Blur detection system
First Claim
Patent Images
1. A method of detecting and correcting blur in a digital image stored in a digital file as a sequence of DCT coefficients arranged in a plurality of blocks representing a grid of frequency components, each said block representing a portion of said image, said method comprising:
- (a) reading a plurality of DCT coefficients from said sequence of DCT coefficients, said plurality of DCT coefficients comprising at least two DCT coefficients from each of said plurality of blocks;
(b) calculating from said plurality of DCT coefficients a first blur indicator that quantifies the amount of blur in the block having the least amount of blur among all of said plurality of blocks;
(c) calculating from said plurality of DCT coefficients a second blur indicator that quantifies the amount of blur throughout said digital image; and
(d) selectively applying a filter to said digital image based upon the value of said first blur indicator and said second blur indicator.
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Abstract
A system of estimating and reducing image blur in digital images stored in a digital file as a sequence of DCT coefficients arranged in a plurality of blocks. The disclosed system may preferably calculate one or more blur indicators from selected ones of the sequence of DCT coefficients and selectively filter a digital image based upon the calculated one or more blur indicators.
85 Citations
12 Claims
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1. A method of detecting and correcting blur in a digital image stored in a digital file as a sequence of DCT coefficients arranged in a plurality of blocks representing a grid of frequency components, each said block representing a portion of said image, said method comprising:
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(a) reading a plurality of DCT coefficients from said sequence of DCT coefficients, said plurality of DCT coefficients comprising at least two DCT coefficients from each of said plurality of blocks; (b) calculating from said plurality of DCT coefficients a first blur indicator that quantifies the amount of blur in the block having the least amount of blur among all of said plurality of blocks; (c) calculating from said plurality of DCT coefficients a second blur indicator that quantifies the amount of blur throughout said digital image; and (d) selectively applying a filter to said digital image based upon the value of said first blur indicator and said second blur indicator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of detecting and correcting blur in a digital image stored in a digital file as a sequence of DCT coefficients arranged in a plurality of blocks representing a grid of horizontal and vertical frequency components, each said block representing a portion of said image, said method comprising:
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(a) obtaining a two-dimensional histogram that associates DCT coefficients with respective discrete vertical and horizontal frequency component combinations; (b) summarizing said two-dimensional histogram with a one-dimensional histogram that associates DCT values with respective radial frequency components; (c) calculating at least one blur indicator from said one-dimensional histogram; and (d) selectively applying a filter to said digital image based upon said at least one blur indicator; (e) where said one-dimensional histogram is obtained by dividing said two-dimensional histogram into a plurality of regions of generally increasing frequency and averaging the DCT coefficients within each region for each of said blocks; (f) where said blur indicator is the ratio of a average DCT values of a selective two of said regions.
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11. A method of detecting and correcting blur in a digital image stored in a digital file as a sequence of DCT coefficients arranged in a plurality of blocks representing a grid of horizontal and vertical frequency components, each said block representing a portion of said image, said method comprising:
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(a) obtaining a two-dimensional histogram that associates DCT coefficients with respective discrete vertical and horizontal frequency component combinations; (b) summarizing said two-dimensional histogram with a one-dimensional histogram that associates DCT values with respective radial frequency components; (c) calculating at least one blur indicator from said one-dimensional histogram; and (d) selectively applying a filter to said digital image based upon said at least one blur indicator; (e) where said one-dimensional histogram is obtained by dividing said two-dimensional histogram into a plurality of regions of generally increasing frequency and averaging the DCT coefficients within each region for each of said blocks; (f) further including a first blur indicator and a second blur indicator; (g) where said first blur indicator is the maximum average DCT coefficient within a selective one of said regions and said second blur indicator is the ratio of a average DCT values of a selective two of said regions. - View Dependent Claims (12)
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Specification