Thursday, January 28, 2010

Color Management

A couple of years ago I posted a question to this blog asking why my images appeared to have higher contrast when posted here than when viewed in Lightroom and other applications on my desktop. I think I finally know the answer to that question.

I've recently added a second display (NEC P221w) and I've been working to calibrate and profile the new display to match my primary display (Eizo CE210w). After some struggles I think I have the displays set up pretty well but noticed that I'm still seeing oversaturated reds on my website on both displays. As it turns out, what I mistook for higher contrast on this blog was actually a color management issue in the browser.

Most of you will not be affected by this issue because it requires a particular combination of software and hardware:

a color-managed browser (Safari, Firefox)
a wide-gamut display (both of the above are)
Mac OS X ? (I'm not clear at this point about Firefox on Windows)

The bottom line is that color-managed browsers make certain assumptions about the color profiles of images on the web that may not be correct, causing the color to shift in the wide gamut displays.

There's a lot of good information here: http://www.gballard.net/photoshop/srgb_wide_gamut.html

If this problem is of interest to you please pass along any other resources you find.



4 comments:

Ray Meibaum said...

I installed Google Chrome in an attempt to view my site in a browser that's not color-managed, but I'm seeing oversaturated reds in this browser too. It's going to take some time to sort this one out...

Preston said...

Ray, there isone thing I've tried with some, but not complete success. I noticed that the JPEGs I export from Ligthroom never seemed to match color exactly. I assumed this is the result of viewing RAW files in the ProPhoto color space in Lighroom and exporting to sRGB. I'd expect to get some loss of fidelity, but sometimes the change was dramatic. Recently I started exporting files intended for the web as an sRGB TIFF, tweak in Lightoom, then export to JPEG. Because JPEG is a lossy compression, I'm still seeing a contrast change, but colors are very close.

Preston said...

Now that I'm home, I'm trying a further experiment. On a Windows 7 machine, I have a dual monitor setup with a NEC P221W wide gamut as my primary display and an old standard 17-inch Dell LCD as the secondary. Both are calibrated with a ColorMunki Photo. Web safe color charts (like http://html-color-codes.com/) look identical on both monitors.

Comparing the gballard.net samples in unmanaged browsers the colors look exactly right on both monitors. In Safari for Windows, the tagged images actually look neutral, but extremely desaturated, while the untagged images are definitely too yellow on both monitors.

It is clear to me now that we can't expect that a browser to render accurate color. To insure that images are displayed accurately across computers with calibrated monitors, we need to use applications like X-Rite's Digital Pouch. If anyone is interested in seeing Digital Pouch, let me know and I'll create one for download.

Ray Meibaum said...

Thanks for researching this further. I uploaded an HTML web gallery from Lightroom last night and I think the colors are pretty accurate. While the browsers are likely to show some variation, it's possible that it's only the Flash gallery photos that display the extreme red. I use an older version of monoslideshow for my online portfolio - maybe it's the combination of the browser and Flash? I've read that older versions of Flash are not color-managed.
Interesting that the Flash gallery shows the same problems in the Chrome browser. If you get time try comparing the 11th photo in the Architecture portfolio with the photo on the dealer page and let me know how they compare on your wide-gamut. My displays show extreme red saturation in the Flash version.

Thanks again for the help.