Re: OptiCAL/Spyder black and white target points?
Re: OptiCAL/Spyder black and white target points?
- Subject: Re: OptiCAL/Spyder black and white target points?
- From: email@hidden
- Date: Tue, 30 Sep 2003 09:13:26 EDT
In a message dated 9/28/03 9:46:28 PM, email@hidden writes:
>
I was just reading Colorvision's Spyder/Optical Guide (after
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downloading the most recent Optical update) and read the following:
>
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"It is preferred with Windows PC's that the Spyder be plugged into a
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separate PCI USB card rather than into USB ports built into the
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motherboard."
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Anyone know why the USB ports on a contemporary motherboard might be
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considered inappropriate for using hardware calibration devices?
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There are occasional problems with built in USB on Windows boxes; it works
for most users, but its always better to use an added USB card if available
with
the Spyder. Sorry I can't recall the exact issue, I'm on site at GraphExpo
>
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I also wonder about the Spyder's .30 black 'precision mode' target
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setting in the previous version of Optical? In Real World Color
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management there's a test for the black point outlined which suggests
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raising and lowering the black value of a selected area of a 100%
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black image in RGB and noting whether a difference can be seen when
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lightening 1 to 2% while using the monitor colorspace. With a
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blackpoint target of .30 I easily see a difference between 0 and 1
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and continue to see a difference if I set my brightness even lower.
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Is .30 is too high? I'm using a Mitsubishi DPro2040u.
>
The .3 value was a guesstimate that most monitors; clearly if most can hit
it, then its not a tight fit for all of them. Thats why the new version reads
the black point on your initial pass through, and the inserts that actual
value
into the software for the next iteration. Bruce's method is educational, but
not really a practical enduser workflow.
>
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With the most recent version of Optical I now note that there are NO
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longer any preset default settings for white or black points and when
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I select proceed the suggested defaults are .19 and 88. Is the
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visual target offered by Precal perhaps more accurate than any pre-
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defined measurement?
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Clearly...
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Does this also suggest that the old 80 luminance
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was too low? The Precal suggested luminance range for the RGB color
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guns in 85-95. Is higher better? I'm not matching multiple monitors
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in a group workspace.
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Whitepoint is rather different. Here you are making a choice of how bright
you wish to burn your candle (and how soon you want to burn your candle out,
with CRTs at least). The old value was one most calibratable CRTs could reach,
though many users would choose to increase it. The same is still true now. For
LCDs you could work from a full throttle approach similar to the newer
measured
blackpoint value method, where you run the monitor at its actual maximum
luminance, but with CRTs limiting this value is prudent. If you work in a
darkened
space, 80 may suffice, or if you want to avoid replacing your monitor more
frequently than strictly necessary... but with the current low cost of
excellent
CRTs, I'm willing to burn them brighter, and live with the consequences.
C. David Tobie
email@hidden
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