Re: Off Topic: Which colorspace to use

[CDTobie@aol.com]

In a message dated 10/12/99 9:58:35 PM, miller.abel@solopoint.com writes:

>I assume that representing the tonal response of these photoprinters of
>
>which you speak (e.g. LightJet, Fuji, Lambda, etc.) must require greater
>
>than 8-bits per channel? If not, wouldn't any space larger than 24-bit
>True
>
>Color be wasted?
>
>
>
>And since, without adding bits to each channel, you can't pay Paul without
>
>robbing Peter, more purple (for example) must mean tonal resolution was
>
>"stolen" from complimentary colors and the available "numbers" were simply
>
>remapped to mean something different. This must result in posterization,
>
>even if subtle.

My prediction is that these printers (and filmwriters) will be the first 
devices to break the 8 bit per channel limit and start utilizing high bit 
data through to output. That is because the huge gamut they are capable of 
will benefit from having more than 256 levels per channel. But at the moment 
we still must optimize the data in it's high bit state, then convert to 8 bit 
at the last minute to get the needed format for certain operations, and for 
printing. So while having only 256 levels (or even considerably fewer) does 
not show on press output, and 256 seems sufficient for Epson inkjets, 
photoprinters are indeed capable of resolving this number of levels and will 
show posterizations in large areas of very even gradients. The only solution 
at the moment is to dither such areas selectively by selecting them, 
feathering the selection, then applying noise or blurring to break up the 
posterized lines. I suppose a clever software developer could devise a smart 
filter that would search for areas that meet this criteria and automatically 
break  up the posterizaton, but probably by the time the product was 
developed and marketed the problem would have been transcended.

C. David Tobie
Design Cooperative
CDTobie@designcoop.com
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