Curve (tonality)
In image editing, a curve is a remapping of image tonality, specified as a function from input level to output level, used as a way to emphasize colours or other elements in a picture.[1][2]
Curves can usually be applied to all channels together in an image, or to each channel individually.
Applying a curve to all channels typically changes the brightness in part of the spectrum. Light parts of a picture can be easily made lighter and dark parts darker to increase contrast.[3]
Applying a curve to individual channels can be used to stress a colour. This is particularly efficient in the
Lab colour space due to the separation of luminance and chromaticity,[4] but it can also be used in RGB, CMYK or whatever other colour models
the software supports.
See also
- Blend modes
- Image histogram
- Hurter–Driffield curve
- Tone reproduction curve
References
- ^ The gimp manual
- ^ Adobe web site on curves in Photoshop
- ^ Detailed instructions on the usage of the 'curves' and 'levels' functionality of image editing software; PhotoshopEssentials.com
- ISBN 0-321-35678-0.
External links
- Defanging the Curves Vampire, Dan Margulis, December, 1996