Lobster

I have been investigating the "demo" version of this tool and like it.


From their website:
What does Lobster do?

Lobster works inside Photoshop to accurately separate the tonality and colour of your image using the Layers palette.

Lobster creates four new layers from your RGB image: Luminosity (a very specific type of tonality) and Red-Green-Blue Chromaticity Set. (Covering Hue and Saturation).

This separation allows a "divide and conquer" approach to the editing of your images, where for example changes can be safely and accurately made to your Luminosity layer without affecting the Hue and Saturation of your file - an action not possible in Photoshop.

Lobster gives you new uses for and insights into the following elements of Photoshop:
Levels, Curves, Selective Color and all other Adjustment Layers.

Lobster website