ASX340CS datasheet(43/74 Pages) ONSEMI

43 / 74 page

ASX340CS_DS Rev. F Pub. 6/15 EN

©Semiconductor Components Industries, LLC, 2015.

ASX340CS: 1/4-Inch Color CMOS NTSC/PAL Digital Image Sensor

Overlay Adjustment

To ensure a correct position of the overlay to compensate for assembly deviation, the

overlay can be adjusted with assistance from the overlay statistics engine:

• The overlay statistics engine supports a windowed 8-bin luma histogram, either row-

wise (vertical) or column-wise (horizontal).

• The example calibration statistics can be used to perform an automatic successive-

approximation search of a cross-hair target within the scene.

• On the first frame, the firmware performs a coarse horizontal search, followed by a

coarse vertical search in the second frame.

• In subsequent frames, the firmware reduces the region-of-interest of the search to the

histogram bins containing the greatest accumulator values, thereby refining the

search.

• The resultant X, Y location of the cross-hair target can be used to assign a calibration

value of offset selected overlay graphic image positions within the output image.

• The calibration statistics patch also supports a manual mode, which allows the host

to access the raw accumulator values directly.

Figure 25:

Overlay Calibration

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