Quantitative Video analysis for Qualitative Research: Glossary

A video file contains a series of images, and each image is a matrix that can be operated on.

A framerate of 25 fps means that there are 25 frames (images) per second.

The bit rate tells about the variation of each pixel, an 8-bit image stores values from 0-255.

A colour image uses 4 planes, Alpha, Red, Green, Blue, while greyscale only uses 1 plane.

A semicolon at the end of a line will not display the commands output.

Toolboxes need to be added to path before they can be used.

Motion videos display the parts of the video that change between frames.

A motiongram displays how motion changes over time.

Quantity and centroid of motion are quantitative features.

A motion average image is a kind of open-shutter technique.

A motion history video visualizes motion trajectories.

All functions can be run on any type of video input.

A video is trimmed in time, cropped in space, and downsampled in pixels.

There are a number of things to set and modify in the code, most of which are documented in the help files.

Optical flow shows the direction of motion, but is much more CPU-consuming.

MGT is the starting point for a lot of more advanced analyses.

An MGT struct can be used to organize and manipulate different types of data.