Re: a beginners question
Re: a beginners question
- Subject: Re: a beginners question
- From: RaymondCheydleur <email@hidden>
- Date: Tue, 18 Aug 2009 09:29:54 -0400
- Thread-topic: a beginners question
> From: Dov Ram <email@hidden>
> I was looking (and trying to understand) the so called "response
> type"..(Response Types. T, E, I, A, G, Tx, Ex, & HIFI)
>
Well to be equally brief... Use what your local Standards/Specification
group recommends this way you can hit their aim points. Generally this means
Status T unpolarized in the US and Status E, polarized in Europe.
Slightly longer version...
Each of these Response types really are different ways to weight the
spectral range and curve of the different filters used in densitometry which
is basically just a simple calculation: Density = log (1/Reflectance).
So in the T and E examples above, V,C and M have identical weightings but
the Y filter is different, generally calling resulting in calling Status T
wideband yellow response and Status E, narrowband response.
Status I is a "true" narrowband response that is not in common use today
anywhere that I am aware of. Status A is used in photo applications and the
filters are better suited for the dyes in photo materials... But
historically some printers who had very different ink sets than CMYK (think
greeting cards for instance) have used this because it was a better fit for
their materials.
Response G is an X-Rite only response which really goes back to the point
when the Status densities were not really defined and each company had it's
own filter set. Generally response G is in the 500 series serves as a bridge
to the past as are....
Tx, Ex which "refine" the Status T and E responses to be closer to the old 3
filter densitometers instead of the more accurate spectrodensitometers.
Basically this was again a bridge to allow companies with a lot of
historical data and aims to set a 500 series to mimic the response of a 400
series. We should be long past the time that is needed, particularly as we
move to more use of colorimetry in the pressroom and most aim data is
captured spectrally and any density aims are calculated from the spectral
data just like the 500 series does automatically.
HiFi is an X-Rite only response and is essentially a melding of the
traditional density status types to try and extend densitometry beyond
traditional CMYK.
The ISO 5 series explains the status response functions very well and is
about to go to press with a new version that explains the spectral basis of
the various Status response curves.
RayC
Ray Cheydleur
OEM Project Manager
X-Rite Incorporated
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden