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PDP508XD Calibration & Benchmark

by Vincent Teoh
16 August 2007
TLC Broadcast

Baseline CCT (Correlated Colour Temperature)

If you are not going to calibrate the greyscale of Pioneer PDP508XD yourself or employ a professional calibrator to do so, the [Movie] preset should get you closest to D65. On my review sample, this yielded a greyscale that looked a tad cool for lower stimulus (i.e. darker regions of the picture) and slightly warmer at the top-end, but overall it was still much better than the over-blue default [Standard] preset.

Pre-calibration [Movie] mode CCT Pre-calibration [Movie] mode RGB tracking
Pre-calibration [Movie] mode CCT
Pre-calibration [Movie] RGB tracking

Greyscale Calibration

As with the PDP4280XD, the [Movie] preset gave the best gamma profile on the PDP508XD, so that's where I began my work. I ended up with this:

CCT RGB Tracking
Calibrated [Movie] mode CCT
Calibrated [Movie] RGB tracking

Final CCT was a touch warm at the top and bottom end, but dEs (delta errors) were below 4 from 30% stimulus onwards with only a minor spike at 100%. But more importantly, gamma tracking looked very good:

Gamma Gamma Tracking
Calibrated [Movie] mode gamma
Calibrated [Movie] gamma tracking

Whereas the PDP4280XD I reviewed 1 month ago suffered from a dip below 20% stimulus resulting in some loss of shadow detail, gamma tracking on the PDP508XD remained flat throughout at very close to 2.2. And to achieve this I didn't even need to access the hidden ISF C3 mode... in any case I didn't manage to obtain the necessary software from Pioneer to do so.

Another quirk present on the PDP4280XD that had seemingly disappeared from the Pioneer PDP508XD was the variation in peak brightness with each different [PureCinema] mode. As a precaution, I still recommend that you start your calibration only after selecting the [Pure Cinema] mode that you're most likely to use for that input.

Unless a Pioneer engineer divulges the info, I guess I will never know why such differences exist between the PDP508XD and the PDP4280XD. But it is worth bearing in mind that the former is the (current) flagship model while the latter is designated to be the budget version. Different screen sizes may also require separate circuitries to drive the respective panels.

Baseline Colour Chromaticity

Colour Space 1 Colour Space 2
Pre-calibration [Colour Space] 1
Pre-calibration [Colour Space] 2

The default [Colour] setting in the [Movie] preset was -6, which explains the undersaturated gamut for [Colour Space] 2. Prior to calibration, [Colour Space] 1 was – on the other hand – oversaturated (green and cyan in particular) judging from the CIE chart.

Colour Calibration

[Colour Space] 2 was severely undersaturated between 0% and 75% saturation. To correct the undersaturation, [Colour] needed to be increased to +15, which unfortunately introduced colour decoding errors causing red push to seep through. My choice of gamut for HD is still [Colour Space] 1, due to better overall colour balance and saturation.

Benchmark Test Results

Dead pixels None
Screen uniformity Perfect
Overscanning on HDMI, Component 2.5 percent (0% in [PC] mode)
Blacker than black Passed
Black level Best I've ever seen/ tested (even better than 4280XD)
Black level retention Stable
Primary chromaticity Excellent
Scaling Good
Video mode deinterlacing Excellent
Film mode deinterlacing Competent 3:2/ 2:2 cadence detection
Viewing angle Excellent (> 160°)
Motion blur Normal for plasmas
Digital noise Some settings may cause increased PWM noise
Sharpness Defeatable edge enhancement
Image retention None
Posterization Effectively none
1080p/24 capability (PS3) Accepts 24fps; no telecine judder

The black level on Pioneer PDP508XD measured even lower (albeit by just a hair) than the PDP4280XD, contributing to the highest calibrated contrast ratio I've recorded at HDTVTest so far. The rest of the findings were not dissimilar to the PDP4280XD, so please have a look at the relevant section in that review if you need more detail.


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