Posted on February 27, 2018 By Eric Pfoutz
Vivitek HK2288 4K UHD Home Theater Projector Review – Calibration Settings: Calibration Presets Notes, Best Mode Calibration, Brightest Mode Calibration
Note: The projector had over 107 Hours on the bulb before I calibrated it and took the light measurements. A brand-new bulb will most likely have slightly higher measured lumens.
The HK2288 has 5 modes: Movie, Night, Day, Presentation and User. I spent most of my time with Night, Day and Movie. All of these modes have the same controls. They all offer 3 color temperature options (Normal, Cool, Warm) with just a single-point (gain) grayscale adjustments. The gamma presets include 1.8, 2.0, 2.2, 2.4, S-Curve. It also offers up a full CMS (color management system).
A note about User mode: Along with Day & Night modes, User is also preset to warm color temp, however User warm preset is very green, not warm at all. It looked to me that User set to warm was really what other DLP manufactures call “native bulb”. This mode is the brightest and least usable IMO.
During my calibration of HK2288 I experienced an issue that is coming all too common with modern digital projectors, white level clipping. Basically, no matter what mode I was in the whites would clip below 235 no matter where or how low I set the contrast. I was unable to resolve anything higher than 228.
Now maybe that sounds very close and that I’m nit picking, but what bothered me was the fact that it could not be corrected. When working properly I should have been able to affect the white point a with the contrast control.
Normally when you over drive the white level (contrast) you will start to clip the whites, loosing detail in the brightest part of the image. Most projectors will clip just above their default contrast values which are often set at their 50% mark. “Video” levels are 16-235 while PC levels are 0 -255. When I calibrate any display, I set the black level (brightness) to resolve down to 16 and the white level (contrast) to 242 or so. I like to have a tiny bit of head room in the whites just in case there is some content that sneaks in higher than 235.
I preformed my best/dark room calibration using Night Mode (default lamp) as a starting point. Out-of-the-box was quite poor with DeltaE as high at 10. Remember we want to be below 3 and I always strive to hit 1 or less if the projector is capable. The average color temp was in the 8000K range (minus red, plus blue & green). The HK2288 offers only one set of RGB (gain) controls – which covers the whole range from 0 to 100 IRE – white) for white (greyscale) balance calibration.
Most projectors spit the range into two, which makes it easier to stay consistently 6500K – and properly balanced) or any other desired color temp. So, achieving a linear grayscale is limited a bit. After calibration I was able to average a DeltaE of 1 or below from 20 to 90IRE and a 4 at 100IRE and 2 at 10IRE, which is pretty good.
Measurements taken at Mid-Zoom with Default Lamp.
Average Gamma Pre-Calibration: 2.29
Average Gamma Post-Calibration: 2.26 @ 784 Lumens
Selecting the projectors gamma to 2.4 actually averaged a 2.29 So I choose to calibrate to 2.20. With only RGB gain controls I was not able to flatten out the brightness bump seen at 90IRE. Average gamma ended up at 2.26.
White Balance calibration settings for Night mode.
Next up I did a bright room calibration using Day Mode (boost lamp). Both pre and post white balance calibration performance was very similar to Night Mode. Post DeltaE was 1.5 or below from 20 to 90IRE and a 4 at 100IRE and 2.5 at 10IRE. With gamma set to 2.2 after calibration gamma hit a 2.02 average with my target set to 2.10.
Average Gamma Pre-Calibration: 2.14
Average Gamma Post-Calibration: 2.02 (target 2.10) @ 983 Lumens
White Balance calibration settings for Day mode.
Lastly, I performed a 4k/HDR calibration using Movie mode, although what mode you are in I don’t think matters. When you send the projector an HDR signal it locks into an unnamed (presumably HDR) mode. Under the image settings both Picture Mode and Gamma are grayed out. Under Advanced tab is where you find the HDR settings. There is HDRControl (Auto/Off) and HDR Settings (Normal, Details & User).
If you choose either Normal or Details you lose the ability to adjust any picture controls (i.e. contrast, brightness, color, CMS, white balance) so I selected User. Normal HDR seems to be near identical to User while Details seems to darken the mid to bright levels of the image.
The contrast control has no effect on peak white and acts more like a gamma control so I left it on its default of 50. Brightness raises the overall white levels and you will blow out the whites if you drive it much beyond its default of 72, so I left it there.
Pre-calibration white balance average 8100k with a plus blue and minus red. DeltaE was at 10 from 60 to 100IRE. After calibration DeltaE was at or below 3 across the entire grayscale. The ETOF (gamma) tracking was fairly linear.
Vivitek advertises the HK288 as a 4k/HDR capable projector but not BT.2020 (P3) capable. Picking what 4K attributes to use (or not to use) is not something you see in flat panels displays. But with no real standards in place for the consumer projector space, manufactures are free to do whatever they want. There are some 4K projectors that only do 4 (faux) K and don’t attempt either HDR or REC.2020.
Measurements taken at Mid-Zoom, Boost Lamp.
ETOF (gamma) Post-Calibration: Tracked fairly flat except for the low end which was slightly brighter than the target @ 974 Lumens.
HDR/Details rolled off the brightness towards the top end making for a darker whites.
White Balance calibration settings for HDR mode.
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