What is the specification for viewing conditions?

[gordo]

A question for you. What is the specification or standard that applies to viewing booths at the press.
I think it's "ISO 3664:2009*Graphic technology and photography -- Viewing conditions" but from its description I'm not sure. ($130 seems a bit expensive to find out it's not the right info)

thanks for any help - gordo

[meddington]

Yep. That would be it. Defining viewing condition requirements, illuminant, CRI, metamerism index, surround, uniformity, etc.

[gordo]

Yep. That would be it. Defining viewing condition requirements, illuminant, CRI, metamerism index, surround, uniformity, etc.

Thanks - a vendor responded to me and said that that document is more directed towards engineers rather than the average printer. In fact, every bit of info that I can find seems complex enough to stun a horse.
Just look at this entry on wikipedia as an example:
h t t p://en.wikipedia.org/wiki/Standard_illuminant#Illuminant_series_D

Very frustrating.

best, gordon p

[meddington]

Thanks - a vendor responded to me and said that that document is more directed towards engineers rather than the average printer. In fact, every bit of info that I can find seems complex enough to stun a horse.
Just look at this entry on wikipedia as an example:
h t t p://en.wikipedia.org/wiki/Standard_illuminant#Illuminant_series_D

Very frustrating.

best, gordon p

Yikes. We'll, the vendor is correct in that its geared more towards engineers/manufacturers, but its not quite as imposing as the example you provided here, and it can be a useful reference for an average printer. Is there something in particular your looking to get out of it?

[gordo]

Is there something in particular your looking to get out of it?

I was asked this question and didn't want to respond without checking my facts. So I started rummaging around the interweb and soon discovered that the info - let alone practical easy to understand info - was pretty near impossible to find. You'd think this kind of basic info would be easy to get.

I do have some questions.
1) How do you measure Lux/Foot candles? Can you use a photography light meter?
2) How is reflectance measured? I.e. For surround it says "neutral surround with luminous reflectance of between 10% and 60%. What does that mean? How is it measured and with what instrument?
3) Chromaticity for the lamp for D65 is u'=0.198, v'=0.468 and for D50 it's u'/10 =.2102, v'/10 = .4889 . What the heck does that mean? How would you measure your lamps to confirm that they're in spec?

best, gordon p

[meddington]

1) How do you measure Lux/Foot candles? Can you use a photography light meter?

Yep, you can use a light meter. Can also measure with an i1Pro spectro and i1Share or Babel Color CT&A.

2) How is reflectance measured? I.e. For surround it says "neutral surround with luminous reflectance of between 10% and 60%. What does that mean? How is it measured and with what instrument?

Not sure as this isn't specified outright. Maybe a gloss meter or some sort of reflectance photometer perhaps? Many designing their own surrounds use a musell N8 or N7 gray paint.

3) Chromaticity for the lamp for D65 is u'=0.198, v'=0.468 and for D50 it's u'/10 =.2102, v'/10 = .4889 . What the heck does that mean?

These are the u', v' chromaticity coordinates in the CIE 1976 Uniform Chromaticity Scale Diagram (along the plankian locus). Although the D50 spectral distribution curve is the "target", the chromaticity is defined with a radius of acceptability within 0,005.

How would you measure your lamps to confirm that they're in spec?

Short answer: you truly can't, unless you have a spectroradiometer that can measure from say 300-780 nm.

more practical answer: Using a light meter to confirm both color temperature and u', v' coordinates. better yet, use an i1Pro with Babel color CT&A Spectral tools. The device isn't capable of measuring far enough into uv, or ir, but can be certainly be useful. See screenshot.

[Alois Senefelder]

Gentlemen,


A little "en-LIGHT-enment " !!!! a PDF hopefully of interest and value


Regards, Alois

[Alois Senefelder]

Enlightenment --- part 3 of Fiat Lux later

[gordo]

Thanks Mike and Alois - most helpful!

gordon p

[Alois Senefelder]

Part 3 the last part --- but first,


"Color is life, for a world without color seems dead. As a flame produces light, light produces color. As intonation lends color to the spoken word, color realized sound to form. Harmony implies balance, symmetry of forces. Colors are primodial ideas, the children of light"

Johannes Itten, from The Art of Color


Regards, Alois