The curves tool on iPhone
Last updated 2 June 2026
The curves tool is the most precise way to shape an image: you bend a line to lift shadows, roll off highlights, or add an S-curve for contrast. A tone curve shapes brightness; per-channel RGB curves shape colour. On the iPhone, EditMe has both, part of EditMe Pro, on the device.
Tone curve and RGB curves
The tone curve maps input brightness to output: drag the middle up to lift, pull the ends for contrast, or use a preset shape. EditMe offers five (linear, S, inverse-S, high-key, low-key). RGB curves do the same per colour channel, so you can warm the highlights and cool the shadows by bending red, green, and blue independently, the precise version of a colour cast.
Curves in EditMe
EditMe gives you a five-point tone curve with five presets, plus independent red, green, and blue curves. Both run on the device with no network, and edits are non-destructive. The curves tools are part of EditMe Pro; the app is free to start.
How it compares
| What you can do | EditMe curves | Sliders only |
|---|---|---|
| Shape any part of the tonal range | Yes | No |
| Preset curve shapes (S, high-key) | Yes | No |
| Per-channel R, G, B curves | Yes | No |
| Runs on device, nothing uploaded | Yes | Varies |
| Non-destructive | Yes | Varies |
Frequently asked questions
What does a curves tool do?
It maps input brightness to output along a line you bend. Lifting the middle brightens, pulling the ends adds contrast, and an S-shape is the classic contrast curve.
What are RGB curves for?
Colour. A separate curve for red, green, and blue lets you tint parts of the tonal range precisely, for example warming highlights while cooling shadows.
Is there a curves tool on iPhone?
Yes. EditMe has a five-point tone curve with presets and per-channel RGB curves, on the device. They are part of EditMe Pro.
Is EditMe free?
EditMe is free to start. The curves tools are part of the optional EditMe Pro; basic editing and film-negative inversion work without it.