articles/Equipment/let-there-be-light-page1
by Mike McNamee Published 10/04/2015
The most frequent query to come up at printing and colour management seminars
is 'why are my prints darker than my screen?' This is an almost universal cry
for uncalibrated system users and has the same underlying cause - the screen is
too bright!
But this is actually only one side of the problem. Yes, your screen may be too
bright, but your print viewing conditions are likely to be too dark, thus
compounding the problem.
Now there is an international standard for this carry-on, called ISO 3664. This
was published in the 70s and has had two revisions, one in 2000 and the latest
ISO 3664:2009 was implemented in 2012. For the casual user, these things only
serve to confuse matters still further. This is especially true because the
standard's main target audience is printing press and press services. There is a
standard set-up specified for viewing prints and (almost as an afterthought) for
comparing prints against screen, soft proofs. The main thing that a press
operator is concerned about is the match between a hard-copy proof and what the
press is producing; throwing a monitor into the system only serves to complicate
matters.
Despite these reservations there are some things to be gleaned and taken on
board from ISO 3664. The illumination level of the viewing area should be at one
of two intensities, according to what you are doing. These are called P1 and P2
as follows:
"P1 Critical comparison of PRINTS
This is recommended when comparing an original and its reproduction, or when
comparing a sample print with a production run. The higher illumination level
enables better judgment for evaluation of higher density zones (shadows). The
illumination
level is 2,000 lux at print level.
However, it is also recommended to make a comparison with the P2 conditions, or
the actual conditions that will be used to view the images, to get an overall
view of tone reproduction.
P2 Practical appraisal of PRINTS
This is recommended when one wants to make a judgment on individual prints. This
viewing condition is not recommended for comparing prints against one another,
with the exception of comparing a print with its image shown on a monitor. The
lower illumination level of P2 makes this task easier. You should be aware that
such a comparison, monitor vs print, should only be performed when the monitor
and print viewing light have the SAME white point, usually D65 or D50. The
illumination level is 500 lux at print level."
In practice the main difference you will notice is that you can see more shadow
detail at the higher luminance viewing level.
The standard specifies that the screen luminance of your monitor should be
between 75 and 100 cd/m2. Some calibration software calls up 120cd/m2 for
laptops. Personally we like 75cd/m2 - apart from anything else it extends the
life of the monitor! This rather low value should be compared with the figures
that are bandied about for iPads, Macbook Pros and some low-end monitors of up
to 400cd/m2. This is the most common finding for those who suffer prints that
are dark compared with their screens - they are working at the default
luminance. The prime requirement for a screen calibrator and its software is
that you can choose and regulate the screen luminance AND check it afterwards!
Often luminance settings are under 'advanced' buttons or 'pro mode'. The current
rash of Retina screens have only served to make matters worse - they are never
going to look like a print!
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