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User profile for user: Reuben Feffer
Reuben Feffer Author
User level: Level2 289 points
Hi,
What's the deal with gamma on iMacs? Mine was set to 1.8 by default. According to the Display Calibrator Assistant, 1.8 is Standard Gamma for Macs, whereas 2.2 is standard for Television and PCs. So, the way I understand it, the whole World is using 2.2, meaning 2.2 created images displayed on a 1.8 iMac look too light, with washed out colours.
I found this interesting quote on Apple's Aperture Support site:
"Unless you have a color management expert instructing you otherwise, select a 2.2 gamma and a D65 white point."
Since most Mac home users don't have a colour management expert, why would they want their screens set to 1.8 by default, if the correct gamma setting is 2.2? I find it odd that Apple are shipping all these new computers with the gamma set to 1.8, when they themselves recommend you change it to 2.2.
17" iMac 2GHz Intel Core 2 Duo, 2GB RAM, 250GB Hard Drive
Posted on Jul 25, 2007 3:27 AM
Question marked as Top-ranking reply
User profile for user: J D McIninch
J D McIninch
User level: Level5 4,091 points
Posted on Jul 25, 2007 7:48 AM
The gamma of 1.8 is a legacy of the publishing industry. Namely, the PC gamma default was set to be the average gamma of CRT-based monitors (2.5) so that you have a 1:1 relationship and don't need correction. Not that all monitors are the same, but it's pretty close. That eventually became 2.2 when the sRGB colorspace was introduced and PC graphics card and drivers startedd making corrections -- the impetus for that being 2.2 was the gamma found on common analog video recording equipment and if you wanted to display or work with video, that was going to get the truest result.
The Mac default setting of 1.8 matched the gamma of offset printers and was chosen specifically so that the color on the display was corrected to match that of the print medium. However, today many printers perform corrections for color spaces and publishers frequently use D65 G2.2 (which has gamma 2.2).
But here's the rub: the optimum gamma correction is actually dependent on the type of display (LCDs and CRTs are much different) and the display luminance, and also whether you are attempting to match a particular medium (printer, display, or video).
There's no "correct default" and the variations in color and brightness won't be fully corrected for by simply changing the gamma setting. For LCD-displays, a lower gamma value is probably more correct, particularly at full brightness.
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User profile for user: J D McIninch
J D McIninch
User level: Level5 4,091 points
Jul 25, 2007 7:48 AM in response to Reuben Feffer
The gamma of 1.8 is a legacy of the publishing industry. Namely, the PC gamma default was set to be the average gamma of CRT-based monitors (2.5) so that you have a 1:1 relationship and don't need correction. Not that all monitors are the same, but it's pretty close. That eventually became 2.2 when the sRGB colorspace was introduced and PC graphics card and drivers startedd making corrections -- the impetus for that being 2.2 was the gamma found on common analog video recording equipment and if you wanted to display or work with video, that was going to get the truest result.
The Mac default setting of 1.8 matched the gamma of offset printers and was chosen specifically so that the color on the display was corrected to match that of the print medium. However, today many printers perform corrections for color spaces and publishers frequently use D65 G2.2 (which has gamma 2.2).
But here's the rub: the optimum gamma correction is actually dependent on the type of display (LCDs and CRTs are much different) and the display luminance, and also whether you are attempting to match a particular medium (printer, display, or video).
There's no "correct default" and the variations in color and brightness won't be fully corrected for by simply changing the gamma setting. For LCD-displays, a lower gamma value is probably more correct, particularly at full brightness.
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User profile for user: Reuben Feffer
Reuben Feffer Author
User level: Level2 289 points
Jul 25, 2007 9:56 AM in response to J D McIninch
Thanks for that reply. It explained a lot.
Still, is it best to leave my iMac's gamma set to 1.8, the same setting that it was shipped with? What do most Mac users do?
Also, if I bought a hardware colour calibrator, would it alter my gamma setting? Maybe that's the best way to do it.
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User profile for user: Doodle
Doodle
User level: Level1 19 points
Jul 29, 2007 5:48 AM in response to Reuben Feffer
"Still, is it best to leave my iMac's gamma set to 1.8, the same setting that it was shipped with?"
Pick one of the following:
1. If you're working with images for publication, it should match the output device as closely as possible.
2. If you just want it to look good for the best viewing experience, set it to where it looks best for you.
That's it.
If I told you a gamma of 2.2 was best but it looked too bright to you, would you leave it there anyway just because i said so?
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User profile for user: Reuben Feffer
Reuben Feffer Author
User level: Level2 289 points
Aug 11, 2007 3:32 AM in response to Doodle
"If I told you a gamma of 2.2 was best but it looked too bright to you, would you leave it there anyway just because i said so?"
No. But basically, I want my iMac's display to be in-line with all the other computers in the World. The majority. I don't want to be seeing things looking brighter or more washed out than they're supposed to be.
I think I'll buy a Spyder2express colour calibrator, and set my gamma to 2.2, since I rarely print anything.
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User profile for user: capaho
capaho
User level: Level4 3,673 points
Aug 11, 2007 4:09 AM in response to Reuben Feffer
I want my iMac's display to be in-line with all the other computers in the World.
I have some bad news for you. All the other computers in the world are not in line. The best setting for your computer is the setting that you like the best.
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User profile for user: Doodle
Doodle
User level: Level1 19 points
Aug 11, 2007 6:12 AM in response to Reuben Feffer
"basically, I want my iMac's display to be in-line with all the other computers in the World. The majority. I don't want to be seeing things looking brighter or more washed out than they're supposed to be."
That's my point... what you said is a contradiction. The majority of computer users, Mac or Windows, don't know what gamma is and they dont care. Why would you want to be like them?
If you don't want to be seeing things looking brighter or more washed out than they're supposed to be, you'll set your monitor/gamma where it looks best for you and you won't worry about all the other people that are seeing images that look brighter or more washed out than they're supposed to be.
You will NEVER have a perfect image, because every moment your monitor is on the picture quality changes. After a year it won't be anything like what it is today.
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User profile for user: Reuben Feffer
Reuben Feffer Author
User level: Level2 289 points
Aug 13, 2007 6:52 AM in response to Doodle
Thing is though, even Apple say:
"Unless you have a color management expert instructing you otherwise, select a 2.2 gamma and a D65 white point."
http://docs.info.apple.com/article.html?artnum=302827
So, it looks like they suggest you don't use 1.8 and use 2.2 instead. I know nothing is ever perfect, but it's good to start off on the right foot, with the right settings.
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Gamma Was 1.8, Should Be 2.2?
