Appeal No. 95-5109
Application No. 08/063,665
measurement value on the basis of contrast components of a
field of a video signal.
In the acknowledged prior art, a conventional circuit
(Figure 2) for generating an auto-focus measurement value
band-limited a digital video signal input Y with a high-pass
filter (HPF) 2 before sending the video signal to an absolute
value circuit (ABS) 3 where the video signal was converted
into an absolute value signal representative of contrast
components of the video signal (specification, page 1). The
absolute value signal output from ABS 3 was then sent to a
detecting unit 4 which generated an auto-focus measurement
value EST via one of various conventional approaches
(specification, pages 1 and 2). The “all integration system”
approach (Figure 3A), the “horizontal line peak hold system”
approach (Figure 3B) and the “vertical peak hold system”
approach (Figure 3C) are three of the conventional approaches
(specification, pages 2 and 3).
The detecting unit in appellant’s disclosed and claimed
invention combines the latter two approaches (i.e., the
horizontal line peak hold system and the vertical peak hold
system) to form an auto-focus measurement value EST. In a
2
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