> ... wondering why Apple would change the Mac to match Windows after 25 years of using gamma 1.8 ...
No, the original Mac had only black & white. No gray (or any other colors besides black & white), and thus no gamma. The earliest Mac for which gamma would have had any meaning was the Macintosh II, introduced in 1987, and that's 22 years ago, not 25. This is no big deal, of course, but then he repeats the error:
> Macintosh, in 1984, introduced us to desktop publishing and to displays with shades of grays.
Nope.
Again, no big deal, but seeing that he got the unimportant facts wrong, gives me rather less confidence is his important facts. Caveat lector.
Note that you can bring your mac's gamma up to 2.2 right now without upgrading: Open System Preferences, Go to "Displays", then the "Color" tab, then click "Calibrate". This will give you the option of setting your gamma to 2.2.
I'm trying it out myself right now. Seems very different, not sure which gamma I like more.
On pre-Snow-Leopard systems, all of the UI is going to look dark and contrasty, contra system and application designers’ intent. If you like it, go for it, but I think it looks terrible. With Snow Leopard changing the default, developers will of course design their apps to fit γ = 2.2, and will lighten everything up, so that it looks right.
I have always used and been a fan of 2.2. It makes sense to use what most others use, imo. When you choose colours for a site you know that most people will see similar colours.
With a gamma of 1.8 I found that on other machines using 2.2, light colours I chose tended to look white and dark colours looked black.
I'd imagine that Snow Leopard makes various tweaks to the source assets to look better at 2.2 gamma. Changing your preferences will have the desired effect on web pages and such, but not necessarily on native controls and system UI.
It seems that Snow Leopard is Apple's attempt at meeting the standards of everyone else. Gamma has been changed to Windows configuration and hard disk space to the standards of manufacturers.
I would say that this will, for the most part, benefit web developers as it will put everyone on the same page.
The gamma in OS X has not been changed to "Microsoft's Standard" but rather to the standard used for the majority of the world's images and video. A gamma correction of 2.2 is necessary for NTSC video and is more or less equivalent to the gamma of the sRGB color space.
The Mac 1.8 gamma was a better match for print output but it's increasing irrelevance makes it only natural to increase the gamma for better video/image viewing.
It is only natural to switch to γ = 2.2, but mainly to agree with the rest of the world. Neither is particularly “better” for image viewing – the difference between the two is trivial and irrelevant, except insofar as it makes images look different on two different machines.
γ is mainly a way to align the metric in our color space with human perception: humans adapt to varying light levels, even in small areas of the visual field, and our judgment of color differences is relative (i.e. relative to magnitude, logarithmic) rather than absolute (linear).
Any operation that requires interpolating between arbitrary colors (e.g. image rotation, scaling, or compositing with transparency) will have errors introduced by any γ ≠ 1.0, so careful image processing applications should convert to γ = 1.0, perform whatever operation, and convert back, but in practice none of them do, because with sufficient pixels, especially if they're mostly opaque, users don’t know they should care.
But storing colors in 8-bit color with γ = 1.0 would be a disaster, because we’d be devoting half of our storage space to the very bright colors, while leaving the dark colors only a few levels of distinction: the darks would end up extremely noisy.
Incidentally, this last is the reason that digital cameras, even though they collect 10 or 12 bits per channel of data, end up with noise in the blacks: cameras gather photons and store them linearly, meaning that the light parts of the image are silky smooth because we can make many fine color distinctions, but not the darks. Hence the general advice to “expose right.”
Soon enough, we’ll just be storing and manipulating images in γ = 1.0 floating point, and thereby get the best of both worlds: operations are technically linear, but the encoding space is assigned logarithmically.
Much of what you have stated here is incorrect. For example, the encoding of a photo affects only quantization noise, and has nothing to do with the noise in the dark pixels (due to shot noise).
There are plenty of sites where you can learn more about camera noise.
No, he's spot on about the advantages of 'linear light' processing. It even makes a big difference to bilinear interpolation when you're doing texture mapping.
This is an incredibly confusing subject, thanks to the overlap of gamma as an encoding technique with all the other issues around color management. Poynton's Gamma FAQ is one of my favorite resources ( http://www.poynton.com/GammaFAQ.html ), but even after five years working on image processing software I still have to make an effort to wrap my head around it all.
Thanks, very informative! I had no idea. All the articles I have read recently have simply made it a 'Windows uses this - OSX has always used this' debate.
As a web developer, I agree wholeheartedly. The Mac gamma correction was more frustrating than any IE6 bug. I'm thrilled to leave it in the past. Thank you Apple!
Well, for the disk size, Windows is still using base2 calculation. I don't quite understand why they just don't use the correct term (GiB (Gibibyte) for base2, and GB (Gigabyte) for base10) and make it user configurable.
I'd prefer the base2 display, as I think it's confusing for example when exchanging USB keys with Windows machines. Furthermore OS X now is inconsistent with file size display, because not all OS X programs use base10 at the moment (for instance QuicktimeX).
I have a vague memory in a cobwebbed corner of my mind that the old NeXT system software had a gamma value of 1. I couldn't find a citation for that, but if I don't have a misfiring neuron this would be the 2nd time that this software has gone through a change in gamma.
Edit: Here is a paragraph that, at least, supports where I got this memory from:
"Some display systems such as NeXT's and SGI's contain hardware lookup tables that correct for monitor gamma. On these systems the frame buffer values provided by the application are corrected for the gamma of the CRT by a lookup table in the display controller, producing a display system gamma of 1.0 which linearly maps frame buffer values into intensity."
As soon as browser vendors decide to add this, it will happen: it’s in CSS3, but the standards process will neither encourage nor prevent browsers from doing this themselves.
Note that Firefox does (or can) actually do proper color management of CSS/HTML colors, unlike any other browser.
> ... wondering why Apple would change the Mac to match Windows after 25 years of using gamma 1.8 ...
No, the original Mac had only black & white. No gray (or any other colors besides black & white), and thus no gamma. The earliest Mac for which gamma would have had any meaning was the Macintosh II, introduced in 1987, and that's 22 years ago, not 25. This is no big deal, of course, but then he repeats the error:
> Macintosh, in 1984, introduced us to desktop publishing and to displays with shades of grays.
Nope.
Again, no big deal, but seeing that he got the unimportant facts wrong, gives me rather less confidence is his important facts. Caveat lector.