Raspy

Exposure vs brightness, highlights vs shadows: what each slider does

Published · 6 min read

Drag Exposure and the photo gets brighter. Drag Brightness and the photo gets brighter. Drag Shadows and, again, brighter. The names come from darkroom and camera vocabulary, and each one touches a different part of the tonal range. Once you know which part, the right slider for a given photo is usually obvious.

Think in three zones

Every photo's tones run from black to white. Call the darkest third the shadows, the middle third the midtones, and the brightest third the highlights. Each light slider has a home zone and a spill into its neighbours. Knowing the home zone is most of the skill.

Exposure

Home zone: everything. Exposure multiplies the light in the whole image, the way a wider aperture or a longer shutter would have. Every tone moves, and bright tones move further than dark ones in absolute terms, so the photo keeps its character while getting lighter or darker overall. Reach for it first when the whole photo is off, and use small amounts; a little goes a long way, and pushing it far clips highlights to white with nothing left to recover.

Brightness

Home zone: midtones. Brightness lifts the middle of the range while holding on to the ends, so blacks stay black and whites stay white. It is the slider for a photo that is correctly exposed but feels dim, and it is the slider people reach for first when they should have used Exposure or Shadows. If the photo looks flat afterwards, that is why.

Highlights

Home zone: the brightest tones. On the iPhone, and in Raspy, dragging Highlights to the right darkens them, which is the opposite of what the name suggests and trips most people up once. It is the recovery slider: a sky that has gone white, a window that has blown out, a face lit too hard by flash. Positive values pull the detail back. Negative values push the bright tones brighter, for a deliberately airy look.

Shadows

Home zone: the darkest tones. Positive Shadows lifts them, revealing what was hiding in the dark without touching the sky or a bright wall. It is the fix for a backlit subject. Negative Shadows deepens them, for a moodier photo. The cost of lifting is noise, since the dark parts of a photo hold the least information, and a halo where a dark edge meets a bright one if you go far.

Brilliance

Home zone: shadows and highlights together, in opposite directions. Brilliance is Apple's one-slider fix: it lifts the dark areas and tones down the bright ones, then adds a little local contrast so the result does not look flat. For a photo shot into the light it is often the only slider you need. It does have a look, and too much of it makes a photo feel processed.

Contrast

Home zone: the ends, pushed apart or pulled together. Positive Contrast makes darks darker and lights lighter; negative flattens the range. Use it last and sparingly. Most photos want a small positive nudge after Shadows or Brightness has been raised, to restore what those sliders flattened.

Black point

Home zone: the very darkest tones. Black point decides what the darkest pixel is allowed to be. Raising it forces the deep shadows to true black, which cures the grey, hazy look that comes after brightening. Lowering it lets them sit above black, for a faded film feel. It is a finishing slider, applied after everything else.

A working order

  1. Exposure, to get the midtones roughly right.
  2. Highlights and Shadows, to fix the ends.
  3. Brightness only if the middle still feels dim.
  4. Contrast, a nudge, if it looks flat.
  5. Black point, to anchor the blacks.

Hold the photo to compare with the original after each step. Under the hood these sliders work in linear light, the way the camera recorded it, so they combine predictably; the order above is about judgement, not maths.