Date   

Scanning Class information??

Dan Margulis <76270.1033@...>
 

This individual has previously taken my ACT course.

Dan Margulis

--------------- Forwarded Message ---------------

To: Dan Margulis, 76270,1033
Date: Mon, Oct 8, 2001, 3:24 PM

RE: Class information

Dear Dan,

Although I have been following all threads with interest, I don't
think this note would be of interest to the discussion group. Having never
posted anything anywhere online before (just shy I guess) I am working on
the assumption that this question is too specific for the group.

I have been seeking out a scanner operator class with no luck (all
that I found are on-site and product-specific classes). I did find one in
the UK but being on the west coast, that's a little further than I care to
travel. I have not seen any such course offered by Sterling-Ledet but am
assuming such information is available to them. I'm hoping for a more
general (if possible) class, and since I am not currently working,
"on-site" is not an option. Hopefully with a class of this type added to my
resume the dry market might dampen up.

Anyway, noticing a new thread in the discussion group as well as your
standing in the education field, I thought I might inquire as to your
knowledge of the availability of any such courses. Any information and/or
recommendations of such courses would be appreciated.

Regards,


Re: UCR vs GCR...or Neither - RAW CMYK?

Dan Margulis <76270.1033@...>
 

Dave Badger writes,

I have been using Photoshop's Medium Generation for a long time now
because
GCR is supposed to give you better saturation and depth in the darker
colors. I believe this to be true and think that, for example, cyan in reds
being replaced partially by black is a good thing.>>

I would think the opposite would be true. In principle the two results
should be the same. In practice, black is much stronger than cyan is, so
any variance in inking would create a color issue, especially since the
dominant magenta and yellow in the reds will have been reduced to
accommodate the black.

Using this setting means the black is more critical on press, so I would
think using UCR or Light GCR would be better for newsprint since their
black
plate would be less controlled or more dot gain.>>

Certainly inking generally is less in control in newspaper printing.
However, 1) the black ink used on newsprint isn't as powerful as in
commercial printing, therefore the impact of a density change isn't as
severe; 2) in commercial printing, if the black runs too heavily one of the
principal suspects always is that the pressman was attempting to compensate
for small type or type that is difficult to print because of thinness in
part of the strokes, such as Bodoni, Baskerville, or to a lesser extent,
Times Roman. Newspapers generally aren't subject to this effect because
their text face is invariably something like Excelsior or Ionic or Times
Europa that is specifically designed for legibility at the expense of
aesthetics.

So, while I'd agree with the general policy of using a skeleton black in
newspapers, I think there's more of a case for using a heavier black than
there is in other forms of offset.

This statement seems to indicate that people who use Photoshop's Medium
GCR setting are unsophisticated users. Yet you've said one form of UCR/GCR
is not necessarily better then another.>>

Those experienced in preparing images for CMYK, especially if the target is
a press, by and large certainly favor a lighter black than the Photoshop
default. One form of black generation isn't necessarily better, except in
an image-by-image context, and except in the context of how variable one
expectst the output device to be. A lot of the reasons for preferring a
lighter black vanish if the output is going to be inkjet rather than press.

Can you further explain why you favor a skeleton black and are there any
other downsides to GCR then those you listed above?>>

In addition to the issues mentioned earlier, the services of our friends in
the color management community become more important if you're using a
heavier black. Photoshop makes the wrong assumption that black has the same
dot gain as the other inks, whereas in real life it's usually higher. But
it's very much case by case, so a lot of users have incorrect black dot
gain values unless they've really gone to a lot of effort.

If you are using a skeleton black and your black dot gain value is too low,
this isn't great but it isn't a tragedy. If you're using a heavier black
that affects colored areas, you're really risking a muddy sep.

Dan Margulis


Re: Smooth Skin?

Lee Varis
 

APR wrote:

What's the best way to smooth skin on photos?
I've seen *those* web sites where the girls skin looks real smooth.
How do you do that? Is it bluring AB channels?
There are many ways to smooth out complexions but if there are real
physical skin features (not just noise) that need to be smoothed then
blurring the AB channels is not going to do it. One of my favorite
techniques is to make a duplicate layer and run the median or dust and
scratches filter on the new layer with enough of a radius to smooth out
any defects. Option-click on the layer mask icon at the bottom of the
layers pallet to create a black layer mask thus hiding the newly blurred
layer completely. Now you can paint into the layer mask with white using
a soft airbrush, smoothing just those areas that require it.

You'll probably need to add some noise to the blur layer to match the
underlying layer - a small amount in the blur image should be enough to
kill any banding artifacts from the median filter as well. If you have
areas of skin highlights that approach white you might want to add the
noise in an overlay layer. Create a new layer and enable the overlay
apply mode. Fill this layer with 50% gray and group it with the
underlying blur layer. Now run the noise filter on this gray layer.
Noise is applied to the underlying smooth skin but ramps off as the
values approach white and black so you get cleaner highlights and shadow areas.

--
regards,

Lee Varis
varis@...
888-964-0024
www.varis.com


Smooth skin?

John Opitz <jas10286@...>
 

<: Smooth Skin?
What's the best way to smooth skin on photos?
Is it bluring AB channels?

Hector Davila>

The Gaussian Blur Filter. Don't make selections to target skin
areas(doing that is like chasing rainbows amd setting traps for
unicorns). Do it to the whole image. Then take a snapshot of this
state. Next undo gaussian blur. Use the history brush in lighten and
darken modes(5-15% opac.) to paint back the areas you want to smooth.
Make sure you click on the snapshot(history state) to paint back from.


John Opitz


Re: UCR vs GCR

Ruud uit het Instituut
 

Oops, to fast..

I wrote
But PCR was in fact the same as the german definition 'unbunt' on the Hell
scanners or the American GCA (Gray Component Addition) and it's opponent
GCR.

Last thing was wrong,
GCR has nothing to do with GCA, it's the same as UCR, I shouldn't mention it
in that sentence.

Ruud de Korte


Re: UCR vs GCR

Ruud uit het Instituut
 

Dan Margulis wrote

We also fall victim to a terminology trap here--there's no real agreement
on what constitutes a "UCR" sep, other than that it's a subset of "GCR".

You're right. IMO the terminology went wrong when vendors started to make
their own definitions. I worked with the old Magnascanners from Crosfield.
There I could choose between UCR and PCR or a combination of those two.
UCR = Under Color Removal
PCR = Poly Color Removal
The difference between those two was that UCR was only active in the
neutrals and PCR in the colors.
But PCR was in fact the same as the german definition 'unbunt' on the Hell
scanners or the American GCA (Gray Component Addition) and it's opponent
GCR.

So UCR and GCR both mean the same and are active in the neutrals (the L axis
in Lab).
PCR, unbunt and GCA are also the same and use the combination of all three
axis in Lab.

Excuse my English, I seem to have a Dutch accent.

Ruud de Korte


Smooth Skin?

Hector Davila
 

What's the best way to smooth skin on photos?
I've seen *those* web sites where the girls skin looks real smooth.
How do you do that? Is it bluring AB channels?

Thanks
Hector Davila


Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)

Dan Margulis <76270.1033@...>
 

--------------- Forwarded Message ---------------

From: INTERNET:samarsh@...
To: Dan Margulis, 76270,1033
Date: Mon, Oct 8, 2001, 4:09 AM

RE: Scanner Training Advice (was: UCR vs GCR...or Neither - RAW CMYK?)

Dan, once again - thank you for your time and knowledge.

I am sending this mail to you off list - in case it is not appropriate
for the list. Please feel free to forward this to the ACT list if it is for

general consumption.

======

Dan writes:

Four years ago, in
reviewing the new Scitex line, I wrote:

"Basic scanning may be easy, but the exceptions are lethal.
Scitex's has
several sets of preset CMYK parameters for different printing
conditions--but, unbelievably, none for the most common of all,
SWOP. Users
can create these parameters for themselves--if they happen to
be one of the
twenty or so individuals on the planet capable of figuring out
Scitex's
exceedingly opaque implementation of black generation."
Dan, I have checked out the archives at Electronic Publishing for
EverSmat Supreme articles but found nothing with any 'meat'
and nothing written by you.

Do you have any links or archives of the reviews or articles you
have written on these scanners or related software (oXYgen)?

Now for the real question...

Our newish scanner still has some 'free' training that came with
it - that the main pre press guy did not need (experienced
scanner op). Lucky for me - I am being offered the short
CreoScitex training, which from all reports is worth a quite a bit of
money (if it did not come with the scanner).

I would like to make the best of this oportunity - but have not had
access to this type of training before.

I have no real high end scanning experience, but am comfortable
with a scanner, Photoshop and by the numbers workflows.

I was wondering if you and perhaps the list have any thoughts on
how I could maximise the training. I know many on this list attend
specific training or seminars - are there any tips from all those
people who have 'been there - done that'.

If this is a standard 'abc123' taining course - then there might not
be too much room to ask questions or to get into the deeper
aspects, which may be beyond the simple training session.

From what I have read on one old message list - the training is
focused on CMYK table or device link scanning, with the ICC and
DT/SOOM workflows pretty much ignored. As I am in pre press
for a traditional printer - this does not seem to be a problem (they
would probably ask for this anyway).

Any thoughts or links would be greatly appreciated. I have
considered posting this on the Scan-Hi End list - but I respect
the opinions of this list and will hold off on any cross posts until
the issue is well and dead.

Sincerely,

Stephen Marsh.


Re: UCR vs GCR - So RAW is really UCR...

samarsh@...
 

--- In colortheory@y..., Dan Margulis <76270.1033@c...> wrote:

There isn't any such animal. The scanner records R,G, and B
data which
becomes, with mild variation, C, M, and Y. The black data is
calculated
from the other three.
Thanks Dan. It was a shock to me to find that you could turn UCR
and GCR functions off for the CMYK conversion...I took the
setting at 'face value' (silly me).

Then I blew the dust off Macromedia xRes and it had similar
features.

As Photoshop is my major experience...I did not know what was
going on.

So I take it that you are saying that even though UCR is off - this
is still a UCR sep, just different to Photoshops flavour.

You gotta love CreoScitex - UCR/GCR off is still UCR. So there
must be a difference between the active UCR settings and the off
setting...perhaps one year I will have time to play and see.


No, this is traditional UCR, black only appearing where
necessary to
achieve darkness, not to hold neutrality.
What was throwing me was that there is no 'cross over' on the
gray ramp where the CMY and K plates interact in the
threequarter tones and shadow, as in Photoshop.

The scitex gray ramp looks so 'alien' when UCR/GCR is off...that
I thought that something else was going on. When these
functions are on, the ramps look closer to Photoshop - but they
have very different defaults with steeper curves etc.

Sure, and many others express their column width in pica
ems, or indicate
that they have 2% dot gain.
Chuckling...

Thank's for your time and thoughts Dan - as ever your words
leave me smiling.

Regards,

Stephen Marsh.


Re: UCR vs GCR...or Neither - RAW CMYK?

Dave Badger <dbadge@...>
 

on 10/6/01 3:00 PM, Dan Margulis wrote:

Dot gain and black generation are different animals. If you believe that an
image will correct or print better with a higher black component, that
decision would presumably the same on either 100# Kromekote or newsprint.
I have been using Photoshop's Medium Generation for a long time now because
GCR is supposed to give you better saturation and depth in the darker
colors. I believe this to be true and think that, for example, cyan in reds
being replaced partially by black is a good thing. Yet no black substitution
take place in lighter skin tones, so the start point of this setting seems
fine.

Using this setting means the black is more critical on press, so I would
think using UCR or Light GCR would be better for newsprint since their black
plate would be less controlled or more dot gain.

Printers who insist on one method or another generally are completely out
of touch. Right now, their clients can be divided into those who know what
they're doing, in which case they are probably using a skeleton black, and
those who don't, who are probably using the Photoshop default of a heavier
black. Yet from time to time both groups get good results.
This statement seems to indicate that people who use Photoshop's Medium GCR
setting are unsophisticated users. Yet you've said one form of UCR/GCR is
not necessarily better then another.

The same pluses and minuses apply: with a heavier black,
one risks muddier images, and they're harder to correct in Photoshop. OTOH
a heavier black will hold neutrality better, and also make it easier to
print the job in register, or rather make a misregistered job look more
acceptable.
Can you further explain why you favor a skeleton black and are there any
other downsides to GCR then those you listed above?


Dave Badger


Re: UCR vs GCR...or Neither - RAW CMYK?

Dan Margulis <76270.1033@...>
 

Stephen writes,

I use one of those expensive Scitex scanners you mention - and I would
have to agree with your take on their default tables black generation. I
have not been able to make a custom black generation curve in Photoshop
that even comes close.>>

The question is why you would want to. The whole point of variant black
generations is that theoretically the colors remain the same--in principle
Heavy GCR gives the same result in print as UCR. In practice it doesn't,
but the difference between Photoshop's Light GCR and Scitex's is going to
be very small in the overall scheme of things.

In part this is due to how hard the black generation curve is to edit -
and that Photoshop _only_ gives the option of UCR or GCR separation
methods.>>

*All* separations, saving those that are CMY only, are UCR or GCR.

The Scitex scanner in default CMYK tables settings scans into
CMYK with GCR and UCR turned OFF. You get 'raw' CMYK.>>

There isn't any such animal. The scanner records R,G, and B data which
becomes, with mild variation, C, M, and Y. The black data is calculated
from the other three--there are no CMYK-native scanners.

It seems that CMY are used throughout the image to describe neutral
tones. I guess this is similar to using GCR with no black generation.>>

No, this is traditional UCR, black only appearing where necessary to
achieve darkness, not to hold neutrality.

Now I use GCR light black or UCR most of the time, unless more black can
help (when doing Photoshop seps). This is very much an individual image and
output based decision - gone are the days when one setting suited all (now
that I know better). I have not reached this level on the scanner yet.>>

Your policy is a good one, but I doubt that it's worth worrying about
extending it to the scanner. When you run across something that needs a
nonstandard black, do it in Photoshop-it's a lot easier. Four years ago, in
reviewing the new Scitex line, I wrote:

"Basic scanning may be easy, but the exceptions are lethal. Scitex's has
several sets of preset CMYK parameters for different printing
conditions--but, unbelievably, none for the most common of all, SWOP. Users
can create these parameters for themselves--if they happen to be one of the
twenty or so individuals on the planet capable of figuring out Scitex's
exceedingly opaque implementation of black generation."

Dot gain is never explicitly mentioned in the scanner software.>>
Dot gain and black generation are different animals. If you believe that an
image will correct or print better with a higher black component, that
decision would presumably the same on either 100# Kromekote or newsprint.

But from what you are saying, knowing the amount of UCR or
GCR is pointless without knowing the black generation method,
as in the start point for black?>>

In order to conceptualize the kind of black that's being generated one
needs to know the start point of the black and the how the slope of the
curve varies. A percentage is only going to be relevant at one point on the
curve. In darker areas, the percentage of black will be higher and in
lighter areas it will be lower.

I thought that the use of the term 50% GCR was an old drum scanner or
traditional separation terminology.>>

It's sort of like the percentages used in the "Amount" field of the Unsharp
Mask filter or the dot gain percentage in CMYK setup. The user doesn't need
to know what the percentages mean, just that a higher percentage increases
the effect. Unlike these two, however, which *do* have meanings that an
interested user could find out, "50% GCR" is meaningless without further
explanation, except that it probably generates less black than 60% GCR.

Many printers still list this in their separation spec sheets - instead
of the more 'regular' or 'standard' Photoshop terminology. But just like
SWOP, they do not mention a start point
- only the amount of UCR or GCR.>>

Sure, and many others express their column width in pica ems, or indicate
that they have 2% dot gain.

Dan Margulis


Re: Profiles for digicams

Ron Bean <rbean@...>
 

Dan Margulis <76270.1033@...> writes:

[Re: Epson's "PIM" system]

I had a demo of this at Seybold Boston, but, when I asked the person giving
it (who otherwise seemed OK) whether this was an ICC-compatible profile, he
had no idea what that meant, so there may be some question as to whether
the following information is accurate.
After reading the PDF paper on their website, I think the person
who told me about it was also misinformed.
http://www.printimagematching.com/pdf/what_is_pim/pim_wp.pdf

This came up in a discussion about why the Minolta Dimage 7 comes
with profiles that don't work in Photoshop, thus forcing you to use
Minolta's software (which is, by all accounts, very poorly written).
But I don't think this has anything to do with it.

As nearly as I can understand, this is a proprietary system that has
nothing to do with ICC, but Epson claims that most of the camera
manufacturers are already on board. By some means or another, the camera
produces a mini-profile of what it is shooting, and hooks are attached that
the printer can grab onto on output. As far as I could determine this was
strictly an amateur thing, in that Photoshop could not access these hooks
itself.
I don't think it's really a profile. It uses the EXIF information
in the JPEG file, which includes things like shutter speed,
aperture, exposure compensation, and white balance setting, but
also program modes like "portrait", "landscape", etc which gives
it a clue about the subject.

Consumer digicams are supposed to output sRGB (more or less), but
consumer inkjet printers already have a larger gamut, so this is
some kind of attempt to use more of it. It is specifically aimed
at people who don't want to deal with a color-managed workflow,
and want a point-shoot-print solution that is (hopefully)
somewhat better than the usual drugstore prints from 35mm film.

If the JPEG from the camera is really sRGB, then the gamut is
inherently limited but they can probably fake it. The Minolta
Dimage 7 uses a non-standard colorspace, possibly for this
reason. But the implementation leaves something to be desired--
the consensus seems to be that it can make very good images, but
only if the photographer learns to work around it's quirky
design.


Re: UCR vs GCR...or Neither - RAW CMYK?

samarsh@...
 

Dan writes:

I suspect that the answer probably depends on how many
printers use
expensive scanners and scan directly into CMYK. If so, they're
almost
certainly going with the manufacturer's default, which is
ordinarily a
light black, UCR style, but Scitex products will produce a darker
black
than Screen products which in turn produce a darker black
than anything
from Heidelberg/Linotype/Hell. If they're using Photoshop to
make the seps,
odds are that they're going with a heavier GCR, because most
printers don't
know much about the topic--the knowledge, if anywhere, is in
prepress, and
it's fairly rare there.
Dan, this is a good opening for bringing up a subject which has
been bugging me for a while.

I use one of those expensive Scitex scanners you mention - and I
would have to agree with your take on their default tables black
generation. I have not been able to make a custom black
generation curve in Photoshop that even comes close.

In part this is due to how hard the black generation curve is to
edit - and that Photoshop _only_ gives the option of UCR or GCR
separation methods.

To mimick the defualt scanner sep, I would need to make two
Photoshop conversions, one using CMY only and another to
make a custom black plate to plug into the CMY file!

The Scitex scanner in default CMYK tables settings scans into
CMYK with GCR and UCR turned OFF. You get 'raw' CMYK.

By evaluating the separation setup curves in the scanner for the
off setting - one can get a basic understanding of the process.

It seems that CMY are used throughout the image to describe
neutral tones. I guess this is similar to using GCR with no black
generation. This is the closest description to the CMY behaviour
that I can come up with, and is not a good example.

Black curve seems to start at around 40% and seems irrelevant
to the 'linear' neutral CMY curve (where cyan is run higher).

Shadow aimpoints are very high in all four colours, often
delivering TAC of 360%.

This is out of my 'desktop' experience and must be a throwback
to more traditional scanning or separation. This 'raw' CMYK is
very different to Photoshops UCR or GCR separations.

Basically - there seems to be no way to make the built in settings
of Photoshop behave in a similar way - since UCR or GCR is
always in use for a separation.

Now back to UCR or GCR.

The Scitex software does use the % term for GCR. There is no
mention of none, light, medium, heavy or maximum black
generation - as in Photoshop.

As a side note - my 'antique' copy of Macromedia xRes had a
similar approach.

The conversion from RGB to CMYK was 'raw'. After the file was in
CMYK, then the UCR/GCR command was run...you could even
apply this command to a CMYK file created in other software.

A dialog box was presented with the choice of UCR or GCR and
their related controls, including start point for the grey
component, black limit, TAC and percent of UCR or GCR (with
UCA as an option as well).

All this was applied as a post separation move - instead of
during separation...which seems weird to my Photoshop
experience, but it may have some uses. I have not kicked these
options around much - since xRes gathers actual and virtual
dust.

As for your comment on the knowledge being is pre press, and
that it is usually lacking - I have to agree.

Before reading your works, I used GCR med black generation as
a general rule - but did experiment with light black generation.

Now I use GCR light black or UCR most of the time, unless
more black can help (when doing Photoshop seps). This is very
much an individual image and output based decision - gone are
the days when one setting suited all (now that I know better). I
have not reached this level on the scanner yet.

But most users that I have seen use GCR Med and the other
defaults in Photoshops built in settings as a standard - if they
are not using a profile such as SWOP v2 or US Flatsheet v2 etc.

Rather than just use the Photoshop terminology, here's
what they have to say:

"Current recommendations suggest that a safe range of GCR
to use is between
30% and 60%. A 50% GCR setting removes 50% of the gray
component normally
produced by the chromatic color and compensates by adding
an equivalent
amount of black."

This naive description is roughly equivalent to me telling you
that I would
like to meet you at 2 p.m. today on the corner of First and Main,
without
telling you in what city. Any sane method of GCR will use a
relatively low
percentage of black in light greys and a relatively high one in
darker
greys. The SWOP definition is meaningless, worthless. And if
SWOP doesn't
know what it's talking about, how can we expect the individual
web printers
to?
Well, if using xRes then I guess I would enter 50% as the
percentage of UCR or GCR - with a start point of around 25%. It
seems that xRes does work this way - there are no light,
medium, heavy or max options.

The same for my Scitex separation method - if GCR is chosen
then you have no choice but to enter a percentage value for UCR
or GCR, and a black start point %, black limits, TAC etc.

Dot gain is never explicityly mentioned in the scanner software.

But since xRes is history, then the question is a lot harder for
Photoshop - which does not use these terms. Instead we have
UCR, or GCR - none (cmy) light, med, heavy and max black
generation.

But from what you are saying, knowing the amount of UCR or
GCR is pointless without knowing the black generation method,
as in the start point for black?

I take it that the black start point in more traditional separation
software is what Photoshops named black generation settings
do, or perhaps the custom black generation curve option?

I thought that the use of the term 50% GCR was an old drum
scanner or traditional separation terminology. Since I entered
pre press through typesetting - I just presumed that this was a
gap in my knowledge, that would have been covered if I originally
trained in repro instead of type.

Many printers still list this in their separation spec sheets -
instead of the more 'regular' or 'standard' Photoshop
terminology. But just like SWOP, they do not mention a start point
- only the amount of UCR or GCR.

As for the original post - I work for an Australian commercial
printer and we will take pretty much any separation you can throw
at us (for good coated stock). We use CTP and only have one
four colour flatsheet litho press - so things are pretty tight in
process control. Before working here, I would have considered
the seps we produce mud - but everyone seems happy...

I am glad that I am not the only one having problems
understanding all this...I thought it was just me. <g>

Regards,

Stephen Marsh.


Re: UCR vs GCR

Dan Margulis <76270.1033@...>
 

Gordo writes,

What about % of usage rather than how it is done?>>
I doubt that anyone has reliable information on this. You may in fact be
the first person in the history of the world who has ever asked this
question.

What percentage of US sheetfed printers use UCR for their separations as
opposed to GCR?>>

In the US I don't even know what the percentage would be of printers who do
their own seps. I would guess that this might be higher for sheetfed than
for web.

We also fall victim to a terminology trap here--there's no real agreement
on what constitutes a "UCR" sep, other than that it's a subset of "GCR". I
usually employ what Photoshop calls "Light GCR", but if pressed, I would
describe this as being a "skeleton black", not "GCR". Other people might
disagree.

I suspect that the answer probably depends on how many printers use
expensive scanners and scan directly into CMYK. If so, they're almost
certainly going with the manufacturer's default, which is ordinarily a
light black, UCR style, but Scitex products will produce a darker black
than Screen products which in turn produce a darker black than anything
from Heidelberg/Linotype/Hell. If they're using Photoshop to make the seps,
odds are that they're going with a heavier GCR, because most printers don't
know much about the topic--the knowledge, if anywhere, is in prepress, and
it's fairly rare there.

What percentage of US web publication printers use UCR for their
separations as opposed to GCR?>>

Probably the most telling point here is that SWOP itself, the nominal
standard-setting organization for publication printing, is close to
clueless about GCR. Rather than just use the Photoshop terminology, here's
what they have to say:

"Current recommendations suggest that a safe range of GCR to use is between
30% and 60%. A 50% GCR setting removes 50% of the gray component normally
produced by the chromatic color and compensates by adding an equivalent
amount of black."

This naive description is roughly equivalent to me telling you that I would
like to meet you at 2 p.m. today on the corner of First and Main, without
telling you in what city. Any sane method of GCR will use a relatively low
percentage of black in light grays and a relatively high one in darker
grays. The SWOP definition is meaningless, worthless. And if SWOP doesn't
know what it's talking about, how can we expect the individual web printers
to?

Dan Margulis


Re: 16 bit challenge

gowens01GO@...
 

--- In colortheory@y..., Jan Steinman <Jan@B...> wrote:
From: gowens01GO@n...

The lab let me know the frame was damaged
by making a 4x6 print...

So I thought I might as well make 8bit/16bit files... on my Sprintscan which is
supposed to scan at 10 bits.
My gut feeling is that a scan from a print isn't going to be a good test, since the dynamic range has been compressed to 1.8 or so.
Hi Jan,

Just wanted to say that my scan was from the negative not a print. I
let the scanner remove the color cast and then I did a eyedropper color
balance. The $1800 cost of my scanner out weighs the cost of getting
drum scans on a regular basis.

The biggest drawback I see to using 16 bit is the doubling of the file
size. For a small business like myself that extra storage cost would be
prohibitive. But that doesn't mean 16 bit should not be used. but
rather one must know when and how to use it to advantage.

Gary Owens


Re: More Seybold Information

hjswim2@...
 

Dan: < For those who are interested in more information about Seybold, with
an emphasis on large-format digital printers, list member Harald Johnson has
put together an extensive report, which I have read and recommend. For those
who are interested, it is at
http://www.geocities.com/hjswim56/seybold_sf01/index.html >

Thanks for the nice review, Dan.

FYI, Yahoo just sent me a notice that I've "exceeded my allotted amount of
data transfer we provide for a free website... we had to temporarily turn
your site off to keep the bandwidth within this limit." So if you get a busy
signal, try again later.

I guess I'm going to have to finally get a *real* website ;-)

Harald Johnson


More Seybold Information

Dan Margulis <76270.1033@...>
 

For those who are interested in more information about Seybold, with an
emphasis on large-format digital printers, list member Harald Johnson has
put together an extensive report, which I have read and recommend. For
those who are interested, it is at

http://www.geocities.com/hjswim56/seybold_sf01/index.html

Dan Margulis


Re: UCR vs GCR

Gordon Pritchard <gordon_pritchard@...>
 

What about % of usage rather than how it is done?

What percentage of US sheetfed printers use UCR for their separations as
opposed to GCR?

What percentage of US web publication printers use UCR for their separations
as opposed to GCR?

How does that usage compare to Europe and Asia?

thx


Gordon Pritchard
Commercial Print Specialist
CreoScitex
Vancouver Canada
T: 604.451.2700 ext 2870
C: 604.351.2437
gordon_pritchard@...
http://www.creoscitex.com

Print - dot's what it's about!<
----------
From: Dan Margulis
Sent: Thursday, October 4, 2001 5:22 AM
To: Color Theory
Subject: [colortheory] UCR vs GCR

Gordo writes,

I would like feedback on forum member's understanding of how color
separations are done in Europe, America, and Asia. I have been told that
the following are representative numbers:>>

From what I've seen there's little difference in black generation practice
internationally. The same pluses and minuses apply: with a heavier black,
one risks muddier images, and they're harder to correct in Photoshop. OTOH
a heavier black will hold neutrality better, and also make it easier to
print the job in register, or rather make a misregistered job look more
acceptable.

Photoshop's "UCR" setting produces a lighter, higher-contrast black than
its "Light GCR", but for printing purposes I think there is little
practical difference. "Medium" or "Heavy" GCR would change the process, in
some ways for better and in some ways for worse.

Although there are some people who swear by one method or another, the
truth is that it doesn't make that much overall difference *unless* one is
making decisions image-by-image, in which case it can be a big deal.

Printers who insist on one method or another generally are completely out
of touch. Right now, their clients can be divided into those who know what
they're doing, in which case they are probably using a skeleton black, and
those who don't, who are probably using the Photoshop default of a heavier
black. Yet from time to time both groups get good results.

in Europe
- Newspaper printers use GCR of about 240>>

The 240 is a total ink limit, having nothing to do with one's GCR
decision.
240 is also pretty standard in the U.S. Because newspaper black isn't as
rich as elsewhere, and because registration problems are common in
newspapers, there is a school of thought that believes in relatively heavy
GCR, although I don't think it's the majority.

- Rotogravure use primaraly UCR of about 310 (might also be GCR)>>
That 310 should be a *minimum*, not maximum shadow. There is no upper ink
limit in gravure. A very light black is certainly traditional in gravure
but I don't really understand why. The two main drawbacks to using more
black in offset don't apply. Large solid or semi-solid inked areas don't
automatically create higher densities elsewhere, as they do in offset.
Also, a major cause of excessive black inking in offset is a desire to
make
the type more readable. In gravure, which is ordinarily CMYKK, that
objection doesn't apply because the type is on a separate cylinder from
the
images.

- Commercial web offset use primaraly UCR of about 310>>
310 is a reasonable limit although somewhat higher than in the United
States. Again, the more knowledgeable users are generally using a light
black but they're probably not in the majority.

- sheetfed offset: usually no GCR>>
Here is the only area where I think there may be a difference. A lot of
European printing features an *extremely* short black. If you have access
to any Heidelberg software for separating, you'll see an example. Shadow
value in such a method is likely to be on the order of 98c88m88y65k,
whereas in the U.S. you'd be more likely to encounter 85c75m75y80k.

Dan Margulis


To unsubscribe from this group, send an email to:
colortheory-unsubscribe@...



Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/



Re: 16 bit challenge

Jan Steinman <Jan@...>
 

From: gowens01GO@...

The lab let me know the frame was damaged
by making a 4x6 print...

So I thought I might as well make 8bit/16bit files... on my Sprintscan which is
supposed to scan at 10 bits.
My gut feeling is that a scan from a print isn't going to be a good test, since the dynamic range has been compressed to 1.8 or so.

Although many CCD scanner manufacturers claim a certain number of bits, unless the CCD is cooled (beau coup bux), you probably aren't getting 10 *useful* bits out of it -- the last bit or two is probably mostly noise. (Most CCD sensors have a room-temperature range of about 26 db, which is about 8.5 bits of information.)

Also because of the high noise floor, most CCD scanners don't bother with log amplifiers, which can spread a small dynamic range over a greater number of bits.

The scanner may still deliver 10 bits, but spreading out the middle third of the CCDs range over 10 bits is like blowing up a tiny JPEG into a poster -- it's just making up the information, NOT retrieving anything new from the source material.

I appreciate Gary's offer, but I think a proper test will require a raw drum scan of a transparency.
--
: Jan Steinman <mailto:Jan@...>
: Bytesmiths <http://www.Bytesmiths.com>
: 19280 Rydman Court, West Linn, OR 97068, 503.635.3229


Live Picture

Jan Steinman <Jan@...>
 

From: Dennis Dunbar <dennis@...>

some hue
shifts seem smoother in 16 bit mode, but all of these I have done in
Live Picture, not PhotoShop...

I tried lots of
ideas to get the right color in PS, but easily accomplished it in LP...

Perhaps it's just LP's advantage...
Is LivePicture still kicking? Has someone picked it up and groomed it? Is there anything newer than 2.6.1 (the latest version I have)?

For doing HUGE images, LP couldn't be beat, but cheap RAM put a nail in that coffin. However, I still work with 1.5GB images (4"x5" film drum-scanned at 5,400 spi) and Photoshop pages, pages, pages, even with 2GB in the computer. (Adobe, we're all still waiting for a MacOS X native version...)
--
: Jan Steinman <mailto:Jan@...>
: Bytesmiths <http://www.Bytesmiths.com>
: 19280 Rydman Court, West Linn, OR 97068, 503.635.3229