EP0286286A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Image processing
Assignee: Crosfield Electronics Ltd
•
Filing: 1988-03-25
•
Granted: —
•
Expires: 2008-03-25
Abstract
Abstract A method and apparatus for processing digital data representing the colour content of abutting blocks of pixels defining an image. The method comprises, for each block i) determining a measure of the variation in colour content of pixels in the block; and, ii) if the variation lies within a predetermined range, applying a compression algorithm to the digital data defining the block.
Inventors
- 👤 Peter William Stansfield
- 👤 Alastair Reed
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 22:02
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/41
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
60 words
A method of processing digital data representing the colour content of abutting blocks of pixels defining an image, the method comprising, for each block i) determining a measure of the variation in colour content of pixels in the block; and, ii) if the variation lies within a predetermined range, applying a compression algorithm to the digital data defining the block.
Claim 2
Independent Claim
60 words
A method of processing digital data representing the colour content of abutting blocks of pixels defining an image, the method comprising, for each block i) determining a measure of the variation in colour content of pixels in the block; and, ii) if the variation lies within a predetermined range, applying a compression algorithm to the digital data defining the block.
Claim 3
Dependent Claim
32 words
A method according to claim 1, wherein step i) is performed in the frequency domain by determining the energy (E) of the block by summing the squares of all the ac coefficients.
Claim 4
Dependent Claim
20 words
A method according to claim 1, wherein step i) is performed on the block of pixels in the spatial domain.
Claim 5
Dependent Claim
141 words
A method according to claim 3, comprising a) determining for each set of pixels within a window of predetermined dimensions smaller than the block the difference between the colour content values of the pixels and comparing the maximum difference (W' max ) obtained with a pre-determined first threshold (Ti); b) determining whether the difference (D) between the values of the pixels with the maximum and minimum colour content values in the block lies within second predetermined limits (T 2 ,T 3 ), the lower limit being greater than zero; and c) applying a compression algorithm to the digital data defining the block if the difference (W m a x ) determined in step (a) is less than the first threshold (T 1 ) and the difference (D) determined in (b) falls outside the second pre-determined limits (T 2 ,T 3 ).
Claim 6
Dependent Claim
63 words
Apparatus for processing digital data representing the colour content of abutting blocks of pixels defining an image, the apparatus comprising processing means (2,3) for (i) determining a measure of the variation in colour content of pixels in each block; and, for each block, (ii) applying a compression algorithm to the digital data defining the block if the variation lies within a pre-determined range.
Claim 7
Dependent Claim
63 words
Apparatus for processing digital data representing the colour content of abutting blocks of pixels defining an image, the apparatus comprising processing means (2,3) for (i) determining a measure of the variation in colour content of pixels in each block; and, for each block, (ii) applying a compression algorithm to the digital data defining the block if the variation lies within a pre-determined range.
Claim 8
Dependent Claim
14 words
Apparatus according to claim 5, wherein the processing means comprises a suitably programmed computer.
References Cited (Backward Citations)
FR2508747A1
Cited
EP0096219A2
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.