purple blue/RGB working space
purple blue/RGB working space
- Subject: purple blue/RGB working space
- From: lasse seppala <email@hidden>
- Date: Fri, 8 Mar 2002 09:35:57 +0200
email@hidden wrote:
Is there a (n easy) way to avoid having blue turn into purple when printing?
Other colors print pretty well.
Perceptual intent looks a little less purple than relative.
Details: ColorSync workflow, conversion in PS6 from Adobe RGB to
custom printer (RGB) profile for Epson inkjet. Upon conversion, the
screen preview shows "blue" but print is purple. Screen calibrated
with ProveIt and meter.
Scott Olswold wrote:
If your blue is B=255 and R,G = 0, then your blue will go into purple pretty
readily no matter what CMYK space you're hitting for. I've found the same
kind of troubles with colors right around there. I often call them the
"PowerPoint Blues"--it's the application and blue color most desktop
printers have a big issue with.
Andrew Rodney wrote:
on 3/4/02 11:33 AM, Armand Rosenberg at email@hidden wrote:
My blue is around RGB=70,100,180 and I print using an RGB profile from PS6.
It's likely the profile. It's common to see this effect with some profiles.
What did you use to build it?
Scott Kilbourne wrote:
We use color management on Macs and PC's using iQueue to convert
from Adobe >RGB98 to the required output space (Fuji Pictrography,
other digital printers, >SWOP, etc.). We have trouble with some
folks working in AdobeRGB98 space and >then having their output
gumut limited when converting to the smaller output >spaces. This
happens most with images/graphics that use "artificial" colors >that
the artist added. After trying for the 100th time to explain to
them what >happened ("No, 255,0,0 in AdobeRGB98 is not a fully
saturated red in Fuji space >- it gets remapped to a duller
red-orange because it is so far out of gamut.") >I am rethinking our
work flow.
Terry Wyse wrote:
As far as the saturated red becoming a dull orange, have you upgraded to
ProfileMaker 4 yet? They have a new "ChromaPlus" gamut mapping option that
helps to push out of gamut colors in the source space near the edges of the
destination space, assuming the source is larger than the destination. In a
quick test I did, it worked for both perceptual and colorimetric intents (I
assumed it would only work for perceptual rendering but I was wrong -
again!). This new gamut mapping option may help in your situation.
Subject: Re: RGB working space in PS
Todd Emory <email@hidden> wrote:
<>I'm considering Adobe98, but I have had other people tell me ColorMatch
<>is better. Opinions???
From: Henrik Holmegaard <email@hidden>
<You must have the colors on the input side which you wish to print on
<the output size. ColorMatch doesn't support colors which are
<printable on standard digital printing systems.
<ColorMatch is the size of a physically measured monitor space. A
<space this size can't supply the colors that you can print on an HP
<5000PS with CcMmYK inks and bright white Sihl 3909 / MPA J35 paper.
<For instance, printable saturated blues and cyans aren't supported.
<Look up the CHROMiX ColorThink 2beta20 QuickTime screenshots in the
<'Monitors' chapter of the soft-proofing cookbook on the ColorSync
<home page.
<Use an RGB working space such as Adobe RGB (1998) or better still
<eciRGB10. The reason eciRGB10 is preferable is that you can load that
<in ALL the tools from Adobe and know that you can define Y 100% on
<the press. This you cannot do with Adobe RGB (1998) which in other
<words doesn't function as a universal 'RGB PCS'. The eciRGB10 space
<was specifically developed to support the largest ISO offset space.
<Because eciRGB10 is D50 and not D65 like Adobe RGB (1998), it is not
<possible to convert RGB into CMYK with the effect that the blue white
<point is proofed in the separation. This effect is also shown in the
<color cookbook.
<You can pick up eciRGB10 on
http://www.eci.org see 'Profiles'. The
<space was developed by Karl Koch of Color Solutions. Anybody can
<recreate it anywhere because the Pshop settings required to do so are
<in the download documentation.
<Hope this helps.
I agree, that eciRGB is better than Adobe98 in those aspects Henrik
Holmegaard mentioned above, but still I see it to be little bit
overlarge and in a "wrong" angle or position for prepress work.
Problems in Adobe98 can be found mostly in saturated blues, greens
and yellowish turning reds plus sometimes greenish light yellows. All
these issues can be easily fixed when you know what you are looking
after, but it would be nice to work without any extra steps. So I
have made a couple of workingspaces to fix some problems (basically
for prepress-work) - maybe creating some new ones. I have tested them
and using them myself occasionally with good results (Adobe98 is
anyway kind of standard for daily work).
My experimental workinkspace is made by loading colors from
pressprofiles I know working well. It would have been enough only to
load colors from one press using stochastic raster and good paper
(same shape but larger gamut, than others have), but I wanted to have
all press colors surely inside. So it clips blues a lot, but it is
better not to have colors you can4t print anyway.
With this aproach you can get rid of "powerpoint blues" and get rich
and vibrant colours also from "artificial" colours (coming from
unknown workingspace or simply gamut stretching e.g.
sRGB-illustration by assigning new space). And for stochastic raster
with good paper Adobe98 is simply a little bit small in greens and
blues also for normal photograps.
My only concern is the clockwise "rotation" of my profile. Most the
other working spaces are in different "angle" than mine, because
their origin is monitor colours rather than press colours. Can you
see any problems with this?
I understand that most workingspaces are actually originating from
monitors, but is there some other reason to follow monitor lines?
Whitepoint is 5000k and gamma 2.2, bradford transform. Is there some
points to stick with 2.2 gamma, or would it be some other "better"
gamma point and why?
You can make workingspace yourself primaries are:
R 0,68960 0,31040
G 0,25242 0,68288
B 0,11244 0,11378
If somebody has time and interest to play with them, I would be glad
to here your comments. Profiles (and a couple gamut screenshots) can
be found in public folder on Apples iDisc, connect user "lseppala" or
I can e-mail them.
For evaluating RGB-spaces you can find testcharts on site: www.hutchcolor.com
Adobe98 is a kind of standard and easiest and safiest way to go now
in prepress, but surely not the best one for every situation.
Hopefully Adobe also some day includes some more choices with their
products.
The new ProfileMaker chroma+ algorithm works fine for output
profiles, but it don4t fix problems with blues IMO. Does somebody
know, what RGB space PM4 assumes as source, when perceptual tables
are calculated?
Regards
Lasse Seppdld
A-lehdet
Finland
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