Official JVC RS20 / HD750 Calibration and CMS thread (NEW FIRMWARE V1.1) - Page 14

Originally Posted by umr

What you would find with better tools are that display gamuts are frequently not as wrong as cheaper instruments indicate. Because of this people are running out of range and creating artifacts.

Originally Posted by umr

The key is to do it subtly with the colors that we are most sensitive to that differ from film the most while not not ruining the most important colors. Basically you must reverse the process used to convert the film. JVC has the best shot at this of anything I have seen.

Originally Posted by deandob

This is worth exploring further. I assume its like an audio compressor/expander, if you know the original compression curve you can fairly accurately restore the original dynamic range. As the JVC has a larger color gamut it can support a higher than REC709 color "dynamic" range but we have to reduce it so that it matches the source.

If we knew how the colors were compressed in the color space originally, it should be possible to recover some of the original colors. After all, isn't this why JVC designed this projector with such a wide gamut? As a manufacturer, wouldn't it have made sense to set it up for just the REC709 color space so that 99.9% of users would not have a problem with oversaturation. But they chose to build this projector with an expanded gamut - so there must have been a good reason for it. Maybe the reason is so that professional calibrators like UMR can restore a more film like look to the projector, so that the expanded gamut becomes an advantage for the JVC projector rather than a disadvantage - and the basis of a well kept secret (calibrators secret sauce). If we could recover some of the film color space outside Rec709 that would be a distinct advantage of having the PJ calibrated.

I'm speculating on the above, however a good topic to explore further....

Now I have to go back to my HT to complete my DIY JVC projector calibration, where I have +- 1 dE error on grayscale except for 10% where the error is more like 12 dE too green and very obvious. Not sure how I can tackle that, and I certainly did not have this type of error when I calibrated the bulb after 50 hours (its now 150 hours). I also punched in lovingDVD's settings and possibly because of the 10dE error, the image now looks significantly worse than my original calibration effort.

Can I confirm that you want to set HCFR to ""use gamma reference to compute greyscale dE"?? Also that you want to get your target gamma set before fine tuning the grayscale? I can see some interaction between the 2.

Originally Posted by Ignace

Restoring the original gammut is only possible if they have applied a certain non-linear curve (saturation wise) to it, if they just kept everything linear and just limited the gammut we can never reproduce the gammut. On the other hand if they applied a non-linear curve we probably are not able to reconstruct because the CMS of the JVC does work linear according saturation? Or is the last not true? I didn't measure myself yet. Then we need an external "expander" to do the job? No?

Two things that I can come up with for the choice of an extended gammut are:
- Marketing, for impressing the people with highly saturated colors, like all consumer products.
- Restore the movie extended color gammut by means of external converters, since to me it is very difficult to extend the gammut through the built in CMS without screwing up the so important skin tones?

Ignace.

Originally Posted by umr

Who said Rec. 709 is the goal for film? Film is not Rec. 709. The cool thing about these units is that they can restore part of the lost film gamut while not distorting key colors.

We can hit Rec. 709, but that will not restore the look to what we see in a reference theater.

Originally Posted by Lawguy

Okay. I see your approach now. You are not calibrating to REC 709 or any other standard. That is fine by me so long as your clients understand that they are not getting a conventional video calibration. There can be lots of debate about how good of an idea this is. Certainly many people think it is a good idea and we have seen lots of people on these forums creating custom gamuts.

Purists will be horrified but the proof is in the pudding. I am skeptical that you can consistently "recreate" the actual colors that were used in given films but I can see how doing this might create a more pleasing experience overall.

Originally Posted by umr

I give people what they want. If someone wants Rec 709 that is what I give them if possible. If they want what I like I give them that if possible. You also cannot deliver what a display cannot do. I am discussing what I personnely like here and what this product is best at. If I want Rec 709 I watch my 151FD which is upstairs.

Originally Posted by Ohlson

umr
Interesting!
Can you offer calibration for both film gamut and hdtv gamut? Does RS20 have multiple memories that can handle two gamuts?
Is your film gamut white point less bright than hdtv gamut white point?

First came original aspect ratio.
Now displays are soon capable of original color gamut!

Originally Posted by umr

Even if I told you exactly what I was doing you would never spend the money to do it. It would cost you a bunch of time and money to replicate it. I have custom calibration software that I use with a programmable video generator and a $24,000 spectro integrated with a rig that can measure accurately to 1 IRE on these products. It would only benefit my competitors if I was to divulge exactly what I do.

Originally Posted by Bulldogger

I would love to have someone like you do a calibration on my projector. You have been recommended by a few people whose opinion I trust. The problem is my fear of shipping damage. There was a high rate of damage on these projectors,considerably more so than normal. The first unit that my dealer examined, had to be returned. As a result, I decided to try myself. I tried contacting a local ISF guy first but he was unable to help me as he only did television sets and did never answered my questions about adjusting the CMS. Rather than try another, I purchased a meter and will see what I can do. If I am not happy with the results, I will sell the i1pro and chalk it up to the fun of the hobby, and try contacting another local guy.

Originally Posted by umr

The RS20 can handle multiple gamuts.

You can make the light output what you like. I tend to like SMPTE light levels, but you could setup multiple different ones along with the gamut. It is a very flexible product assuming you are not trying to toss up too big an image.

I temporarily crank open my iris when guests are over for football and run a little light in the room.

Originally Posted by Jeff Smith

Is there a Dummies Guide to this for a smart guy, good learner (but not a computer geek), that hasn't figured out where all the settings are that you speak of? .

Originally Posted by Bob Sorel

....As far as the use of cheap or lesser tools to perform calibrations, Jeff (UMR), you seemed to think that your Eye-One Pro was good enough to charge me $100 per hour for your work with it calibrating my Ruby a few years ago. If it was "good enough" for a *professional* to be using back then, I can't imagine that it would be all that bad an instrument to be using now. Or are you offering to go back to all of your past customers and give them a freebie with your new gear?

Originally Posted by Bob Sorel

As far as the use of cheap or lesser tools to perform calibrations, Jeff (UMR), you seemed to think that your Eye-One Pro was good enough to charge me $100 per hour for your work with it calibrating my Ruby a few years ago. If it was "good enough" for a *professional* to be using back then, I can't imagine that it would be all that bad an instrument to be using now.

Originally Posted by Bob Sorel

My reference was mainly to the posts regarding the "uncompressing" of the film gamut by expanding the gamut of REC 709. If you don't reverse the algorithm of the original processing which "compressed" the gamut to REC 709 in the first place, then "uncompressing" it is simply impossible.

Originally Posted by umr

If you would measure many products you would find that few really do reproduce Rec. 709. Most are doing some kind of color space manipulation to keep the key colors on target to some degree while enhancing the primaries without getting carried away. If you move the primaries to Rec. 709 on many of these you will make the key colors too desaturated like the THX mode on this product.

What I am using today did not exist three years ago when I was at your place. The i1 Pro is not horrible for all things, but it does have limitations. If you worked on as many products as I do you would see its issues.

Most professional calibrators strive to improve their calibration capabilities. I migrated from a CP-5000 to a C-5 and now the Microspec.

If you do not agree with a gamut stretch that is fine with me. After seeing many films in high quality theaters I find Rec. 709 to be highly deficient for the task of film reproduction. You may like it which is fine by me. You can watch what you want on your display. I will watch what I want on mine. It really does not matter. If you would measure many products you would find that few really do reproduce Rec. 709. Most are doing some kind of color space manipulation to keep the key colors on target to some degree while enhancing the primaries without getting carried away. If you move the primaries to Rec. 709 on many of these you will make the key colors too desaturated like the THX mode on this product.

Originally Posted by Bob Sorel

And you are not going to restore the original film gamut by expanding the gamut of your calibration either, although it is theoretically possible by using an exact reverse LUT of the original LUT used to reduce the gamut to REC 709.

Originally Posted by mhafner

The LUT need not be strictly invertible at all. It hardly will be.

Originally Posted by umr

If you move the primaries to Rec. 709 on many of these you will make the key colors too desaturated like the THX mode on this product.