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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

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.

akirk 17y ago
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).
Gibbon 17y ago
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. Gamma explained: http://www.thehelpful.com/gammaexplained.html http://www.thehelpful.com/gammaexplained.html
- ianbishop 17y ago
  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.
- jacobolus 17y ago
  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.
  - thirdaxle 17y ago
    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.
    - petewarden 17y ago
      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 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.
qeorge 17y ago
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!

akirk 17y ago

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).

Gibbon 17y ago

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. Gamma explained: http://www.thehelpful.com/gammaexplained.html http://www.thehelpful.com/gammaexplained.html

ianbishop 17y ago
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.
jacobolus 17y ago
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.
- thirdaxle 17y ago
  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.
  - petewarden 17y ago
    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 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.

qeorge 17y ago

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!