thumb|right|A two-dimensional pink noise grayscale image, generated with a computer program; some fields observed in nature are characterized by a similar power spectrum thumb|right|A 3D pink noise image, generated with a computer program, viewed as an animation in which each frame is a 2D slice Pink noise, noise, fractional noise or fractal noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave interval (halving or doubling in frequency) carries an equal amount of noise energy.
thumb|right|a two-dimensional pink noise grayscale image generated with a computer program; some fields observed in nature are characterized by a similar power spectrum thumb|right|a 3d pink noise image generated with a computer program viewed as an animation in which each frame is a 2d slice pink noise noise fractional noise or fractal noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal in pink noise each octave interval (halving or doubling in frequency) carries an equal amount of noise energy