Some people claim that images displayed on a Safari browser look better than that on Firefox. This turned out to be caused by inability of older Firefox to adapt system's color management conventions. Thus, if you calibrate your system using Spyder, or Colo Munki, or Pantone Huey, your images will look calibrated using 'preview' but will look slightly off color on Firefox.
Firefox 3.0 added color management capability and this article tries to depict on how to enable this capability. There are some notes however that say that enabling this option slows down your computer, but i did not notice any on mine.
1. Type "about:config" on your address bar.
2. There will be a warning window. Click OK anyways
3. type in color in the filter box
4. Double click on gfx.color_management.enabled so that it turns from false to true.
5. You dont actually need to enter the following value, since after enabling the above, Firefox will adapt to system's ICM profile. However, should you want to specify, look for the variable gfx.color_management.display_profile and enter your ICM file location. For example mine will be: \\WINDOWS\system32\spool\drivers\color\monitorprofilestef.icm (notice the \\ in front).
Hakuna Matata is Lion King language for "no worries for the rest of your days." Enjoy your stay....