PhotoCurves is one of the most powerful and flexible image editing tool available on the iPhone, essentially enabling you to create your own filters. Since photographers effectively paint with light, curves is central to their practice because it affects light's two primary influences: tones and contrast.

Open an image in PhotoCurves, tap a point on the curve itself, and drag it to the desired position. This will bend the curve. Bending the curve will take input tones and selectively stretch or compress them. A tonal curve is controlled using any number of anchor points. A diagonal line through the center will therefore leave tones unchanged. To remove a control point, click and drag it off the graph.

The curves/effects can be layered to produce even more dynamic results. You can also zoom in and out (pinching motion), as well as pan (swiping motion).

PhotoCurves supports editing in RGB, CMYK and CIELAB color spaces.

OTHER FEATURES:
-Load photos from your camera and your photo albums
-Edit in portrait or landscape mode
-Hide the toolbar in full screen mode
-Resume previous sessions if interrupted
-Save to 4 different output sizes; 640x480, 800x600, 1024x768, 1600x1200 (Change through settings menu)

For even more features and control check out PhotoForge also available on the app store.