Help layer for tonal differences during D&B

[Anneke]

When I use D&B for retouching photos, I always make a group of layers that make the image B&W with a bit higher contrast, so it's easier to see where to D&B.
Sometimes there's also tonal differences after D&Bing freckles or other dark spots. Is there a similar approach to make those tones more clear? Like a kind of layer that is more black when the tone is more off? Some kind of hue map?

[gmitchel]

My video called "Dodging & Burning" shows you how to create your own tone map.

http://www.thelightsright.com/DodgingAndBurning

I use a blank layer and the brush tool to quickly draw with bright red and bright green where I want to dodged and burn. I even write out how much I want to dodge or burn. 10%, 25%, etc.

Cheers,

Mitch