Topic: Does OS X adjust LUTs by default? (Read 4647 times)

Serge Cashman · « **on:** June 14, 2006, 06:58:42 pm »

From what I understand OS X users who use hardware calibrators to calibrate their monitors to 2.2 (or Native) gamma percieve the UI elements (which are not colormanaged) as too dark. Does it mean that default OS X settings include videocard LUT adjustments to simulate gamma 1.8 on an average monitor?

Gregory · « **Reply #1 on:** June 14, 2006, 10:02:17 pm »

strange. my iMac's monitor is calibrated to 2.2 using the Spyder2 hardware. none of the UI elements on my monitor are 'dark'.

(iMac Duo Core 2GHz/2GB, OS X 10.4.6)

Serge Cashman · « **Reply #2 on:** June 14, 2006, 10:08:33 pm »

Thanks for your reply. Then either my assumption is incorrect or they stopped doing it on intel macs.

Gregory · « **Reply #3 on:** June 14, 2006, 10:55:46 pm »

are there any specific UI elements/applications that you're worried about?

Serge Cashman · « **Reply #4 on:** June 14, 2006, 11:04:32 pm »

I'm just trying to make sense of people stating that calibration to 2.2 makes the UI look too dark. I'm a PC user myself, but quite Mac-savvy. I'm trying to learn as much about cross-platform color management as I can and this issue is very confusing.

Gregory · « **Reply #5 on:** June 14, 2006, 11:21:47 pm »

I'm not an expert, not even close but...

I've used the Spyder2 for several months and setting the gamma to 1.8 or 2.2 looks pretty much the same after calibration. maybe I'm not as sensitive to the UI elements as others but they look perfectly 'normal' to me, someone who's been using Macs for 15+ years (ouch! getting old...)

Serge Cashman · « **Reply #6 on:** June 15, 2006, 02:54:00 pm »

If somebody cares to test you could use one of the profiles from Bruce Lindbloom's page. If I only knew which one. I suppose it's A - no vcgt tag. Just make sure how to get back to using the profile you are using now....

http://www.brucelindbloom.com/index.html?Vcgt.html

<edit> After considerable effort reading through Norman Koren pages I believe that A or B are the "no LUT adjustment" profiles you should use for comparison (in non-colormanaged applications).

61Dynamic · « **Reply #7 on:** June 15, 2006, 08:48:17 pm »

Sounds like people don't understand the difference between 1.8 and 2.2 gamma. A display calibrated to 2.2 will appear to have deeper shadows than one calibrated to 1.8 (everything else being equal).

(It also does not matter if UI elements are color managed or not. The monitor profile will effect everything.)

Serge Cashman · « **Reply #8 on:** June 15, 2006, 09:06:45 pm »

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The monitor profile will effect everything.)
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That's not entirely correct. It affects colormanaged applications differently (provided the result of a calibration is described in the TRC tags of a profile). LUT adjustments of the vcgt tag affect everything. TRC descriptions affect colormanaged applications only.

Ideally in colormanaged applications images look the same independant of the monitor gamma setings AFAIK.

61Dynamic · « **Reply #9 on:** June 15, 2006, 09:28:47 pm »

As far as UI elements, I thought they where color managed in OS X as well since ColorSync is ingrained into the OS.

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Ideally in colormanaged applications images look the same independant of the monitor gamma setings AFAIK

The Gamma effects color managed apps as well just as it should. It doesn't make sense that it wouldn't. What would be the point in calibrating the display to one particular gamma if the color managed app didn't honor that?

Serge Cashman · « **Reply #10 on:** June 15, 2006, 10:20:14 pm »

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What would be the point in calibrating the display to one particular gamma if the color managed app didn't honor that?
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They do honor it. But they are also aware of the monitor profile and the working space so they adjust the output accordingly.

You can calibrate a display to any gamma within reasonable boundaries (Native and L* being shining examples). Non-colormanaged applications would appear different. That was the reason for my initial question.

UI elements are not colormanaged AFAIK. Not that there's anything wrong with it.

digitaldog · « **Reply #11 on:** June 18, 2006, 10:10:09 am »

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Does it mean that default OS X settings include videocard LUT adjustments to simulate gamma 1.8 on an average monitor?
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The default profile does.

Serge Cashman · « **Reply #12 on:** June 18, 2006, 11:31:29 am »

Thank you Andrew. Now I understand the 1.8 gamma issue.

Author Topic: Does OS X adjust LUTs by default? (Read 4647 times)