Digital BW, The Print

You wrote "you can't really build a custom profile to counter this
effect since no 
spectrophotometer/profile bundle is designed to deal with metamerism."
This is about to change. I had a lengthy discussion with a
Gretag/Macbeth engineer at PhotoPlus Expo in NYC last month.
He said that Q1 - 2003, software will be available for the EyeOne to
make it act as a spectroradiometer (Boy, that's my word-of-the-week)
The concept is that a standard profile is built; the EyeOne (presumably
on a laptop) is placed under the display light source (the EyeOne, I
assume is pointed at the light source to measure the ambient light).
This data then modifies the profile to create one which, under that
specific light source, exhibits no metamerism)
Also, ColorByte's profiles for Imageprint come in 3 flavors (cool white,
daylight and tungsten). The metamerism issue is being addressed.



 
Stan Shire
Associate Professor/Department Chair
Photographic Imaging
Community College of Philadelphia
Adobe Photoshop 6 A.C.E.
Author: Hands On Photoshop 7: Tutorial Workshops

215 751-8320
sshire@...
-----Original Message-----
From: sanfo2003 <SandyCornelius@...> [mailto:SandyCornelius@...]

Sent: Sunday, December 08, 2002 3:10 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Re: New Lepp Profiles for 2200
 
The problem I'm running into with greyscale images on the 2200 is 
with metamerism. From what I understand metamerism is caused by an 
unaligned distribution of pigment particles in the ink that causes 
the reflected light to scatter. It seems that as the thickness of the 
the ink layer varies so does the metamerism effect thus getting a hue 
shift across tones. The fundamental hue will change depending on the 
frequency of light reflecting off the ink pigment, this is why you 
get the characteristic magenta cast under tungsten light and green 
cast under daylight. Since the hue is constantly shifting within 
lighter and darker areas of the print due to metamerism, you can't 
really build a custom profile to counter this effect since no 
spectrophotometer/profile bundle is designed to deal with metamerism.

Another phenomenom that we have to deal with is that the human eye 
can pick up a subtle color cast in a greyscale image right away when 
the same cast may go unnoticed in a color image. Tons of toner 
solution has been sold in the conventional darkroom field to take 
artistic advantage of this ability to pick up a color cast in 
greyscale. 

So, as far as digital greyscale images are concerned, one could have 
a spot-on profile but still have an unacceptable print due to 
metamerism. The bottom line is this: metamerism is an ink issue and 
must be solved there before greyscales are beautifully consistant 
using archival pigment inks.

Mechanically Epson printers are there, now Epson should concentrate 
on their drivers and inks to deal with the above. I know it can be 
done (in fact, some say ColorByte's ImagePrint 5.0 RIP has already 
done it, although it wouldn't run on my machine), and when it is we 
can concentrate on the art -- and Epson can sell more printers and 
ink. I would call that a win-win situation.


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