Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, CDTobie@a... wrote:
>
> In a message dated 1/14/06 12:04:03 PM, koloshor@y... 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.

Nice waffle, but you know what I meant.

> > 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.

Man, you are rude and sarcastic. But I'll try to address your points
more prefessionally than you're addressing mine.

> 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.

Yes, it's quite emperical. Because you're not reading enough colors,
you can have two metameres, colors that appear identical to both a
human eye and a "laboratory-grade" spectro, that will not map to the
same LAB values when converting from your 6 space to LAB 3 space. But
you already knew this. 
 
> The Datacolor 1005 fairs amazingly well in such tests.

Which tests would those be? Have you got some numbers to share, other
than "amazingly well"? Something like the papers that Color Savvy
presented about their eight color system?

> > 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...

No, hard fact, based on my own testing with 4, 6, 8, 10, and 12 color
LED based systems, including ones that used 12 LEDs for the
illuminants and a three band detector to check for fluorescence.
 
> > 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. 

I'd hazard that you would get a close grouping from the Pulse and
Eye-One and both the PrintFIX scanner and PrintFIX pro would be outliers.
 
> > 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.

I will, as soon as I have access to one.