[argyllcms] Re: Spyder 3 pro
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 17 Jan 2011 23:46:12 +1100
Kit Johnson wrote:
room, but I share my room with my partner.) As mentioned, the ambient light
sensor on the Spyder 3 Pro doesn't work in linux. After dispcal -v -P
0.5,0.3,1.0 -q l -y l samsung, I press '6' and it reports: "Need ambient
measurement capability, but instrument doesn't support it. Instrument doesn't
have an ambient reading capability."
Hmm. Mine is a Spyder3 Pro, and it works fine. Please mail me a trace
for "spotread -D5 -a 2> log.txt" and then hitting the space
bar and then quitting.
* Should I profile the monitor once only, in a darkened room, and at the
final point where the icc profile is created using colprof, use -d to
specify viewing conditions?
o -d md (for working at night)
o -d mb (working in the day time - it is always bright here in
Thailand)
o what about working under fluorescent light? Is that simply a
no-no?
Seems reasonable, but it's really better to walk before running.
Get the monitor calibrated and profiled under the simplest conditions,
live with it a while before deciding to get elaborate.
* Should I consider changing the brightness setting on my monitor as bright
(for working in the daytime), and dark (for working at night), and have
two icc profiles ready to load when I am working?
Maybe. It's best from a user comfort point of view to match the display
to the surrounding light level. Serious color users on the other hand, often
want to use comparable light levels to those that they use in their hard copy
evaluation. This is why they opt for fixed viewing conditions.
I am trying to calibrate an LCD monitor, Samsung F2380, which has particular
problems with 'black crush' - displaying dark shades of grey as blacks. My
monitor's factory settings are brightness 100 and contrast 75. I read in the
argyll documentation it's often best not to change these, so haven't.
Loosing black levels is not necessarily a problem with calibration or profiling,
but a lack of suitable gamut mapping. See
<http://www.argyllcms.com/doc/CrushedDisplyBlacks.html>
After "dispcal -v -P 0.5,0.3,1.0 -q l -y l samsung", I get the adjustment menu
and have questions about each step:
1. Adjust CRT brightness to get target level (target 2.15, current 0.88).
Should I ignore this because I don't have a CRT?
Yes, unless you have specific controls to adjust offset, ignore it.
3. White level: Initial is 214. I read
(http://forums.dpreview.com/forums/read.asp?forum=1002&message=34040861)
that I should aim for white luminance of between 100-140 cd/m2. It looks
like I am way over. Should I reduce the brightness setting on my monitor
accordingly?
It's up to you to decide what brightness you want, depending on your
circumstances.
From a comfort point of view it shouldn't be too different to the surround
level.
You may want to match levels used in evaluating prints.
4. Black point: Target Br 2.13, x 0.3063, y 0.3276
/ Current Br 0.94, x 0.3267, y 0.3049 DE 19.4 R- G+ B-- . This looks
way off too (DE 19.4). However, I cannot see any offset controls on my
LCD.
Nothing to do there then.
I tried reducing LCD brightness to 50, from 100, which appeared to improve black
point:
Target Br 1.20, x 0.3004, y 0.3159
\ Current Br 0.49, x 0.3205, y 0.3040 DE 16.4 R- G++ B-
, but not a lot. But it did reduce white level to 125. Should I take it that
50 brightness is 'better' because of these results?
Not especially. The black level steps are there to support setting up
displays that have an ability to adjust the black level. If yours doesn't,
don't get hung up on it.
On visual inspection of a
test chart, it appeared to make it harder to distinguish between very dark
grays, i.e. it made black crush worse. Does it all depend on the brightness of
the room I am in? I imagine if I proceed with calibration it will give
significantly different results if proceed with 50 vs 100 brightness?
It could depend on many things. It's important to try and use real controls,
rather than ones that manipulate the signal levels, and which may loose levels
and/or have very bad side effects. So brightness should be a back light
adjustment. Your ability to distinguish blacks will depend a lot on
flare, and this depends on the level of ambient lighting. So a dim
display in a bright room will not only be fatiguing, it will loose
visual levels.
Graeme Gill.
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