RE: Eye-One Diagnostics
RE: Eye-One Diagnostics
- Subject: RE: Eye-One Diagnostics
- From: "Ray Cheydleur" <email@hidden>
- Date: Fri, 2 Jan 2004 13:53:40 -0500
- Thread-topic: Eye-One Diagnostics
Richard Kenward <email@hidden> wrote:
>
Interesting observation which actually I have not read about before!
>
Perhaps someone from X-rite would like to comment?
Snip
Henrik Holmegaard <email@hidden>
(1) An incomplete PDF project released in 2000 as the icc abc series,
written with Heidelberg and X-Rite, explained why there is a
discrepancy of 2D in L* as between the Digital Swatchbook and the DTP
41,
Snip
(2) You may want to search the archives for contributions on the
Digital Swatchbook with respect to chroma accuracy
Snip
--------
Finally rising to Henrk's bait after a fine holiday... (sorry this is a
long one)
First to the REAL topic
If an instrument does not pass diagnostics, it should not be used until
it does, or you confirm with an alternate piece of software that you
have exposed a software problem... This is certainly true for an X-Rite
instrument, and I suspect for our competitors as well.
Now on to the FUD about the Digital Swatchbook as voiced by Henrik...
Q#1)This is strictly a question of backing material... The DTP41 and
Digital Swatchbook have good correlation with each other (and many other
spectros both from X-Rite and Gretag) when measuring media that is
relatively opaque, or thinner media when both are read against black
(the density standard, or for back printed materials.)
When reading thinner materials, for color management purposes it is
often desirable to measure against white to minimize unwanted background
absorption in light colors. There is some debate (!)whether this should
be self backing (more blank sheets of the material being printed on) or
a "standardized" white backing which minimizes problem inherent in
self-backing (for more on this see the recently updated CGATS.5.) In any
case the DTP41 has a two options for white backing; the standard
switchable black/white block, and an optional raised white ceramic
block. The potential 2L* shift between the DS and the DTP41 result when
very bright paper samples are used for self-backing using the DS and the
standard white backing is used in the DTP41. This effect can be
minimized by using the optional raised white backer.
Note that this is a real issue with ANY measuring system... Compare
measurements with a Spectrolino Spectroscan with a white table vs. a
black table... Or any spot reader on a dark desktop with no backing, and
self-backed... This is a complex topic that I've spent many hours in
standards committees reviewing but don't let Henrik's FUD worry you,
consistency of method is a much bigger problem.
Q#2)I did not search the archives, don't recall it, but can guarantee it
just isn't so. I'm not sure what Henrik is thinking here but I've got
thousands of comparison readings against multiple instruments from
multiple manufacturers that prove otherwise. The only case where a
difference can be almost assured, is with fluorescent materials. In this
case NO instrument can necessarily be expected to read like another, be
it the Digital Swatchbook, DTP41, EyeOne, Spectrolino or X-Rite 939.
Frankly it is rare that a quality instrument (from a major manufacturer)
that:
1) passes calibration/diagnostics
2)is within certification
and
3)is of recent vintage
is the real problem in getting good color management results.
Have a great New Year!
RayC
Raymond Cheydleur email@hidden
Lead applications specialist
Graphic Arts and Imaging, Developer Support
X-Rite Incorporated www.xrite.com
Customer Service: 888-826-3059 or 616-534-7663
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