Why do Chrome and Firefox show heavily desaturated colors compared to Safari on OS X Mavericks?

Color space is the biggest issue here. Any value you enter as a color is relative to that color space's gamut and range in relation to where that value falls in L*A*B*. So C73333 does not produce the same hue in different color spaces.

As an example, I took your values and made a small image filled with that color. I used my monitor's profile as the color space (it's larger than Adobe RGB in some hues, a bit short of it in others). I then converted the file to the sRGB color space and filled it with the exact same color. Adobe RGB and my monitor profile both produce that hue as a much richer and vibrant red because of where that value falls relative to 255, 0, 0 (the most saturated possible red) as RGB values. In sRGB, 255, 0, 0 is nowhere near as saturated since it's a much smaller space, so C73333 also falls to a much more desaturated color to maintain its position between 255, 0, 0 and 0, 0, 0. It has to since the richer red of my monitor is outside of sRGB's space.

Here's how it looks to me. My monitor profile on the left, and the exact same value of C73333 when applied as sRGB.

So what's basically happening is that Chrome and Firefox are ignoring any embedded profiles of the images on a web page, if they have one, and displaying them as sRGB. In the case of images saved without a profile, they (and also Safari) default to applying sRGB on the fly. Which results in a duller color range than what your monitor may actually be capable of reproducing.

Safari then is the only one of the three attempting to display tagged images according to their embedded profiles rather than everything as sRGB. Chrome and Firefox are not.

Hope that makes sense.

I just don't get why Chrome on my Macbook Air displays everything as sRGB while on the iMac it seems to apply the embedded profile?

That is a very good question. They should behave the same. I don't (and won't) use Chrome, so can't comment on it otherwise.

1. It actually is a color management problem. Safari is the only browser (of those 3) that fully supports color management, meaning that it also treats CSS colors as sRGB (like recommended by W3C).

Yes, that would be the correct way to do it since colors defined in CSS are just values with no way of assigning a particular profile. So treating them as sRGB is the default behavior, same as an untagged image.

2. Neither Firefox nor Chrome support this out of the box. Chrome being the biggest problem as there is only a command line fix available for the Windows version. Firefox can quite easily be set up to support color management even for untagged images and CSS colors: Go to about:config and set "gfx.color_management.enablev4" to "true" as well as "gfx.color_management.mode" to "1".

Excellent find! I always kind of wondered why Firefox behaved differently. You would think a browser that's been around this long would have color management built in and set as the default. Not the user having to manually turn it on.

but Google Chrome still got this huge problem and it doesn't seem to get fixed. There already is a ticket (since 2010!), even with replies from 2014, but I don't see anybody taking action here.

Chrome does have a huge usage over everything else, which really surprises me since I think it's a lousy browser. I tried it not to long ago to see what all the fuss was about, and wondered why anyone would use Chrome, or what they thought was so great about it.

However, I still don't understand why Chrome on my Macbook Air behaves as described (not displaying colors correctly), but on the iMac actually handles the colors totally well (even though it shouldn't be possible at all).

That is a very weird mystery. I assume they're the same version?

Must be a bit longer than I thought I last tried Chrome. I downloaded it again just now and it is greatly improved over the last time I tested it.

According to numerous sites, Chrome has supported color management on the Mac side for a while now. It didn't at all before, which was one of the things I hated about it. But there's confusion on that.

This site from 2012 says Chrome is color managed. This one from August 2013 says it isn't. But yet again, this test page running in Chrome does show the car in the orange color it's supposed to be, which the author says means, yes, it is color managed. That was for version 19 of Chrome though, and the current is version 34. So quite a bit of updating since then.

I'm liking Chrome quite a bit more than before.

Same here.

On the left i'm using chrome and on the right Safari

The difference is huge 😮

Yup, normal for Chrome or Firefox. Both of these browsers only color manage tagged images. Nothing else. Safari color manages everything, whether it's tagged with profile or not, or even can be.

Your screen grabs are a perfect example of that. Safari is automatically applying sRGB to the web content. Since that's a small color space, it gets pushed to less saturated color. Firefox exerts no color control whatsoever on the same page, so the same RGB values they used get displayed according to your monitor's much larger color gamut.

Which is the way the color was intended to appear? Only the person who made the web page would know for sure.