Posted on June 11, 2018 By Nikki Zelinger
ViewSonic PX727-4K Projector Review – Calibration Settings: Calibration Presets Notes, Best Mode Calibration, Brightest Mode Calibration & 4K Calibration
Note: The projector had over 53 Hours on the lamp before I calibrated it and took the light measurements. A brand-new bulb may have slightly higher measured lumens.
ViewSonic has included 5 picture preset modes for the PX727 (Bright, Standard, Movie, User 1 & User 2). I spent most of my time with User 1, User 2 & Standard modes. All of these modes have the same controls, what sets them apart is how these controls are preset. They all offer 3 color temperature options (Normal, Cool & Warm) 2-point white balance adjustments, gamma presets and full CMS (color management system).
For my Best/Dark Room calibration I used User 1 and renamed it Best/DARK. I kept the lamp on normal and would have kept Brilliant Color off but oddly the PX727 lacks the Brilliant Color feature which is found in most DLP projectors in this price range. With the default contrast set to 58 the projector clipped whites around 228, but thankfully lowering contrast to 48 corrected this. I kept color enhancement and skin tone off. I recommend you keep sharpness to 6 or lower and super resolution to 4 or lower for 1080i/p content.
User 1 out of the box with it’s bright gamma and blueish white balance showed DeltaE ranging quite high form 5 on the low end of the grayscale to +12 on the high end. The average color temp was 7100K range, a bit cooler than our target of 6500K (D65). After my white balance calibration, I was very pleased to see the DeltaE shrink to 1.25 or less across the board.
I usually target a 2.4 (BT.1886) gamma for my Best/Dark calibration but found that the projector is really tuned to a 2.2 and trying to calibrate it to a 2.4 yielded poor results, so I used 2.2 as my target. The default gamma setting of 2.3 actually measured an average of 1.95. After calibration resulted in a fairly flat 2.25 average.
Measurements taken at Mid Placement with Normal Lamp.
Average Gamma Pre-Calibration: 1.95
Average Gamma Post-Calibration: 2.25 @ 1119 Lumens
White Balance calibration settings for Best/Dark Room (user 1 mode).
DeltaE is a metric for understanding how the human eye perceives color difference. The term delta comes from mathematics, meaning change in a variable or function. The suffix E references the German word Empfindung, which broadly means sensation. Simply put, look at DeltaE as a measure of grayscale/color accuracy. 3 and under is considered ‘Excellent’ and imperceptible by the human eye.
Next up I did my Bright Room/Quick Cal calibration using Standard Mode with normal lamp. After some experimenting I found doing the white balance calibration worked best from the warm preset. By doing this it helped to keep the lumen output a little higher than if I had used normal. I compromised on lowering contrast to just 49. Had I lowered it further it would have improved the rather large DelatE error I was getting at 100% IRE but at the cost of lumen output which Is important for a bright room calibration. As with my Best/Dark Room I kept color enhancement and skin tone off and sharpness to 6 and super resolution to 4.
My target gamma for Bright Room/Quick Cal was 2.10. I was having problems with obtaining a flat gamma using the usual 2.0 or 2.2 presets. I discovered that custom 2 gamma preset helped with this issue and I was able to get a fairly flat gamma response with a 2.05 average. With the brighter gamma I found turning brightness to 48 preserved shadow detail without the blacks looking washed out.
Average Gamma Post-Calibration: 2.05 (target 2.10) @ 1462 Lumens
White Balance calibration settings for Bright Room/Quick Cal (standard mode).
Lastly, I did a 4K/HDR calibration. Any of the 5 modes can be used for 4K/HDR, I used User 2 and renamed it 4K/HDR. I kept the lamp on normal. Contrast is defaulted to 58 in User 2 and I kept it there. I lowered gamma from 2.3 to 2.2 and kept the color temp at normal. Pre-calibration white balance showed a small plus blue and minus green errors stating at the low (dark) end of the grayscale and getting progressively worse as it got brighter.
When it comes to trying to improve these (HDR) errors with calibration you kinda ignore 60-100 IRE. It may be possible to improve those higher IRE’s by lowering contrast but you lose those precious lumens that we re so desperate to keep for HDR content. With 1080p content I was able to keep Super Resolution at 4 but using the new Ghostbusters UHD as my reference I observed noise in the image especially noticeable on some of the sweaters worn by some of the ladies in the film. Turning Super Resolution off eliminated the noise.
Most DLP 4K/HDR projector that I have calibrated have swapped out (or re-named) their gamma control setting when fed an HDR signal. So, Gamma becomes HDR Brightness for example. Well with the PX727 you actually get 2 gamma controls for HDR. It keeps your traditional (power) gamma control and adds an HDR gamma control called EOTF. ETOF does effect both the high and low end of the grayscale while Gamma effects mostly the low end. I seemed to get the best results on my screen with gamma set to 2.2 and ETOF set to low. I wished there was a position between low and mid as I felt there was a big difference between them with mid looking washed out on my screen. Now your settings may be different depending on your screen size and gain.
Measurements taken at Mid Placement Normal Lamp.
ETOF (gamma) Post-Calibration: Low tracked fairly flat except for the low end which was slightly brighter than the target and the high end rolling off. 1192 Lumens.
White Balance calibration settings for 4K/HDR (user 2 mode).
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