average
Mathematical average. Sum of all values divided by the number of values provided.

covariance
In probability theory and statistics, covariance is a measure of how much two random variables change together. http://en.wikipedia.org/wiki/Covariance

oauthrequest
jsOAuth's submodule for signing http requests

pnm
A Portable Any Map parser http://netpbm.sourceforge.net/doc/pnm.html

psnr
Peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic range, PSNR is usually expressed in terms of the logarithmic decibel scale.

ssim
The structural similarity (SSIM) index is a method for measuring the similarity between two images. The SSIM index is a full reference metric; in other words, the measuring of image quality based on an initial uncompressed or distortion-free image as reference. SSIM is designed to improve on traditional methods like peak signal-to-noise ratio (PSNR) and mean squared error (MSE), which have proven to be inconsistent with human eye perception.

torque
Control servos via a SSC or Torobot servo controller

variance
In probability theory and statistics, variance measures how far a set of numbers is spread out. http://en.wikipedia.org/wiki/Variance