Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., "Editor P.O.V. Image Service" 
<editor@p...> wrote:
snip
> This was the problem I think... On the one hand.. we are speaking 
> greyscale.. you have been speaking RGB,
No, I'm not. Again, four channels, four. Printed through a four channel 
driver, to four inks.
Sorry Keith, you're still not grasping what's happenning in a partioned 
quad ink four channel file. But really, none of us actually need to.

> Remember that we are starting with a file with only 256 levels anyway.. 
Not really, Austin was quoting Jon's statement about Piezo from a 16 
bit file, far more than 256 levels.

>  So those transitional levels are going to be pseudo-values or 
> interpolations of a sort..
nope.
Anyway, I'm done with this. But perhaps those who find this stuff 
fascinating may enjoy the following info from Bruce Linbloom, this is 
quoted from him, not about quads, but of interest.
Tyler


Note that any 16-bit image saved out of Photoshop will have, at a 
maximum, 32769 unique levels per channel, not 65536 as one might 
expect.  This is a 
limitation of Photoshop's internal architecture.  A true 16-bit image 
may therefore lose levels and number of unique colors simply by opening 
and saving 
with Photoshop.  The limited Photoshop style 16-bit encoding is 
detected and reported by Levels.  Another subtle, but interesting 
variant is that opening and 
saving can change the actual pixel values without reducing the number 
of levels or the number of unique colors.  An example of this would be 
a raw, 14-bit 
image from a BetterLight scanback.  There will be the same number of 
unique levels and colors both before and after Photoshop, but the pixel 
values in the 
saved file will be a little different from those of the original.

Note that converting from 16-bits to 8-bits in Photoshop adds noise to 
the image.  This may affect the number of levels and/or unique colors 
in the 8-bit 
image.  For example, if you start with a 16-bit image having all its 
pixels set to the same color, and then convert it to 8-bits, you may 
find that the 8-bit image 
has more than one unique color.

Note that passing an 8-bit image through profiles or mode changes in 
Photoshop causes noise to be added to the image, thus increasing the 
number of levels 
and/or unique colors.  This behavior may be controlled with the Color 
Settings setup,  in Advanced Mode, "Use dither (8-bit/channel images)".  
For example, 
if you start with an 8-bit RGB image having all its pixels set to the 
same color, and then convert it to CMYK, you may find that the CMYK 
image has more 
than one unique color.