Two-dimensional finite impulse response filters

• US 4,821,223 A
• Filed: 09/23/1986
• Issued: 04/11/1989
• Est. Priority Date: 10/04/1985
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: David, Morgan W. A.
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): Shaw, Dale M.
• Application Number:
  US06/910,523
• Time in Patent Office: 931 Days
• Field of Search: 364/724, 364/724.16, 364/724.13, 364/724.05, 364/724.01
• US Class Current: 708/308
• CPC Class Codes: H03H 17/0202 Two or more dimensional filters; Filters for complex signals multidimensional convolutions G06F17/153

Abstract

A two-dimensional finite impulse response (FIR) filter comprises a demultiplexer for demultiplexing an input data signal comprising adjacent digital words into p (e.g. 2) slower data signals each having a slower rate equal to 1/p (e.g. 1/2) of the data rate of the input signal and each comprising every p^th (e.g. every alternate) word of the input signal. The slower data signals are passed to p (e.g. 2) filter portions each comprising a horizontal FIR filter and a vertical FIR filter. The horizontal filters are each connected to receive all of the slower data signals and all of them are operative simultaneously to effect horizontal filtration by periodically processing sets of adjacent words of the input signal, the sets of adjacent words being processed at any one time by the respective horizontal filters being offset with respect to one another by one word. A multiplexer receives output signals of the filter portions to form a filtered output data signal having a data rate equal to that of the input data signal.

Claims

1. A two-dimensional finite impulse response (FIR) filter comprising:

a demultiplexer for demultiplexing an input data signal comprising consecutive digital words into p slower data signals, where p is an integer greater than 1, such having a slower data rate equal to 1/p of said data rate of the input data signal and each comprising every p^th word of said input data signal;

p FIR filter portions each connected to receive all of said slower data signals, all of said p FIR filter portions being operative at said slower data rate simultaneously to effect horizontal filtration by periodically processing sets of consecutive words of said input data signal, said sets of consecutive words being processed at any one time by the respective filter portions being offset with respect to one another by one word in the horizontal direction; and

a multiplexer connected to receive output signals of said p FIR filter portions to form a filtered output data signal having a data rate equal to that of said input data signal;

wherein each of said p FIR filter portions comprises a vertical FIR filter and a horizontal FIR filter, said vertical FIR filter of said FIR filter portion has an input connected to said demultiplexer so as to receive directly only a respective one of said p slower data signals, and said horizontal FIR filter of each said FIR filter portion has p inputs of which one is connected to an output of said vertical FIR filter of the same FIR filter portion and the at least one other is connected to the output of the vertical filter of the at least one other FIR filter portion, whereby the at least one other of the p slower rate signals is received by the FIR filter portion indirectly, namely after vertical filtration in the at least one other FIR filter portion.

2. A two-dimensional FIR filter according to claim 1, wherein p=2.

3. A two-dimensional finite impuse response (FIR) filter comprising:

a demultiplexer for demultiplexing an input data signal comprising consecutive digital words into p slower data signals, where p is an integer greater than 1, each having a slower data rate equal to 1/p of said data rate of the input data signal and each comprising every p^th word of said input data signal;

p FIR filter portions each connected to receive all of said slower data signals, all of said p FIR filter portions being operative at said slower data rate simultaneously to effect horizontal filtration by periodically processing sets of consecutive words of said input data signal, said sets of consecutive words being processed at any one time by the respective filter portions being offset with respect to one another by one word in the horizontal direction; and

a multiplexer connected to receive output signals of said p FIR filter portions to form a filtered output data signal having a data rate equal to that of said input data signal;

wherein each of said p FIR filter portions comprises a plurality of horizontal FIR filters each corresponding to a respective row of an array of words of said input data signal and line delay means for delaying said p slower data signals by amounts corresponding to the spacing in time between said rows of said array, wherein the p horizontal FIR filters of said p FIR filter portions corresponding to each said row of said array are connected to process sets of consecutive words of said input data signal corresponding to that row, said sets being offset with respect to one another by one word in the horizontal direction, and wherein each of said p FIR filter portions comprises summing means for summing output signals from said plural horizontal FIR filters of that filter portion to produce said output signal of that filter portion.

4. A two-dimensional FIR filter according to claim 3, wherein p=2.