DIY DOLBY 1080p 3D, Color correction not really needed...

I've tried using catalyst control center color corrections, but the results were far from what I would consider acceptable. There is variation from projector to projector because of the light mixture produced by the bulbs, but even others that had success using directshow filters had to use more complicated corrections than what is in catalyst controls.

I agree with you that this method is generally superior otherwise, though.

subscribed.

Unfortunately it's long since (nearly a year now) dismantled. I plan on trying again using the CMS in the 3d-theater once that gets released though. So I can't really get any pictures...

I was using flat-lensed infitec filters and glasses. I've heard that dolby and infitec, in spite of dolby being a licensed infitec implementation, use slightly different frequencies - if so that might impact the color balance.

My projectors that I with were Optoma EW1610's, which (if I remember correctly) use UHP lamps.

There's a thread somewhere - can't find it now - but somewhere on here where a couple guys were using infitec or dolby and had directshow filters handling the color correction (which of course limits the application a little bit since those can't be applied to DirectX or non-HTPC sources.

Personally, even if catalyst corrections would work, I still wouldn't be ready to switch back - I don't really plan to do that until non-HTPC sources can be properly corrected. Which is why I hold high hopes for the 3d-theater box, since it can demultiplex 3d signals and handle color management.

I can't wait to hear more!

Please find my Infitec/dolby color calibration kit version2:
http://jptheking.free.fr/3d/Dolby_ca...ion_kit-v2.zip

This of course is only for playing 3D movies. No gaming.
Jack

EDIT: Documentation can be found here: http://jptheking.free.fr/3d/Dolby_calibration_kit.doc

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:
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.

My conclusion:
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.

My classification:
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.

Jack

What kind of projectors are you using jack-bauer?

I am using two vpl-hw15 from Sony.
http://www.mtbs3d.com/phpbb/viewtopi...aef9&start=104
Jack

More on color correction using projector's settings. Can be used for games.

A magic trick: Use color space

Dolby filters are asymetrical. Left colors are oversaturated while right colors are undersaturated.
Most projectors, if not all, offer two colors spaces to choose from: normal and wide.
Her comes the trick: Apply normal to oversaturated colors and wide to undersaturated colors.
What you have left is decreasing gains to match the other filter's color.

My settings:

You can then use CMS (hue) to tweak the left over color mismatches, if any.
(I am using Left RED hue+10% and Left CYAN hue-5%. That gives very slightly better matches)

My results are so good that I am not able to tell color differences any more when watching a movie

EDIT: I spoke too fast... After watching a few movies, there are some slight differences, but absolutely no eye rivalry any more if you set colors the same brightness. Definitely zero eye strain.

Jack

Subscribed.

Jack,
When you watch 2D, do you remove the dolby filters? If not, are you not worried about the light loss?

Yes I remove the filter (I am using only one projector for 2D).

This could have been an issue for me as I had the idea to integrate the filters right inside the projectors, somewhere between the lamp and the panels. This would have needed some kind of glide mecanism... I have not given up with the idea, but this seems quite difficult with my projectors.
http://www.mtbs3d.com/phpbb/viewtopi...1320&start=104

Jack

So, to switch between 2D and 3D, you:

1. Turn on 2nd PJ
2. Place Dolby Filter in front of 1st PJ (I think I've seen your mounts, they have a little hinge. How hard is it to get the filter in just the right spot?)
3. Use remote to change "colour space" from 2D settings to 3D settings for 1st PJ.

2D=>3D:
1. Plug proj#2 to the mains and turn it on
2. Lower filter in front of proj#1 until the frame touches the lens mounting. At once on the right spot.
3. Press "standard" on the remote (may trigger both PJs. Don't care)

3D=>2D:
1. Turn proj#2 off (and unplug when fans stop).
2. Lift filter on proj#1
3. Press "cinema" on the remote.



(Cinema: Lamp in eco mode, color correction OFF).
(Standard: Lamp at full power, correction ON).

Note: Every 200 Hrs I swap projectors to balance lamp usage (2D is 90% of the time).

That's all . Jack

Awesome, thanks.

Holy cow am I glad I found this. I am a projectionist who has figured out how to make DCPs that will work in 2d and 3d color spaces... but the 3d is just 2d 48fps with left and right sources the exact same, so its not really 3d. I want to fix that ! Using your techniques, how would I go about creating it in the actual footage being shot, not adjusting the projector? what are the color differences left and right? (For I know that this multiplexing effect is the differencel in Dolby 3d)