# US 4,393,407 A · Contour correcting apparatus for video signals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,393,407 A - Document ID: US4393407A - Status: Granted - Kind: A - Application number: 06/203,445 - Filed: 1980-11-03 - Granted: 1983-07-12 - Earliest claimed: 1979-11-07 - Assignees: Canon Kabushiki Kaisha - Inventors: Yoshikazu Yokomizo - Web page: https://patentgrep.com/patent/US4393407A ## CPC - H04N 5/142: {Edging; Contouring} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A contour correcting arrangement for video signals includes a differentiator to differentiate an input video signal, a delay circuit which delays by a predetermined time period the differentiated waveform resultant from the differentiation and the video signal, and a combining circuit for combining the inverted waveform of the differentiated waveform, delayed differentiated waveform, and delayed video signal. ## Claims ### Claim 1 A contour correcting apparatus for video signals, comprising: differentiating means for differentiating an input video signal to produce a differentiated waveform; delay means for delaying said differentiated waveform and said video signal for a predetermined time period to produce a delayed differentiated waveform and delayed video signal; inverting means for phase inverting said differentiated waveform to produce a phase inverted differentiated waveform; and combining means for combining said phase inverted differentiated waveform, said delayed differentiated waveform and said delayed video signal. ### Claim 2 (depends on 1) The apparatus of claim 1 wherein said differentiating means is constructed and arranged to effect a time constant T which satisfies the relationship 1/(5 f.sub.max).gtoreq.T.gtoreq.1/(10 f.sub.max) with respect to the highest frequency component f.sub.max of said video signal. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein said delay means comprises means for delaying said differentiated waveform by a predetermined time period .tau. which satisfies the relationship 1/2T.gtoreq..tau..gtoreq.2 T with respect to said time constant T. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising attenuating means for attenuating the amplitude of said differentiated waveform. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein said attenuating means comprises a variable resistor. ### Claim 6 A contour correcting apparatus for video signals, comprising: a differentiating circuit for performing primary differentiation of an input video signal; an adder for adding an output of said differentiating circuit to said video signal; a delay circuit for delaying an output of said adder by a predetermined time period; and a combining circuit for combining said output of said differentiating circuit and said output of said delay circuit. ### Claim 7 (depends on 6) The apparatus of claim 6 wherein said video signal comprises a signal produced by a solid state pickup device. ### Claim 8 (depends on 7) The apparatus of claim 7, further comprising an attenuator circuit for attenuating an output of said differentiating circuit. ### Claim 9 (depends on 6) The apparatus of claim 6, wherein said differentiating circuit comprises a capacitor and a resistor. ### Claim 10 (depends on 9) The apparatus of claim 9, wherein said differentiating circuit is constructed and arranged to effect a time constant T which satisfies the relationship 1/(5f.sub.max).gtoreq.T.gtoreq.1/(10f.sub.max) with respect to the maximum frequency component f.sub.max of said video signal. ### Claim 11 (depends on 9) The apparatus of claim 9, wherein said delay circuit comprises means for delaying said adder output by a time period .tau. which satisfies the relationship 1/2T.ltoreq..tau..ltoreq.2T with respect to the time constant T of said differentiating circuit. ### Claim 12 (depends on 7) The apparatus of claim 7, wherein said differentiating circuit is constructed and arranged to effect a time constant T which satisfies the relationship 1/(5f.sub.t).gtoreq.T.gtoreq.1/(10f.sub.t) with respect to a transfer frequency f.sub.t of said solid-state pickup device. ### Claim 13 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; differentiating means for effecting primary differentiation of said video signal to produce a primary differentiated waveform; and combining means for combining said video signal and said primary differentiated waveform so that a changing portion of said video signal is emphasized. ### Claim 14 (depends on 13) The video signal contour correcting apparatus of claim 13, wherein said combining means comprises adder means for adding said video signal and said primary differentiated waveform to produce the new signal with an added waveform. ### Claim 15 (depends on 14) The video signal contour correcting apparatus of claim 14, wherein said adder means includes amplitude varying means for varying the amplitude of said primary differentiated waveform thereby modifying the ratio of said video signal to said primary differentiated signal in the added waveform of the new signal. ### Claim 16 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a plurality of change signals which differ from each other in phase and with each change signal being responsive to a change of said video signal; amplitude varying means for producing a plurality of amplitude-modified change signals corresponding to said plurality of change signals, with each amplitude-modified change signal differing in amplitude from a corresponding change signal; and combining means for combining said video signal and said amplitude-modified change signals in such a way that said amplitude-modified change signals do not cancel each other. ### Claim 17 (depends on 16) The video signal contour correcting apparatus of claim 16, wherein said signal forming means comprises duration varying means for varying the duration of said change signal. ### Claim 18 (depends on 17) The video signal contour correcting apparatus of claim 17, wherein said duration varying means comprises differentiating means for differentiating said video signal to produce a differentiated waveform. ### Claim 19 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a change signal indicating the degree of change of said video signal and having duration varying means for varying the duration of said change signal, said duration varying means including differentiating means for differentiating said video signal to produce a differentiated waveform wherein said differentiating means comprises a differentiating circuit constructed and arranged to effect a time constant T which satisfies the following relationship with respect to the maximum frequency component f.sub.max of said video signal: 1/(5.times.f.sub.max).gtoreq.T.gtoreq.1/(10.times.f.sub.max) amplitude varying means for producing an amplitude-modified change signal which differs in amplitude from said change signal; and combining means for combining said amplitude-modified change signal and said video signal. ### Claim 20 (depends on 18) The video signal contour correcting apparatus of claim 18, wherein said amplitude varying means comprises attenuating means for attenuating the amplitude of said differentiated waveform. ### Claim 21 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a change signal indicating the degree of change of said video signal; amplitude varying means for producing an amplitude-modified change signal which differs in amplitude from said change signal; combining means for combining said amplitude-modified change signal and said video signal to produce a combined signal; and delay means for producing a signal delayed by a determined time period from said combined signal. ### Claim 22 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a change signal indicating the degree of change of said video signal; amplitude varying means for producing an amplitude-modified change signal which differs in amplitude from said change signal; combining means for combining said amplitude-modified change signal and said video signal to produce a combined signal; delay means for producing a signal delayed by a determined time period from said combined signal; and additional combining means for combining said amplitude-modified change signal and said delayed signal. ### Claim 23 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; differentiating means for differentiating said video signal to produce a differentiated waveform; combining means for combining said differentiated waveform and said video signal to produce a combined signal; forming means for forming a differentiated waveform which is phase inverted in comparison to said differentiated waveform produced by said differentiating means; and control means for controlling said combined signal in such a manner that, when said combined signal and said phase-inverted differentiated waveform are combined, said phase-inverted differentiated waveform and a differentiated waveform component in said combined signal do not act to cancel one another. ### Claim 24 (depends on 23) The video signal contour correcting apparatus of claim 23, wherein said control means comprises delay means for delaying said combined signal. ### Claim 25 (depends on 24) The video signal contour correcting apparatus of claim 24, wherein said differentiating means is constructed and arranged to effect a time constant T which satisfies the following relation with respect to the maximum frequency component f.sub.max of said video signal: 1/(5.times.f.sub.max).gtoreq.T.gtoreq.1/(10.times.f.sub.max). ### Claim 26 (depends on 24, 25) The video signal contour correcting apparatus of claim 24 or 25, wherein said delay means comprises means for delaying said combined signal by a delay time .tau. which satisfies the following relation with respect to a time constant T of said differentiating means: T/2.ltoreq..tau..ltoreq.2T. ### Claim 27 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a change signal indicating the degree of change in said video signal; delay means for delaying said video signal by a determined time period; and combining means for combining said change signal and said delayed video signal so that a changing portion of said video signal is emphasized. ### Claim 28 (depends on 27) The video signal contour correcting apparatus of claim 27, wherein said signal forming means comprises differentiating means for differentiating said video signal to produce the new signal with a differentiated waveform. ### Claim 29 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; signal forming means for forming a change signal indicating the degree of change in said video signal, wherein said signal forming means includes differentiating means for differentiating said video signal to produce a differentiated waveform; delay means for delaying said video signal by a determined time period; and combining means for combining said change signal and said delayed video signal, wherein said combining means includes inverting means for inverting the phase of said differentiated waveform. ### Claim 30 A contour correcting apparatus for video signals, comprising: video signal generating means for generating a video signal; correction signal forming means for generating a first correction signal for correcting one time-wise portion of said video signal and a second correction signal for correcting another time-wise portion of said video signal; and correcting means for combining said video signal and said first correction signal in a delayed state with said second correction signal. ### Claim 31 (depends on 30) The video signal contour correcting apparatus of claim 30, wherein said correction signal forming means comprises change signal forming means for forming said first correction signal and said second correction signal in response to the degree of change of said video signal. ### Claim 32 (depends on 31) The video signal contour correcting apparatus of claim 31, wherein said change signal forming means includes inverting means for inverting said first correction signal to form said second correction signal. ### Claim 33 (depends on 31) The video signal contour correcting apparatus of claim 31, wherein said change signal forming means includes differentiating means for differentiating said video signal. ### Claim 34 (depends on 30) The video signal contour correcting apparatus of claim 30, wherein said correcting means includes means for producing a signal combined and delayed from said video signal and said first correction signal. ### Claim 35 (depends on 34) The video signal contour correcting apparatus of claim 34, wherein said correcting means further comprises combining means for combining said combined and delayed signal and said second correction signal.