu-ray Disc, about 450 lines were visible at the black side of the test pattern. At the greyer end, only around 200 were visible, which is actually slightly worse when compared to the same area of the pattern without the 100hz processing. The same results carried across to the benchmark disc's real-world tests: on the "Swing" clip, the girl's striped shirt revealed random motion artefacts with the feature turned on, as opposed to the standard uniform blur one would expect with the system turned off.

The bottom line here is Toshiba have done well to implement their 100hz system as an optional enhancement, so it can be enabled or disabled as necessary. Any Frame Interpolation system runs the risk of introducing artefacts, but at their best, they can indeed increase motion resolution with real-world material. The choice is up to the user.

Video Processing

Using both the NTSC and PAL versions of the HQV Benchmark Disc, the Toshiba 40ZF355D LCD TV correctly engaged Film Mode processing for both NTSC 3:2 and PAL 2:2 cadences, when fed with a DVD player outputting interlaced SD video over HDMI (provided that [Cinema Mode] was enabled). This is excellent, and is what we've come to expect from Toshiba, who have consistently excelled in this area in the past, even on their lower-priced models. In fact, if you have a cheaper Upscaling DVD player, we recommend turning off its upscaling functions and sending standard interlaced video to the TV, because it's likely that the Toshiba 40ZF355D will do a better job at processing the signal than a cheaper DVD player will.

The [Cinema Mode] option has two settings: On and Off. Setting it [Off] will force the TV into Video mode constantly, meaning that if a film is showing on TV, you'll lose some resolution. [On] is an Automatic mode which gives priority to Film content, but sometimes causes combing/interlacing artefacts when the TV mistakenly engages Film Mode when Video content is in fact being shown.

The effects of [Cinema Mode] are not limited to standard definition. 1080i/60hz based sources are, in fact, also converted flawlessly to 1080p/24 by the TV and displayed with silky-smooth, judder-free 5:5 pulldown. Although most HD disc players can output 1080p/24 natively, this is nevertheless excellent and a great sign of attention to detail from Toshiba, and should please owners of 1080i HD DVD players which, in reality, are probably going nowhere fast despite the format's demise.

Video-based content was also handled brilliantly. When presented with the "jaggies test" from the Silicon Optix DVD benchmark disc, the 40ZF355D employed highly effective diagonal interpolation, smoothing the edges of the rotating bar as flawlessly as could be expected. We couldn't remember the last time we'd seen the famous "American flag" test looking as clear and as free of jaggies as it does on this TV. Again, if you have anything but a top-end Upscaling DVD player, please have it output the direct signal, and let the Toshiba work its magic.

The quality of the scaling is also very good. The AVIA Guide to Home Theater DVD's "Sharpness" pattern showed that very little ringing was visible around high frequencies, whilst images were still suitably detailed.

4.5 Star Rating: Highly Recommended

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