Re: Dry Time for UltraChrome inks/Calibration
Re: Dry Time for UltraChrome inks/Calibration
- Subject: Re: Dry Time for UltraChrome inks/Calibration
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Thu, 06 Feb 2003 10:25:26 -0600
Graeme Gill wrote:
>
A sequence { a(j) } for j = 1 to n is called monotonic if
>
>
a(j + 1) >= a(j) for all j,
>
or
>
a(j + 1) <= a(j) for all j.
>
>
More generally, in a mapping from one space to another
>
the mapping is "monotonic" when there is a unique
>
mapping of input values to output values. To put it
>
another way, there is only one input value that
>
will map to any given output value.
Good explanation, except that the "<=" and ">=" should be "<" and ">"
respectively.
>
Given that color correction is all about characterizing
>
a devices behaviour and then inverting the profile in
>
order to know what device values to use to get a certain
>
PCS value, reverse mapping uniqueness is a very useful
>
quality.
I agree with Graeme that "invertability" is a desirable property of a device
and its profile. But just to clarify for others, in 3D (or 4D), individual
channels of a device may be non-monotonic while still having an invertable
profile. Similarly, a device whose individual channels are monotonic may
produce a profile that is not invertable.
A "hook" in a profile does not necessarily mean that the profile cannot be
inverted.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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