Digital BW, The Print

Well Said. Thanks!
--- Steve Kale <stevekale@...> wrote:

> I think two very different issues are getting
> bundled into this one topic.
> The differences between them are very important to
> understand. The first is
> whether having a good monitor profile (and proper
> colour management
> settings) is important or not.  The second is the
> fact that the print space
> is very different from the displayed workspace.  I
> regard the first as
> important and would urge that what I would call
> "dumbing down" the monitor -
> deliberately moving it away from a well-profiled
> state - is not a wise
> course of action, particularly if it results from a
> lack of understanding of
> the second. 
> 
> But the biggest issue in this discussion is that the
> print space is a lot
> narrower than the displayed workspace.  We can
> display better black and
> brighter white than we can print - on a
> well-profiled monitor or not so
> well-profiled.  Understanding this is useful.  How
> the workspace and print
> space map to each other are quantifiable - at least
> for those that are
> creating the print spaces (those that write QTR
> curves, IJC curves or RGB
> curves such as Paul's).  If that mapping is
> quantified and then made
> available with the curves then the vast majority of
> the monitor vs print
> issue will likely disappear.  Any residual mismatch
> will in very large part
> only be due to poor monitor profiling.
> 
> It's worth winding back a little to how QTR - Gray
> Lab and QTR - Gray Matte
> Paper and QTR - Gray Photo Paper came about, and
> even before.  Quite some
> time ago there was a discussion as to what the right
> "linearization" in RIP
> printing was and it was generally agreed than a
> sensible practice in RIP
> development was to linearize the printer such that
> Lab's L(uminance)
> readings were linear, ie that in stepping from paper
> white to ink black the
> progression in L would be uniform and linear.  There
> was then a lengthy
> discussion about how we typically worked in Gray
> Gamma 2.2 but the print
> space was linear L from paper white to ink black
> and, importantly we were
> using a Same as Source workflow (meaning there was
> no translation mechanism
> in going from the image workspace to the print
> space).  Given we are using
> Same as Source, the closer the two are aligned the
> better and hence the
> discussion of editing in Lab (rather than Gray Gamma
> 2.2) and Roy's
> derivation of Lab without the a and b channels:  QTR
> - Gray Lab.
> 
> But is is easy to see that even with an image in Lab
> or QTR - Gray Lab there
> is still a marked difference between the workspace
> and the print space for,
> say, matte paper.  Take a piece of paper and draw a
> chart with L on the
> vertical axis and normalised pixel value 0-100 on
> the x-axis. (By normalised
> I mean that whether the image is recorded in 8 bit
> or 16 bit the scale has
> been normalised to 0-100.)  If we were to plot L
> values for Lab or QTR -
> Gray Lab the line would go from (0,0) to (100,100),
> ie from pure black/L=0
> to pure white/L=100.  Now write "darker than Lab" in
> the area below the line
> and "lighter than Lab" in the area above the line. 
> QTR or IJC have implicit
> in their curve creation a linear progression of L
> from paper white to ink
> black, as noted above. But if paper white is L=96
> rather than 100 and ink
> black is L=16 rather than zero we have a very
> different profile than the Lab
> workspace.  Plot the line from (0,16) to (100,96). 
> From the chart it is
> easy to see that the vast majority of images would,
> in these circumstances,
> print lighter than displayed on screen. We would
> also note that they would
> appear flat - the slope of the line is much flatter
> than the Lab line:
> there was reduced gamma and reduced dynamic range. 
> Therefore we still faced
> two issues.  Firstly, the images would still not
> print as they were
> displayed.  Secondly, the linear mapping of images
> to the print space would
> produce "flat" images.  Dealing with previewing the
> image as it would print
> is actually the easy part.  A simple PS curve can
> depict the print space
> quite easily (using the % scale shift the white
> point to (0%,4%) and the
> black point down to (100%,84%) and leave the line
> straight in the middle).
> Carl Schofield also developed a way to use an Eye
> One to generate an ICC
> profile-based soft proof. The more difficult issue
> was to remap on a more
> satisfactory basis (not one-to-one mapping) from the
> workspace to the
> narrower print space and produce a more visually
> pleasing print.  This was
> the big step forward that Roy took in providing us
> all with the Matte Paper
> and Photo Paper ICC profiles.  Now we can use PS's
> colour engine with
> Perceptual Intent to map from the workspace to the
> print space and produce a
> more visually pleasing print in the narrower space. 
> In fact, it does away
> with the need for working in Lab or Gray Lab, we can
> stay in Gray Gamma 2.2
> if we so please because we have an engine for moving
> from the workspace to
> the colour space - we are no longer using a Same as
> Source workflow.  The
> second advantage this gave was that since the
> mapping uses an ICC profile we
> can use PS's soft proofing features for an accurate
> preview of the printed
> image.  In other words, we dealt with the second leg
> of issue I noted in my
> first paragraph.  Any other residual mismatch
> between screen and print is a
> technical problem associated with either a poor
> monitor profile or some
> mismatch between the generic profile provided by Roy
> and any
> printer/ink/paper specific issues.  The success of
> the generic profile is
> indicative of the fact that my second issue leg is
> the critical one, much
> less so the first.
> 
> Now there remains the issue of those workflows that
> remain Same as Source.
> Quite understandably Paul's workflow and the BO
> workflow are still grappling
> with the "matching monitor to the print issue".  Not
> only might they have to
> deal with poor monitor profiles but they still
> haven't provided a solution
> to the second larger issue of providing a mechanism
> for previewing the
> mapping from workspace to print space.  I would
> suggest that this is
> actually easy to do and can be readily provided to
> others using those
> workflows who do not have access to the equipment
> necessary to do it.  I
> would also suggest that focus be given just to the
> larger, second of the two
> issues I noted.  How to do this?  There are two
> methods that come
> immediately to mind.  One requires a densimeter only
> while the second
> requires an Eye One Photo.  Remember I am not
> suggesting that everyone needs
> access to one of these - just those developing the
> curves for that workflow.
> Let's use Paul's workflow as an example. If he had
> access to an Eye One, for
> example, for each of his developed curves (eg
> 2200-UT7-EEM-Neutral) he could
> follow Carl Schofield's soft proofing technique and
> provided with each curve
> an ICC soft proof profile which could be used while
> working up an image.
> (Note, Paul doesn't face the issue faced by QTR and
> IJC on how to map from a
> linear workspace to a narrower linear print space -
> he maps this by hand as
> part of developing his curves.  He simply faces the
> issue of portraying this
> on screen.) Someone with access to an Eye One could
> also provide a BO 1.8
> and BO 2.2 ICC profile for a printer/paper/ink
> combination. Alternatively,
> if, say, Paul does not have an Eye One and so can't
> take advantage of Carl's
> soft proof technique or can't find a similar
> technique that works with his
> 
=== message truncated ===



		
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