RGB Curves

Curves is the closest thing Darkroom has to a blank canvas. With it you can fix exposure, build contrast exactly where you want it, lift blacks into a soft fade, and tune color tone region by region. It's powerful enough that you can recreate most popular film and filter looks with this one tool. Which is exactly why it became the foundation Darkroom was built around.

A simple mental model helps: every pixel is three buckets of light — red, green, and blue. Curves sorts your photo into tonal regions (blacks, shadows, midtones, highlights, whites) and lets you add or drain light from those buckets within each region. Pick a channel from the selector — RGB moves all three buckets at once (brightness and contrast); Red, Green, and Blue move one at a time (color and tone). You'll also find HSL Curves in the same tool. Curves lives in the Edit view toolbar.

The Curves editor in Darkroom with the tone regions and channel selector
Curves divides the image into tonal regions; each point you move remaps how those input tones come out.

Points on and off the track

Curves start with five handles on a track, so it’s easy to get going. Those handles aren’t locked to the track. You can pull a handle off it to place the edit more precisely. Double tap a handle to reset it, and snap it back onto the track when you want that simpler control again.

A few important details:

  • Black and white points can leave the track. You can move the left and right endpoints of the curve inward horizontally to change where those endpoints begin, and move them vertically to create a fade effect on your whites and blacks.
  • Endpoint moves preserve the curve by default. When you move the black or white point, the in-between points move with them by default, helping the overall shape stay intact.
  • In-between points can leave the track too. Shadow, midtone, and highlight handles can move off the track when you want more expressive contrast and color work, just drag them horizontally to move them off the track.

Curve histograms

Every curve — RGB and HSL — shows a relevant histogram behind it. Instead of editing against an empty graph, you can see the tonal or color distribution you’re shaping directly behind the curve itself.

Channel picker

With RGB curves, individual color channels, and HSL curves living together, the channel picker is designed to keep that power navigable. On Mac, Curves uses a stack of expanding curve panels that take advantage of vertical space. On iPhone, the channel picker on the left is scrollable so every curve stays accessible without crowding the editing area.

The RGB curve: selective brightness and contrast

The RGB curve controls the amount of light in your photo, but unlike the Brightness slider, it lets you do it selectively, one tonal region at a time. That's the whole point. Brighten a dark landscape foreground by pulling up only the shadows and midtones, and your clouds keep all their detail instead of blowing out.

Two shapes do most of the work:

  • A bow (up or down) raises or lowers brightness across the regions you bend. Bow the shadows up to open them; bow the highlights down to rein them in.
  • An S-curve adds contrast: lift the highlights, drop the shadows, and the image gains punch while the midtones hold. Flatten it instead to soften a harsh photo.
  • An inverted RGB curve line will create a negative of the image. This can be useful if you want make a photo look like a negative film. Or if you want to color correct a scanned negative film.
  • A raised black point will create a vintage faded look.

Pull a region all the way up and it goes white; all the way down and it goes black — handy for crushing shadows into a silhouette or washing out highlights to focus attention. Keep an eye on the Histogram so you don't clip more than you mean to.

Per-channel Red, Green, and Blue curves

The Red, Green, and Blue channels are where personal style lives. Adjusting them in different regions gives a photo a two-tone cast — say, slightly more red in the shadows and a touch less in the highlights, which is precisely how film stocks earned their signature looks. A film that was more sensitive to green in low light gave shadows a green cast; pull the green channel up in the shadows and you've recreated it.

The trick is restraint and coordination. Color curves usually move together: to build a contrasty, toned look, give all three an S-curve and let the small differences between them create the tone. Big moves on a single channel contaminate neutrals and skin, so make small adjustments, tapping just above or below the curve nudges it 1% at a time for fine control.

Fades

A fade is just a curve move: lift the blacks toward gray and drop the whites toward gray. The result is the soft, airy look that defined the Instagram and VSCO era, and because it crushes nearby values together, it also simplifies detail and pulls the eye toward your focal point. Push it gently for a whisper of softness, or hard for a bold, washed-out style. Bias the channels differently and your fade picks up color: warmer highlights, cooler shadows.

With black and white points able to leave the track, fades are also easier to refine: lift for a matte look, pull endpoints inward to reshape where the fade begins, and let the in-between points travel with the endpoints when you want the overall curve shape preserved.

A useful habit

When an edit starts looking strange and you can't tell which channel is causing it, long-press the channel selector to toggle that single curve off while keeping everything else in place. It's the fastest way to isolate what a curve is actually doing.

Curves works best early, before finishing effects, and pairs naturally with Color Grading for stylistic color, then save the whole thing as a preset to reuse it.

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