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US 5,861,917 AGranted
Focus detection using an image signal extracted before digital signal processing
AssigneeCanon Kabushiki Kaisha
InventorsMotoi Tariki, Hideyuki Arai
Life of this patent
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Abstract
In an image pickup apparatus having an electronic zooming function for enlarging and interpolating an image by electronic image processing of an image pickup signal output from an image pickup device, a focus is detected by extracting a predetermined focal signal varying depending upon a focal state from the image pickup signal before the image pickup signal undergoes enlargement/interpolation processing by electronic zooming.
Claims31
An image pickup apparatus comprising:
- (A) image pickup means for converting an image into an image pickup signal and outputting the image pickup signal;
- (B) signal processing means, connected to an output of said image pickup means, for performing predetermined processing of an image pickup signal output from said image pickup means to enable a field angle to be changed electronically by forming an interpolation signal from the output image pickup signal and by inserting the interpolation signal in the image pickup signal;
- and
- (C) focus detection means for detecting a focal state by extracting a predetermined signal component varying depending upon the focal state from the image pickup signal intermittently read out from the image pickup means but not yet interpolated.
1 more element
An image pickup apparatus, comprising:
- an image pickup device for converting an image into an image pickup signal and outputting the image pickup signal;
- signal processing means for electronically increasing the magnification of the image by intermittently reading out an image pickup signal from said image pickup device at a transfer rate determined by the magnification of the object image, by forming an interpolation signal from the read-out image pickup signal and by inserting the interpolation signal in the image pickup signal;
- extraction means for extracting a predetermined signal component varying depending upon a focal state from the image pickup signal intermittently read out from the image pickup device but not yet interpolated and not yet having electronically changed the magnification of the object image;
- determination means for determining in-focus/out-of-focus states on the basis of the signal component extracted by said extraction means;
- and
- focusing control means for controlling focusing on the basis of a result of the determination of in-focus/out-of-focus states made by said determination means.
3 more elements
An image pickup apparatus comprising:
- (A) image pickup means;
- (B) signal processing means for performing predetermined processing of an image pickup signal output from said image pickup means to change a field angle electronically;
- (C) focus detection region setting means for setting a focus detection region for detecting a focus in a picture frame;
- and
- (D) control means for controlling said focus detection regions setting means so that the focus detection region is within an area defined by the field angle set by said signal processing means, wherein a size of the focus detection region is different from that of said area defined by the field angle.
2 more elements
An image pickup apparatus comprising:
- (A') image pickup means for converting an image into an image signal and outputting the image signal;
- (A) electronic zooming means for processing the image signal output from said image pickup means for electronic zooming by forming an interpolation signal from the output image signal and by inserting the interpolation signal in the image signal;
- and
- (B) focus detection means for detecting a focal state from the image signal not yet interpolated by the processing of said electronic zooming means.
1 more element
An image pickup apparatus comprising:
- (A) image pickup means for converting an image into an image pickup signal and outputting the image pickup signal;
- (B) signal processing means, connected to an output of said image pickup means, for performing predetermined digital processing of an image pickup signal output from said image pickup means to enable a field angle to be changed electronically by forming an interpolation signal from the output image pickup signal and by inserting the interpolation signal in the image pickup signal;
- and
- (C) detection means for detecting an image pickup condition by extracting a predetermined signal component varying depending upon the image pickup condition from the image pickup signal extracted at a point between the output of said image pickup means and said signal processing means and not yet interpolated by a processing of said signal processing means.
1 more element
An image pickup apparatus comprising:
- image pickup means for converting an image into an image signal and outputting the image signal;
- image storing means for storing the image signal output from said image pickup means;
- signal processing means for performing predetermined processing of the image signal stored in said image storing means to enable a field angle to be changed electronically by forming an interpolation signal from the output image pickup signal and by inserting the interpolation signal in the image pickup signal;
- and
- focus detection means for detecting a focus state by extracting a predetermined signal component varying depending upon the focal state from the image pickup signal intermittently read from the image storing means but not yet interpolated.
2 more elements
Dependencies are inferred from the claim text.