Digital BW, The Print

In a message dated 12/7/06 7:41:26 AM, mtoledo@... writes:


> 
> or the epson driver will bypass the ICC when ABW is used?
> 

You can print through an ICC profile to AWB if you configure things that way, 
but the only effect it will have is on the linearity (what areas print what 
darkness of gray), not other factors, such as tint or tone.

C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com


[Non-text portions of this message have been removed]

Yes, that's what I was expecting. 

However, after my initial results I reconsidered. I think that, when
using ABW, the epson driver will still apply whatever color (or
greyscale) correction is appropiate for the selected paper. If this is
the case, selecting an ICC will cause two corrections to be applied on
top of each other. Since the ICC was not designed to be used in this
way, this would not work well in general.  

So to linearize the output one must either (1) play with the ABW
settings, (2) create a PS adjustment curve, or (3) create a custom
profile based on the output obtained using the ABW. 

Right?

Thanks!

Manuel 

 

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, CDTobie@... wrote:
>
> 
> In a message dated 12/7/06 7:41:26 AM, mtoledo@... writes:
> 
> 
> > 
> > or the epson driver will bypass the ICC when ABW is used?
> > 
> 
> You can print through an ICC profile to AWB if you configure things
that way, 
> but the only effect it will have is on the linearity (what areas
print what 

> darkness of gray), not other factors, such as tint or tone.
> 
> C. David Tobie
> Product Technology Manager
> ColorVision Business Unit
> Datacolor Inc.
> CDTobie@...
> www.colorvision.com
> 
> 
> [Non-text portions of this message have been removed]
>

No.  (1) can bring about changes in the luminance ramp but frankly you don¹t
need to if you profile it well enough.  A linear device is good essentially
because profiles ultimately can¹t capture every possible stimulus-response
pair and at some point interpolation is needed.  If a device is linear in
its response then it¹s easier to interpolate.  The only time I would play
with the luminance controls in the driver is if I thought it would help
profiling.  The driver is a very inefficient editor of images.  (2) is just
luminance management in another form.  B&W ICC  profiles are simply transfer
curves in an ICC profile wrapper.  The issue with using a curve is that it¹s
a bit hit or miss, or if you use them properly and utilise measured
stimulus-response behaviour then you are simply ICC profiling manually.  The
issue with doing things manually is you need to know how to scale the data
for white point and black point etc, and frankly it¹s a painful exercise
prone to error.  You have a densitometer or spectrophotometer so why not let
it do the walking.  (3) is the right way to go, profile the Adv B&W driver
properly as use that profile to convert your image on the fly in PS before
the image hits the driver.  The problem is that conventional profiling
software doesn¹t work well with Adv B&W.  Try printing and reading a target
that the profiling software needs and you¹ll just get a bunch of errors
because it is expecting to read colour.  QTR Create ICC solves this problem
and creates B&W ICC profiles for B&W use.  It automates the process of
reading printed responses to a range of stimulus and converting that data
into the appropriate transfer curve for good output.  PS has a function that
does this also.  You can set up a transfer curve and save the result as an
ICC profile.  BUT, you have to enter the points manually, which means you
have to scale your measurements for paper white and ink black manually
before entering them, and your constrained heavily in the number of
observations from which you can create the curve.  You also don¹t have the
benefit of colour soft proofing from the generated file.  All in all a
rather weak contribution in comparison to what Roy has made with QTR Create
ICC.  Don¹t print without it.

From: Manuel Toledo Quinones <mtoledo@....edu>
  

So to linearize the output one must either (1) play with the ABW
settings, (2) create a PS adjustment curve, or (3) create a custom
profile based on the output obtained using the ABW.

Right?




[Non-text portions of this message have been removed]