Viewing Brightness and ICC Printer Profiles

[LGeb]

This is a basic question, but I haven't seen it answered before.

What brightness level do profiles assume prints will be viewed at? If you want to target a lower illumination level, what is the best way to handle this? Is there a setting when making profiles in the higher end software? Is there a simple adjustment curve that works well for most images in Photoshop?

I am asking because many prints appear too dark when viewed in normal room light, but put under a halogen spot light they look great, and match the screen very well. However if I know the print will hang in an area with decreased illumination I need to make an adjustment to the print, knowing I will sacrifice quality if it is moved.

This problem has always nagged me, even when printing in the wet darkroom.

[bjanes]

This is a basic question, but I haven't seen it answered before.

What brightness level do profiles assume prints will be viewed at? If you want to target a lower illumination level, what is the best way to handle this? Is there a setting when making profiles in the higher end software? Is there a simple adjustment curve that works well for most images in Photoshop?

I am asking because many prints appear too dark when viewed in normal room light, but put under a halogen spot light they look great, and match the screen very well. However if I know the print will hang in an area with decreased illumination I need to make an adjustment to the print, knowing I will sacrifice quality if it is moved.

This problem has always nagged me, even when printing in the wet darkroom.
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Quote from [a href=\"http://www.color.org/iccprofile.html]Introduction to the ICC profile format[/url]

"The reference viewing condition is that defined in ISO 3664 as viewing condition P2 using the recommended 20% surround reflectance. This is a graphics arts and photography print viewing environment with a D50 illumination level of 500 lux."

Bill

[LGeb]

Quote from Introduction to the ICC profile format

"The reference viewing condition is that defined in ISO 3664 as viewing condition P2 using the recommended 20% surround reflectance. This is a graphics arts and photography print viewing environment with a D50 illumination level of 500 lux."

Bill
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Thanks Bill, I had skimmed over that document but missed the light reading (which surprised me). Any tips on targeting light levels less than this?

[bjanes]

Thanks Bill, I had skimmed over that document but missed the light reading (which surprised me). Any tips on targeting light levels less than this?
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I'm not sure about how to reply to your quiestion, but have done a bit of research. The CIE viewing conditions are met by various [a href=\"http://www.inkjetmall.com/store/cm/gti.html]Viewing Booths[/url].

In his color management book, Bruce Fraser says that for monitor to print matching, the brightness of a sheet of paper under the viewing conditions should be similar to that of the white on the monitor. He does not bother to match the color temperatures of the monitor and viewer, but suggests that they should not be in the same field of view.

I am not trained in photometry, but will give the following analysis of my current setup for comment.

With my own setup, the monitor (an LCD) is at its native white point (probably about 6500K) and with a calibrated luminance of 140 cd/m^2.

My old Gossen Luna Pro F has a table on the back of the meter for use with the incident light diffuser. With the meter set to DIN 18 (ISO 50), a reading of EV 5 corresponds to 175 lux, EV 6 350 lux, and EV 7 700 lux. Using this table, My Solux 5000K light at 2 feet gives about 500 lux according to the meter. If white paper reflects 90% of the incident light in a Lambertian fashion, I think the luminance for this amount of illumination would be 500 * 0.9 / pi or about 143 cd/m^2. In practice this seems to work out well, but I welcome comments.

As a rough check, I used the reflected light capability of the meter and took a reading from the screen and the paper, and the readings were EV 8.5 from the screen and EV 9 from the paper with ISO set at 50.

Bill