Viewing Light - Need Suggestions

Hikari

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D65 is not a daylight standard. It's a TV standard. Morning and evening daylight is around D50. Average daylight is around D55 and noon daylight peaks at D65. That's neither average nor standard.

What I mean by a "standard" is a defined light output. And D65 is more than a TV standard. Needles to say, in color work, you need to work to some daylight standard. Your choice is dependent on many factors. A good book on color management will cover much of this. And there are many texts that cover viewing conditions with color material.
 

RalphLambrecht

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Can you make a book recommendation?
 

George Collier

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Don't know if it's relevant, but in the printing industry (the business that publishes color photography, and other material) the standard for proof and print viewing is 5000K. Higher color temp "masks" slight differences in blue colors, while lower color temp makes discernment of red, or warmer colors difficult. As I understand it, 5000 was chosen as the best compromise.
I work for a global graphic services company, and I asked the question about the transparency viewing (I found the thought of viewing with incandescent to mimick a projector interesting, and a bit funny), and the answer is that the transparency viewer (which is built into all of our viewing booths) is 5000 also.
The story is that ISO selected 5000 as the compromise for blues and reds, as stated above, to end the chaos in the graphic arts industry. It would be an interesting initiative to apply the same thinking to the gallery lighting business, although I suspect that it is far less unified and controlled, but could be.
 

RalphLambrecht

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... A lightjet print from a digital file printed suing a monitor calibrated to 6500 K looks the same as a negative printed optically on the same type of paper when both are viewed under 5000 K lights.

I don't know what, but something is definitely wrong with that.
 

Hikari

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We have our lab set up the same way--monitor D65, viewing lights D50. It works--the digital print and monitor image are very close. Could it be the optical brighteners in the paper? Could it be the difference of how we perceive a glowing screen verses reflected light. A combination of both? I don't know. But it works well.
 

MattKing

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Do you work with your monitor in an environment illuminated by daylight viewing lights?

I find this interesting as well, and know I cannot explain it.

I wonder if the calibration standards themselves are actually unconnected - they just use degrees kelvin to describe two related, but independent phenomena.
 

Hikari

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I can only speculate. Obviously how the human visual system interprets the two conditions of the glowing monitor and the absorbing ink plays a big part.

And to answer the question, my monitor and viewing lights are in the same room, although the viewing lights are not shining on the monitor.
 

RalphLambrecht

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I can set my iMac monitor to D50 and D65. After doing so and displaying a solid gray, I measured 5100 K and 6400 K with a Gossen Colormeter respectively. To make matters more confusing, I also used three monitor calibration devices. They all produced a much higher color temperature when being set to D65 (around 7-8k K). Interestingly enough, all three produced a different color tint in solid gray, the mac presets did not.

But I'm afraid we're getting off topic.
 

RalphLambrecht

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... Obviously how the human visual system interprets the two conditions of the glowing monitor and the absorbing ink plays a big part. ...

That should not make any difference. Luminance is luminance. The human visual system does not care if light is emitted or reflected. The big difference between a monitor and a print is the subject luminance range (SLR). A print cannot produce much more than 200:1 but monitors go up to 1000:1, in which case a print-to-monitor match is physically impossible, and any software claim promising such a match is nothing but hype. The print vs monitor difference is similar to the print vs slide difference in analog photography.
 

Hikari

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Then explain why my 200:1 print looks like my 1000:1 monitor. (Actually, it can make a big difference if light is emitted or reflected.)
 

RalphLambrecht

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Then explain why my 200:1 print looks like my 1000:1 monitor.

There are a number of possibilities, illusion included:

1. Your image doesn't have a 1000:1 SLR in the first place.
2. Your monitor calibration software reduced your monitor contrast.
3. Your advertised and your actual monitor contrast are not the same.
4. Your subjective comparison is less than perfect. After all, you cannot see both images at the same time, so, you are really comparing the actual observation of one image with what you memorize about other.

Monitor images typically look snappier, more brilliant or all kinds of terms users come up with. A printed image always looks a bit flat in comparison. That normal, because the contrast range of the two is different. As I said, it's similar to the difference between prints and slides.

And that's just the contrast issue.
 

RalphLambrecht

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... (Actually, it can make a big difference if light is emitted or reflected.)

Not to the sensation electromagnetic radiation causes in the human visual system.

You cannot tell if light is emitted or reflected just by looking at it. That's why mirrors work. All they show you is reflected light, and you wouldn't be able to tell if you see an actual light bulb or a mirror image of it, unless you know that a mirror is present.
 

RalphLambrecht

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... It may not be the color temperature itself, but how the monitor renders color at that temperature that accounts for the discrepancy. We are expecting the monitor to render colors at 5000K the same as a light box would, but perhaps it doesn't.

It should work for a white screen. After all, white is what D50 and D65 are all about.
 
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Using 5000 K as a compromise makes a lot of sense to me, and in my view, it puts the 6500 K monitor-calibration standard in question. How, do you think, can they co-exist?

The colour calibration manual that came with my NEC SpectraView Reference 271 monitor explains that the D50 is the standard for press and print work, while D65 is used for web development. From my very limited experience of calibrating other people's screens (Mac and PC) I can see those have been mostly set around D65 or even higher (I've seen 70 and 80 occasionally). Personally, I always thought D65 was a compromise between what a casual web user would see and what was better for good judgment (D50). What you choose depends what you aim to produce, I suppose. Mind it, I always felt D50 on iMacs and Apple monitors did not look quite right, compared with other D50 monitors, like NEC, Eizo, or LaCie. D65 was fine.

As I was preparing to print my book, which contains tritone offset reproductions of my selenium toned black and white prints, I found D50 helped me find a common language with the designer and prepress. When I was adjusting those prints so anyone could see them nicely on my web site, I used D65 instead.

In the end, I am pleased with the results I got. The book really looks like the prints, and the web site is close to the spirit of the selenium tone as I could only hope for.

As for the original question, I use a single 100W tungsten Lucci milky bulb about 2m away from the trays, and I always evaluate the strips and the print hanging over the tray, not while floating in it. I found this to match the illumination that the gallery used very well. Tungsten seems to have a much better RI than any fluorescent strips I have found, and does not affect the visual perception of selenium tone as much.

Ps. The manual for the monitor also stressed that the room illumination ought to match the chosen white balance target, and that a compromise may need to be made should this be an issue.
 
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