Re: Questions about the UI at 1.8 gamma
Re: Questions about the UI at 1.8 gamma
- Subject: Re: Questions about the UI at 1.8 gamma
- From: email@hidden
- Date: Sun, 20 Jun 2004 18:15:35 -0700 (PDT)
A few comments:
First a preamble:
While the thread started with finding a common base for file encoding gamma, 1.8
or 2.2, with your last comments the subject has shifted from file encoding gamma
to overall display system gamma.
Of all the RGB spaces, only the Apple RGB and ColorMatch have an overall system
gamma close to one (that combines the file gamma, the LUT gamma, and the CRT
gamma, as per Poynton FAQ, that you refer below, and the W3C PNG gamma definition
available on www.w3.org). The overall Apple RGB system gamma is about 0.96 while
ColorMatch is 1.0. The overall sRGB system gamma, or Adobe RGB for that matter,
is 1.14 while all TV systems, such as HDTV, NTSC or PAL/SECAM, are as high as
1.28.
As you mention herein, the use of a linear one to one system gamma, what results
when using an Apple computer, is perfect for bright environment viewing. In
comparison, the high NTSC and PAL/SECAM system gamma are designed for dim viewing
environment as you know. The sRGB system is somewhere in between.
My comment:
If Apple designs its system for bright environment, so be it (I am curious to
know how many pro are working in such an environment, but that is yet another
subject). However, it would still be possible to have an overall linear system
gamma by using a 2.2 file encoding gamma AND by changing instead the LUT gamma to
match the bright environment criteria. At least, when someone would look at the
image in a dimmer PC environment, what is assumed by sRGB, the image would look
the same.
Danny Pascale
On Sun, 20 Jun 2004 14:13:38 -0700, John Zimmerer wrote:
>
>
Actually I've made this case many times.
>
>
The short story is:
>
1) A gamma of 1.8 roughly equals the transfer function of printed pages.
>
2) Many, if not most, images are ultimately printed on some output
>
device.
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3) A gamma of 1.8 roughly equals the inverse of the human visual
>
response in average lighting.*
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4) Most users view their displays in very bright environments.
>
>
JZ
>
>
*For a primer on how gamma correction is applied, see Poynton's FAQ:
>
http://www.poynton.com/GammaFAQ.html
>
>
On Jun 20, 2004, at 2:16 AM, neil snape wrote:
>
>
> on 20/06/2004 10:48, John Zimmerer wrote :
>
>
>
>> The Macintosh user interface is designed for a 1.8 gamma, has been for
>
>> many, many years. The Apple displays are at 1.8 as well.
>
> Yes that has been clear enough since the days of the Laser Writer.
>
> The Apple Cinema display doesn't check in at 1.8 gamma native.
>
> Forcing it
>
> there has not worked often for most profilers so far.
>
> I really want to know some advantages of 1.8 Gamma if there are any.
>
> Your
>
> group must have some reasons that have yet to be disclosed to the
>
> users.
>
> As you've recently said there are advantages to not presume sRGB. In
>
> the
>
> same enlightenment are there solid reasons for staying with 1.8 Gamma
>
> after
>
> creating a whole new completely Os level CM platform?
>
>
>
> Neil Snape nsnape @ noos.fr neil_snape @ mac.com
>
> http://mapage.noos.fr/nsnape
>
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