Dolby3D vs polar wars: A new hope...
So far, like defiancecp, I had never been able to do color correction with the graphic card driver and/or the projectors settings. But thanks to Plewacka, I spent a few hours again on the subject. He being able to do fairly acceptable correction made me wonder.
Let me summarize the issues:
Drivers/Projectors use a 2D CMS (saturation+Hue) which is known not to be able to correct the colors efficiently. I happend to find out that gain (brightness) is the most important parameter, which is missing in 2D CMS. Hopefully, with 3D CMS the task would be easier.
Note: Projectors using Xenon lamps would be easier to correct. Unfortunately, I am on the dark side as I use standard UHP lamps, which is worst case as far as wavelenght filtering is concerned.
Plus, the ranges available for all parameters are much too narrow to take care of the huge color shifts needed for Dolby3D or Infitec correction. This if you use the regular menus.
Still, on my projectors, and probably on most, gain can be set for each primary when using the service menu (look in the color temperature section). This for each of four available user profiles. Range appears to be wide enough for the correction. If you can set the gains to 50% or less, there is hope.
I make two kinds of experiments:
1. Only adjust the gains for the 3 primaries
2. Add more tweaking with the 2D-CMS
On my projectors, gains range from 0.45 to 1.5 in the service menu (0.8 to 1.2 in the regular menu).
The values I have been using:
L eye R eye
RED 1.1 0.45
GREEN 0.65 1.0
BLUE 0.9 0.75
I am getting a perfect match for greens. Reds are noticeably different but as long as the brightness look about the same, it is not a problem in 3D viewing. Even if you close one eye then the other, you hardly see any difference. Blues and Magentas are more critical and experimentation must be done with different video clips to get the correct parameters. Using the 2D-CMS helped reduce some colors mismatches, specifically because it can play on secondaries as well as primaries.
This gives a rough 40% light transmission through the filters, more or less what you get with polars.
No correction Unwatchable. Severe eye rivalry on primaries and secondaries.
Gain correction Fair
Gain and CMS Fair to good
AVS script Excellent
As I want to switch easily from 2D to 3D, color correction must set on/off at the touch of a single key. I can do that if I take only the gains into account. If I want to include CMS, it is a little bit more complicated. So, because I am a lazy guy, I tried to watch an entire movie, only using the gain parameters.
We watched Avatar again yesterday night with only the gain settings from the service menu. I was very pleased with the result. Nobody in my audience made any comment about color mismatch (I didn't warn them about the new settings). Although the correction is not perfect, it is way *much* better than with the polars and the terrible silver screen. With my now trained eyes, I could see some differences now and then while watching the movie, but absolutely none to make me reject this very simple kind of correction. There is maybe a slight drop of brightness (*) compared to the AVS script. Nothing dramatic though.
I must add: No headache at the end of the movie
I am seriously thinking about getting rid of the AVS script. Because my CPU is busy in correcting colors, I could not use it to make frame doubling, as I do with 2D. I can do that now and it makes me extremely happy (we watched Avatar with frame doubling). Too bad I spent an enourmous amount of time to do color correction through AVIsynth scripting...
So it seems color correction can be done on the projector side. I wouldn't see any reason not to play games with this settings. Also, a setup with an HDMI splitter and two 3D-XL boxes would hopefully allow any kind of HDMI 1.4 sources to be used.
Sequential Polarized Dolby3D
projectors setups setups
Vivid colors good fair good
Calibrated colors good fair fair (gains) to good(avs)
Ghosting medium poor-medium excellent
Fast motion frame lag! in sync in sync
Brightness fair good good
Other negs Active glasses Hot spot+Grain Dual setup (need splitters)
EDIT: (*) Drop in brightness is explained by the fact that, instead of matrixing the colors, we only set the gain parameter.
For example, red for left eye should be added some green. That means not only changing the color but also its brightness (green goes through the left filter with almost no attenuation). Using CMS helps to recover some light as Hue parameter can be used to drift color.