EP0272762A2
Expired / Lapsed
EP
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Method and system for image coding and display
Assignee: Koninklijke Philips NV
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Filing: 1987-12-21
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Granted: —
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Expires: 2007-12-21
Abstract
Abstract Pixel information representing an image for display is coded using data compression. The data compression consists in obtaining the pixel information as a first matrix of high resolution pixel values, subtracting from this first matrix a second matrix composed of lower resolution pixel values, produced by low pass filtering the first matrix, to produce a third matrix of difference values, sub-sampling the second matrix to produce a fourth matrix of less density lower resolution pixel values and coding the third and fourth matrices. Complementary decoding consists in restituting the second matrix by interpolation filtering the decoded fourth matrix, and combining the restituted second matrix with the decoded third matrix. Loss of accuracy in the decoding method is reduced by coding and then decoding the fourth matrix during the coding method before it is interpolated to full pixel density to form the restituted second matrix which is subtracted from the first matrix to produce the third matrix of difference values. In this way, any sub-sampling and interpolation errors in the restituted fourth matrix occur in both the coding method and the decoding method and therefore cancel out. Figure 3 illustrates the coding method including these coding and decoding steps.
Inventors
- 👤 Norman Dennis Richards
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 15:27
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; H; H04; H04N; H04N1/00; H04N1/21; H04N1/2166; H04N1/217; H04N1/41; H04N1/46; H04N1/64; H04N1/646
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
169 words
A method of image coding by which pixel information for at least one pixel component value of a plurality of pixels forming an image is coded into digital data which can be recorded on a suitable storage medium, comprising the steps of:- (i) obtaining said pixel information as a first matrix of m × n pixel component values, where m and n are integers, (ii) low-pass filtering these pixel component values of the first matrix to produce a second matrix of m × n pixel component values which are in respect of a lower resolution image compared with the pixel component values of the first matrix, (iii) sub-sampling said second matrix of pixel component values to produce a fourth matrix of m / a × n / b pixel component values of reduced density, where a and b are factors of m and n , respectively, and (iv) coding said fourth matrix of pixel component values into a second set of digital data for storage on a storage medium;
Claim 2
Independent Claim
169 words
A method of image coding by which pixel information for at least one pixel component value of a plurality of pixels forming an image is coded into digital data which can be recorded on a suitable storage medium, comprising the steps of:- (i) obtaining said pixel information as a first matrix of m × n pixel component values, where m and n are integers, (ii) low-pass filtering these pixel component values of the first matrix to produce a second matrix of m × n pixel component values which are in respect of a lower resolution image compared with the pixel component values of the first matrix, (iii) sub-sampling said second matrix of pixel component values to produce a fourth matrix of m / a × n / b pixel component values of reduced density, where a and b are factors of m and n , respectively, and (iv) coding said fourth matrix of pixel component values into a second set of digital data for storage on a storage medium;
Claim 3
Dependent Claim
98 words
said method being characterised by comprising the further steps of:- (v) decoding the second set of digital data representing the pixel component values of reduced density to reconstitute the fourth matrix of pixel component values, (vi) interpolation filtering said fourth matrix of pixel component values to restitute said second matrix of pixel component values, (vii) subtracting the restituted second matrix from the first matrix pixel-by-pixel to produce a third matrix of m × n difference values, and (viii) coding said third matrix of difference values into a first set of digital data for storage on a storage medium.
Claim 4
Dependent Claim
98 words
said method being characterised by comprising the further steps of:- (v) decoding the second set of digital data representing the pixel component values of reduced density to reconstitute the fourth matrix of pixel component values, (vi) interpolation filtering said fourth matrix of pixel component values to restitute said second matrix of pixel component values, (vii) subtracting the restituted second matrix from the first matrix pixel-by-pixel to produce a third matrix of m × n difference values, and (viii) coding said third matrix of difference values into a first set of digital data for storage on a storage medium.
Claim 5
Dependent Claim
28 words
A coding method as claimed in Claim 1, including the further step (ix) of recording the digital data produced by steps (iv) and (viii) onto a storage medium.
Claim 6
Dependent Claim
52 words
A coding method as claimed in Claim 1 or Claim 2, wherein the low-pass filtering of the pixel component values of the first matrix in step (ii), and the sub-sampling of the pixel component values of the second matrix in step (iii) are both by a factor of two horizontally and vertically.
Claim 7
Dependent Claim
52 words
A coding method as claimed in Claim 1, Claim 2 or Claim 3, in which the coding of the difference values into the first set of digital data consists in quantizing these difference values into a smaller number of quantized values, including zero, and coding the quantized values using a run-length code.
Claim 8
Dependent Claim
36 words
A coding method as claimed in any preceding Claim,in which the coding of the pixel component values of the fourth matrix into the second set of digital data consists in delta coding these pixel component values.
Claim 9
Dependent Claim
260 words
A coding arrangement by which pixel information for at least one pixel component value of a plurality of pixels forming an image is coded into digital data which can be recorded on a suitable storage medium comprising:- - means for obtaining said pixel information as a first matrix of m × n pixel component values, where m and n are integers, - means for low-pass filtering these pixel component values of the first matrix to produce a second matrix of m × n pixel component values, which are in respect of a lower resolution image compared with the pixel component values of the first matrix, - means for sub-sampling said second matrix of pixel component values to produce a fourth matrix of m / a × n / b pixel component values of reduced density, where a and b are factors of m and n , respectively, - means for coding said fourth matrix of pixel component values into a second set of digital data for storage on a storage medium - means for decoding the second set of digital data to reconstitute the fourth matrix of pixel component values, - means for interpolation filtering said reconstituted fourth matrix of pixel component values to restitute said second matrix of pixel component values, - means for subtracting the restituted second matrix from the first matrix pixel-by-pixel to produce a third matrix of m × n difference values, and - means for coding said third matrix of difference values into a first set of digital data for storage on a storage medium.
Claim 10
Dependent Claim
260 words
A coding arrangement by which pixel information for at least one pixel component value of a plurality of pixels forming an image is coded into digital data which can be recorded on a suitable storage medium comprising:- - means for obtaining said pixel information as a first matrix of m × n pixel component values, where m and n are integers, - means for low-pass filtering these pixel component values of the first matrix to produce a second matrix of m × n pixel component values, which are in respect of a lower resolution image compared with the pixel component values of the first matrix, - means for sub-sampling said second matrix of pixel component values to produce a fourth matrix of m / a × n / b pixel component values of reduced density, where a and b are factors of m and n , respectively, - means for coding said fourth matrix of pixel component values into a second set of digital data for storage on a storage medium - means for decoding the second set of digital data to reconstitute the fourth matrix of pixel component values, - means for interpolation filtering said reconstituted fourth matrix of pixel component values to restitute said second matrix of pixel component values, - means for subtracting the restituted second matrix from the first matrix pixel-by-pixel to produce a third matrix of m × n difference values, and - means for coding said third matrix of difference values into a first set of digital data for storage on a storage medium.
Claim 11
Dependent Claim
28 words
A coding arrangement as claimed in Claim 6, wherein said low-pass filtering means and said sub-sampling means effect filtering by a factor of two both horizontally and vertically.
Claim 12
Dependent Claim
43 words
A coding arrangement as claimed in Claim 6 or 7, in which the means for coding said matrix of difference values quantizes these difference values into a smaller number of quantized values, including zero, and codes the quantized values using a run-length code.
Claim 13
Dependent Claim
31 words
A coding arrangement as claimed in Claim 6, 7 or 8, in which the means for coding the pixel component values of the fourth matrix delta codes these pixel component values.
Claim 14
Dependent Claim
29 words
A coding arrangement as claimed in any one of Claims 6 to 9 including a storage medium on which said first and second sets of digital data are recorded.
Claim 15
Dependent Claim
23 words
A coding arrangement as claimed in Claim 10, wherein said storage medium is an optical record carrier and an associated optical read device.
Claim 16
Dependent Claim
25 words
An optical record carrier for use in an arrangement as claimed in Claim 11, having stored thereon said first and second sets of digital data.
Claim 17
Independent Claim
57 words
A method of coding as claimed in any one of Claims 1 to 5, for use with YUV coding, wherein Y is the luminance component of a pixel and U and V are the two chrominance components, wherein these three pixel component values are available as said picture information in respective first matrices and are coded separately.
Claim 18
Dependent Claim
33 words
A method as claimed in Claim 13, wherein the first matrix of each of the two chrominance component values has half the horizontal resolution of the first matrix for the luminance component value.
Claim 19
Independent Claim
64 words
A method of coding as claimed in any one of Claims 1 to 5, for use with YUV coding, where Y is the luminance component of a pixel and U and V are the two chrominance components, wherein only the luminance component value is said picture information and is coded, the two chrominance component values being available directly for storage on a storage medium.
Claim 20
Dependent Claim
50 words
A coding arrangement as claimed in any one of Claims 6 to 11, for use with YUV coding, where Y is the luminance component of a pixel and U and V are the two chrominance components, wherein all these pixel component values are coded separately starting with respective first matrices.
Claim 21
Dependent Claim
34 words
A coding arrangement as claimed in Claim 16, wherein the first matrix of each of the two chrominance component values has half the horizontal resolution of the first matrix for the luminance component value.
Claim 22
Dependent Claim
63 words
A coding arrangement as claimed in any one of Claims 6 to 11, for use with YUV coding, where Y is the luminance component of a pixel and U and V are the two chrominance components, wherein only the luminance component value is said picture information and is coded, the two chrominance component values being available directly for storage on a storage medium.
Claim 23
Dependent Claim
162 words
A data display apparatus comprising:- - a display device for displaying images composed of discrete pixels each of which is represented by a respective digital code which defines a pixel in terms of chrominance and luminance pixel component values; - a display memory having a capacity for storing the digital codes for an image to be displayed; - a display generator for producing video signals from the digital codes in the display memory to drive the display device; - a mass memory device; - logic means for the selective transfer of digital data in said mass memory device to the display memory; characterised in that digital data stored in said mass memory device is coded by the method claimed in Claim 1, and the apparatus includes decoding means for decoding first and second sets of digital data read out from said mass memory device in respect of an image to be displayed, into said digital codes for storage in said display memory.
Claim 24
Dependent Claim
36 words
A data display apparatus as claimed in Claim 19, characterised in that the coding of said digital data stored in said mass memory device includes the feature of Claims 3, 4, 5, 13, 14 or 15.
Claim 25
Dependent Claim
29 words
A data display apparatus as claimed in Claim 19 or Claim 20, characterised in that said mass memory device is an optical record carrier and associated optical read device.
References Cited (Backward Citations)
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