In a lot of machine vision applications it is important to know the exact time at which a camera records its image. For example if a strobe light is used, the camera should record when the strobe is on and not when the strobe is off! This is done via accurate triggering of the camera.
Another situation where latency or accurate triggering is important is if multiple cameras are being used. To be able to relate images with each other and to construct for example 3D images from a set of 2D images, such as with 3D All Optical Inspection (3D-AOI), it is necessary that the images are recorded at exactly the same time. This is especially true if the object of interest is moving along your inspection machine.