Please change the default setting to 0.
Those experiencing problems can modify the value in about:config, by setting it to 0.
On gfx.color_management.mode, kb.mozillazine.org wrote: Possible values and their effects
[edit]
0) Disable color management.
1) Enable color management for rendered graphics.
2) Enable color management for tagged graphics only. (Default)
Note: These values apply to Firefox 3.5 and SeaMonkey 2. In previous versions, color management was disabled by default via the boolean preference gfx.color_management.enabled set to "false".
Caveats
Without a properly calibrated monitor and a correct color profile, color management may actually make colors look worse.