Re: Profiling backlit media info request
Re: Profiling backlit media info request
- Subject: Re: Profiling backlit media info request
- From: Marc Levine <email@hidden>
- Date: Wed, 17 Jul 2002 09:49:56 -0400
Hi there,
I have a little experience with backlit that I thought I'd share. The first
thing to consider when planning your process is the transmission
capabilities of the media. This is important because the lower the light
transmission is, the more you will restrict the dynamic range of any
transmissive readings you try to record. In other words, the more opacity
your media has, the worse your results will be using a transmission
spectrophotometer.
The alternative is to measure the media using a reflective spectro. I have
worked more with media that has substantial opacity - which works well in
this scenario. I suspect that "frosty" materials may require a white (paper)
backing to extract the gamut of the material under reflective conditions.
Once the profile is measured and built, images will look good under frontlit
conditions, but poor under backlit conditions. Casting light through backlit
media tends to wash out color - much like the effect of stripping dot gain
from an image. The ideal place to compensate for this effect is in the
printer's calibration curves section. Hopefully, you have made calibration
curves on which the profile was constructed. Add to these curves a
"dot-gain" curve that delivers more ink to the media - recovering the color
density that was lost under illumination. It's important to insert this type
of adjustment in the calibration section (if possible) and not in a color
adjustment section. Color adjustments are subject to the ink restrictions of
your ICC profile, while calibration adjustments will affect your densities
post-profile.
Once you have achieved the appropriate densities, you can either continue
modifying your calibration curves of modify your profile (or both) for
specific color content. Once you have locked down the calibration curves,
any future adjustment should probably made in the profile, or the color
adjustment area of the RIP. Stay away from continued editing of your
calibrations as you may increase the potential of something going wrong.
One last note
Hope this helps.
Marc
--
Marc Levine
Monaco Systems
Technical Manager
Sales Division
www.monacosys.com
>
From: email@hidden
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Reply-To: email@hidden
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Date: Tue, 16 Jul 2002 22:04:49 -0700 (PDT)
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To: email@hidden
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Subject: colorsync-users digest, Vol 3 #307 - 13 msgs
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>
Date: Tue, 16 Jul 2002 11:43:55 +0200
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From: Rudy Vonk <email@hidden>
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Reply-To: email@hidden
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To: ColorSync List <email@hidden>
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Subject: Re: Profiling backlit media info request
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>
Andy William asked:
>
>
> Hi, can anyone tell me how to do create a profile from large format
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> backlit inkjet media? Any special spectrophotometer? Special software or
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> special setting?
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>
I wish there were an answer... You need to make choice between shining
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light through it and bouncing light off it. The former may seem to
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correspond to the ultimate real-life viewing conditions, but
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spectrophotometers with transmissive capability and profiling software
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feel comfortable with clear film - the milky white stuff sends them into fits.
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>
In practice, it will depend a little on the individual material (some
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look virtually the same with the lights on and off, others vary
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enormously), which side you print on, etc. I generally get better
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results when profiling as reflective media on the side the ink is on,
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and editing a little as necessary, but this is partly because we
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consciously choose materials that look good with the backlights off.
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>
If anybody has a more sophisticated approach that works, I shall gladly
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adopt it.
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--
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__________________________________
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Rudy Vonk
>
Oviedo, Spain
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<email@hidden>
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+34 607 354100
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