Documentation

Light

Exposure, contrast, highlights, shadows, whites and blacks, plus Auto and HDR.

Light is where most edits begin. The six sliders divide the tonal range between them, so you can move one part of it without dragging everything else along.

SliderWhat it doesWhen to reach for it
ExposureShifts the whole image brighter or darker.The first thing to set. Get overall brightness roughly right before touching anything else.
ContrastPushes darks down and lights up around the midtones.To add punch to a flat frame, or to soften an overly harsh one by going negative.
HighlightsRecovers or brightens the upper tones without moving the rest.Pull it down to bring back detail in a blown sky.
ShadowsLifts or deepens the lower tones.Lift it to open up a dark foreground without flattening the whole picture.
WhitesSets where the brightest pixels land.To set a true white point after the broader tones are in place.
BlacksSets where the darkest pixels land.To restore real black in a washed-out image, or lift it for a faded, filmic look.

Auto

Auto analyses the photo on the device and sets the light sliders to a sensible starting point. It is a starting point, not a verdict: every value it picks stays editable, so treat it as a first draft you then push around.

HDR

HDR switches the panel to work in the extended brightness range that modern iPhone and iPad displays can show, so highlights can go beyond conventional white rather than clipping at it.

Highlights and Whites sound alike but are not. Highlights compresses or expands a broad band of upper tones; Whites moves the clipping point itself. Recovering a bright sky is usually Highlights; setting the top of the tonal range is Whites.

For tonal control finer than six sliders, use the tone curve in curves, HSL and grading. To apply any of this to part of the picture only, put it behind a mask.