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Basic Guide to Color Calibration using a CMS (updated and enhanced) - Page 58

post #1711 of 1936
Thread Starter 
Quote:
Originally Posted by dominickwok View Post

So you need to increase Saturation to get the perfect RGB combination (i.e. xy coordinate) of 107% / 107% / 0%. You get it?

This will provide excessive luminance. 100%, 100%, 0% is correct. RGB percentages are useful only for a human interface that provides RGB controls (Lumagen Radiance and Samsung CMSs come to mind). The Epsons have an HSL interface.
post #1712 of 1936
Where do I get the correct color % combination for each color? Like 100%, 100%, 0 for yellow? Also I didn't know I could use the cie chart in live reading mode when displaying one color windows. That alone helped me a lot last night when I did another calibration. It let me see which way the color was moving when adjusting hue and sat.
post #1713 of 1936
Quote:
Originally Posted by jmoakk View Post

Where do I get the correct color % combination for each color? Like 100%, 100%, 0 for yellow? Also I didn't know I could use the cie chart in live reading mode when displaying one color windows. That alone helped me a lot last night when I did another calibration. It let me see which way the color was moving when adjusting hue and sat.

What calibration software are you using?
post #1714 of 1936
hcfr, I know where the reading is in the software. I just dont know what the reading should be for each color.
post #1715 of 1936
Quote:
Originally Posted by jmoakk View Post

hcfr, I know where the reading is in the software. I just dont know what the reading should be for each color.

You can refer to the following post:

http://www.avsforum.com/avs-vb/showt...7#post16166537

In that post, it points you to the following link to download an Excel spreadsheet:

http://www.avsforum.com/avs-vb/showthread.php?t=1111066

The "Calibration Aid" tab of the spreadsheet lists out the correct RGB% for each 100% saturated primary/secondary (as well as for each 75% saturated primary/secondary). Please note that the RGB% (e.g. 107% / 107% / 0% for 100% sat. yellow) is the % shown by HCFR - that's nothing to do with anything else such as external video processor).
post #1716 of 1936
Hi Tom,

Excellent guide. Any chance you could update it for Lumagen Radiance owners?

I'm mostly confused as to why the Radiance offers both a "Color Gamut" and "Color Decoder" setting under it's CMS system. Can't you adjust everything using just the Color Gamut controls? Why would you ever need to mess with the color/hue controls under the ColorDecoder menu?

Also, any general tips for calibrating the JVC RS40? It's difficult to decide what to adjust on the projector vs. on the Radiance.

Thanks.
post #1717 of 1936
Thread Starter 
The color decoder controls are legacy features that the CMS renders obsolete.

Use the PJ's controls to get the gamma/grayscale close, and then refine with the Lumagen's controls.

Quote:
Originally Posted by Wizziwig View Post

Excellent guide. Any chance you could update it for Lumagen Radiance owners?

I'm mostly confused as to why the Radiance offers both a "Color Gamut" and "Color Decoder" setting under it's CMS system. Can't you adjust everything using just the Color Gamut controls? Why would you ever need to mess with the color/hue controls under the ColorDecoder menu?

Also, any general tips for calibrating the JVC RS40? It's difficult to decide what to adjust on the projector vs. on the Radiance.
post #1718 of 1936
Quote:
Originally Posted by krasmuzik View Post

zoyd

check out the front projector forum - Hugh2/hughman did that very study of changes to color control impact on the CIELCH measures (same dE as CIELUV) of his JVC - but it is rumoured the firmware version may behave slightly different. I would say it is generally the case that you have to shift color brightness significantly before color saturation moves with video color controls - he posted several sets of numbers on that starting here....

http://www.avsforum.com/avs-vb/showt...&#post10426396

I have observed similar with Sony Ruby/Pearl - the dL hit to move in the primaries with the color control per spec resulted in much worse dE than leaving primaries be and only shorting dL a bit under spec.

Of course Tom's post was how to use a CMS and video decoder that is capable of getting you the perfect result - as his other posts on color demonstrate - sometimes this can be an exercise in futility in picking the worst vs. best compromises.

The only thing I would add is to repeat the measures with 100% patterns - as sometimes displays can have settings impacting bright colors like DLP's BrilliantColor(tm) or any dynamic iris - which maybe can be turned off - but if not - compromise between light/dark colors time!

Also if doing tint with this method of sensoring rather than filtering - I would do it after greyscale not before - because secondaries shift with greyscale - with filters this is irrelevant because you have bluescale not greyscale!

Using red brightness to set color levels will only work if your set has no red push - if it does then the color will probably be too low overall - so again measure blue/green levels to find the compromise in between.

I also use 100% white for greyscale to first establish my clipping limits - I find hot white colortemp blowouts much more annoying than the tweak to contrast they give.


Did you change your settings for the Ruby in the service menu or regular user menu? Do you have any instructions on how to use the Ruby's color management system in the user menu? I find it difficult to use.
post #1719 of 1936
Originally Posted by TomHuffman

Thus, I think that a better method for setting Contrast is to just set it at a level consistent with good color performance and reasonable light output for a given display device. What's a reasonable level?

CRT tubes: 35 fL
Plasma: 35 fL
LCD flat panel: 50 fL
Digital rear projection: 35 fL
Digital front projection: 15 fL

If you use HCFR, you can determine fL by multiplying the peak output (100% Y) by 0.29

--------------------------------------
What would the recommendation be for an SXRD (LCOS) rear projection set?
post #1720 of 1936
Greetings all.

I have been doing calibration now as a hobby on my own TV's as well as a few families TV's for a few years and have never really run into something I couldn't figure out.. It has been a while since I have done this and I ran into a question on a friends LG Plasma.
This LG Plasma is about 7yrs old. When I go into the color settings for the unit it has a USER option. Selecting the user option then brings up a RGB screen with a slider for each R, G, B, from minus 30 to plus 30 I believe for each color. Now normally there are two sets, one for Contrast and the other for Brightness to be able to set the grey scale properly but this set only has one. I know most computer monitors only have one set of sliders. So would I put up a 100% white pattern on the screen set my ref in Calman to D6500 and adjust the sliders till I am as close as I can get, probably starting with a warm setting?
I am trying to get the model number from the TV so I have a bit more info. I might be able to get into a service menu to give me some more options on this thing. I am using an eye-one pro meter with the Calman software.

Thanks guys! Any help appreciated!
post #1721 of 1936
Quote:
Originally Posted by ericlhyman View Post

Originally Posted by TomHuffman

Thus, I think that a better method for setting Contrast is to just set it at a level consistent with good color performance and reasonable light output for a given display device. What's a reasonable level?

CRT tubes: 35 fL
Plasma: 35 fL
LCD flat panel: 50 fL
Digital rear projection: 35 fL
Digital front projection: 15 fL

If you use HCFR, you can determine fL by multiplying the peak output (100% Y) by 0.29

--------------------------------------
What would the recommendation be for an SXRD (LCOS) rear projection set?

I dont believe this chart is correct. There is no reason whatsoever not to calibrate an LCD to 35ftl also. None the black level on bad lcd sets is .015 at worst generally.

35 is the standard and all sets should be calibrated to this. This is one reason why people dont liek the look of LCD. They are being calibrated incorrectly.

This made sense when black levels of lcd were .05 and higher in order to get some kind of contrast. It is no longer needed.
post #1722 of 1936
Thread Starter 
I agree. This is out of date.

Edit: In fact, this was edited some time ago to 30-50fL. I just edited it again to 30-40fL.

Quote:
Originally Posted by serialmike View Post

I dont believe this chart is correct. There is no reason whatsoever not to calibrate an LCD to 35ftl also. None the black level on bad lcd sets is .015 at worst generally.

35 is the standard and all sets should be calibrated to this. This is one reason why people dont liek the look of LCD. They are being calibrated incorrectly.

This made sense when black levels of lcd were .05 and higher in order to get some kind of contrast. It is no longer needed.
post #1723 of 1936
Quote:
Originally Posted by TomHuffman View Post

I agree. This is out of date.

Edit: In fact, this was edited some time ago to 30-50fL. I just edited it again to 30-40fL.

Good deal When I saw you posted I got worried I drew your ire. So often when I post something against what a sticky says or goes against the grain I get into.

Whew
post #1724 of 1936
1) Setting Contrast
Why is 30 - 40 ftL the recommended LCD contrast setting? If movie theaters use 12 - 14 ftL settings, then I want to try those settings to see if they'll replicate the movie theater experience on the LCD screen. But if the 30-40 ftL are the standards used by post production people, then I'll give it a shot because accuracy is important.

2) Setting greyscale:
If my television is missing greyscale controls like RGB Cuts or Gains, then what can be done? Can I influence greyscale with other controls -- such as color temperature settings, dynamic range standard / out of standard settings, black expansion for shadow detail settings, contrast control, and C.M.S settings?
post #1725 of 1936
Quote:
Originally Posted by SecondaryColors View Post

1) Setting Contrast
Why is 30 - 40 ftL the recommended LCD contrast setting? If movie theaters use 12 - 14 ftL settings, then I want to try those settings to see if they'll replicate the movie theater experience on the LCD screen. But if the 30-40 ftL are the standards used by post production people, then I'll give it a shot because accuracy is important.

30-40 fL is for direct view displays such as LED/LCD and Plasma Flat-Panel displays

12-14 fL is for front projectors
post #1726 of 1936
Quote:
Originally Posted by SecondaryColors View Post

2) Setting greyscale:
If my television is missing greyscale controls like RGB Cuts or Gains, then what can be done? Can I influence greyscale with other controls -- such as color temperature settings, dynamic range standard / out of standard settings, black expansion for shadow detail settings, contrast control, and C.M.S settings?

If your set has any setting related to color temperature, try the setting of warm / warm1 / warm2. Usually this sets it closer to D65 than any setting of normal / standard / cool, etc.
post #1727 of 1936
Quote:
Originally Posted by serialmike View Post

35 is the standard and all sets should be calibrated to this. This is one reason why people dont liek the look of LCD. They are being calibrated incorrectly.

Isn't 35 only for dimly lit/dark rooms?
I would love to have some kind of equation/calculation which takes into account the ambient lighting of the room when coming up with the target contrast ftL.
Now, it seems 35 ftL is just the lower end of the scale which probably is too dark for most people's viewing conditions.
post #1728 of 1936
Thread Starter 
Quote:
Originally Posted by rickardl View Post

Isn't 35 only for dimly lit/dark rooms?

No. 35 ft-L is the recommended peak luminance of color monitors under ordinary viewing conditions. See SMPTE RP 166.
post #1729 of 1936
Quote:
Originally Posted by TomHuffman View Post

No. 35 ft-L is the recommended peak luminance of color monitors under ordinary viewing conditions. See SMPTE RP 166.

I don't have RP 166, but does the doc specify what "ordinary viewing conditions" are?
post #1730 of 1936
Hi everyone

I have a quick question regarding calibration. How often should you recalibrate your projector? I have an Epson 8700UB. I calibrated it when it had 0 hrs on the bulb using Eye One Lt, AVSHD disc and HCFR software. It now has 500 hrs. Should I do a recalibration?
post #1731 of 1936
Quote:
Originally Posted by den110 View Post

Hi everyone

I have a quick question regarding calibration. How often should you recalibrate your projector? I have an Epson 8700UB. I calibrated it when it had 0 hrs on the bulb using Eye One Lt, AVSHD disc and HCFR software. It now has 500 hrs. Should I do a recalibration?

Yes, typically if you are going to pay someone to do the calibration you would wait at least 200 hours to allow the lamp to settle in. I now have my own equipment and plan to check my own projector every 500 hours (6 months)
post #1732 of 1936
Thread Starter 
Quote:
Originally Posted by rickardl View Post

I don't have RP 166, but does the doc specify what "ordinary viewing conditions" are?

  • All light sources in use during picture assessment or adjustment should approximate D65.
  • The ambient light reflected from the screen should be the lowest possible level.
  • Reflections on the monitor screen should not cause a perceptible impairment from the normal viewing position.
  • Illumination at the viewing area should be between 20-100 lux.
Other than warning against direct light reflecting off the screen surface, there is no requirement for "dimly lit/dark rooms".
post #1733 of 1936
The most important factor (other than minimizing ambient reflected light) related to the brightness of a direct view monitor is the brightness of the surround - i.e. the lighted area around the screen that is visible to the viewer. It should be D65 and 10% of the screen brightness, i.e. 3.5 fL. The brightness of the surround changes the optimum gamma and optimum brightness of the monitor. Those are the specified conditions for telecine rooms, so you would ideally duplicate those conditions in your direct-view monitor viewing room.
post #1734 of 1936
Thanks!

Quote:
Originally Posted by TomHuffman View Post

  • All light sources in use during picture assessment or adjustment should approximate D65.
  • The ambient light reflected from the screen should be the lowest possible level.
  • Reflections on the monitor screen should not cause a perceptible impairment from the normal viewing position.
  • Illumination at the viewing area should be between 20-100 lux.
Other than warning against direct light reflecting off the screen surface, there is no requirement for "dimly lit/dark rooms".

Quote:
Originally Posted by gregr View Post

The most important factor (other than minimizing ambient reflected light) related to the brightness of a direct view monitor is the brightness of the surround - i.e. the lighted area around the screen that is visible to the viewer. It should be D65 and 10% of the screen brightness, i.e. 3.5 fL. The brightness of the surround changes the optimum gamma and optimum brightness of the monitor. Those are the specified conditions for telecine rooms, so you would ideally duplicate those conditions in your direct-view monitor viewing room.
post #1735 of 1936
...
post #1736 of 1936
Quote:
Originally Posted by gregr View Post

The most important factor (other than minimizing ambient reflected light) related to the brightness of a direct view monitor is the brightness of the surround - i.e. the lighted area around the screen that is visible to the viewer. It should be D65 and 10% of the screen brightness, i.e. 3.5 fL. The brightness of the surround changes the optimum gamma and optimum brightness of the monitor. Those are the specified conditions for telecine rooms, so you would ideally duplicate those conditions in your direct-view monitor viewing room.

So, what's the preferred method, measure the fL avg behind the screen with a handheld, add ~10%, adjust monitor backlight or contrast to be at +10% (38.5 fL) as the starting point. Or, is there a valid way to use a colorimeter for this? T
post #1737 of 1936
If I warmed up my tv for 60 minutes before calibrating, does that mean that I have to warm up my tv for 60 minutes before watching movies afterwards?
post #1738 of 1936
no, 1 hour warm-up is overkill. I've never measured any changes in color/gray scale even after 5 minutes of on time. warm-up is more important for the meters but 20 minutes for those are adequate.

edit: [was referring to plasma display, measured change in Y over 1 hour was 1%, maximum shift in gray scale 0.3 dELuv ]
post #1739 of 1936
Quote:
Originally Posted by SecondaryColors View Post

If I warmed up my tv for 60 minutes before calibrating, does that mean that I have to warm up my tv for 60 minutes before watching movies afterwards?

A good article if you have not read it yet

http://www.spectracal.com/downloads/...s%20Enough.pdf
post #1740 of 1936
Thread Starter 
I just tested a Samsung LED, and I got very different results.



I would agree that CCFL LCDs take forever to warm up. You may still get meaningful increases in luminance 30 minutes after turning it on. However, LED LCDs--at the least this Samsung--are much more stable than the SpectraCal test suggests. An hour after turning it on, its luminance was down only 2.8%, which is a negligible change.

More interesting to me is the change in chromaticity, which, although small, is probably worth considering.

In my opinion, 30 minutes is adequate warm-up time, but this is obviously a matter of judgment and practical time constraints.
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