.

Try Babelcolor.
http://www.babelcolor.com/main_level/ColorChecker.htm

If you are comparing a hard copy of the GM chip chart to an image of the same chart on a monitor, you'll need the right ambient lighting on the chip chart. Otherwise, metamerism will occur, due to variations in the ambient light's spectral power distribution causing the colors to shift on the chart. The best to use would be GM's D65 Sol Source lamp or our former Ideal-Lume Ultra. Neither are available from GretagMacbeth (now X-Rite) or us any more. You might find a Sol Source still in stock somewhere. The next most accurate D65 source is our Ideal-Lume Pro.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.

"Advancing the art and science of electronic imaging"

Scaling for color charts is not an issue - remember that your starting point is really a 6 pixel by 4 pixel picture for the chart you had picked.

Trying to use this technique with a front projector is going to be very challenging. Any substantial level of light that hits the screen will wash out the colors. Your lamp will be shining on the color chart and you would need to shield it from the screen while you can see both. That will be a trick.

I believe the Pearl does support 10 bit color data.

Aye the complications! I'm good at woodworking. I guess I can build a box which I can peek at, then cover. Looking back and forth should get me "close enough". I'd say probably a little over one dE?

I doubt your light source will be that close from what you are talking about spending. I would guess you would be lucky to be within 5 dE u'v'. Hitting all of the colors within one dE will be impossible with a Pearl even if you have a perfect reference chart and lamp.

Darn, so I guess that'll have to be my "good enough" :(

Which would be better, calibrating using the Denon's controls to a properly set up Pearl, or using the Pearl with everything at the Denon's neutral position either off or 0 for all settings?

I assume you mean the Denon DVD player.

Usually, you need to consider both. The best approach is to do the least adjustment possible in the player unless it has the wrong black setup. The reason for this is that the processing in the Pearl will generally be of a higher level of quality than the DVD player and massaging the YCbCr numbers more than once is generally a bad idea. Since the projector must do this to adjust picture, color, brightness, tint and sharpness it should be avoided in the player. There are exceptions to this, but that is the rule I follow.

Thanks for the link to the BabelColor site. I found many of the papers interesting and very educational.

I read an interesting paper on the comparisons of RGB color spaces that had this comment in the papers conclusion:
Danny Pascale, BabelColor Company.

To place the conversion errors in perspective, we have to take into consideration the conditions in which these images will be seen. One of these conditions is the observation time. According to a review article by Has & al.,24 an inexperienced user will take approximately 5 seconds to notice a deltaE*ab difference of 15 from an original. The time goes up to 10 seconds for a deltaE*ab of 10, and 15 seconds for a deltaE*ab of 5. Another study25 has shown that errors of less than 2,5 deltaE*ab are not visible on real world images shown on a CRT. In essence, the threshold value of deltaE*ab = 1 can only be achieved only by prolonged comparative viewing in a controlled environment.I’ve wondered about the applicability of the HVS threshold ~ @ deltaE = unity with regards to display calibration. It seems the above author and cited studies would place the HVS threshold @ deltaE >2.5 for a short-term, non-comparative environment where the image is also largely the only illumination source.

Dave

Thanks for the link to the BabelColor site. I found many of the papers interesting and very educational.

I read an interesting paper on the comparisons of RGB color spaces that had this comment in the papers conclusion:
I’ve wondered about the applicability of the HVS threshold ~ @ deltaE = unity with regards to display calibration. It seems the above author and cited studies would place the HVS threshold @ deltaE >2.5 for a short-term, non-comparative environment where the image is also largely the only illumination source.

Dave

Our errors are much higher than that when you consider the entire color gamut. Only around D65 does it come that close. When you start looking at RGBYCM things are much worse.

...

So is that CI for "custom installer" just a marketing gimmick?

Probably, but these are very nice players.

Our errors are much higher than that when you consider the entire color gamut. Only around D65 does it come that close. When you start looking at RGBYCM things are much worse.

Agreed. But what is the HVS threshold for perception of these errors in a short-term, non comparitive display environment? Does ISF have a 'good enough' target?

Dave

Agreed. But what is the HVS threshold for perception of these errors in a short-term, non comparitive display environment? Does ISF have a 'good enough' target?

Dave

I believe ISF is targeting +-0.005 xy for D65. I have seen no suggested specification for primaries and secondaries. You would also be lucky if any instrument is within 0.0015 xy for all of the spectra in question. Almost all instruments are calibrated for Luminent A. What performance you get off of that will depend on the device.

Would the Ideal-lume standard do the job?

The lamp in the Ideal-Lume Standard is not D65. That's a much tighter tolerance that typically costs more to acheive. Precision comes with a cost in just about every field. SMPTE C broadcast monitors are REALLY expensive.

One thing I have found in the lighting field. Many products claim to be "6500K" or "D65" but are not. I have measured many of these products over the years in my effort to locate more affordable and/or practical solutions. NIST uses our Ideal-Lume Pro in their reference video viewing environment. It's the most affordable, pre-assembled solution of its kind that I've encountered. This is due to the patented 7 phosphor mix GretagMacbeth developed for the lamp. Even 98 CRI 6500K lamps aren't good for your purpose since they only use 3 or 4 phosphors. Their spectral power distribution is too limited. There will be significant peaks and dips in various portions of the spectrum. This results in metamerism, or color shift in corresponding points in the overall spectrum. The primaries may look ok since the 3 major phosphors roughly correspond to red, green and blue, but everything else illuminated can be skewed. Here's a link to JKP's site, for an assortment of spectral graphs of various illuminants: http://videoessentials.com/res_facts.php#spectral . As one can see, spectral power distribution can be quite uneven in many examples.

Many displays can track a reasonably accurate gray scale. However, that's just the center area of color space. If the color primaries aren't accurate, like most displays, the farther one moves outward toward saturated colors, the less accurate the image will be. Joe Kane's Samsung projectors, certain other Samsung DLPs, and few others, allow precise tweaking of the primaries and secondaries.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.

"Advancing the art and science of electronic imaging"

I believe ISF is targeting +-0.005 xy for D65. I have seen no suggested specification for primaries and secondaries.

That's also the SMPTE tolerance for SMPTE C phosphors in broadcast monitors: SMPTE RP167, Annex A.14.