Re: Profiling a Dell UltraSharp 2405FPW LCD
Re: Profiling a Dell UltraSharp 2405FPW LCD
- Subject: Re: Profiling a Dell UltraSharp 2405FPW LCD
- From: Roger Breton <email@hidden>
- Date: Fri, 29 Jul 2005 08:51:47 -0400
Doug,
> I need to profile a new 24" Dell UltraSharp flat panel display using
> a Spyder colorimeter and preCal/Optical connected to a Mac 17"
> Powerbook. I understand that it's not the optimal color critical
> display, but then neither is my PB.
Many users are in the same boat as you.
> One "problem"... it's incredibly bright.
Could you describe/measure its uncalibrated Luminance?
Is it 250 Cd/m2? 400 cd/m2? What?
> As in pin-you-against-the-
> wall bright. It makes my 17" PB screen look like dog doo.
I imagine.
> I'm seeing
> hues and shades of colors, higher saturation and rich solid blacks
> I've never seen before.
OK. You've convinced me ;-)
> But... the question
> is how do I profile the Dell given that it's native brightness is
> probably optimized for over-lit corporate office environments?
I'd profile along the line of a soft-proofing viewing ISO standard like
12646:2004, CIE xy chromaticities set to D50, gamma set to 2.2 (as Nathan
hinted) and Luminance (Y) set from 80 to 120 Cd/m2.
> - brightness (which fails to make much of a dent in the brightness)
That's expected as it controls the "black" point.
> - contrast (inactive, I assume due to the PB card limitations)
Why? You have to investigate this as it is THE way to lower the screen
Luminance. Otherwise you'll be stuck with an ever dazzling monitor to work
with. There must be a control somewhere, talk to the manufacturer's support.
> And it has individual RGB level controls that are labeled:
Good.
> - Normal preset (sRGB)
> - Red preset (warmer image)
> - Blue preset (cooler image)
> - User Preset, which allows me to set the RGB levels individually
You want User Preset.
> My first stab at profiling it was based on what I now realize was bad
> logic. (I tried to make the display as dark as possible when I
> probably should have tried to make the room as light as possible.)
I don't see that as bad logic? First, set your ambiant light conditions to
work with a display, and that does not need to be very bright. In the order
of 60 to 90 Lux is plenty. Others may disagree for reasons of theirs but
that's my opinion and I'm willing to listen to counter arguments.
> Anyway, I cranked down the brightness control to zero, and adjusted
> the RGB levels downward using PreCal until the white luminance value
> was about 95.
Wow, das is sehr gut! FWIW, my Minolta CS-100 tells me my Eizo CG21 emits
114 Cd/m2 to my eyes as I'm writing these lines to you. The amount of light
falling on my screen is a little 26 Lux -- it gets higher during the day.
> I figured this would bring the Dell closer to the PB
> display and create a level that was more appropriate for my rather
> dark office.
Right.
> Since PreCal requires a color temperature to be
> selected, and doesn't have a native white point setting, I chose 6500
> in PreCal.
Fair. Good for ISO-3664 but not for screen to proof acording to these eye
balls. Again, I respect the opinions of others in this matter.
> There no kelvin-based temperature settings on the Dell.
You don't want to use them anyway.
> Once I finished with PreCal, I fired up Optical, selected 6500 and a
> gamma of 1.8 and let 'er rip.
Well, I think at that point you should have selected 'native' because you
already done the work in PreCal as far as 6500K was concerned. But I don't
think it makes a real difference.
> The resulting profile is obviously wrong. It makes photos too dark
> and contrasty. So how should I go about it? Specifically...
Maybe the profile is OK but what you say is that it has changed the
appearance of your color images in a way that you don't recognize? Do you
have the alternative of other instruments or software to calibrate and
profile your display? Or perhaps access to another Spyder?
> - There is such a vast difference between the Dell and the PB display
> in terms of brightness,
Even when your Dell is calibrated at 95 Cd/m2? What is the calibrated
Luminance of your PowerBook in comparison? Fire OptiCal on both of your
display and look for the Y value or measure a R=G=B=255 white field on your
screen in the Colorimeter window.
> I figure I should forget about trying to get
> the two to match. Would you agree?
Well, let's just say: don't dumb down your Dell too much.
> - Should I even use PreCal?
Yes, since you have it. Might as well use it.
> Since I can't set the color temperature
> of the display to a standard kelvin setting, I'm guessing there's no
> point.
On the contrary, my dear Watson. Don't trust those Kelvin presets, they're
never where they say they are, in my experience.
> And, in terms of casually eyeballing, the "normal" sRGB preset
> looks the best.
You could use that sRGB preset and profile on top of that, if you like that.
> - Should I make any attempt to lower the brightness of the display,
> either with the individual RGB controls or the brightness control
> before profiling?
I'd say aim for some meaningfull Luminance value. The latest crop of iMatch
software has us aim for 140 cd/m2. I think it's still too much but I don't
agree you'd leave it on full blast neither.
> Full brightness is a bit breath taking.
You almost need sunglasses!
> I probably
> could never get my ambient office level bright enough in
> relationship, especially at night.
Aha! You rmind me of a photographer who was telling me that he like to do
all his retouching during the evening. Interesting.
> Although I could place lighting fixtures in my line of sight.
Don't bother. Aim for an illuminance level between 30 to 100 Lux and you'll
be fine.
> - What gama should I use in Optical?
2.2 for sure. See Bruce Lindblookm site for the scientific lowdown.
> I've always used 6500/1.8 on the
> Mitsubishi, and native/1.8 on the PB. I get confused about gamma. Do
> I see more shades of gray with higher gamma, or fewer?
Neither. 2.2 tones down the darker tones more than 1.8. But it happens to be
closer to our natural Lightness perception.
> Thanks in advance for your thoughts...
>
> Doug
Thank's for hanging here.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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