Hello Jeroen,
find attached a short description of black length and black width from the PrintOpen
documentation.
Regards,
Guenter Bestmann
Heidelberger Druckmaschinen AG
Research & Development
Black generation with length and width:
In normal color composition, black begins in the midtones (starting point of black length)
and increases slowly towards shadow. The effective range of black in chroma varies (black
width).
"Black length"
You define the starting point for black (relative to cyan) with the "Black
length" slider: from a very short black (skeleton black) to a long black (full
range).
- Short black: A black known as skeleton black is produced if the slider is in position
"2".
Depending on your process, the first two levels can produce very similar results since a
sudden use of black has to be avoided. If a hue can be created using three colors, no
black is used. Black will only be added for very dark shades of black. The portion of
black will increase considerably with the density. Note: The minimum setting is
"2" because values less than that are of no use for reproduction. If skeleton
black is used for images, the amount of black ink can be adjusted for the text without
adversely affecting the images during the printing process. This reduces the effect of any
moiré that may appear, although the dot area is greater and the gray balance (see also
Gray balance) is susceptible to fluctuations in the printing process.
- Standard black: A standard black is produced in slider positions "5" to
"7".
The use of black begins in the midtones and slowly increases towards shadow. This is the
most widely
used type in color composition.
- Full range: A long black is produced in slider positions "8" to
"10".
The use of black already begins in the quarter tones and slowly increases towards shadow.
Examples:
For a short black set the slider to position "3", this corresponds to a 70%
starting point for black relative to cyan.
For a long black set the slider to position "7", this corresponds to a 30%
starting point for black relative to cyan.
"Black width"
You define the effective range of black with the "Black width" slider: from a
narrow black ("Only in gray") to a wide black ("Full extent"). The
effective range also depends on the setting for black length.
- Narrow black: Black only affects a narrow range around the gray axis if the slider is in
position "0"
(minimum setting). Only in very dark colors does it go further outwards.
- Standard black: Standard black is produced in slider position "5". Its effect
is moderate, going up
into the chroma range. This is the most frequently used black in color composition.
- Wide black: Black goes way into the chroma range if the slider is in position
"10" (maximum setting).
An optimal black is calculated by PrintOpen on the basis of the settings for "Black
length" and "Black
width" and the information taken from the color data.
-----Original Message-----
From: eci-en-admin(a)lists.transmedia.de [mailto:eci-en-admin@lists.transmedia.de] On Behalf
Of Jeroen Duller (Grafiplus)
Sent: Thursday, July 07, 2005 8:00 AM
To: eci-en(a)lists.transmedia.de
Subject: RE: [ECI-EN] RE: Adobe and the Fogra ISO profiles
Abe,
Besides this topic... Talking about PrintOpen and Black generation...
I read in the ECI ISOcoated.pdf the Black Lenght is set to 9 and the Width to 5.
My question is:
What is the range in PrintOpen to set Black to. Is it a value between 0 to 10 or 0 to 20?
Or something else? I don't use PrintOpen but I want to refer to ISOcoated in my
profile creation.
Jeroen Duller
________________________________
GrafiPlus GrafiPlus
Kobaltweg 38 Zandvoortstraat 45
3542 CE UTRECHT 2800 Mechelen
+31 30 2415555 +32 15435193
jeroenduller(a)grafiplus.nl jeroenduller(a)grafiplus.be
www.grafiplus.nl www.grafiplus.be
________________________________
-----Oorspronkelijk bericht-----
Van: eci-en-admin(a)lists.transmedia.de
[mailto:eci-en-admin@lists.transmedia.de] Namens Abe Hayhurst
Verzonden: dinsdag 5 juli 2005 23:13
Aan: eci-en(a)lists.transmedia.de
CC: pconstab(a)adobe.com
Onderwerp: [ECI-EN] RE: Adobe and the Fogra ISO profiles
1. If you prefer the smoothness of the Adobe gamut mapping over the FOGRA/ECI profiles,
then why not use the FOGRA datasets and create your own profiles based on them? They would
share the same gray balance, primaries, secondaries, etc., but would use your
"smoother" gamut mapping.
2. I use PrintOpen, which was used to generate the FOGRA/ECI profiles, to generate my
profiles. I would say that there is less difference between the Perceptual rendering
intent and the Relative Colorimetric rendering intent of Adobe profiles than PrintOpen
Profiles. We don't find the lighter midtones objectionable.
3. Same as #1. If you like your gamut mapping strategies better, then why don't use
the same colorimetric data as FOGRA/ECI and use your own gamut mapping.
4. I don't think licensing will be an issue. ECI is distributing the profiles.
5. I prefer a longer black as it keeps things more stable on press. It also allows you to
achieve more chromatic colors in the shadow areas.
Thanks,
Abe Hayhurst
We Do Graphics, Inc.
1150 N. Main St.
Orange, CA 92867
714-997-7390
abe(a)wedographics.com
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