Re: Advice
Re: Advice
- Subject: Re: Advice
- From: Robin Myers <email@hidden>
- Date: Wed, 05 Mar 2003 15:17:26 -0800
Kevin Cunningham wrote:
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I'd like to do linearizations, measure ink limits and consistency
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checks along with creating display, RGB output, CMYK output and scanner
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profiles. The output profiles are mainly for large format inkjet
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printers but I use them for desktop inkjets and laser printers. I use a
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variety of RIPs Wasatch, Shiraz, (Jaws), Visual Edge (Harlequin). I'm
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also playing a bit with GIMP print and CUPS on OS X.
There are a number of instrument choices, depending on your requirements
and the size of your budget.
For reading printer test charts there are three basic type of
instruments, depending on the amount of automation. The types are:
manual, semi-automatic and fully automatic.
'Manual' is where you move the instrument yourself to each patch on a
test chart to take the measurement. This is an incredibly mind numbing
experience when the number of patches exceeds a few dozen. Manual
measurement is very useful for making random individual measurements
such as spot checks on press sheets or measuring palette colors from
swatch books. Instruments in this class are the basic Spectrolino, the
EyeOne used in single measurement mode, the Spectrocam in single
measurement mode, and many others.
'Semi-automatic' measurement means that the instrument will perform
some, but not all measurements, with a mimimum of human interaction. For
some instruments, such as the DTP-41, the instrument will read a row of
patches automatically and the operator manually moves the target over to
the next row. Instruments such as the EyeOne and SpectroCam require the
operator to manually move the instrument along a row of patches with the
instrument automatically detecting and measuring the patches in the row.
This is accomplished with a plastic guide placed on the target and moved
manually by the operator for each row.
'Fully automatic' measurement is only offered by one instrument in this
group; the Spectrolino when attached to the Spectroscan table. The
Spectrolino/Spectroscan will measure an entire target of patches without
human intervention. The iCColor will also read an entire chart
automatically. If you have to make profiles often, these devices can be
very cost effective although they are more expensive initially.
For measuring transparencies there are only two choices; the Spectrolino
attached to the Spectroscan T table (the 'T' denotes a transparency
capability) and the DTP-41T. The Spectrolino/Spectroscan T requires the
operator to manually position the each patch of the transparency over a
backlit measurement 'spot'. The DTP-41T can semi-automatically read a
strip of patches, so it is the best choice for heavy duty transparency
target measurement.
Some of these instruments can also read emissive devices such as CRTs,
LCDs, viewing booths and light sources. The Spectrolino and EyeOne will
do this.
Here is a summary chart:
Mode Type of measurements
M S F R T E
-----------------------------------------------------------------
Spectrolino X X X
Spectrolino/Spectroscan X X X X
Spectrolino/Spectroscan T X X X X X
iCColor 200 series X X
iCColor 300 series X X X
EyeOne X X X X
DTP-41 X X
DTP-41T X X X
SpectroCam X X
M = manual, S = semi-automatic, F = fully automatic
R = reflective, T = transmissive, E = emissive
Oh, there is another item you should consider for reflective
measurement; a UV blocking filter. Depending on your profile generation
software, this can be an essential item. Software that makes profiles
from spectral measurements can detect Fluorescent Whitening Agents (FWA)
in the paper and remove their effect in the profile. ProfileMaker 4 does
this. Profile software that uses colorimetric values (just about every
other package) cannot detect FWAs and needs a UV blocking filter in the
instrument to make good profiles (remember, this is my opinion, please
relax your fingers on the flame thrower triggers). The Spectrolino has a
removable UV blocking filter, the EyeOne can be purchased with a fixed
UV blocking filter, so can the iCColor and the DTP-41.
My personal recommendation for one instrument for everything is the
Spectrolino with the Spectroscan T. With it's removable filters (Null
filter, UV blocking, D65 simulator, Polarizer), the fully automatic
Spectroscan stage, transparency capability with the Spectroscan T and
the ability to read emissive devices, it is the most versatile. It is
also the most expensive of those listed.
If your wallet has few ducats, the EyeOne is probably the most
cost-effective. Decide whether you need the UV filter or not (I would
recommend it for print work) and you can measure reflective, emissive
and get semi-automatic chart measurement.
Good luck,
Robin Myers
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| References: | |
| | >Advice (From: Kevin Cunningham <email@hidden>) |