Shaping light by hand, on a grey layer

A darkroom technique that survived

Under an enlarger, you held a piece of card on a wire over part of the print to give it less light (dodging, making it lighter) or cupped your hands to give one area more: burning, making it darker. Every great print of the twentieth century was made this way. Ansel Adams’s negatives were ordinary; his prints were maps of where he had held his hands.

The digital version is the same idea and it is still the most powerful local tool in editing, because it works on form rather than on regions. A curve applied to a selection has an inside and an outside. Dodging and burning has neither; it has a gradient of emphasis that follows the shape of what is in the picture.

Do not use the Dodge and Burn tools

The tools with those names in the toolbar paint directly on the pixels. They are destructive, they shift saturation as a side effect, and they are hard to modulate. Nobody who does this for a living uses them.

The technique everyone actually uses:

1. New layer, filled with 50 per cent grey (Edit > Fill > 50% Grey).
2. Set its blend mode to Soft Light or Overlay.
3. Mid-grey is the neutral value in both modes, so the layer is currently invisible.
4. Paint with a soft brush at 5 to 10 per cent opacity: white to lighten, black to darken, X to swap between them.
5. Build up in many passes. Ten strokes at 5 per cent is controllable; one at 50 per cent is a decision.

Everything about that is reversible. Paint the opposite colour to undo locally. Drop the layer opacity to reduce the whole effect. Delete the layer to start again. Add a mask to the grey layer if you want to fence the work.

Soft Light is gentler and better for skin and subtle form. Overlay is roughly twice the strength, better for shaping a landscape or pushing a background down.

The same technique works in GIMP (fill with 50 per cent grey, set the layer mode to Soft light), Krita, Photopea and Affinity. No tool is missing here.

The alternative: two curves and two masks

The other standard method, preferred by some retouchers because it is fully re-editable:

• A Curves layer pulled up, mask inverted to black: this is your dodge layer. Paint white on its mask where you want it lighter.
• A Curves layer pulled down, mask inverted to black: your burn layer. Paint white where you want it darker.

The advantage over the grey layer is that you can change the strength of all your dodging at once by re-editing the curve, long after the painting is done. The disadvantage is two layers and two masks instead of one. Both are correct; pick one and get fluent.

What you are actually doing

Dodging and burning is not brightness correction. It is three separate jobs, and knowing which one you are on stops the work looking arbitrary.

Directing the eye. The viewer looks at the brightest, highest-contrast thing in the frame. Darken the corners and the edges slightly, lift the subject slightly, and the picture reads in the order you intended. This is why almost every advertisement and film poster is darker at the edges.

Building form. A face, a fruit, a fabric fold is a three-dimensional object described only by light. Deepening the shadow side and lifting the lit side makes it rounder. Reversing it makes it flat. This is drawing, and it responds to the same understanding a painter uses.

Evening out what the light did badly. A hot spot from a flash, a bright patch of floor, a distracting white sign in the background. This is correction, and it is the least interesting of the three.

Checking your own work

Dodging and burning at 5 per cent is subtle by design, which means it is easy to produce a blotchy, uneven mess without noticing until the print.

The viewing layer is how retouchers check. At the top of the stack, add:

• A Black and White adjustment layer, which removes the colour so you are judging tone only.
• Above it, a Curves layer with a very steep S: nearly vertical through the middle. This exaggerates every tonal variation enormously.

Switch that group on and your gentle dodging becomes glaringly visible, along with every lumpy edge and every patch you missed. Fix it, switch the group off, and the actual image is clean. Turn the viewing layers off before exporting; leaving them on is a classic and embarrassing mistake.

The limits

It does not create data. Dodging a black shadow lifts it to a noisy grey, because there was nothing there to reveal. Burning a clipped highlight gives you grey with no texture. Check what is actually in the area before spending twenty minutes on it.

It amplifies noise in the shadows. Lifting a dark region multiplies its noise along with its signal. Denoise first if the file is noisy, or restrict your dodging to areas with real signal.

It bands in 8-bit. Very gentle work over a smooth gradient (a studio backdrop, a sky) lands between the available levels and shows as terracing. This is a 16-bit job.

And it is slow. Properly dodging and burning a portrait is 20 to 45 minutes of work. It is why high-end retouching costs what it does, and why it is not the right tool for 400 catalogue images, where a masked curve is.