Fonts of characters are read by a display of 7 segments. It is a form of an electronic display device which is widely used in electronic meters, basic calculators and electronic meters etc.

The coordinates of image define locations of object points on film. The exterior orientation of a camera defines location of points in space and direction of view. The inner orientation of camera defines geometric parameters of imaging process.

PMI system or phase measuring interference system can capture over 2 million data samples. After capturing, it interprets m and n compiles data into a 3-D image of test surface.

Scanning laser gauge can provide an accuracy of ±0.25 ?m for objects of 10 to 50 millimeter diameter. It can also be used for objects of diameter from 0.05 to 450 millimeter and offers repeatability of 0.1 ?m.

For a grayscale image, intensity of image varies across brightness spectrum. This variation is gradual. The intensity is a whole number at any point in a range of 0 to 255, thus it can pick a value from 256 different values.

Chamberscopes offer more magnification than conventional rigid borescopes. They have zoom facility and used for rapid inspection of large chambers. They include variable direction of view with high intensity lightning.

Backlighting is suited when a simple silhouette image is required to obtain maximum image contrast. When certain key features on surface of object are to be inspected, front lighting is used.

A camera may typically form an image 30 times per sec i.e. at 33 m sec intervals. At each time interval entire image has to be captured and frozen for processing by an image processor. An analog to digital converter is used to convert analog voltage of each detector into digital value.

The interferometer uses 2 linear diffraction gratings. These gratings are used to split and recombine light into reference and test beams. The diffracted light of first order from first grating reflects off at a grazing angle and it is test beam. The zero order diffracted light is reference beam and passes parallel to surface.

Tracking and cylindrical bore or or defect inspections are applications of circular scanning. In circular scanning, tracking means obtaining coordinate data necessary to position sensing system along defined patterns.