Re: Highlight TVI Not Accurate in Profile
Re: Highlight TVI Not Accurate in Profile
- Subject: Re: Highlight TVI Not Accurate in Profile
- From: Jeremy Hansen <email@hidden>
- Date: Fri, 30 May 2014 17:58:56 -0500
Hi, William.
I'd say Steve gave you the first part of the answer.
I believe the rest has to do with the fact that there are not infinite
grid-points in the tables of an ICC profile. Furthermore, there aren't
necessarily grid-points in the profile for every measured interval in the
source data.
The values between grid-points are interpolated. I think what you are
pointing out is that the interpolation between paper-white and the lowest
grid-points in the profile are unreliable for the flexo process. I would
agree.
Let's say that there is a grid-point in the profile at 5% (not sure if
that's a reasonable supposition, but doesn't matter). That would explain
why you have pretty reasonable agreement there, between your measurement
and the profile interrogation (considering the first part of the answer).
As you move down away from the grid-point, toward paper-white, the profile
interrogation provides an ever poorer assessment, as the profile is unaware
of the unique highlight characteristics of your process. A smooth
transition between the 5% and paper-white is assumed. But, in this case,
that's not reality. This ain't offset! : )
Jeremy
On Fri, May 30, 2014 at 3:33 PM, William Whitfield <email@hidden> wrote:
> Greetings,
>
> To simply my previous post.
>
> 1 - I make a profile of an IT8 target that shows a high TVI in the 1.96%
> area, which is available in all colors in an IT8 target. To reiterate, via
> 530 readings of press piece and ColorAnt reading the measurement file.
>
> 2 - I have a press piece that I can see has the same high TVI in the 1.96%
> areas.
>
> 3 - I use the profile made from the printed IT8 target in my proofing
> workflow (CGS) and the result does not match what the press piece shows as
> the high TVI in the 1% area. To make the match work, which I have done
> successfully, I had to create a graduation curve that greatly increases the
> highlight values.
>
> 4 - Why? Being naive, or relatively so, I thought the profile would show
> the same TVI as I measure on press piece.
>
> -Bill-
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