is the estimation of which pixels in a frame are different from those in the previous frame.

In video encoding, the process of analyzing previous or future frames to identify blocks that have not changed or have only changed location. Motion vectors are then stored in place of the blocks. This is very computation-intensive and can cause visual artifacts when subject to errors.

This compression method is based on the premise that whilst not all of the picture remains static, some of the picture content will remain in the next image, but in a different place - corresponding to moving objects. Motion estimation is the process by which the encoder tries to ascertain from where in the previous picture a particular area of image came.

The technique of calculating and predicting movements of image elements, normally expressed as a series of motion vectors. MPEG Moving Pictures Experts Group (or often Motion Picture Experts Group); a working group under ISO/IEC and its set of standards for coding of moving pictures and associated audio. Standards are the MPEG-1 and the MPEG-2.

The process of estimating motion vectors during the encoding process.

Finding optimal (or near-optimal) motion vectors.