From brief critical looks to in-depth analysis and reviews, proper calibration is a crucial component in establishing a level playing field between different displays. When I review a TV for AVS Forum Forum, the first step is to calibrate the display as precisely and accurately as possible.
The most reliable way to measure a display is with a spectrophotometer, which splits light into its component wavelengths. This results in accurate wavelength measurements, regardless of the light source. Tristimulus colorimeters use color filters to isolate the wavelengths of the primaries (red, green, and blue) they measure. The problem is that any particular set of color filters doesn’t necessarily respond the same way to different light sources. However, it’s possible to measure a display with a spectrophotometer and create a profile that allows a colorimeter to measure that display accurately by offsetting the reading from the color filters. Colorimeters use those profiles to take accurate readings of different types of displays.
If a spectrophotometer doesn’t need profiles, why not use one to perform all calibrations? Because spectrophotometers are slower and often more expensive than colorimeters. But speed is perhaps even more important than cost, since a typical calibration involves hundreds or even thousands of measurements.
You can use a generic profile (plasma, white LED, etc.) with a colorimeter for non-critical work. However, with a generic profile, there is no guarantee that any individual display will calibrate accurately. The solution is to use a colorimeter in conjunction with a spectrophotometer on every display in order to create custom profiles. With this approach—which I learned about when I took the THX Video Calibration 2 Professional Workshop last year—you can take full advantage of a spectrophotometer’s accuracy and enjoy the speed of a colorimeter.
Because I write TV reviews, I need a spectrophotometer and colorimeter to do the best possible job. I had planned to use an X-rite i1Pro2 spectrophotometer in conjunction with a Spectracal C6 colorimeter.
At CES 2015, I met up with Guillermo Keller, president of Colorimetry Research. Ray Coronado (Rayjr on AVS Forum) introduced us when we happened to run into each other at a private speaker demo. During that meeting, Guillermo graciously offered to loan me Colorimetry Research’s new meters—the CR-100 colorimeter and CR-250 spectrophotometer, for use in official AVS Forum TV and projector reviews. Of course, I jumped at the opportunity.
When the Colorimetry Research kit arrived at my studio, the build quality of the two meters created a very positive first impression—they are both made of solid precision-machined metal.
The CR-100 ($5000) is a fast and sensitive tristimulus colorimeter. It weighs 12 ounces and contains no moving parts—it’s 100% solid state. It connects to a computer via USB and draws very little power. I compared the CR-100’s performance to my Spectracal C6 ($700) meter and found the CR-100 was two and a half times faster. The CR-100 has luminance range from 0.0002 fL to 1500 fL, and it syncs to refresh rates between 10 and 500 Hz. It’s a very rugged device—Colorimetry Research meters remind me of high-end professional camera gear.
The CR-250 ($7000) trades speed for accuracy. It weighs 16 ounces, connects via USB, and has the same lightsaber-like form factor as the CR-100. An internal shutter allows it to take an automatic dark reading before each meter read—some meters require you to cover the lens to achieve this. The CR-250 has a luminance range from 0.05 fL to 45,000 fL and syncs to refresh rates between 10 and 10,000 Hz. The two meters together make a potent (albeit expensive) combo—fast, accurate, lightweight, compact, and rugged.
Here are the two meters mounted on a tripod.
The kit included a special tripod-mounted bracket for the two meters. The compact and narrow shape of the meters lets you mount them side by side on the bracket. Once you assemble the kit and mount it on a tripod, you can easily position the meters.
As I use the CR-100 and CR-250 together, I will blog about it in this thread. I have a lot of interesting reviews and evaluations to perform with these meters. For example, the first thing I did with the CR-250 was to take some basic measurements in Theo Kalomirakis’ personal home theater, the Roxy 2.0. Just yesterday, I visited Value Electronics to perform a quick 2-point grayscale calibration on a LG 77EG9700 UHD/4K OLED as part of a brief critical look at that exciting TV.
My first use of the CR-250 was at Theo’s personal home theater.
I’m also working on an in-depth review of the Panasonic AX900 UHDTV. It’s purported to be one of the most accurate TVs on the market, so it ought to provide a good test for the meters. In preparation for that review, I recalibrated my Samsung PN64F8500 reference TV using a custom profile and the CR-100. Thanks to its speed, I was able to use continuous-read mode with Spectracal’s CalMan calibration software to fly through 2-point, 10-point, and CMS adjustments. I wound up with an accurate calibration in record time.
I will update this post and this thread on a regular basis, so stay tuned.