In
video compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...
algorithms
In mathematics and computer science, an algorithm () is a finite sequence of mathematically rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for per ...
a residual frame is formed by subtracting the
reference frame from the desired
frame. This difference is known as the error or residual
frame. The residual frame normally has less
information entropy
In information theory, the entropy of a random variable quantifies the average level of uncertainty or information associated with the variable's potential states or possible outcomes. This measures the expected amount of information needed ...
, due to nearby video frames having similarities, and therefore requires fewer
bits to compress.
An
encoder will use various algorithms such as
motion estimation
In computer vision and image processing, motion estimation is the process of determining ''motion vectors'' that describe the transformation from one 2D image to another; usually from adjacent video frame, frames in a video sequence. It is an wel ...
to construct a frame that describes the differences. This allows a
decoder to use the reference frame plus the differences to construct the desired frame.
See also
*
Motion compensation
Motion compensation in computing is an algorithmic technique used to predict a frame in a video given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video ...
References
Video compression
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