Video Calibration

ChromaPure 2.2 Video Calibration System and Lumagen Radiance Mini-3D Video Processor


Lumagen Mini-3D Video Processor Features

The Lumagen Radiance is a full CMS device that allows for you to do full grayscale and gamma adjustments (with 2, 5, 11, 12 or 21 points), color gamut, color, hue, and more. It also does colorspace conversions correctly, and supports scaling for use with anamorphic projectors and non-standard display resolutions (such as 1366x768). Even though most displays now contain some sort of CMS system, many can either be hidden in the service menus, or not contain all of the features that you need to get a correct calibration.

Recently I’ve begun to setup my basement to work with a front projector setup. While I decide what I want to install, I built myself a simple screen and borrowed a friend’s older Panasonic AE-900U projector. While the 900U was a very well regarded projector when it was released, it’s now a bit long in the tooth as it’s only 720p, and lacks a decent CMS system. To see how this would benefit from an actual CMS, I hooked up the Mini-3D and performed an automatic calibration. The charts below will show you the results before, and after, the Radiance and its auto-calibration. Had I desired to further tweak the Radiance, I’m sure I could have achieved even better final numbers.

After it was complete, the results were nothing short of stunning. While pixel structure was still visible if I looked carefully as it was still only 720p on a 96” screen, the picture now had a ton of pop to it. Since screen surfaces are also all very different in terms of color reproduction, it’s hard to impossible to copy the settings for a projector from someone else. Even something as simple as the wall color in your room will affect the image that is reflected back to you, making a calibration even more important than with an LCD or Plasma display.

Watching Cars (my son is in love with Cars, so I get to watch it multiple times a week now) the improved grayscale, color, and gamma all made a huge difference. As much as I hate to use the same term over and over, everything just popped off the screen; with shadow detail as good as I can get for this projector, and Lightning McQueen now a bright, vivid red that really stands out. Seeing how much of a difference this can make with a projector that was this old, I’m pretty sure I’d take the combination of a cheaper projector and Lumagen Radiance over a more expensive projector any day. Most displays don’t put out nearly as good an image as they are capable of, and the Lumagen made even an old 720p projector put up an image that almost anyone would be perfectly happy with.

When I put on the first part of the final Harry Potter film to show my wife, skin tones were very natural, and shadow detail was far superior to what it has been before the calibration. The color palette for the film is muted at times, and can be a little blue tinted, but it looked fantastic running through the Radiance. The recent Matt Damon film The Adjustment Bureau had a pretty good transfer that really looked nice in my theater. The image had a very natural look to it, not overly processed after it was completed, and simple details like a shirt texture really came out. Swapping between having the Radiance in the signal path and removing it made a huge difference, and really brought out everything that was on the disc.

Configuring the Lumagen manually without the auto-calibration from ChromaPure was of course more difficult, but still not too challenging. The manual that Lumagen includes goes through the process that you should use for doing a calibration. Just like with the auto-calibration you should set Brightness and Contrast in the display before you do anything in the Lumagen. You also should measure the different color temperatures available in your display (Often labeled Cool, Neutral, Warm, Natural, or a combination of those) and determine which comes closest to the D65 standard.

Once those are set, you can then begin using the Radiance to correct the grayscale, gamma, and color gamut. Here you will go color-by-color, and then by IRE levels to set these values correctly. As I mentioned earlier, if your display is lacking Luminance in a color, the Radiance can’t add any additional luminance to a color, it can only take it away. There have been a few displays and projectors that haven’t been able to produce a fully saturated image recently, and the Radiance can’t correct for that. However, you might be able to adjust the color control, or the individual CMS color controls, to account for this before calibration. While not ideal as you’d prefer to do all the color gamut corrections inside of the Radiance, it’s better than having an under-saturated image.

Another ability of the Radiance is to have quick access to four different image settings. When most people calibrate their display, they usually aim for a color temperature of 6500K with a gamma of 2.2. In most cases this would be correct, but in some cases you might want something different. If you have a truly pitch-black theater, you might want a gamma closer to 2.4 or 2.6, as many films are mastered using this gamma target in virtually pitch-black room. If you watch a lot of Black and White films, those were typically shot for a temperature of around 5400K instead of 6500K, and possibly a different gamma though I am not sure. If you watch sports a lot on this display, you might want a gamma closer to 1.9 as shadow detail isn’t that important to us while watching football. Finally, if you are doing 3D content, since the glasses can reduce the amount of light reaching you then you also might want a lower gamma level, or to account for the color shift of the lenses.

With the four quick access modes in the Lumagen, you could easily do four separate calibrations and assign them to the different slots, letting you change between image modes at the press of a button. It’s a good amount of work to try to do four different calibrations, but it’s a feature that no display that I know of offers.

Lumagen could improve upon their literature for the Mini-3D to make it easier to read and use. For example, in the manual there is a line saying, “The gamut calibration command usage is described in a Tech Tip on the Lumagen support web page.” It would be nice if this Tech Tip was included in the manual so the user didn’t need to reference back and forth from the manual to the web site. Additionally they have no images or diagrams that show the menu system or adjustment screens in the manual either. I would also like to see them possibly offer some video examples on their website showing the calibration steps to make it easier for someone to get started. The Radiance has all the power you can ask for, so it would be a shame if users weren’t able to properly utilize it.