VX6854LC datasheet(103/114 Pages) STMICROELECTRONICS

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VX6854LC

Defect categorization

110

Defect categorization

13.1

Pixel defects

Illuminated defects are tested with a flat field illumination and a pass-fail criteria that is a

percentage deviation from a local mean. In order that the sensor can be effectively tested in

a reasonable test time, it is necessary to put the limits of gain error above the normal noise

distribution of photon shot noise and sensor noise otherwise false single pixel fails will be

detected. A typical defect criteria for single-pixel gain errors is ± 9%. In fact, any element in

the array outside ±9% is a “minor” fail, and outside of ± 25% is a “major” fail. Note that the

defect detection method is applied to raw bayer images.

13.2

Sensor array area definition

For specific aspects of pixel defect testing the image sensor array is subdivided into two

regions as illustrated in Figure 43.

Figure 43. VX6854LC pixel defect test area

The inner array in Figure 43 is centre justified, in the x and y axis, with respect to the outer

array. The inner array is 50% of the full width and 50% of the full height of the larger outer

array, therefore the inner array is one quarter of the area of the outer array.

Outer array

Inner array

1032 pixels

2064 pixels

1552

pixels

776

pixels

VX6854LC 데이터시트(PDF) 103 Page - STMicroelectronics