Secrets Q & A
- Written by Mark Vignola
- Published on 24 August 2010
Bootcamp - Introduction to CalMAN Calibration
The course that I attended was taught by SpectraCal Sales President Jeff Murray. Jeff is a veteran of the industry hailing from the Sencore side of the SpectraCal equation. Our venue was a conference room in a hotel in Durham, NC. The crew from SpectraCal had clearly been up early that morning because by 8AM they had set up several workstations. Each station had an LCD panel, various light meters and video devices, including video processors, pattern generators and Blu-ray players.
We began with a general introduction to why we care about a calibrated picture and introduced the concept of the "directors intent". Those who are familiar with calibration DVDs from Avia or Joe Kane will be familiar with this concept. When we reproduce video material, we are looking to mirror what the creator of the material intended us to see. Life in The Matrix is meant to look green and distinct in color from the 'real world' in the movie "The Matrix"- this was an artistic choice made by the Wachowski's. Video engineering groups have outlined a set of definitions to assure that the The Matrix looks the same on every display. Unfortunately, it is often the case that displays are not reflective of these standards. Why? Because TV manufacturers have found that our brains, often subconsciously, have preferences for picture characteristics that are away from the standards. In addition, they know that their TV's are going to be displayed in brightly lit showroom floors - an environment vastly different from your living room. In order to take advantage of both our preferences and this retail environment, display manufacturers specifically set-up TVs to be appealing to us in these settings, often in gross violation of the standards that I described above. The result is an inaccurate reproduction of the video material and a departure from the original artistic vision of the content creator.
Once we were introduced to why we should want a calibrated picture, Jeff then talked about how displays of any type reproduce a picture (and the rules that they are supposed to adhere to) and quickly moved into the basics of calibrating the traditional user controls: Brightness, Contrast, Tint, Color and Sharpness. We then turned quickly to basic 2-point gray scale using a meter and the CalMAN software. After the lecture we were turned loose on the various calibration stations to try out what we had learned. Each of the work stations had a 1080p LED LCD around 42 inches in size. The sets had been selected because they had a core set of calibration features: the ability to calibrate gray scale, blue only mode for setting color and tint, and a color management system (more on that later). The sets were from Samsung, Mitsubishi and Toshiba and were in the middle of the their respective manufacturer product ranges. I don't know the exact model numbers, but Jeff commented that none of these sets were particularly high-end.
Right off the bat, all of the displays were connected to QuantumData 780 pattern generators. These are high-end, field ready, touch screen pattern generators. The generators were being controlled via USB by the laptop computers on our stations so that when we called up a program in the CalMAN software, it automatically changed the pattern accordingly. There were a variety of meters around the room, from very high-end to more modest, enthusiast-targeted models. My station had a Klein K-10 ($7000) and a Chroma5 ($~700 - and the meter I use at home). Other stations had Kleins and/or X-rite i1Pros.
CalMAN has several pre-programmed layouts and we loaded up the "Basic ISF Calibration" work-flow. Technically, an ISF calibration includes 2-point grayscale and setting of the basic picture controls (Color/Tint/Brightness/Contrast). As we navigated through the workflow on the software, the necessary patterns came up on our screen accompanied by text descriptions of what our goal was for each pattern. For grayscale, we interacted with the meter, CalMAN and the TVs settings for high and low gray point, iterating back and forth until we had correct settings for both. As Jeff promised, by lunch we had done a full 2-point ISF calibration.
Post lunch the discussions got more advanced as we were introduced to the ins and outs of human sight and how this pertains to various color measuring technologies. How our eyes perceive color, and specifically changes in color directly relates to the means in which we attempt to quantify color for reproduction purposes. In addition, it also relates to the way in which we measure colors as they are being reproduced. Different meter technologies take different approaches to this task - each having specific advantages and disadvantages. We were introduced to the main meter technologies and talked about why and how one technology is chosen over another. By giving us a solid background in how we see and measure color, we were then able to move onto the most complex topic of the afternoon: advanced Color Gamut Calibration.