Gamma in Snow Leopard & iShell

[Peter Bogdanoff]

Apple has changed the default gamma in Snow Leopard.

Why your Web content will look darker on Snow Leopard

If you're a Web designer, expect your CSS colors & your untagged/unmanaged images to look darker on Snow Leopard than on previous versions of the Mac OS. You'll also seeless of a visible color shift when going from Photoshop to Flash or other unmanaged environments (e.g. Internet Explorer).

Why is that? Apple has switched to a default gamma of 2.2, which is what Windows has used for years. Colors that aren't color-managed are going to look darker on the whole. Your whole display will now be closer to what Windows users see*.

http://blogs.adobe.com/jnack/2009/09/why_your_web_content_will_look_darker.html

Several years ago I asked Matt about how to deal with the gamma difference between Mac (1.8) and PC 2.2 when working with cross-platform projects. He said something like, "We handle gamma internally in iShell."

I didn't really notice what iShell was doing until I did a project recently where I used a QuickTime video embedded within a picture to give the effect of only a part of the large overall image changing while the rest was static. I put it together on a Mac and the effect shows in iShell like I intended--you're unable to make out what is the movie and what is the still image, they blend together well. 

However, on a PC the still image is lighter and the QT movie is darker (higher gamma). You can see clearly the rectangle of the QT video. Apparently, this is a result of iShell automatically adjusting the gamma of the project window to the Mac's 1.8 but not affecting the QT window which is drawn on top. To get the two to match, I would have to go back and change the gamma of either element and have a version the shows only when the environment is Windows (which I haven't done--no one seems to care about the variance besides me).

Now, when content is created in Snow Leopard's default gamma setting, it seems that that same project played on a PC will be too light: iShell, in Windows, will adjust the project to try to match a Mac 1.8 gamma, but Mac's gamma is now 2.2.

I haven't yet installed Snow Leopard, so I can't check this out. I don't know if it will be a problem for some people or really anyone... Or if iShell now needs to consider what Mac OS the project was created in so it knows what to do with PC display.

Peter Bogdanoff

(310) 825-8494

UCLA School of the Arts and Architecture

240 Charles Young Drive N

Broad Art Center 2275

Los Angeles, CA 90095

[Matt Veenstra]

iShell only adjusts gamma based on QuickTime adjusting the gamma. We
do not change the overall gamma particularly.

What I would try to do to solve this is place the .png file in a movie
element and see if this works on both platforms. This might solve the
problem.