How to Use the Curves Tool in Cleanr
Cleanr's curves tool is a tone adjustment feature available exclusively in the AI Pro tier, letting you reshape photo tonality using a catmull-rom spline interface for precise highlight, midtone, and shadow control.
What is Cleanr's Curves Tool
Cleanr by MRVL is a complete photo cleanup studio in one app, and the curves tool is one of its advanced adjustments. The curves feature uses a catmull-rom spline, which means you can click and drag points along a diagonal line to brighten or darken specific tonal ranges in your photo. Unlike simple sliders, curves let you adjust shadows, midtones, and highlights independently in a single tool. This is useful when a photo needs more nuance than brightness or contrast alone can provide. The curves tool sits alongside HSL colour adjustments and selective adjust (brush-mask edits) in the AI Pro subscription tier. As of January 2026, it remains one of the most powerful tonal controls available in mobile photo editors.
Accessing the Curves Tool
The curves tool is only available if you subscribe to Cleanr's AI Pro tier (£12.99 per month or £99.99 per year). Free and Plus users will not see the curves option. To access it, open Cleanr, select a photo, and look for the adjustments panel. You'll find curves listed alongside brightness, contrast, saturation, warmth, and sharpness. Tap the curves icon to open the spline editor. The interface shows a diagonal line from bottom left to top right; this represents the tonal range of your image. The X-axis is input (original brightness), and the Y-axis is output (adjusted brightness).
Using the Curves Interface
To adjust the curves, tap anywhere on the diagonal line to add a control point. Drag that point upward to brighten that tonal range, or downward to darken it. A point near the bottom left controls shadows; points in the middle affect midtones; points near the top right control highlights. The catmull-rom spline automatically smooths the curve between your points, so you don't create harsh transitions. Start with one or two points for subtle adjustments. If you add too many points, the curve becomes unpredictable. Once you've shaped the curve to your liking, tap outside the editor or press apply to commit the change. You can undo and redo curves adjustments just like other edits in Cleanr.
Common Curves Adjustments
A gentle S-curve (dip shadows slightly, lift highlights slightly) increases contrast without changing overall exposure. Lifting the entire curve brightens the photo; lowering it darkens it. If shadows are crushed (too dark with no detail), drag the shadow point upward to recover detail. If highlights are blown (pure white with no texture), drag the highlight point downward to recover highlights. Curves work best after you've done object removal and auto-enhance, so you're refining an already clean image. Remember that curves are non-destructive in Cleanr; you can always reset or adjust them further without losing quality.
When to Use Curves vs Other Tools
If you only need to brighten or darken a photo, use the brightness slider. If you want to tweak individual colours (reds, greens, blues), use HSL colour (also AI Pro). If you want to brighten or darken only part of your photo (e.g., just the face), use selective adjust with the brush mask. Curves are best for global tonal shaping when simple adjustments aren't enough. Cleanr also includes a full suite of other editing tools like sky replacement, background removal, object removal, and portrait blur, so curves are just one of many options depending on what your photo needs.
AI Pro Tier and Other Advanced Features
Curves are exclusive to AI Pro (£12.99/mo, £99.99/yr), which also includes HSL colour adjustments, selective adjust, face retouch via Vision face detection, and generative fill for brush-based content-aware inpainting. If you only need basic cleanup, the Free tier offers auto-enhance, object removal, background removal, sky replacement, and 3 free enhancements per day with no watermark. The Plus tier (£3.99/mo, £29.99/yr) unlocks unlimited edits and batch processing of 10 photos. For most faith creators and small business owners, Plus is enough; curves are for photographers who want pixel-level tonal control.
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Frequently asked questions
Is the curves tool free in Cleanr?
No. Curves are exclusive to the AI Pro tier (£12.99/mo or £99.99/yr). Free and Plus subscribers do not have access to the curves tool.
What is a catmull-rom spline?
It is a mathematical curve that smoothly interpolates between control points you add to the line. This means Cleanr automatically creates smooth transitions between your adjustments, avoiding harsh jumps in brightness.
Can I use curves on batch exports?
Yes. The AI Pro tier includes unlimited batch processing (50+ photos), so you can apply curves adjustments to multiple photos at once.
How do curves differ from brightness and contrast sliders?
Brightness and contrast are global and uniform. Curves let you adjust shadows, midtones, and highlights independently, offering far more tonal control in a single tool.
Can I save curves presets in Cleanr?
Cleanr saves your edit history in the cloud (Plus tier and above), so you can reapply previous edits to new photos, but custom curves presets are not saved separately as downloadable files.
What other AI Pro features work with curves?
Curves work alongside HSL colour adjustments, selective adjust (brush mask), face retouch, and generative fill. All are part of the AI Pro subscription.