Autofocus with confidence measure
AssigneeSony Corporation
InventorPingshan Li
Life of this patent
Estimating the term…
Abstract
Autofocusing is performed in response to a weighted sum of previous blur difference depth estimates at each focus adjustment iteration. Variance is also determined across both past and present estimations providing a confidence measure on the present focus position for the given picture. Focus adjustment is repeated until the variance is sufficiently low as to indicate confidence that a proper focus has been attained. The method provides more accurate and rapid focusing than achieved by the best current depth-based techniques, such as those utilizing most recent depth estimation to determine the next lens position. In contrast to this, the present apparatus and method combines all previous depth estimation results in the autofocus process to determine the next lens position based on statistical models and confidence measure.
Claims20
An apparatus for controlling automatic focus, comprising:
- (a) a computer processor configured for controlling an imaging device and associated focus control element;
- (b) memory coupled to said computer processor;
- and
- (c) programming stored in said memory and executable by said computer processor for carrying out an autofocusing process comprising:
- (i) capturing object images;
- (ii) estimating depth between captured image pairs to arrive at a depth estimation;
- (iii) determining a weighted mean of depth estimations and variance which spans both past and present depth estimations;
- (iv) adjusting focus with a focusing movement performed in response to said weighted mean of the depth estimations;
- and
- (v) repeating steps (i) through (iv) until said variance reaches a value that indicates sufficient confidence that a proper focus position has been attained.
An apparatus for electronically capturing images, comprising:
- (a) an imaging device;
- (b) a focus control element coupled to said imaging device and providing a focal range to said imaging device;
- (c) a computer processor coupled to the imaging device and said focus control element;
- (d) memory coupled to said computer processor;
- and
- (e) programming stored in said memory and executable on said computer processor for carrying out an autofocusing process comprising:
- (i) capturing object images;
- (ii) estimating depth between captured image pairs to arrive at a depth estimation;
- (iii) determining a weighted mean of depth estimations and determining variance across present and past collected image pairs;
- (iv) adjusting focus in response to said weighted mean of the depth estimations;
- and
- (v) repeating steps (i) through (iv) in the autofocusing process until said variance reaches a value indicating that sufficient confidence in proper focus has been attained.
A method of automatically adjusting camera focus, comprising:
- (a) capturing a first object image by a camera device;
- (b) capturing an additional object image by the camera device;
- (c) estimating depth between captured image pairs in response to inputting blur difference values between captured object images into a focus matching model which is solved to generate a depth estimation;
- (d) determining the weighted mean of depth estimates and variance across past and present depth estimates;
- (e) adjusting camera focus position with a camera focusing movement within an autofocusing process in response to said weighted mean of the depth estimations;
- and
- (f) repeating steps (b) through (e) until said variance reaches a value indicative of sufficient confidence in achieving a proper focus for the camera device.
Dependencies are inferred from the claim text.