Levels in Paint by Zaweba: black, grey and white points

Levels is one of the oldest and most useful adjustments in photo editing. It does three simple things well: sets what counts as black, what counts as white, and where the middle sits. Get those three right and most photos look clearer and more natural. Paint by Zaweba offers Levels with a histogram, a clipping warning, eyedroppers and Auto options.

Reading the dialog

The histogram shows how many pixels there are at each brightness, from black on the left to white on the right. Below it are three draggable input points: black, grey and white. Below those are output points.

You can work on the combined RGB, or on red, green or blue alone.

Setting the black and white points

A photo that looks flat or hazy usually has a histogram that doesn't reach the ends. There's empty space on the left, the right or both. Drag the black input point right to where the histogram begins, and the darkest pixels become true black. Drag the white point left to where the histogram ends, and the brightest become true white. The picture gains contrast without anything being forced.

The clipping warning shows which pixels are being pushed to pure black or pure white. A little clipping in specular highlights or deep shadows is fine; large patches mean you've gone too far and detail is being lost.

The grey input point controls midtone brightness. Drag it left and the picture brightens in the middle without moving black or white; drag it right and it darkens. It's a gentle way to lift a slightly dark photo.

Output points do the opposite of input points. Moving the black output point right makes the darkest tone a dark grey rather than black, softening shadows. Moving the white output point left dims the brightest tone. These are useful for a faded print look, or for preparing a picture for a printer that struggles with deep blacks.

Fixing colour with channels and eyedroppers

If a photo has a colour cast, working on red, green and blue separately helps. Set the black and white points for each channel to where its histogram begins and ends, and the cast often vanishes.

The eyedroppers are quicker. The black eyedropper, clicked on something that should be black, sets that as black. The white one does the same for white. The grey eyedropper, clicked on something that should be neutral grey, such as concrete or a grey jumper, removes a cast by making that point neutral.

Auto

Auto offers per-channel contrast or monochromatic contrast, clip percentages and neutral midtones. Per-channel contrast treats each colour separately and can fix a cast. Monochromatic contrast adjusts all channels together, which keeps colour as it is. Clip percentages decide how much of each end is allowed to clip. Neutral midtones nudges the middle tones towards neutral grey.

Auto is a good first try. Use it, look, and then fine tune.

Where Levels goes wrong

Dragging the black and white points into the histogram, rather than to its edges, clips detail. Watch the clipping warning.

Using the grey eyedropper on something that isn't really neutral, like skin or a warm wall, will put a cast in rather than take one out.

And apply Levels as an adjustment layer where you can. That way you can reopen it, mask it or lower its opacity later.

Levels in Paint by Zaweba is quick to learn and does a lot. Many photos need little more than a careful black point, white point and a touch on the grey.