EP0171954A2
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Image enhancement
Assignee: Crosfield Electronics Ltd
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Filing: 1985-07-25
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Granted: —
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Expires: 2005-07-25
Abstract
Abstract Apparatus is described for enhancing an image represented by picture signals corresponding to respective colour components of successive elements of the image, the apparatus comprising signal generating means (27Y, 27M, 27C) for generating sharp and unsharp signals from the picture signals. Fringe signal generating means (28Y, 28M, 28C) derives a plurality of fringe signals by combining the sharp and unsharp signals in a predetermined manner; correction means (29) applies modifying functions to the sharp or unsharp signals or other premodified picture signals to derive modified picture signals; and adding means (30) sums the fringe signals with the modified picture signals to derive a plurality of output signals.
Inventors
- 👤 Simon Christopher Ellis
- 👤 Robert John Oldershaw
- 👤 Ignazio Barraco
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:15
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/58
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
97 words
A method of enhancing an image represented by picture signals corresponding to respective colour components of successive elements of the image, the method comprising deriving sharp and an unsharp signals (s,u) from the picture signals; deriving a plurality of fringe signals (P 1 ,P 2 ,P 3 ) by combining the sharp and unsharp signals in a predetermined manner; applying modifying functions to the sharp or unsharp signals or other premodified picture signals to derive modified picture signals (y,m,c,b); and summing the fringe signals with the modified picture signals to derive a plurality of output signals (y',m',c',b').
Claim 2
Independent Claim
97 words
A method of enhancing an image represented by picture signals corresponding to respective colour components of successive elements of the image, the method comprising deriving sharp and an unsharp signals (s,u) from the picture signals; deriving a plurality of fringe signals (P 1 ,P 2 ,P 3 ) by combining the sharp and unsharp signals in a predetermined manner; applying modifying functions to the sharp or unsharp signals or other premodified picture signals to derive modified picture signals (y,m,c,b); and summing the fringe signals with the modified picture signals to derive a plurality of output signals (y',m',c',b').
Claim 3
Dependent Claim
39 words
A method according to claim 1, further comprising deriving a black signal (b) from the picture signals; deriving a black fringe signal (P4); and summing the black fringe signal with the black signal to derive a black printer signal.
Claim 4
Dependent Claim
33 words
A method according to claim 2, wherein the black fringe signal (P 4 ) is only summed with the black signal (b) if the black signal has a value above a predetermined threshold.
Claim 5
Dependent Claim
45 words
A method according to claim 2 or claim 3, further comprising comparing the fringe signals (P l -P 3 ) to determine the fringe signal with the smallest value, the determined fringe signal being used additionally to constitute the black fringe signal (P 4 ).
Claim 6
Dependent Claim
62 words
A method according to claim 2 or claim 3, further comprising comparing the modified picture signals (y,m,c) corresponding to each fringe signal (P 1 -P 3 ) to determine the modified picture signal with the smallest value, the fringe signal corresponding to the modified picture signal having the smallest value being used additionally to constitute the black fringe signal (P A ).
Claim 7
Independent Claim
48 words
A method according to any of claims 2 to 5, wherein the modified picture signal whose fringe signal corresponds to the black fringe signal (P 4 ) is compared with the black signal (b), the black fringe signal being modified in accordance with the results of the comparison.
Claim 8
Independent Claim
39 words
A method according to any of the preceding claims, further comprising comparing each modified picture signal (y,m,c) with a threshold, and summing the modified picture signal and the fringe signal only if the modified picture signal exceeds the threshold.
Claim 9
Dependent Claim
104 words
Apparatus for enhancing an image represented by picture signals corresponding to respective colour components of successive elements of the image, the apparatus comprising signal generating means (27Y,27M,27C) for generating sharp and unsharp signals from the picture signals; fringe signal generating means (28Y,28M,28C) for deriving a plurality of fringe signals by combining the sharp and unsharp signals in a predetermined manner; correction means (29) for applying modifying functions to the sharp or unsharp signals or other premodified picture signals to derive modified picture signals; and adding means (30) for summing the fringe signals with the modified picture signals to derive a plurality of output signals.
Claim 10
Dependent Claim
104 words
Apparatus for enhancing an image represented by picture signals corresponding to respective colour components of successive elements of the image, the apparatus comprising signal generating means (27Y,27M,27C) for generating sharp and unsharp signals from the picture signals; fringe signal generating means (28Y,28M,28C) for deriving a plurality of fringe signals by combining the sharp and unsharp signals in a predetermined manner; correction means (29) for applying modifying functions to the sharp or unsharp signals or other premodified picture signals to derive modified picture signals; and adding means (30) for summing the fringe signals with the modified picture signals to derive a plurality of output signals.
Claim 11
Dependent Claim
76 words
Apparatus according to claim 8, further comprising black fringe signal generating means for generating a black fringe signal from the one or more fringe signals, wherein the correction means is arranged to generate a black signal from the sharp or unsharp signals or other premodified picture signals, and the adding means is arranged to add the black fringe signal from the black fringe signal generating means to the black signal to derive a black printer signal.
Claim 12
Dependent Claim
41 words
Apparatus according to claim 9, wherein the black fringe signal generating means comprises first comparison means (32) for comparing the fringe signals, and means for generating a signal which has a value corresponding to the fringe signal with the least value.
Claim 13
Dependent Claim
69 words
Apparatus according to claim 9 or claim 10, wherein the black fringe signal generating means (31) further includes second comparison means (33) for comparing the black signal from the correction means with a threshold, the black fringe signal generating means (31) and the adding means (30) being arranged so that the black fringe signal is only added to the black signal if the black fringe signal exceeds the threshold.
Claim 14
Dependent Claim
64 words
Apparatus according to any of claims 9 to 11, further comprising fourth comparison means (41) for comparing the black signal with the modified picture signal corresponding to the black fringe signal and for producing an appropriate output signal; and gain adjustment means (42) responsive to the output signal from the fourth comparison means (41) to adjust the magnitude of the black fringe signal accordingly.
Claim 15
Dependent Claim
55 words
Apparatus according to any of claims 8 to 12, further comprising fifth comparison means (42) for comparing the or each modified picture signal for which a fringe signal has been generated with a threshold, the arrangement being such that the modified picture signal is only summed with a fringe signal if the threshold is exceeded.
Claim 16
Dependent Claim
48 words
Apparatus according to any of claims 8 to 13, the apparatus further comprising third comparison means (38) for comparing the modified picture signals, and means for generating a signal which has a value corresponding to the fringe signal associated with the modified picture signal having the least value.
References Cited (Backward Citations)
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