US4953400A
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US
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Method of measuring the yarn density of a woven fabric or the stitch density of a knit fabric for readjusting the production machine in question
Assignee: WETENSCHAPPELIJK EN TECHNISCH CENTRUM VAN DE BELGISCHE TEXTIELNIJVERHEID AFGEKORT TOT "CENTEXBEL"
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Filing: 1989-08-15
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Granted: 1990-09-04
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Expires: 2009-08-15
Abstract
Abstract A method of measuring the yarn density of a woven fabric or the stitch density of a knitted fabric by recording a video image of the woven or knitted fabric to be examined by means of a video camera, converting the video image by an analog-to-digital converter into digital video information, storing the digital video information in a digital image memory and converting said information by a central processing unit into the yarn density or stitch density. The digital video information is converted by a digital band filter (14) with central circle frequency (ω o ) into a yarn or stitch density, and that the digital band filter (14) is arranged in such a manner that it operates according to the formula: Y.sub.k =A.sub.m ·X.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A o X k -B 1 ·Y k-1 -B 2 Y k-2 . . . B n Y k-n wherein: X k represents a series of points of the digital information characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital information characterisitcs via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frequency ω o and the interspace T.
Inventors
- 👤 Filip O. P. Bossuyt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:19
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/36; G01N33/367; D; D04; D04B; D04B35/00; D04B35/10; G06; G06T; G06T7/00; G06T7/0002; G06T7/0004; G06T2207/00; G06T2207/30; G06T2207/30108; G06T2207/30124
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
227 words
A method of measuring the yarn density of a woven fabric comprising: recording a video image of the woven fabric to be examined by means of a video camera, converting the video image by an analog-to-digital converter into digital video data, storing the digital video data in a digital image memory, retrieving and passing the digital image memory data to a central processing unit and converting said data by said central processing unit into the yarn density whereby said converting by said central processing unit comprises converting said digital image memory data by a digital band filter with a central circle frequency 107 o which digital band filter is arranged in such a manner that it operates according to the formula: Y.sub.K =A.sub.m ·X.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital information characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital information characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frequency ω o and the interspace T, the converting by said digital band filter being followed by a computation proper of the yarn density from the data converted by said filter.
Claim 2
Independent Claim
227 words
A method of measuring the yarn density of a woven fabric comprising: recording a video image of the woven fabric to be examined by means of a video camera, converting the video image by an analog-to-digital converter into digital video data, storing the digital video data in a digital image memory, retrieving and passing the digital image memory data to a central processing unit and converting said data by said central processing unit into the yarn density whereby said converting by said central processing unit comprises converting said digital image memory data by a digital band filter with a central circle frequency 107 o which digital band filter is arranged in such a manner that it operates according to the formula: Y.sub.K =A.sub.m ·X.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital information characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital information characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frequency ω o and the interspace T, the converting by said digital band filter being followed by a computation proper of the yarn density from the data converted by said filter.
Claim 3
Dependent Claim
32 words
The method of claim 1, in which the central circle frequency ω o of the band filter is adjustable as a function of the yarn density of the fabric to be examined.
Claim 4
Dependent Claim
18 words
The method of claim 1, in which before conversion of the digital video data, this data is enhanced.
Claim 5
Dependent Claim
42 words
The method of claim 3, wherein the enhancement of the digital video data includes at least one of the following steps: contrast expansion, elimination of redundant data from the digital video data and accentuation of relevant data in the digital video data.
Claim 6
Dependent Claim
38 words
The method of claim 1, in which converting by a central processing unit comprises deriving a yarn frequency graph from said digital video data, the filter converting the digital image memory data corresponding to said yarn frequency graph.
Claim 7
Dependent Claim
21 words
The method of claim 5, wherein the yarn frequency graph is computed by isolating one line from the digital video data.
Claim 8
Dependent Claim
30 words
The method of claim 5, wherein the data corresponding with the yarn frequency graph is determined by the computation of a row or column histogram from the digital image data.
Claim 9
Dependent Claim
69 words
The method of claim 1, wherein the yarn density is computed, by computing the average of the filtered data corresponding with the yarn frequency graph, subtracting said average from said filtered data, counting the number of whole periods N in the filtered data, counting the number of measuring points N p in said N periods, and resolving the equation: density=N/(N p ×s), in which s is a scale factor.
Claim 10
Independent Claim
184 words
An apparatus for measuring the yarn density of a woven fabric, which comprises: a video camera for recording an analog video image of the woven fabric to be examined, an analog-to-digital converter for converting the analog video image into digital video data, an image memory for storing the digital video data, and a processing unit for converting the digital video data into the yarn density, said processing unit comprising a digital filter with central circle frequency ω o and operating according the formula: Y.sub.k =A.sub.m ·X.sub.k-m +.sub.Am- ·X.sub.k-m+. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k- wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q; the central circle frequency ω o and the interspace T, and a computer unit for the computation proper of the yarn density from the data converted by said filter.
Claim 11
Independent Claim
184 words
An apparatus for measuring the yarn density of a woven fabric, which comprises: a video camera for recording an analog video image of the woven fabric to be examined, an analog-to-digital converter for converting the analog video image into digital video data, an image memory for storing the digital video data, and a processing unit for converting the digital video data into the yarn density, said processing unit comprising a digital filter with central circle frequency ω o and operating according the formula: Y.sub.k =A.sub.m ·X.sub.k-m +.sub.Am- ·X.sub.k-m+. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k- wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q; the central circle frequency ω o and the interspace T, and a computer unit for the computation proper of the yarn density from the data converted by said filter.
Claim 12
Dependent Claim
14 words
An apparatus as claimed in claim 9, which further comprises a suitable display unit.
Claim 13
Dependent Claim
20 words
The apparatus as claimed in claim 9, in which said processing unit comprises means for calculating a yarn frequency graph.
Claim 14
Dependent Claim
26 words
The apparatus of claim 11, in which the means for deriving a yarn frequency graph comprise means for isolating one line from the digital video data.
Claim 15
Dependent Claim
29 words
The apparatus of claim 11, in which the means for deriving a yarn frequency graph comprise means for computing a row or column histogram from the digital image data.
Claim 16
Dependent Claim
33 words
The apparatus of claim 9, in which the central circle frequency ω o of the digital band filter is adjustable in function of the yarn density of the woven fabric to be examined.
Claim 17
Dependent Claim
55 words
The apparatus of claim 9, comprising an image enhancing unit for enhancing the digital video data, which comprises at least one of the following devices: a device for contrast expansion, a device for elimination of redundant information from the digital video data and a device for accentuation of relevant data in the digital video data.
Claim 18
Independent Claim
227 words
A method of measuring the stitch density of a knitted fabric comprising: recording a video image of the knitted fabric to be examined by means of a video camera, converting the video image by an analog-to-digital converter into digital video data, storing the digital video data in a digital image memory, retrieving and passing the digital image memory data to a central processing unit and converting said data by said central processing unit into the stitch density, whereby said converting by said central processing unit comprises converting said digital image memory data by a digital band filter with central circle frequency ω 0 , which digital band filter is arranged in such a manner that it oeprates according to the formula: Y.sub.K =A.sub.m ·K.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -V.sub.1 ·H.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frquency ω o and the interspace T, the converting by said digital band filter being followed by a computation proper of the stitch density from the data converted by said filter.
Claim 19
Independent Claim
227 words
A method of measuring the stitch density of a knitted fabric comprising: recording a video image of the knitted fabric to be examined by means of a video camera, converting the video image by an analog-to-digital converter into digital video data, storing the digital video data in a digital image memory, retrieving and passing the digital image memory data to a central processing unit and converting said data by said central processing unit into the stitch density, whereby said converting by said central processing unit comprises converting said digital image memory data by a digital band filter with central circle frequency ω 0 , which digital band filter is arranged in such a manner that it oeprates according to the formula: Y.sub.K =A.sub.m ·K.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -V.sub.1 ·H.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frquency ω o and the interspace T, the converting by said digital band filter being followed by a computation proper of the stitch density from the data converted by said filter.
Claim 20
Dependent Claim
32 words
The method of claim 16, in which the central circle frequency ω o of the band filter is adjustable as a function of the stitch density of the fabric to be examined.
Claim 21
Dependent Claim
18 words
The method of claim 16, in which before conversion of the digital video data, this data is enhanced.
Claim 22
Dependent Claim
43 words
The method of claim 16, in which the enhancement of the digital video data includes at least one of the following steps: contrast expansion, elimination of redundant data from the digital video data and accentuation of relevant data in the digital video data.
Claim 23
Dependent Claim
38 words
The method of claim 16, in which converting by a central processing unit comprises deriving a stitch frequency graph from said digital video data, the filtering converting the digital image memory data corresponding to said stitch frequency graph.
Claim 24
Dependent Claim
22 words
The method of claim 20, in which the stitch frequency graph is computed by isolating one line from the digital video data.
Claim 25
Dependent Claim
31 words
The method of claim 20, in which the data corresponding with the stitch frequency graph is determined by the computation of a row or column histogram from the digital image data.
Claim 26
Dependent Claim
69 words
The method of claim 16, in which the stitch density is computed by computing the average of the filtered data corresponding with the stitch frequency graph, subtracting said average from said filtered data, counting the number of whole periods N in the filtered data, counting the number of measuring points N p in said N periods, and resolving the equation: density=N/(N.sub.p ×s), in which s is a scale factor.
Claim 27
Independent Claim
187 words
An apparatus for measuring the stitch density of a knitted fabric, which comprises: a video camera for recording an analog video image of the knitted fabric to be examined, an analog-to-digital converter for converting the analog video image into digital video data, an image memory for storing the digital video data, and a processing unit for converting the digital video data into the stitch density, said processing unit comprising a digital band filter with central circle frequency ω o and operating according to the formula: Y.sub.k A.sub.m ·X.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frequency ω o and the interspace T, and a computer unit for the computation proper of the stitch density from the filtered data converted by said filter.
Claim 28
Independent Claim
187 words
An apparatus for measuring the stitch density of a knitted fabric, which comprises: a video camera for recording an analog video image of the knitted fabric to be examined, an analog-to-digital converter for converting the analog video image into digital video data, an image memory for storing the digital video data, and a processing unit for converting the digital video data into the stitch density, said processing unit comprising a digital band filter with central circle frequency ω o and operating according to the formula: Y.sub.k A.sub.m ·X.sub.k-m +A.sub.m-1 ·X.sub.k-m+1. . . +A.sub.o X.sub.k -B.sub.1 ·Y.sub.k-1 -B.sub.2 Y.sub.k-2. . . -B.sub.n Y.sub.k-n wherein: X k represents a series of points of the digital data characteristic at interspace T before the digital filtering; Y k represents the said series of points k of the filtered digital data characteristic via digital filtering at the same interspace T; the coefficients A and B are a function of the quality Q, the central circle frequency ω o and the interspace T, and a computer unit for the computation proper of the stitch density from the filtered data converted by said filter.
Claim 29
Dependent Claim
14 words
The apparatus as claimed in claim 24, which further comprises a suitable display unit.
Claim 30
Dependent Claim
18 words
The apparatus of claim 24, in which said processing unit comprises means for calculating a stitch frequency graph.
Claim 31
Dependent Claim
26 words
The apparatus of claim 26, in which the means for deriving a stitch frequency graph comprise means for isolating one line from the digital video data.
Claim 32
Dependent Claim
29 words
The apparatus of claim 26, in which the means for deriving a stitch frequency graph comprise means for computing a row or column histogram from the digital image data.
Claim 33
Dependent Claim
33 words
The apparatus of claim 24, in which the central circle frequency ω o of the digital band filter is adjustable in junction of the stitch density of the knitted fabric to be examined.
Claim 34
Dependent Claim
56 words
The apparatus of claim 24, which comprises an image enhancing unit for enhancing the digital video data, which comprises at least one of the following devices: a device for contrast expansion, a device for elimination of redundant data from the digital video data and a device for accentuation of relevant data in the digital video data.
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