Visually comparing Xenon to D65 ?? - AVS Forum
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post #1 of 18 Old 05-05-2008, 10:11 AM - Thread Starter
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I find the following puzzling and have yet to get an explanation when posted to film forums so I will try it here.

D5400 from my Xenon lamp house ( I have several ) looks very blue almost like I am watching a Sony TV at D9200. These xenon lamps are indeed rated at d5400.Watching a film driven by xenon has what I call a xenon tint or blueish look to it yet D65 is a higher temp & should look the bluest of the two leaving D54 redder. If someone prefers the look of film should our electronic displays shoot for a higher temp then D65 to hit that xenon look?

For viewing movie material are we wrongfully calibrating our displays to D65? While D65 may be ISF spec, to my eye it does not resemble film in color. Maybe two color memories are needed leaving D65 for sporting events and watching HDTV.
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post #2 of 18 Old 05-05-2008, 11:44 AM
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Alan G.
I guess those doing Blu-ray transfers shoot for a color look that is similar to film within the HD gamut and white point.

How is the xenon lamp filtered in your lamp house pre film and by the film. Perhaps you can make a spectrum analysis of your film projector projecting white through film. Perhaps some remaining short wave lenght light can tease our eyes into perceiving the blue tint you talk about.

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post #3 of 18 Old 05-05-2008, 11:51 AM
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Alan,

D54 does not look blue, it looks reddish. Also, it's important to differentiate between D54, which is a point on the CIE chart, and a CCT of 5400K, which is a line on the chart, and at one extreme can look blue. Regardless of the rating, if you measure one of these lamps that look blue, it will have x and y values that are not D54 but more towards blue. (I don't think that there is a D54 standard illuminant and I am referring to x and y values that would correspond to one.)

Using D65 calibration is one of the essential components to have accurate colors for consumer sources. If you use a different white reference, you don't get a film look, just inaccurate colors.
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post #4 of 18 Old 05-05-2008, 12:14 PM - Thread Starter
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Good start


Ok lets throw out D54 on the CIE chart and CCT at 5400k.

Projecting film the lamp is not filtered. Visually it has indeed without any mistaken a blueish cast and movies projected using a xenon light source visually when side by side looks to be at a much higher color temp compared to d65 via electronic display. To my eye when calibrating an electronic display 7500 seams to emulate the xenon look. Please separate using xenon in an electronic display which is filtered I am talking xenon in the lamp house projecting film...they look completely different.
Now D54 via our electronic display is indeed redder and even still does not resemble the bluer color output of a xenon bulb rated at D5400.
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post #5 of 18 Old 05-05-2008, 01:26 PM
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Calibrating a projector used with a consumer D65 source to D75 may produce whites that look like film projection, but it can't produce accurate colors. By definition, the colors will be wrong and if they match film, the film colors are also wrong. Without getting into complications like gamma, there are three projector requirements for accurate color: correct primaries, correct white, and correct decoding. Calibrating white to D75 violates one of these. All of this assumes that the source is correct.
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post #6 of 18 Old 05-05-2008, 01:27 PM
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Alan, are you saying the overall look of film is more blue than D6500 calibrated digital projection ? Does white look more blue or just the overall impression ?

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post #7 of 18 Old 05-05-2008, 02:11 PM - Thread Starter
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It looks more blue. I will be viewing another screening tonight and I will pay special attention and follow up. The lamp itself with no film on the screen is 100% without a doubt more blue and looks like d9200 to the eye. I have a spectra radiometer and I could measure but I have to lug quit a bit of equipment to get to the bottom of this. I was hoping for an answer to save me the work
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post #8 of 18 Old 05-05-2008, 03:56 PM
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Quote:
Originally Posted by Alan Gouger View Post

It looks more blue. I will be viewing another screening tonight and I will pay special attention and follow up. The lamp itself with no film on the screen is 100% without a doubt more blue and looks like d9200 to the eye. I have a spectra radiometer and I could measure but I have to lug quit a bit of equipment to get to the bottom of this. I was hoping for an answer to save me the work

Yea, kinda takes the fun out of it.

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post #9 of 18 Old 05-05-2008, 04:20 PM
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Alan, do you have a IR filter in the lamphouse? This includes the dichroic coatings on the reflector. It may in fact be cutting way into the red and giving you a higher color temperature.
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post #10 of 18 Old 05-05-2008, 04:53 PM - Thread Starter
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Quote:
Originally Posted by Kevin Bright View Post

Alan, do you have a IR filter in the lamphouse? This includes the dichroic coatings on the reflector. It may in fact be cutting way into the red and giving you a higher color temperature.

No filters. Im running them wide open. I have three lamp houses. two with a 500 watter and one with a 800 or 900 watter. At some point this week I will be changing my system around and will try each lamp house again to decide which will fit best my new configuration. At that point I am going to drag out the meter and see what Im getting.
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post #11 of 18 Old 05-10-2008, 10:23 PM
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Alan,
Have you had any opportunity to do any measurements yet ?

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post #12 of 18 Old 05-11-2008, 06:40 AM - Thread Starter
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Not yet Art. Yesterday was a long day. I was in my booth until 1 am last night. I had some friends over to help with the lifting & rearranged the equipment ( smaller footprint ) and wired for a different lamp house, still not done. I will not get a chance for measurement until later this week.
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post #13 of 18 Old 05-11-2008, 06:49 AM
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This all very interesting. I was just wondering how it was coming along.

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post #14 of 18 Old 05-11-2008, 06:54 PM - Thread Starter
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Later this week I will drag out my measurement equipment and see what color temp the Xenon lamphouse is outputting.

It is impossible to freeze film so Ive done the best I can. Superb colors and sharpness without any artifacts. You can sit 2 feet to the screen and watch the movie very comfortably, something you cannot do with our electronic displays.

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post #15 of 18 Old 05-11-2008, 07:21 PM
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Wow. I want one!



Alan, I love how you raise the bar for what people say is the past, being film. I'm not sure anything is going to be able to replace it.

I hate to go a little OT, but what do you think of IMAX dumping film?

I truly feel that it is a huge mistake. Digital is NOT ready.

I cannot wait to see Batman in IMAX when it comes out. I've seen the preview and it's one of the most amazing transfers I have ever seen.

Oh, and the pic, that woman or what ever it is IS SCARY!!!!!!!!

Cliffy
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post #16 of 18 Old 05-12-2008, 08:55 AM - Thread Starter
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Hey Cliff

We will have to wait and see what Imax digital has in store for us. I do not see how it can compete with large format film but at this point we are all speculating.
I do think our displays are capable of throwing out a much better image then what we are use to seeing. The source is the limiting factor. Maybe they will project something beyond standard DCI content.
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post #17 of 18 Old 05-28-2008, 11:39 AM
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Alan,

Depending on the lamp housing you are using they push the color temp higher for all the same wrong reasons video manufacturers do. I have run in to this with after market consoles for projectors.

Where did you get that print? 35mm?

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post #18 of 18 Old 05-28-2008, 01:04 PM - Thread Starter
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Hi Jim

Email sent.

Yes I have just learned the reflectors in the lamp house and the negative lens adds its own flavor of color shift. I never would have expected this but this confirms what I was seeing.
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