Selectively boost or decrease saturation using a saturation mask. For boosting saturation, this helps avoid blowing out already-saturated areas, and for decreasing saturation, this helps avoid washing out the whole picture. YOU MUST INSTALL THE HSBHSL plugin that comes on the photoshop disc (it is not automatically installed when installing photoshop). To install, find the plugin in the Goodies/Adobe Photoshop/Optional Plug-Ins/ folder (the folder names may vary slightly depending upon your version). Copy the HSBHSL folder to your adobe program directory plugins (the path will be something like C:/Program Files/Adobe/Adobe Photoshop/Plug-Ins). Then restart Photoshop. The plugin should show up as a filter in the "Other" category. This action gives you several different variations--a number of different boosts/desats using the channel mixer (each labeled with the amount of effect) and one boost and one desat using the Hue/Saturation control (since the saturation can easily be adjusted after running the effect when using the Hue/Sat control). You are also left with a copy of the Saturation Mask as an alpha channel. The positive of the saturation mask is used when decreasing saturation. The negative is used when increasing saturation.
