US5978519A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic image cropping
Assignee: Xerox Corp
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Filing: 1996-08-06
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Granted: 1999-11-02
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Expires: 2016-08-06
Abstract
Abstract The present invention describes a method for automatic cropping of images containing regions where intensity levels are uniform and other regions where intensity levels vary considerably. An image to be automatically cropped is scaled down to a grid and divided into non-overlapping blocks. The mean and variance of intensity levels are calculated for each block. Based on the distribution of variances in the blocks, a threshold is selected for the variance. All blocks with a variance higher than this threshold variance are selected as regions of interest. The regions of interest are then cropped to a bounding rectangle.
Inventors
- 👤 James E. Bollman
- 👤 Ramana L. Rao
- 👤 Dennis L. Venable
- 👤 Reiner Eschbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:59
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/70
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
127 words
A method for automatically cropping an image, comprising: scaling down said image to a grid having four sides; dividing said grid into a plurality of non-overlapping blocks; calculating a mean intensity level for each of said blocks; calculating a variance of an intensity level for each of said blocks; creating a variance profile for said blocks; calculating a threshold variance based on said variance profile; selecting said blocks having said variance higher than said threshold variance as regions of interest; cropping said regions of interest to a bounding rectangle; calculating a profile of edge strengths for said blocks; calculating a threshold edge strength from said profile; and selecting said blocks having an edge strength higher than said threshold edge strength and not selected as regions of interest.
Claim 2
Independent Claim
127 words
A method for automatically cropping an image, comprising: scaling down said image to a grid having four sides; dividing said grid into a plurality of non-overlapping blocks; calculating a mean intensity level for each of said blocks; calculating a variance of an intensity level for each of said blocks; creating a variance profile for said blocks; calculating a threshold variance based on said variance profile; selecting said blocks having said variance higher than said threshold variance as regions of interest; cropping said regions of interest to a bounding rectangle; calculating a profile of edge strengths for said blocks; calculating a threshold edge strength from said profile; and selecting said blocks having an edge strength higher than said threshold edge strength and not selected as regions of interest.
Claim 3
Dependent Claim
16 words
The automatic image cropping method of claim 1, wherein said intensity level is a luminance intensity.
Claim 4
Dependent Claim
18 words
The automatic image cropping method of claim 1, wherein said intensity level is a red, green, blue intensity.
Claim 5
Dependent Claim
45 words
The automatic image cropping method of claim 1, wherein said mean is calculated by the formula ##EQU3## wherein g i is the intensity level of the i th pixel in the block, and N is a height and a width of each block in pixels.
Claim 6
Dependent Claim
17 words
The automatic image cropping method of claim 4, wherein said variance is calculated by the formula ##EQU4##
Claim 7
Dependent Claim
26 words
The automatic image cropping method of claim 1, wherein said threshold voltage variance is selected as a point on a curved portion of a variance profile.
Claim 8
Dependent Claim
18 words
The automatic image cropping method of claim 6, wherein said threshold variance is adjusted by a selectivity factor.
Claim 9
Dependent Claim
20 words
The automatic image cropping method of claim 7, wherein said threshold variance is reduced to select more regions of interest.
Claim 10
Dependent Claim
16 words
The automatic image cropping method of claim 7, wherein said selectivity factor is about forty percent.
Claim 11
Dependent Claim
16 words
The automatic image cropping method of claim 1, wherein said grid is 256 by 256 pixels.
Claim 12
Dependent Claim
17 words
The automatic image cropping method of claim 1, wherein said non-overlapping blocks are 4 by 4 pixels.
Claim 13
Dependent Claim
28 words
The automatic image cropping method of claim 1, wherein said bounding rectangle is defined by a first selected block along each of the four sides of the grid.
Claim 14
Dependent Claim
19 words
The automatic image cropping method of claim 1, further comprising subjecting an autocropped image to a post-processing image operation.
Claim 15
Dependent Claim
23 words
The automatic image cropping method of claim 1, further comprising scaling said bounding rectangle to a larger or smaller dimension having a border.
Claim 16
Dependent Claim
21 words
The automatic image cropping method of claim 14, wherein said border is a default border of about 1% of said dimension.
Claim 17
Dependent Claim
21 words
The automatic image cropping method of claim 1, further comprising marking unselected blocks inside selected regions for further post-processing image operations.
Claim 18
Dependent Claim
28 words
The automatic image cropping method of claim 1, further comprising removing details corresponding to noise in the background of the cropped image to provide a better bounding rectangle.
Claim 19
Independent Claim
148 words
An apparatus for automatically cropping an image, comprising: means for scaling down said image to a grid having four sides; means for dividing said grid into a plurality of non-overlapping blocks; means for calculating a mean intensity level for each said blocks; means for calculating a variance of an intensity level for each of said blocks; means for creating a variance profile for said blocks; means for calculating a threshold variance based on said variance profile; means for selecting said blocks having said variance higher than said threshold variance as regions of interest; means for cropping said regions of interest to a bounding rectangle; means for calculating a profile of edge strengths for said blocks; means for calculating a threshold edge strength from said profile; and means for selecting said blocks having an edge strength higher than said threshold edge strength and not selected as regions of interest.
Claim 20
Independent Claim
148 words
An apparatus for automatically cropping an image, comprising: means for scaling down said image to a grid having four sides; means for dividing said grid into a plurality of non-overlapping blocks; means for calculating a mean intensity level for each said blocks; means for calculating a variance of an intensity level for each of said blocks; means for creating a variance profile for said blocks; means for calculating a threshold variance based on said variance profile; means for selecting said blocks having said variance higher than said threshold variance as regions of interest; means for cropping said regions of interest to a bounding rectangle; means for calculating a profile of edge strengths for said blocks; means for calculating a threshold edge strength from said profile; and means for selecting said blocks having an edge strength higher than said threshold edge strength and not selected as regions of interest.
Claim 21
Dependent Claim
23 words
The apparatus of claim 18, further comprising an input means for acquiring said image and an output means for storing said autocropped image.
Claim 22
Dependent Claim
23 words
The apparatus of claim 19, wherein said input means is selected from the group consisting of a digital scanner and a digital camera.
Claim 23
Dependent Claim
31 words
The apparatus of claim 20, wherein said output means is selected from the group consisting of a printer, a LCD display, a CRT display, a magnetic media, and a photographic printer.
References Cited (Backward Citations)
US4809064A
Cited
US5115271A
Cited
US5450502A
Cited
US5485568A
Cited
US5363209A
Cited
US5640468A
Cited
US5608544A
Cited
US5666503A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-01 | 2003-05-03 | 2003-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-01 | 2007-05-03 | 2007-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-01 | 2011-05-03 | 2011-11-02 | $7700.00 | Window Closed / Lapsed |