Digital BW, The Print

In a message dated 1/14/06 12:04:03 PM, koloshor@... writes:


> Most excellent information. I was looking for some data on this,
> mainly the number of LEDs and their colors. You've at least given me
> the number.
> 
> Hard to believe it's six. Not 16, not even 12.
> 
Its 18 actually, but in sets of three, so there are six discreet colors of 
LED.
> 
> There's controversy in grating or prism based spectros over whether
> you need 31 bands to properly measure color (like SpectroLino or
> DPT-41), or if 16 bands and some interpolation (like Eye-One and
> Pulse) but one thing eveyone can agree on, is that 6 narrowband colors
> is definitely not enough.
> 
Enough for what? For printer profiling its all about measuring Lab values of 
printed color patches, not how many angels can dance on the head of a pin. So 
you take a laboratory-grade spectro as a standard, and you measure 
representative materials with the affordable, available devices, and you see what the 
resulting Lab values look like. No theorizing required, its an empirical issue. 
The Datacolor 1005 fairs amazingly well in such tests.
> 
> I'd put 6 narrow band colors up against 3 good colormetric filters (as
> in a digital camera based solution) and expect the 6 narrow band
> filters to lose, every single time.
> 
More theorizing...
> 
> The only way a system like this approaches workability is if the
> people who created the system use it to make profiles of multiple
> paper/ink combinations using a better (read "somebody else's")
> spectro, then use their "limited" spectro only to adjust these
> profiles to minor variations in a particular user's printer. As far as
> I can tell, this is what the origional (scanner based) printfix did,
> to such a degree that you could only use it to "profile" a small
> assortment of ink and paper combinations.
> 
PrintFIX used an RGB scanner to read patches. PrintFIX PRO uses an LED 
Spectrocolorimeter. Comparing the Lab values from the the Datacolor 1005 in PrintFIX 
PRO to the values from the PrintFIX scanner, and to a Pulse or EyeOne, would 
give you three closely grouped results, and a distant outlier. 
> 
> For B7W use, a definite weakness of LED based narrowband systems is in
> their ability to judge neutrality.
> 
> I'd suggest you measure some neutrals with a 1005 unit and decide what you 
think of it, rather than damning it sight unseen for an entire class of uses.

C. David Tobie
Product Technology Manager
ColorVision, Inc.
CDTobie@...
www.colorvision.com



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