US5321769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Printed matter inspection method
Assignee: YOZAN BUILDING
•
Filing: 1992-09-03
•
Granted: 1994-06-14
•
Expires: 2012-09-03
Abstract
Abstract It is possible to inspect a printed matter precisely because lines are surely and accurately extracted by the present invention. Extraction of lines are the important point for the judgment if a character is correctly printed or not. The printed matter inspection method according to the present invention comprises the following steps: i) an image of a predetermined area including a line is input; ii) a density projection is performed on said input image; iii) a start point and end point of change of density are emphasized in said density projection; iv) the center pixel in each predetermined convolution is substituted by the minimal density pixel in each said convolution; v) a density projection is performed; and vi) said printed matter defective or not is judged according to said density projection in v).
Inventors
- 👤 Tooru Takahashi
- 👤 Aki Kikuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:25
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/0002; G06T7/0004; G06T7/0006; G06V; G06V10/00; G06V10/98; G06V10/993; G06T2207/00; G06T2207/20; G06T2207/20068; G06T2207/20172; G06T2207/20192; G06T2207/30; G06T2207/30176
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
136 words
A method for inspecting printed material, said method comprising the steps of: inputting an image of a predetermined area of said printed material, said predetermined area including a line; performing a first density projection operation on said input image to obtain a first density projection; emphasizing a start point and an end point of a change of density in said first density projection relative to remaining portions of said first density projection to obtain an emphasized projection; convolving at least one predetermined portion of said emphasized projection to obtain a convolved projection by replacing a center pixel in each predetermined convolved portion with a pixel in the convolved portion which has a minimal density value for that portion, thereby obtaining a convolved projection; and determining whether said printed matter is defective according to said convolved projection.
Claim 2
Independent Claim
136 words
A method for inspecting printed material, said method comprising the steps of: inputting an image of a predetermined area of said printed material, said predetermined area including a line; performing a first density projection operation on said input image to obtain a first density projection; emphasizing a start point and an end point of a change of density in said first density projection relative to remaining portions of said first density projection to obtain an emphasized projection; convolving at least one predetermined portion of said emphasized projection to obtain a convolved projection by replacing a center pixel in each predetermined convolved portion with a pixel in the convolved portion which has a minimal density value for that portion, thereby obtaining a convolved projection; and determining whether said printed matter is defective according to said convolved projection.
Claim 3
Dependent Claim
44 words
The method of claim 1, said emphasis step including the steps of: calculating a second derivative of brightness of a pixel in said first density projection; multiplying said second derivative by a scaling factor; and substracting said scaled second differential from said pixel brightness.
Claim 4
Dependent Claim
14 words
The method of claim 2, wherein said scaling factor is a unity scaling factor.
Claim 5
Dependent Claim
37 words
The method of claim 2, wherein said emphasis step further comprises the steps of: determining the dullness of an edge at a location corresponding to said pixel; and choosing said scaling factor based on said edge dullness.
Claim 6
Dependent Claim
51 words
The method of claim 4, said choosing step comprising the steps of: selecting a first scaling factor when said edge has a first dullness level; and selecting a second scaling factor smaller than said first scaling factor when said edge has a second dullness level lower than said first dullness level.
Claim 7
Dependent Claim
27 words
The method of claim 1, wherein pixels in said emphasized projection are arranged in a rectangular matrix, and said predetermined convolution portion is a 3×3 submatrix thereof.
Claim 8
Dependent Claim
31 words
The method of claim 1, said determining step comprising the step of determining that said printed matter is defective when said convolved density projection indicates only the presence of said line.
Claim 9
Dependent Claim
32 words
The method of claim 1, said determining step comprising the step of determining that said printed matter is defective when said convolved density projection indicates that said line overlaps with printed characters.
Claim 10
Dependent Claim
42 words
The method of claim 1, said determining step comprising the steps of: comparing said convolved density projection with a defect-free template; and determining that said printed matter is defective when said convolved density projection does not substantially correspond to said defect-free template.
Claim 11
Dependent Claim
52 words
The method of claim 1, said determining step comprising the steps of: calculating at least one characteristic value of portions of said convolved density projection corresponding to pixels within a predetermined distance from said line; and determining that said printed matter is defective based on said at least one calculated characteristic value.
Claim 12
Dependent Claim
17 words
The method of claim 10, wherein one of said at least one characteristic value is mean brightness.
References Cited (Backward Citations)
US4251799A
Cited
US5204910A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-06-13 | 1997-12-13 | 1998-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-13 | 2001-12-13 | 2002-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-13 | 2005-12-13 | 2006-06-14 | $7700.00 | Window Closed / Lapsed |