Video Calibration

CalMAN Video Display Analysis System

ARTICLE INDEX

Calibrating Your Display

The process of calibrating a display with CalMAN could not be easier.  The preset workflow lays everything out and guides you with easy to understand instructions.  Once you’ve started up the program an intro screen takes you through the process of selecting your meter and method of pattern generation.  The main calibration screen is divided into three parts.  On the left side is the workflow tree.  This gives you access to all the help topics and the actual calibration steps.  I advise anyone using this program for the first time to read through all the help topics before moving on.  The articles appear in the large center section of the CalMAN screen.  They are easy to read and well-illustrated.  Though it’s not necessary to have a degree in color science to calibrate your TV, the process is much easier if you understand the theory behind what you’re doing.

The workflow is arranged in a tree configuration down the left-side pane.  You simply click on each step.  When you do either a help article or the appropriate charts appear.  The help article will tell you which patterns to use to set a particular display parameter.  If charts are on the screen the help for them is in the right-side pane.  Not only are you guided through the pattern selection, the help also tells you what adjustments to make on your display to achieve the desired result.  When you have completed the workflow, you can generate a report which shows all your results for color gamut and grayscale tracking.  Clicking on individual charts in any screen brings up a help article that explains that chart and what it’s showing you.

Although I use the Professional version of CalMAN to review displays, I tested the software with a Home license to evaluate its functionality for the do-it-yourselfer.  I used the X-Rite EyeOne Display 2 meter to measure a Pioneer PRO-111FD plasma TV and a Panasonic AE2000U projector.  The Display 2 is a tri-stimulus meter.  It’s a decent all-around tool that works on all display types.  It’s not as accurate as more expensive tools like the EyeOne Pro but as part of a $299 package, it performs reasonably well.  To measure a plasma or any direct-view TV, you simply attach the meter to the center of the screen with its integrated suction cups.  It’s very light and includes a counterweight to hang over the back of your screen in case it comes loose.  A cable connects it to your laptop’s USB port.

After starting up CalMAN, the introductory screens automatically find the attached meter and allow you to select your pattern source.  Once this is done, you select a list of inputs on your TV and initialize the meter with a dark measurement.  This is very important as it affects the accuracy of the readings you take.  You must cover the meter’s sensors completely.  I use a thick piece of cloth so no light gets in.  With meters like the Display 2 you need to redo this dark measurement every 15 minutes or so to maintain accuracy.  CalMAN thoughtfully includes an on-screen timer to remind you.  When you’re in the calibration screen you can re-initialize the meter at any time by pressing F4.

After setting brightness and contrast, you are presented with a screen that lets you measure the color temperature of your TVs different presets (first screen shot shown below).  The help for this screen is on the right side.  Here’s where you can use the multi-tab system.  CalMAN allows you to create multiple screens so you can easily compare measurements.  For example, you can create a tab for each color temp preset on your TV then measure them.  By looking at the data for all the presets, you can determine which one is closest to D65 or 6500k.  This gives you the best starting point for calibrating grayscale.

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Next up is the actual grayscale calibration.  This screen includes a bullseye and a color balance chart .  It’s quite easy and intuitive to use.  You alternately display 30% and 80% window patterns and adjust the RGB High and Low controls until both patterns measure correct.  The software can take continuous readings so you can make adjustments in real time.  The goal is to have the point in the center of the bullseye.  The color balance chart shows which colors are too high or too low as you make your adjustments.  While it’s rare to achieve a perfect chart, CalMAN makes it easy to maximize the potential of your particular display.

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The next step is to adjust the color decoder (color and tint controls).  CalMAN takes a novel approach to this.  When you buy calibration discs like Avia or Digital Video Essentials, their method of decoder adjustment involves the use of color filters and a split color pattern.  I can tell you from my own experience this almost never works.  The only way the filter method can be accurate is if the display’s primaries precisely match the filters.  If they don’t match, you will not get correct results.  The only other way to adjust color and tint without instruments is to selectively turn off the primaries.  Some displays like Samsung LCD and plasmas or the DreamVision projector I recently reviewed feature a blue-only mode.  This control shuts off the Red and Green primaries.  Then you can very easily adjust color and tint by displaying a split color bar pattern.

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Since very few displays have a way to turn off primaries, CalMAN includes a slick way to adjust color and tint using the meter.  You start by measuring a 100% white pattern.  Then you measure magenta and cyan patterns to achieve the lowest color error, expressed as Delta E*.  There are other Delta values (Delta C* and Delta H*) that tell you whether to adjust the color or tint controls.  Following the steps in the right-side pane of this screen will make it easy to set your controls to their best positions.  Using this method I was able to achieve excellent results in a short time.

I followed the same procedures as above to measure my Panasonic projector.  Only the meter’s setup was different.  I attached the included diffuser to the Display 2 and set up the meter to read from the projector by attaching it to a tripod near the screen.  You can measure light reflected off the screen without the diffuser if you wish but I found this more difficult as the meter has to be angled just right to allow light to hit the sensors.  When I had finished, I generated a concise report showing the results of my work (shown below).

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