Non-destructive dodge and burn
In Photoshop there’s many ways to dodge and burn, layer copies set to lighten and darken, gray layer set to overlay, dodge and burn directly on a copy of the original etc..
However, when you are working on large images, for example medium format RAWs every layer you jump eats HUGE amounts of ram, when you start with a 45MB original you realy want to keep the number of layers down to a minimum.
My favorite way that is adjustable and also takes very little RAM is to create one curves adjustment layer for the shadows, and another one for the highlights. After adding them, turn the shadow curves adjustment layer off and adjust the highlights, never mind that you are affecting the whole image, we will fix that in a sec. Then turn the highlights curves adjustment layer off and adjust the shadows layer.
Select the layer mask of both the curves adjustment layers and hit control+I to flip the mask to black. (If you, like me love shortcuts and can remember them, you can hold down alt when adding the layer mask and it will add a hide all (Black) layer mask)
Now just paint with a soft white brush set to 10% opacity on these layers to build up your dodge and burn.
Not only do you now have just a couple adjustment layers that takes up next to no RAM, you can at any time go back and re-adjust the overall tone of your dodging and burning and since you are using a curves adjustment layer you can even set control points in the curves to make them affect les or more of the overall tone in your dodging and burning.
I useually add both these adjustment layers to a group and then add a mask to the group. I paint in the shadows and highlights paying no mind to getting small halos around fine edges. Then when I’m done I use the group layer mask to fix up any halos I have because I painted over edges.
