Official JVC RS20 / HD750 Calibration and CMS thread (NEW FIRMWARE V1.1) - Page 7 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #181 of 1634 Old 04-30-2009, 08:03 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Thanks Jeff! Doesn't look too bad, I'll have a look at the numbers later, I can't just now.
Manni01 is online now  
Sponsored Links
Advertisement
 
post #182 of 1634 Old 04-30-2009, 08:15 AM
AVS Special Member
 
Bulldogger's Avatar
 
Join Date: Dec 2000
Location: Clinton,MS
Posts: 6,644
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 20
Quote:
Originally Posted by Manni01 View Post

Good news, thanks for the feedback!

Let us know how you're tracking at 75% and 100% when you will have done your calibration.

I have not yet started. It seemed pointless until I could see what was going to happen with the CMS. Now I need to buy the equipment. Has anyone used the Chroma 5 to calibrate the RS20?

Never become so involved with something that it blinds you.
Bulldogger is offline  
post #183 of 1634 Old 04-30-2009, 08:23 AM
AVS Special Member
 
Lawguy's Avatar
 
Join Date: Sep 2004
Posts: 5,705
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Bulldogger View Post

I have not yet started. It seemed pointless until I could see what was going to happen with the CMS. Now I need to buy the equipment. Has anyone used the Chroma 5 to calibrate the RS20?

I was thinking of getting one.

Affable Nitwit
Lawguy is offline  
post #184 of 1634 Old 04-30-2009, 08:33 AM
AVS Special Member
 
Highlander_AVS's Avatar
 
Join Date: Jul 2007
Location: Italy
Posts: 1,016
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Lawguy View Post

.... I think (but can't be sure) that the best calibration is the one that uses the least amount of control adjustments.

+1
This has been always my thoughts ....
Then if this means that 75% will requires the least amount of control adjustments, I'll choose to calibrate with 75% Patterns obviously checking that it tracks right at 100% too !!
Highlander_AVS is offline  
post #185 of 1634 Old 04-30-2009, 09:03 AM
AVS Club Gold
 
Mark Petersen's Avatar
 
Join Date: Dec 2000
Posts: 4,671
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Bulldogger View Post

I have not yet started. It seemed pointless until I could see what was going to happen with the CMS. Now I need to buy the equipment. Has anyone used the Chroma 5 to calibrate the RS20?

That's what I use. It works well, even into the low IRE's.
Mark Petersen is offline  
post #186 of 1634 Old 04-30-2009, 09:04 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by Lawguy View Post

JeffY has much less of a Y problem using Manni's numbers than I did. On the other hand, my xys using Manni's numbers look better than JeffY's.

Yes, it doesn't look too bad, but the Y on blue seems really low. Do you have an idea why? It measures fine on my PJ, but about half the expected value on yours.

I've run the numbers from my last calibration into Greg's calculator, and I get very good results (see attached).

What I don't understand is why the dE given by HCFR is completely different at 75% and mostly similar (but not equal) at 100%. Any idea why?
LL
LL
Manni01 is online now  
post #187 of 1634 Old 04-30-2009, 09:08 AM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Here are my "my Spyder 3 is colour blind, I'll use my eyes instand settings"

R -4,-22,11
Y 5,-44,37
G -6,-42,35
C -2,-46, 37
B 6, -4, 3
M -2,-4,0
JeffY is offline  
post #188 of 1634 Old 04-30-2009, 09:13 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by JeffY View Post

Here are my "my Spyder 3 is colour blind, I'll use my eyes instand settings"

R -4,-22,11
Y 5,-44,37
G -6,-42,35
C -2,-46, 37
B 6, -4, 3
M -2,-4,0

That's really interesting!

Your settings are very close to mine, except for blue which is completely different!

I'll try to measure them on my PJ and show you what they turn out like.

The radiance is out of the chain, right?
Manni01 is online now  
post #189 of 1634 Old 04-30-2009, 09:33 AM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Manni01 View Post

That's really interesting!

Your settings are very close to mine, except for blue which is completely different!

I'll try to measure them on my PJ and show you what they turn out like.

The radiance is out of the chain, right?

Radience? I wish!, only a lowly HDP Pro, but yes colour controls are switched off.
JeffY is offline  
post #190 of 1634 Old 04-30-2009, 09:36 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by JeffY View Post

Radience? I wish!, only a lowly HDP Pro, but yes colour controls are switched off.

Do you have any explanation for the difference with blue?

By eye, nothing seems wrong on my PJ, and as you can see with the results from Greg's calculator my dE are pretty good.

Do yo think there can be so much variation from a unit to another?
Manni01 is online now  
post #191 of 1634 Old 04-30-2009, 09:41 AM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
It must be a projector variance, your blue settings are way too dark and a bit purple (especially dark blues) on my projector.
JeffY is offline  
post #192 of 1634 Old 04-30-2009, 09:45 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by JeffY View Post

It must be a projector variance, your blue settings are way too dark and a bit purple (especially dark blues) on my projector.

The hue may be bad calibration on my part as well (there are obviously many ways to move the color towards the target using hue and saturation), but I'm really surprised with the variation on Y, which is more straightforward.

Is this something you have experienced in the past (brightness on one color being so different from one PJ to another)?

Anyway I'll try your settings tonight if I can and I'll report.
Manni01 is online now  
post #193 of 1634 Old 04-30-2009, 10:54 AM
Member
 
Ignace's Avatar
 
Join Date: Apr 2009
Posts: 34
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi guys,

I'm just new to this forum.
First of all, I want to thank everybody to make this new firmware reality!

I had a Barco projector before and switched to this new JVC a few weeks ago, because of it's good contrast, gamma response and mainly good "film-look" potential. Knowing the good colors of the Barco I was afraid to loose this aspect. Even though I saw too much saturated colors when I first saw the projector, but I believed/hoped it could be solved. Thanks JVC, for updating the CMS!

Personally I don't have any experience in calibration, but I do have experience with video processing since I work at Barco.

This week I played a bit with the "old" CMS without using any measuring devices, OK I used the RGB filters that cames with the DVE DVD, to have an idea about the luminance of the primaries and secondaries compared to white, and I was able to give the projector already a much better look (less saturated). I also noticed how easily green start to clip on a black to green ramp pattern. I also noticed that the brightest red and blue do have a hue shift, I hope this is gone with the new CMS?

This weekend I will try out the new firmware and I also took a Minolta CS-200 (from my work) to have a first impressions of what real color calibration is. I hope the CS-200 is a good reference for performing color calibrations? I also found the Excel spreadsheet helping the calibration process, thanks to the people involved creating this spreadsheet! This helps me a lot, since I didn't found yet the x,y coordinates for the secondaries.

I'll publish my experiences next week...

Kind regards,
Ignace.
Ignace is offline  
post #194 of 1634 Old 04-30-2009, 11:06 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by Ignace View Post

Hi guys,

I'm just new to this forum.
First of all, I want to thank everybody to make this new firmware reality!

I had a Barco projector before and switched to this new JVC a few weeks ago, because of it's good contrast, gamma response and mainly good "film-look" potential. Knowing the good colors of the Barco I was afraid to loose this aspect. Even though I saw too much saturated colors when I first saw the projector, but I believed/hoped it could be solved. Thanks JVC, for updating the CMS!

Personally I don't have any experience in calibration, but I do have experience with video processing since I work at Barco.

This week I played a bit with the "old" CMS without using any measuring devices, OK I used the RGB filters that cames with the DVE DVD, to have an idea about the luminance of the primaries and secondaries compared to white, and I was able to give the projector already a much better look (less saturated). I also noticed how easily green start to clip on a black to green ramp pattern. I also noticed that the brightest red and blue do have a hue shift, I hope this is gone with the new CMS?

This weekend I will try out the new firmware and I also took a Minolta CS-200 (from my work) to have a first impressions of what real color calibration is. I hope the CS-200 is a good reference for performing color calibrations? I also found the Excel spreadsheet helping the calibration process, thanks to the people involved creating this spreadsheet! This helps me a lot, since I didn't found yet the x,y coordinates for the secondaries.

I'll publish my experiences next week...

Kind regards,
Ignace.

Hi Ignace, welcome to the forum.

I'm sure others will comment about the shifts, but as far as I'm concerned I can't see any, and everyone agrees that clipping on green is gone with the new CMS.

If the CS-200 is as good as their luxmeter, it must be excellent, but I have personally no experience with it.
Manni01 is online now  
post #195 of 1634 Old 04-30-2009, 11:22 AM
AVS Special Member
 
lovingdvd's Avatar
 
Join Date: Jul 2002
Posts: 8,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 23
Hi Manni - I suspect that the issue with blue Y you are seeing is possibly measurement error. Perhaps the blue is not bright enough for your meter to get a good reading off the screen. You are measuring off the screen I take it.

I *highly* recommend trying the RGB color filters that come with various calibration DVDs (DVE etc). You can use these with many patterns, but I prefer those on the AVS HD 709 disc.

What these patterns will do is provide you with a great way to check your Y levels without having to rely on a meter! And that seems like just what is needed at this point for you.

If you use the color filters you will KNOW immediately whether your Y values are correct, especially for blue. If the color filters show a mismatch, then I'd be 99% sure that your meter and calibration is wrong, and vice-versa. This will tell you definitively where things stand. Give it a try and let us know what you find. If you need a refresher on how to use these, let me know.
lovingdvd is offline  
post #196 of 1634 Old 04-30-2009, 11:28 AM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by lovingdvd View Post

Hi Manni - I suspect that the issue with blue Y you are seeing is possibly measurement error. Perhaps the blue is not bright enough for your meter to get a good reading off the screen. You are measuring off the screen I take it.

I *highly* recommend trying the RGB color filters that come with various calibration DVDs (DVE etc). You can use these with many patterns, but I prefer those on the AVS HD 709 disc.

What these patterns will do is provide you with a great way to check your Y levels without having to rely on a meter! And that seems like just what is needed at this point for you.

If you use the color filters you will KNOW immediately whether your Y values are correct, especially for blue. If the color filters show a mismatch, then I'd be 99% sure that your meter and calibration is wrong, and vice-versa. This will tell you definitively where things stand. Give it a try and let us know what you find. If you need a refresher on how to use these, let me know.

Thanks for this suggestion LDVD, I'll give it a try.

I (and I'm sure others) would love a refresher about how use these, especially given the fact that in my case, it would be a fresher, not a re-fresher

I have DVE basics and the filters, as well as the AVS 1.2 patterns, so please give instructions with whichever you think are better.

Thanks for this kind offer!
Manni01 is online now  
post #197 of 1634 Old 04-30-2009, 11:29 AM
Member
 
decny's Avatar
 
Join Date: Dec 2008
Posts: 36
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
First, a huge thank you to everyone...even though I only understand about 1% of what is discussed here. I have been using the collective numbers from the old thread as my "calibration" and have been thrilled beyond my wildest dreams. I have just gone over the 100 hours on the bulb, so am wondering whether now is the time to bring someone in to calibrate officially. However, I've e-mailed some folks in the New York area (hour from NYC), but none have calibrated this model JVC. If anyone has a list of calibrators in NY, that would be helpful.

Second. When you install the upgrade, do the setting defaults go beyond just erasing your custom color settings? Will I have to reset EVERYTHING, including HDMI settings, screen position, projector mount preference (ceiling, etc.), etc.? Just wondering because I had the installers do all this and haven't done anything myself (except create a custom color setting with numbers posted on the old thread). Sorry, really new at this...but happy.

This forum is great and I look forward to participating on a more intelligent level in the future.



My Equipment

JVC DLA HD 750 Projector
Pioneer Elite VSX01 TXH Receiver
Pioneer BDP 51FD Blu-Ray
M1300 Draper Clarion 100" 16X9HD
12M Series #9 HDMI Cable
4300EX Replacement Power Conditioner
4 B&W DM303 Speakers
B&W ASW300 Sub
B&W LCR3 Center
decny is offline  
post #198 of 1634 Old 04-30-2009, 11:39 AM
AVS Special Member
 
lovingdvd's Avatar
 
Join Date: Jul 2002
Posts: 8,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 23
Quote:
Originally Posted by Manni01 View Post

Thanks for this suggestion LDVD, I'll give it a try.

I and am sure others would love a refresher about how use these, especially given the fact that in my case, it would be a fresher, not a re-fresher

I have DVE basics and the filters, as well as the AVS 1.2 patterns, so please give instructions with whichever you think are better.

Thanks for this kind offer!

First - run, do not walk, to your color filters. I am excited about this for you. It will tell you definitively which (if any?) of your Y values are incorrect.

Its been a while since I used these and I've never really had a completely solid grasp on it, but I'll try to explain it at a very high level here. Then hopefully someone else can chime in...

Basically take your RGB filters from DVE but use the AVS HD 709 1.2 patterns. The patterns you want are the ones that look like vertical color bars with blinking color blocks in various places within and above the bars.

This is all from memory and may be rough but the general idea is this - start with the blue filter and hold it up to one eye while closing the other one. Look at the blue bar on the screen from your normal seating distance.

If the Y value is correct, then the blinking (white?) blocks should be virtually invisible and the bar should look solid blue while viewing through the filter. To give you an idea of what a WRONG Y setting looks like, take the Brightness for Blue and crank it up or down a lot on purpose just to watch what happens with the filter. The correct/ideal setting is the one where the white blends the most into the blue.

Then you can repeat this for red and green, switching filters accordingly (use red filter to view red bar, green filter to view green bar). I think the secondaries can be done too but would have to play with the pattern to recall how.

My understanding is that this technique is considered to be quite accurate and my recommendation, especially in your case where this is confusion over which if any meter to try, is to dial in Y based on the filter and forget about the meter for now.

Bottom line is that regardless of what your meter tells you, the setting can only be right if it looks right through the filters. I think this will be a VERY interesting experiment for you, as it will give you an idea of which of your meters is most accurate in this regard, as well as tell you where the correct setting is!

Keep us posted on what you find - I am very curious to hear the results.

Hopefully someone with more experience using these filters will chime in and provide more details on the technique as well, but this should get you started.
lovingdvd is offline  
post #199 of 1634 Old 04-30-2009, 11:45 AM
AVS Special Member
 
Lawguy's Avatar
 
Join Date: Sep 2004
Posts: 5,705
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by decny View Post

However, I've e-mailed some folks in the New York area (hour from NYC), but none have calibrated this model JVC. If anyone has a list of calibrators in NY, that would be helpful.

Where around NYC are you? If you are on Long Island (as I am) maybe I can help you out.

Affable Nitwit
Lawguy is offline  
post #200 of 1634 Old 04-30-2009, 12:07 PM
Member
 
decny's Avatar
 
Join Date: Dec 2008
Posts: 36
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'm in Northern Westchester. Thanks!
decny is offline  
post #201 of 1634 Old 04-30-2009, 12:31 PM - Thread Starter
AVS Special Member
 
Manni01's Avatar
 
Join Date: Sep 2008
Posts: 2,220
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 93
Quote:
Originally Posted by lovingdvd View Post

First - run, do not walk, to your color filters. I am excited about this for you. It will tell you definitively which (if any?) of your Y values are incorrect.

Thanks a lot for this Ric.

I did a quick test with DVE filters and the AVS 1.2 patterns.

Results are interesting: green and blue are fine Y wise, maybe one notch difference, but not much.

The only color which was slightly blinking was red, wich I moved from 3 to 6.

I didn't have time to check JeffY's settings but I will after tonight's movie.

Thanks again for your help, it puts my mind at rest!
Manni01 is online now  
post #202 of 1634 Old 04-30-2009, 12:44 PM
AVS Special Member
 
lovingdvd's Avatar
 
Join Date: Jul 2002
Posts: 8,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 23
Quote:
Originally Posted by Manni01 View Post

Results are interesting: green and blue are fine Y wise, maybe one notch difference, but not much.

Yep, that's par for the course if things are set up correctly.

Quote:


The only color which was slightly blinking was red, wich I moved from 3 to 6.

If you feel like experimenting it would be interesting to see what your measurement is at 3 vs 6, just to compare. But I would tend to trust your eyes and the filter over the measurement.

Quote:


Thanks again for your help, it puts my mind at rest!

You're very welcome! I would be curious to hear what the results are with the filters (whether they look correct) if you put in the CMS settings used with the suspected bad meter - just to see if they are more significantly off than what you saw with the filters when using the "good" meter.
lovingdvd is offline  
post #203 of 1634 Old 04-30-2009, 01:09 PM
AVS Special Member
 
stereomandan's Avatar
 
Join Date: Dec 2005
Location: Michigan
Posts: 1,316
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 20
Quote:
Originally Posted by Manni01 View Post

I wish I had posted this as my first attempt, and hope you'll forgive me for the confusion, but hopefully this sets the record straight.

Note: the greyscale and saturation data is in the 3rd attempt HCFR file, as this was my main calibration. The 100% just shows what you get at 100% stimulus, and only the gamut info is relevant in this file.

Manni01,

I took a look at your calibration and the lower saturations look great. Thanks for measuring the 30 saturation windows. JVC certainly did a stellar job with the CMS on this attempt! You can really nail the calibraiton with this projector and know that you are getting the best picture possible.

Dan
stereomandan is offline  
post #204 of 1634 Old 04-30-2009, 01:26 PM
Senior Member
 
karrih's Avatar
 
Join Date: Jul 2007
Posts: 253
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by JeffY View Post

It must be a projector variance, your blue settings are way too dark and a bit purple (especially dark blues) on my projector.

I also used Mannis settings for a while and about only weakness I noticed today was slightly unnatural sky color, much like you describe.
karrih is online now  
post #205 of 1634 Old 04-30-2009, 01:33 PM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'm glad to see others use colour filters, I was starting to feel like an old fogey.
JeffY is offline  
post #206 of 1634 Old 04-30-2009, 01:33 PM
AVS Special Member
 
gregr's Avatar
 
Join Date: Nov 2001
Posts: 2,127
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Guys,

You can't use color filters to adjust a CMS. The CMS is creating pseudo RGB primaries and complementary colors that are each made up of combinations of all three real primaries. i.e. pseudo-red = a * Red, + b * Green + c * Blue. If you look at psuedo-red through a Red filter, you only see the luminance produced by a * Red, and don't see the psuedo-red luminance contributions from Green and Blue. Similar for psuedo-Yellow you only see the Red component, not the pseudo-Red component in pseudo-Yellow. So there is no way with filters to see the pseudo-Red, pseudo-Green, or pseudo-Blue components of the pseudo-Colors. That sounds a little confusing, is it clear?

In addition to the above, when you adjust a 6-axis CMS the optimum relationship between the primary and complementary colors no longer form straight connecting lines passing through the reference white - unless you get a perfect match of all colors to the target color gamut. If you don't have a perfect match, i.e. the pseudo colors aren't exactly at the target colors, then the best accuracy will be achieved by minimizing the dE differences from the target of each color. So even if there were such a thing as perfect pseudo-filters (which there isn't) the filter method would still not produce optimum results. This is another way of saying that you are not trying to match the luminance (Y) values of the target, but rather the Y values (and x,y points) that minimize dE for each color relative to the target.

You can use my Display Calibration Calculator to compute the dE values, and/or to find the Y values for your measured x,y points that minimize the dE error for each color. Just put in your x,y values and your Y value and click Compute to get the dE value. Then vary the Y value (in the calculator) until you minimize the dE value, and use that Y value as your target.

Greg Rogers
Video Engineer/Product Designer

gregr is offline  
post #207 of 1634 Old 04-30-2009, 01:36 PM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by stereomandan View Post

Manni01,

I took a look at your calibration and the lower saturations look great. Thanks for measuring the 30 saturation windows. JVC certainly did a stellar job with the CMS on this attempt! You can really nail the calibraiton with this projector and know that you are getting the best picture possible.

Dan

There is a big caveat, and it's that you need a precise colour meter. The cheap ones just aren't good enough.
JeffY is offline  
post #208 of 1634 Old 04-30-2009, 01:40 PM
AVS Special Member
 
JeffY's Avatar
 
Join Date: Mar 2001
Location: England
Posts: 3,667
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by gregr View Post

Guys,

You can't use color filters to adjust a CMS. The CMS is creating pseudo RGB primaries and complementary colors that are each made up of combinations of all three real primaries. i.e. pseudo-red = a * Red, + b * Green + c * Blue. If you look at psuedo-red through a Red filter, you only see the luminance produced by a * Red, and don't see the psuedo-red luminance contributions from Green and Blue. Similar for psuedo-Yellow you only see the Red component, not the pseudo-Red component in pseudo-Yellow. So there is no way with filters to see the pseudo-Red, pseudo-Green, or pseudo-Blue components of the pseudo-Colors. That sounds a little confusing, is it clear?

In addition to the above, when you adjust a 6-axis CMS the optimum relationship between the primary and complementary colors no longer form straight connecting lines passing through the reference white - unless you get a perfect match of all colors to the target color gamut. If you don't have a perfect match, i.e. the pseudo colors aren't exactly at the target colors, then the best accuracy will be achieved by minimizing the dE differences from the target of each color. So even if there were such a thing as perfect pseudo-filters (which there isn't) the filter method would still not produce optimum results. This is another way of saying, that you are not trying to match the luminance (Y) values of the target, but rather the Y values (and x,y points) that minimize dE for each color relative to the target.

I agree, but if you can get close with the saturation and hue then using the filters to dial in the brightness isn't a bad thing IMO. Unfortunately most of us are dealing with very dodgy colour meters so the filters are better than nothing.
JeffY is offline  
post #209 of 1634 Old 04-30-2009, 02:06 PM
AVS Special Member
 
lovingdvd's Avatar
 
Join Date: Jul 2002
Posts: 8,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 23
Quote:
Originally Posted by gregr View Post

...In addition to the above, when you adjust a 6-axis CMS the optimum relationship between the primary and complementary colors no longer form straight connecting lines passing through the reference white - unless you get a perfect match of all colors to the target color gamut...

Thanks Greg. This brings up a related question that's been on my mind for months that I'm hoping you can answer please...

As you may have read in my prior posts, I purposely like to dial in a custom gamut that is a bit more over saturated than Rec 709. For instance I like Red a bit more deep/cherry than at its reference Rec 709 point.

When I input my xy for RGB they are purposely a bit more oversaturated than the normal Rec 709 coords. Therefore indeed I did notice two side affects of this - just like you are saying above: 1) the Y changes for all the colors from the reference level to your new calculated Y based on the xy coords, and 2) the target xy of the secondaries also changes accordingly. Therefore I know exactly what you mean about no longer drawing the line perfectly through the white point.

OK so this leads me to my question... When purposely over saturating my primaries, should I then use the calculator's new xy coords for the *secondaries* as well? I assume so. Obviously I should use the calculated Y instead of the reference Y in either case.

It's kinda strange - because in a way I want the over saturation of primary colors. Yet for some colors like yellow I'd prefer the color to look more like its Rec 709 spec (for example, so that banana still looks the right shade of yellow). I know this is a bit contradictory (because I want some colors to look as natural as possible while others to look a bit souped up).

So that makes me wonder whether it should be all or nothing - meaning that if I am going to slightly oversaturated the primaries than I really need to also use the NEW calculated xy for the secondaries too (and Y too of course). Or whether it can also look ok to mix these by using my over saturated primaries while still trying to keep the secondaries at their Rec 709 coords. Thanks!
lovingdvd is offline  
post #210 of 1634 Old 04-30-2009, 02:40 PM
AVS Special Member
 
gregr's Avatar
 
Join Date: Nov 2001
Posts: 2,127
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by lovingdvd View Post

Thanks Greg. This brings up a related question that's been on my mind for months that I'm hoping you can answer please...

As you may have read in my prior posts, I purposely like to dial in a custom gamut that is a bit more over saturated than Rec 709. For instance I like Red a bit more deep/cherry than at its reference Rec 709 point.

When I input my xy for RGB they are purposely a bit more oversaturated than the normal Rec 709 coords. Therefore indeed I did notice two side affects of this - just like you are saying above: 1) the Y changes for all the colors from the reference level to your new calculated Y based on the xy coords, and 2) the target xy of the secondaries also changes accordingly. Therefore I know exactly what you mean about no longer drawing the line perfectly through the white point.

OK so this leads me to my question... When purposely over saturating my primaries, should I then use the calculator's new xy coords for the *secondaries* as well? I assume so. Obviously I should use the calculated Y instead of the reference Y in either case.

It's kinda strange - because in a way I want the over saturation of primary colors. Yet for some colors like yellow I'd prefer the color to look more like its Rec 709 spec (for example, so that banana still looks the right shade of yellow). I know this is a bit contradictory (because I want some colors to look as natural as possible while others to look a bit souped up).

So that makes me wonder whether it should be all or nothing - meaning that if I am going to slightly oversaturated the primaries than I really need to also use the NEW calculated xy for the secondaries too (and Y too of course). Or whether it can also look ok to mix these by using my over saturated primaries while still trying to keep the secondaries at their Rec 709 coords. Thanks!

If you want to use a primary or complementary that is different from your (otherwise) standard target, i.e. if you want Rec 709 except for a more saturated red, or perhaps you want all of the primaries a little more saturated, then you are on your own when adjusting a CMS. There is no reason to then expect a particular relationship between the x,y points and their Y values to somehow be better than some other relationship. i.e. you have purposely deviated from a one-to-one color mapping between the source and display, so there is no way to then say what the "best" choice will now be for x,y and Y values except what looks good to you. You changed the x,y points because they looked better to you, so pick the Y values that also look best you too.

What some people seem to find confusing about the Display Calibration Calculator is that they don't realize it is simply a tool to make certain types of calculations when those calculations are relevant to your objective. If you are not targeting a standard colorimetry with a CMS, then the xyY relationships between the primary and complementary colors no longer have any physical or perceptual relevance. You basically decided to do what looks good to you so you are on your own. Practically speaking however, you may want to adjust to a standard as close as possible first, and then make minor subjective changes that please you after that, rather than simply making totally arbitrary adjustments from the start. The former is much more likely to yield more pleasant results.

So why does the calculator allow you to enter custom RGB targets, or to copy your measured RGB values to the target section?? That is apparently what confuses some people. The reason is so that you can adjust the YCbCr to RGB color decoding, NOT a CMS (or in the rare case that you have video sources based on a Standard other than Rec. 601 or SMPTE C). The Color decoding should be adjusted to the standards before adjusting a CMS. I think it is best to make sure the video signals are being converted to the correct RGB values, even if you are then going to dial in some non-standard CMS settings. The reason for that is because unless the Color Decoding is standard it can produce various non-linear effects that can degrade any CMS adjustment (even a "subjectively custom" one), and you will know what an accurately adjusted CMS would have looked like (even if you still want to modify it later).

Greg Rogers
Video Engineer/Product Designer

gregr is offline  
Reply Digital Hi-End Projectors - $3,000+ USD MSRP

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off