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MultiCam Boards Documentation > MultiCam Documentation > MultiCam User Guide > General Topics > Line-Scan Inspection Topics > The Video Line
The Video Line

The observed line is divided into a set of aligned pixels. In the case of a digital line-scan camera, the produced video signal is a set of digital values corresponding to the light intensity measured for each consecutive pixel.

On a timing diagram, the output signal of a digital line-scan camera can be represented as follows.

The observed line is repetitively scanned pixel after pixel from left to right, and the corresponding light intensity is translated into a set of digital numbers. The digital numbers are quickly output over a digital bus at a speed known as the pixel frequency.

A fixed number of pixels is output for each line. The operation consisting in outputting a full line information is called the readout process.

The readout process is periodically repeated. The recurrence period is called the line period, associated to its inverse value the line frequency.

It should be understood that the line information of two successive readout processes is not identical. Because the inspected web moves, the observed light intensity pattern under the camera changes, and so changes the digital output pattern.

Note. The left to right order presented in this explanation is for example only. Mechanical and optical considerations may lead to the opposite order as well.