Background redundancy: Occurs when the subject does not occupy the entire field of view, so that individual images (frames) of a clip contain large areas of background. This is especially frequent in images of vermiform animals like nematodes.
Clip: a sequence of images recorded chronologically in one operation.
Codec: A compression/decompression algorithm. This allows reduction of the file size of the source clip through a range of algorithms, some of which will preserve image quality while others will reduce it. Some codecs decompress at the same speed as compression, while others take longer to compress than to decompress. Also, different movie player programs are equipped with different selections of codecs.
Duration redundancy: Occurs when some of the frames at the start and/or end of a source clip contain no focused parts of the nematode. In order to obtain a complete series of focusing levels, it is best to start recording a fraction of a second earlier than strictly required, and to stop recording a fraction of a second later. In that case, the clip will definitely include the outermost surfaces of the specimen, but the first and last frames of the source clip will be redundant.
Finished clip: A clip edited, modified and/or compressed in various ways to optimize information content and minimize file size.
Frame: One individual image in the chronologically contiguous series of images that constitutes a clip.
Frame redundancy: Occurs when some frames in a source clip are effectively indistinguishable. While it is an essential advantage of video capture that many levels of focus are recorded in one operation, this does not mean that all levels of focus can and should be captured. Usually, only about 25-30 levels are significantly different - as is also the case with 4-D microscopy - rendering the remainder of the captured focusing levels basically redundant.
Pixel redundancy: Occurs when the data rate of video capture exceeds the value required for maximal discernible quality of the final images. In other words, redundant information is stored because more bytes are assigned to each pixel than can be depicted on the end user's computer display.
Redundancy: The recording and storage of more information than effectively needed. Five kinds are distinguished here: background, duration, frame, pixel and resolution redundancy.
Resolution redundancy: Occurs when the resolution of video capture exceeds the maximal value imposed by limits of clip file size. In other words, redundant information is generated because more pixels are stored per frame than can be accommodated within file size limits set by data storage devices (e.g. 1.4 Mb maximal capacity for floppy disks) or transmission methods (e.g. 1 Mb maximal size for email attachments sent through certain service providers).
Scrubbing: Playback of a clip (forwards or in reverse) by clicking and dragging a slider at the bottom of a video display window.
Sequence: A series of clips edited and arranged in sequential order so as to obtain a finished "video program".
Source clip: An unedited clip as obtained immediately after capture, prior to any editing or modification.