Possible solution of FF plugin being grayed out when opening an image

This have happened to me too sometimes with many plugins and not only FF, that I open a image and some of the photoshop options are grayed out, and you ask and wonder, WHY this option I have used many times before is not available now ?

And long time searching for a solution to fix it and asking yourself why this happens, and then I found that it was because the image I have choosen is NOT in normal RGB colors, it can have CMYK, or Indexed colors, or in LAB color space, and you do not know it, and try many things and nothing works because you did not notice that little detail that blocks some of the features AND plugins of photoshop.

In this very good FAQ about photoshop you can see the following

Quote
Why is it that some filters are grayed out or not available? This is a common complaint and is due to the fact that certain filters will only work in 8-bit RGB color modes. So when filters are grayed out, it is usually because you are in a CMYK or LAB color mode.

Also there is this Kodak Plug-In Frequently Asked Questions

Quote

I have an image open but the plug-in is grayed out on the menu. Why can't I run the plug-in on this image? The plug-ins work with any RGB digital image file, whether from cameras, film or print scanners or any other source of digitization. If your image is in some other color format like CMYK, just convert the image to RGB format with your image editor before applying a plug-in. If you aren't using the Professional version of the plug-in, make sure that your image is in 8 bit mode. The standard plug-ins do not support 16 bit mode.

Quote
GMM wrote: Thank you SpaceRay! This is very helpful! And an extra thanks from the support team who now know how to deal with this issue

Thanks to you for helping us solve the problems

So be aware that the image you want to use IS IN 8 BIT RGB FORMAT.

For the greater majority of plugins that work with Photoshop they require that:

1 - The image must be a 8 bit RGB file - NOT TRUE FOR FF

2 - Can´t use 16 bit or 32 bit RGB files - NOT TRUE FOR FF

3 - Can´t use the PRO RGB files that are normally in 16 bit - NOT TRUE FOR FF

4 - CAN use the ADOBE RGB if it is in 8 bit RGB - TRUE, AS WELL AS 16- AND 32-BIT RGB

5 - CAN´T use CMYK, Indexed or LAB color space profiles - NOT TRUE FOR FF

6 - Also most probably it will not also work with grayscale color space, must be grayscale image with 8 bit RGB - TRUE FOR FF

7 - Can´t use RAW files without being converted first to RGB 8 bit - TRUE, YOU CAN CONVERT TO A 16-BIT OR A 32-BIT FORMAT AS WELL

8 - Can´t use many of the other weird image formats that are available - PROBABLY TRUE

(text in italics added by moderator)

Of the Photoshop supported formats, FF supports RGB, CMYK, and LAB. And it supports all the bit depths that Photoshop supports for each of those.

BTW, the way to check is to switch the mode of the picture and see if FF is grayed out.