When I open the Filters dropdown menu in CS6 I get the Filters Gallery in gray color instead of black and it won't open. What am I doing wrong - or what should I do to make it work? Thanks!

You may have to switch your mode to 8 bit. I have found the same thing and I find it a little odd that we still have to do this.........

This is incorrect! Almost all filters work just fine in 16 bit and many in 32 bit. If they don't there is something wrong with your installation.

The first thing to try is to reset your preferences file. This is always the first thing to try when PS isn't working right.

Interesting, I reset the preferences and I still can't access the filter gallery unless I switch to 8 bit. Also interesting that when doing a search on the web for "grayed out filter gallery CS6" replies from as recent as 1 month ago state that the image must be in 8 bit mode.........
Is this correct?

I use filters constantly in 16 bit mode. The only time I am ever in 8 bit mode is after an image has been JPEGed for WEB use which is long after a filter would be used. This has been this way for several generations of Photoshop. Most filters became 16 bit at the introduction of CS and almost all of them are now. Something is not right with your set-up but I don't know off the top of my head what it might be.

Only a few of the special effects filters are 8 bit only. certainly the entire Filters menu should not be grayed out. Not even when working with 32 bit color per channel images.

Make sure you do the preference file reset:
http://www.dummies.com/how-to/content/troubleshooting-in-photoshop-cs6.html

I'm having the same results as Randy in that I can only open a file in the Filter Gallery if I convert it to 8 bit. I thought it might be that I start my files in Prophoto RGB (not regular RGB), so I switched one to RGB, but that gave me the same grayed out result. How could we both have installed CS6 incorrectly if that is the problem? System is Windows 7 Professional.

From the link you supplied:

"Commands aren't available,

You move the cursor to the menu and click, only to discover that the command you want is grayed out! Your next stop should be the Image→Mode menu. Check to make sure that the image's color mode and color depth are appropriate for the command you want to use. (Many of Photoshop's filters, for example, can be used only with 8-bit/RGB images.)"

I'm just trying to understand why you see something entirely different than I do ( Mac versus PC ?)

From this link, http://feedback.photoshop.com/photoshop_family/topics/filter_gallery_not_functioning

"Gail Spitler 1 month ago
The words "Filter Gallery" is in light gray rather than the usual black for active menu items.
Gail


Chris Cox (Employee) 1 month ago
That means that it's disabled, probably because your document is in a bit depth or color mode that the filter gallery does not support.

Again, is your document 8 bit/channel RGB?

Gail Spitler 1 month ago
Thanks Chris - you have the key. Document is not 8-bit."

The only filters not available in 16 bit mode are the Distort and the Pixelate filters. All others are available in 16 bit mode. Here's proof:

OK, I think I just figured it out. The question is specific to the Filters Gallery which all it does is give you a representation of what each of the filters will look like on your image. That is still an 8 bit item. But almost all of the filters it represents are 16 bit filters and are available as my screen shot above illustrates.

LOL,
EJ it's apparent you don't turn your photos into digital art. (Not a bad thing) The only group of filters available to you are "stylize" that are in Filters Gallery.
Filters Gallery has these groups:
Artistic
Brush Strokes
Distort
Sketch
Stylize
Texture

Yeah, I just missed the word "Gallery" in Marc's initial question.