Digital BW, The Print

Hi Bill

Thanks for popping in.  I think we are talking here about things at a finer
level of detail.  The BIG issue with B&W printing today is that colour
management doesn't work to our satisfaction.  Hence we have for now
discarded it.  Boy, it would be easier if we didn't have to!  Here we are
talking about the finer points of how and to what extent do we want to align
(because we don't have a system for managing difference) our workspace and
print space, and how do we measure whether we have been successful.  (We
were also debating the somewhat side issue of just what those spaces should
be but I think we have settled on LAB as a good enough place for now.) I
think we agree that a linearized printer is best but we are discussing
"linearized in what fashion?".  The software we have is VERY tweakable and
so allows the debate.

Cheers

Steve




> From: <BKPhoto@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 8 Dec 2004 17:06:28 EST
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] Re: Tonal range and linearization
> 
> 
> Steve, et al:
> 
> I've been following this thread and enjoyed the exchange of information. I
> have a few comments that, I believe, correspond to a few of things Tyler has
> been talking about. I’ll keep this as short as possible.
> 
> On the desktop we use software to control the behavior of hardware. With
> displays, for example, the machine is calibrated to known standards and a
> profile 
> is then built that describes the color gamut and gamma of the device. Inkjet
> printers are linearized and although calibration and linearization perform
> similar functions, for their respective devices, they aren't the same thing.
> Displays aren't linearized. The calibration includes a gamma setting.
> 
> All image devices used in the digital darkroom—cameras, scanners, displays
> and, most important to this discussion, inkjet printers—include a gamma
> setting. 
> As do analog film and printing paper. Gamma is built into imaging systems to
> account for human vision, which is anything but linear. In fact, you can think
> of gamma as an attempt to objectify our subjective experience of the world
> (which explains, in part, why we have different gamma settings to choose from
> in 
> the digital domain).
> 
> Linearization controls the amount of ink used in each ink channel. The basic
> idea is to accurately map the image file information, including whatever gamma
> you've selected, to the printed surface. One of the issues with current OEM
> print drivers, which cannot be linearized, is that the image file gamma has to
> be mapped to the driver gamma bias. People like Paul Roark have done an
> amazing job of working through this issue.
> 
> With good software, linearization can be tweaked when necessary or desired
> (it just depends on how far you want to crack open the "black box"). Printer
> driver software, OEM or RIP, doesn't "care" what color space or profile is
> attached to an image file. It does care what gamma the image represents. It
> exists 
> to manage the hardware functions of the machine and translate pixel
> information 
> into droplets of ink.
> 
> Years ago, Kodak developed a methodology for mapping image density to code
> values, called the "Jones Plot". It addresses the issue of how image
> information 
> is translated from one form into another. It’s useful to us because there
> are, in fact, significant semantic issues currently at play in the digital
> darkroom. In time, these issues will resolve themselves (talking about the
> translation of image information is a little like talking about resolution,
> where the 
> same terminology is used to describe different things).
> 
> Long story short (Ha!): if possible, it is best to work with a linearized
> inkjet printer. If a system is properly color managed you should be able to
> work 
> with any conventional gamma setting offered through Photoshop's working modes
> (or build your own, including any variation of the LAB model) and produce
> prints that appropriately match the image on the display.
> 
> 
> Bill Kennedy
> Associate Professor of Photocommunications
> St. Edward's University
> 512/448-8680
> 
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
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