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Author Topic: Apple iMac & Studio Displays - Display Calibration  (Read 4756 times)

GWGill

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #100 on: May 29, 2022, 07:26:24 pm »

So I was having a bit of think about it, and there is a fundamental difference between displays and sensors in regard to long term stability, and it comes down to energy density. A display has a minimum energy density dictated by the required brightness. A sensor has no minimum. Energy density drives long term behavioural changes, due to things like dopant, semiconductor and metal migration, thermal cycling, chemical reactions, etc. In contrast a sensor has orders of magnitude lower energy density, and in the role of display measurement, is on for a very small fraction of the time of the display.

None of that says that you can't make a display with excellent out of the box and longer term stability, but in the long run, relying on sensors to be consistent is likely to be a better bet than relying on the display not to change.
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routlaw

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #101 on: May 29, 2022, 07:32:43 pm »

So I was having a bit of think about it, and there is a fundamental difference between displays and sensors in regard to long term stability, and it comes down to energy density. A display has a minimum energy density dictated by the required brightness. A sensor has no minimum. Energy density drives long term behavioural changes, due to things like dopant, semiconductor and metal migration, thermal cycling, chemical reactions, etc. In contrast a sensor has orders of magnitude lower energy density, and in the role of display measurement, is on for a very small fraction of the time of the display.

None of that says that you can't make a display with excellent out of the box and longer term stability, but in the long run, relying on sensors to be consistent is likely to be a better bet than relying on the display not to change.

Good points, makes sense to me. "Energy density" at least for us non engineering people seems a bit nebulous, but from what I gather the sensor is a mostly passive device either receiving or reading electrical impulses of one form or the other while a monitor is burning daylight nearly constantly as long as it is on and being used. Thanks
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GWGill

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #102 on: May 29, 2022, 09:07:14 pm »

"Energy density" at least for us non engineering people seems a bit nebulous,
Energy density = watts (dissipated) per cubic mm. Implies current density and temperature rise.
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digitaldog

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #103 on: May 31, 2022, 11:23:08 am »

Here is a synopsis of color management that provides an overview of some of the issues encountered in this complex and wonderful subject:
Color Spaces & Management
Unfortunately there quite a few misunderstandings presented there.  :'(
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digitaldog

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #104 on: May 31, 2022, 02:27:16 pm »

Given the unspecified misunderstandings, perhaps in the pursuit of accuracy would it be better if I deleted the link?
You can or you can ask about the misunderstandings which you may believe after reading that article. Up to you.
FWIW, let's start with this: cameras, scanners, and humans don't have a color gamut.
Only devices, or systems, that render color have a color gamut. Digital cameras do not have a color gamut (they have a color mixing function). Same with scanners. Dr. Roy S. Berns from RIT stated, in Billmeyer and Saltzman’s Principles of Color Technology: "Color gamut: Range of colors produced by a coloration system." Color gamut applies to systems that produce color (Printers, TVs Displays, projector) and color spaces as well.
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Doug Gray

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #105 on: May 31, 2022, 10:06:46 pm »

You can or you can ask about the misunderstandings which you may believe after reading that article. Up to you.
FWIW, let's start with this: cameras, scanners, and humans don't have a color gamut.
Only devices, or systems, that render color have a color gamut. Digital cameras do not have a color gamut (they have a color mixing function). Same with scanners. Dr. Roy S. Berns from RIT stated, in Billmeyer and Saltzman’s Principles of Color Technology: "Color gamut: Range of colors produced by a coloration system." Color gamut applies to systems that produce color (Printers, TVs Displays, projector) and color spaces as well.

Yeah. Lots of bad info about "gamuts" In particular input devices (cameras, etc.) don't have a gamut in the sense they respond to any spectral combo. Rather, their problem is that the response is, at best, only approximate to that of human vision. So 2 colors that appear to be different can create the same sensor response. So what color is that response supposed to be mapped to? This is the big problem with cameras (digital or film), scanners and such.

And then there's the dynamic gamut limits v luminance that are intrinsic to printing and any colored surface.

Here's a good paper describing Pointer's Gamut (max from a large number of real world objects) and MacAdam's gamut limits which are the theoretical limit of any colored surface. These are compared with the capabilities of various RGB gamuts.

https://philservice.typepad.com/Pointer_MacAdam_Wide-Gamut_Displays_v2.pdf
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routlaw

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Re: Apple iMac & Studio Displays - Display Calibration
« Reply #106 on: June 02, 2022, 01:44:26 pm »

Interesting link and read, thanks for that. The results do not surprise and what I had sensed but couldn't prove scientifically.
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