Can someone explain to me why MacOS has a different default gamma than the other 98% of the computers in the world?

I mean, there's no doubt in my mind that the reason is Completely Fucking Stupid, but I'm curious what the rationale is anyway.

And further, why, after the decade-plus that we've had graphical web browsers, the software doesn't compensate for this silliness when displaying images? I'm pretty sure that JPEG files can include the gamma with which the images were created, making it possible for it to adjust the image appropriately when rendering it to a different screen, and yet, no software seems to do that.

I noticed this most recently when I walked by rzr_grl's machine and saw her copy of this entry, and thought, ``Oh, look at that. I guess bluce has a Mac; here I'd been assuming he just posted a picture that was almost entirely black.'' But no, it looks fine on her screen.

Computers suck.

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11 Responses:

  1. grahams says:

    I dunno, the photo looked fine on my WinXP box...

  2. I've created a poll for testing monitor gamma some time ago. Check it out here.
    My monitor's gamma used to be 1.5, but after seeing that everyone else's was closer to 2, I adjusted it in video card settings.

    By the way, gamma is just half of the problem. Brightness and contrast also need to be calibrated, pictures show no detail if it's set incorrectly. The test charts are here.

    • ralesk says:

         My monitor would be around hmmmmmm 3.75?  Yay for 3.5 years old MAG D510.  My 89-APR manufactured EGA monitor is better and has never been to repair with /any/ sorts of problems. :}

  3. malokai says:

    there are macs on this planet without photoshop and adobe gamma correction?

  4. rahaeli says:

    Most of the Mac users with Clue have adjusted their gamma so that it coincides with the Rest Of The World, anyway :)

  5. thedward says:

    JPEG files don't (alas) contain gamma information. AFAIK, the only even vaguely widely used (on the interweb at least) image format that does encode gamma information is PNG. If you want a lossy format, you could use JNG. It is natively supported by Mozilla, and there is a plug-in available for MSIE. I don't know about other browser support.

    • ralesk says:

         And, yay for gamma support, PNG gamma rendering is borked in all MSIE :}  Oh well, I use Mozilla anywayz :]

  6. chanson says:

    Macs have a 1.8 gamma instead of a 2.2 gamma to make better use of the color space, or something like that.

    Macs also have this great technology called ColorSync that uses a simple step-by-step calibration process (or a monitor with color sensors like my old ColorSync Display 17) to generate an ICC profile for the display. (Oh, yeah, this also works across multiple displays.)

    Internet Explorer 4.5 - way back in 1999 - introduced support for ColorSync. If a GIF or JPEG or PNG image has an attached ICC color profile (or gamma information), it's color-matched to the display. If it doesn't have any such information, I think IE assumes it's in the sRGB color space (a device-independent RGB color space that was invented to mimic the behavior of the average PC monitor) and color-matches it to the local display from that.

    This support is still in modern versions of IE. I believe OmniWeb on Mac OS X also does color-matching as a side effect of using Cocoa for displaying images. I don't know if Mozilla or Chimera (Cocoa Mozilla) use ColorSync; if they don't they should. It's pretty cool.

    Oh yeah, ColorSync is also fast. Back in 1999 I was working on a utility that had to convert from a particular CMYK color space to the display's RGB space for preview. I had a hand-coded conversion that took too long; I replaced it with a couple ColorSync calls and it was so fast it wasn't at all worth trying to optimize my hand-coded version. And this was on a sizable image (a few hundred by a few hundred pixels) rather than just a small web graphic. Oh, and if I had a multiprocessor machine it would have been even faster (even back then)...

  7. raph says:

    Here's a definitive discussion:

    In any case, the nonstandard gamma value is just one of the many usability problems people have to deal with in a mixed world including Macinstoshen. I've also noticed that gamma can vary widely between native Macos 9 and the classic emulation layer.

    It shouldn't be necessary for JPG's to include gamma info. On the Web, just assume a standard gamma of 2.2. Browsers should work around the tone curve distortion introduced by the platform if necessary. ColorSync is pretty cool technology, but is massive overkill for what is really a very simple issue.

  8. raph says:

    By the way, I get the distinct impression that most Macintosh people consider an overall system gamma of 1.8 to be superior to the standard 2.2. In fact, 2.2 is better by most objective technical criteria (particularly tone resolution in shadow areas, which is dramatically worse at 1.8 than 2.2). I suspect that the lower value was chosen as a compromise between the mistaken belief that 1.0 is somehow "most correct" and the prevailing values, but I have no proof of this.

    In any case, I'm always amused by the mistaken technical beliefs on the part of Mac zealots. Don't get me wrong, I like Macs (it's easily the best choice for my kids), but they're still pretty flawed machines.