U.S. patent application number 11/873282 was filed with the patent office on 2008-04-17 for signal compressing signal.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Mun Hen-Hee, Jeong Je-Chang.
Application Number | 20080089421 11/873282 |
Document ID | / |
Family ID | 30002405 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080089421 |
Kind Code |
A1 |
Je-Chang; Jeong ; et
al. |
April 17, 2008 |
SIGNAL COMPRESSING SIGNAL
Abstract
A multi-scanner scans a signal according to several different
patterns. A scanning pattern selector determines which scanning
pattern produced the most efficient coding result, for example, for
runlength coding, and outputs a coded signal, coded most
efficiently, and a selection signal which identifies the scanning
pattern found to be most efficient.
Inventors: |
Je-Chang; Jeong; (Seoul,
KR) ; Hen-Hee; Mun; (Seoul, KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
416, MAETAN-DONG, YEONGTONG-GU
SUWON-SI
KR
|
Family ID: |
30002405 |
Appl. No.: |
11/873282 |
Filed: |
October 16, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10612013 |
Jul 3, 2003 |
7292657 |
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11873282 |
Oct 16, 2007 |
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09703649 |
Nov 2, 2000 |
6680975 |
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11873282 |
Oct 16, 2007 |
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08024305 |
Mar 1, 1993 |
6263026 |
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11873282 |
Oct 16, 2007 |
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Current U.S.
Class: |
375/240.22 ;
375/240.24 |
Current CPC
Class: |
H04N 19/46 20141101;
H04N 19/61 20141101; H04N 19/192 20141101; H04N 19/15 20141101;
H04N 19/60 20141101; H04N 19/129 20141101; H04N 19/146 20141101;
H04N 19/152 20141101; H04N 19/176 20141101; H04N 19/18
20141101 |
Class at
Publication: |
375/240.22 ;
375/240.24 |
International
Class: |
H04N 11/02 20060101
H04N011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 29, 1992 |
KR |
92-3398 |
Claims
1. A decoder for decompressing a compressed video signal, the
compressed video signal containing entropy encoded data
representing a set of video spatial frequency coefficients of an
individual sub-block which have been scanned using a selected one
of a plurality of different scanning patterns to produce a set of
reordered coefficients and also containing a scanning mode signal
indicating the selected one of the plurality of different scanning
patterns, the decoder comprising: an entropy decoder operative to
decode the entropy encoded data and to output entropy decoded data;
and a scanner operative to scan the entropy decoded data according
to the selected one of the plurality of different scanning patterns
as indicated by the scanning mode signal, wherein the plurality of
different scanning patterns includes FIG. 3H.
2. The decoder according to claim 1 wherein the entropy encoded
data and the scanning mode signal are multiplexed together as part
of coded data signal.
3. The decoder according to claim 1, wherein the entropy encoded
data, the scanning mode signal and the additional information are
multiplexed together as part of coded data signal, and wherein said
decoder further includes a demultiplexer which demultiplexes the
entropy encoded data, the scanning mode signal and the additional
information.
4. The decoder according to claim 1, wherein the entropy encoded
data is encoded according to a variable length encoding regime.
5. The decoder according to claim 1, wherein the scanner scans the
entropy decoded data according to a runlength decoding regime.
6. The decoder of claim 1, further comprising a dequantizer which
dequantizes the scanned data output by said scanner and outputs
dequantized data.
7. The decoder of claim 6, further comprising an inverse discrete
cosine transformer which inverse discrete cosine transforms the
dequantized data output by said dequantizer.
Description
CROSS-REFERENCES TO RELATED PATENT APPLICATIONS
[0001] This is a Continuation of application Ser. No. 10/612,013,
filed Jul. 3, 2003; which is a Continuation of application Ser. No.
09/703,649, filed Nov. 2, 2000; which is a Continuation of
application Ser. No. 08/024,305, filed Mar. 1, 1993; the
disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a signal compressing
system. A system according to the present invention is particularly
suited for compressing image signals. The present disclosure is
based on the disclosure in Korean Patent Application No. 92-3398
filed Feb. 29, 1992, which disclosure is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0003] Image signals may be compressed by motion-compensated
interframe discrete cosine transform (DCT) coding such as is
defined by a MPEG (Moving Picture Expert Group) international
standard. This form of signal compression has attracted much
attention in the field of high definition television (HDTV).
[0004] FIG. 1 is a block diagram of such a conventional
motion-compensated interframe DCT coder. In the shown coder, an
image signal is divided into a plurality of sub-blocks. The
sub-blocks are all of the same size, for example 8.times.8,
16.times.16, . . . . A motion estimator 40 produces a motion
vector, defined by the difference between the current image signal
and a one-frame delayed image signal, output by a frame memory 30.
The motion vector is supplied to a motion compensator 50 which
compensates the delayed image signal from the frame memory 30 on
the basis of the motion vector. A first adder 8a serves to produce
the difference between the present frame and the delayed, motion
compensated frame. A discrete cosine transform portion 10 processes
the difference signal, output by the first adder 8a, for a
sub-block. The motion estimator 40 determines the motion vector by
using a block matching algorithm.
[0005] The discrete cosine transformed signal is quantized by a
quantizer 20. The image signal is scanned in a zig-zag manner to
produce a runlength coded version thereof. The runlength coded
signal comprises a plurality of strings which include a series of
"0"s, representing the run length, and an amplitude value of any
value except "0".
[0006] The runlength coded signal is dequantized by a dequantizer
21, inversely zig-zag scanned and inversely discrete cosine
transformed by an inverse discrete cosine transforming portion 11.
The transformed image signal is added to the motion-compensated
estimate error signal by a second adder 8b. As a result the image
signal is decoded into a signal corresponding to the original image
signal.
[0007] Refresh switches RSW1, RSW2 are arranged between the adders
8a, 8b and the motion compensator 40 so as to provide the original
image signal free from externally induced errors.
[0008] The runlength coded signal is also supplied to a variable
length coder 60 which applies a variable length coding to the
runlength coded image signal. The variable length coded signal is
then output through a FIFO transfer buffer 70 as a coded image
signal.
[0009] In motion-compensated adaptive DCT coding, the interframe
signal can be easily estimated or coded by way of motion
compensation, thereby obtaining a high coding efficiency, since the
image signal has a relatively high correlation along the time axis.
That is, according to the afore-mentioned method, the coding
efficiency is high because most of the energy of a discrete cosine
transformed signal is compressed at the lower end of its spectrum,
resulting in long runs of "0"s in the runlength coded signal.
[0010] However, the scanning regime of the aforementioned method
does not take account of differences in the spectrum of the
motion-compensated interframe DCT signal with time.
[0011] A method is known wherein one of a plurality of reference
modes is previously selected on the basis of the difference between
the present block and that of a previous frame and the image signal
is scanned by way of a scanning pattern under the selected mode and
suitably quantized. With such a method, however, three modes are
employed to compute the energies of the intermediate and high
frequency components of the image signal in accordance with the
interframe or the intraframe modes in order to determine the
appropriate mode. This mode determining procedure is undesirably
complicated.
SUMMARY OF THE INVENTION
[0012] According to the present invention, there is provided a
signal compressing system, comprising coding means for scanning an
input signal according to a plurality of different scanning
patterns to provided coded versions thereof and selection means for
selecting a said scanning pattern which produces efficient coding
according to a predetermined criterion and outputting a scanning
pattern signal identifying the selected scanning pattern.
[0013] Preferably, the input signal is an inherently
two-dimensional signal, for example, an image signal.
[0014] Preferably, the coding means codes the input signal
according to a runlength coding regime.
[0015] Preferably, the system includes a variable length coder to
variably length code the coded signal, produced by scanning
according to the selected scanning pattern.
[0016] Preferably, the system includes discrete cosine transformer
means to produce said input signal. The transformer means may be a
motion-compensated interframe adaptive discrete cosine
transformer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] An embodiment of the present invention will now be
described, by way of example, with reference to FIGS. 2 and 3 of
the accompanying drawings, in which:
[0018] FIG. 1 is a block diagram of a conventional adaptive
interframe DCT coding system employing a motion compensating
technique;
[0019] FIG. 2 is a block diagram of a coding system embodying the
present invention;
[0020] FIGS. 3A-3H show various possible scanning patterns
according to the present invention; and
[0021] FIG. 4 is a block diagram of a decoding system according to
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Referring to FIG. 2, an input signal is divided into
equal-sized sub-blocks, for example, 8.times.8, 16.times.16, . . .
. A motion estimator 40 determines a motion vector by comparing the
current frame and a one frame delayed signal from a frame memory
30.
[0023] The motion vector is supplied to a motion compensator 60
which, in turn, compensates the delayed frame signal for movement.
A first adder 8a produces a difference signal representing the
difference between the present frame and the delayed,
motion-compensated frame. A DCT coder 10 DCT-codes the difference
signal. The DCT coded image signal is quantized by a quantizer 20
and then dequantized by a dequantizer 21. The dequantized signal is
supplied to a second adder 8b, via IDCT 11, which adds it to the
output of the motion compensator 11. This produces a signal
corresponding to the original image signal.
[0024] The output of the motion compensator 50 is applied to the
adders 8a, 8b by refresh switches RSW2 and RSW1, respectively.
[0025] The quantized image signal is also supplied to a
multi-scanner 80 which scans it according to a plurality of
predetermined patterns.
[0026] A scanner pattern selector 90 selects the scanning pattern
which produces the minimum number of bits to represent the current
sub-block. The scanning pattern selector also produces selection
data which identifies the selected scanning pattern.
[0027] The image signal output by the scanning pattern selector 90
is variable length coded by a variable length coder 60. The
variable length coder 60 compresses the image signal output by the
scanning pattern selector 90. The variable length coder 60 operates
such that a large proportion of the data samples are each
represented by a small number of bits while a small proportion of
the data samples are each represented by a large number of
bits.
[0028] When a discrete cosine transformed image signal is quantized
and runlength coded, the number of "0"s is increased over all,
while the number of "0"s decreases as the magnitude of the signal
increases. Accordingly, data compression is achieved because "0"
can be represented by only a few bits and "255" can be represented
by a relatively large number of bits.
[0029] Both the variable length coded signal and the selection data
are supplied to a multiplexer MUX1 which multiplexes the variable
length coded signal and the selection data, and optionally
additional information such as teletext.
[0030] Since the variable length coded signal has data words of
different lengths, a transfer buffer 70 is employed to temporarily
store the multiplexed signal and output it at a constant rate.
[0031] FIG. 4 shows a decoding system at a remote station that
receives and extracts the encoded data. In FIG. 4, demultiplexer
100 receives coded data and, in an operation inverse to that
performed at the coding system, extracts the variable length
encoded data, the scanning pattern information and the additional
information that had been multiplexed together at the coding
system. Variable length decoder 110 variable length decodes the
variable length encoded data, and scanner 120 receives the variable
length decoded data and reconstructs the original sub-block using a
scanning pattern indicated by the extracted scanning pattern
selection signal. The scanner would necessarily have to select one
from a plurality pattern that was available for encoding. Using
components having the same margin as dequantizers 21 and IDCT 11 in
the encoder system, dequantizer 120 dequantizes the signal output
from the scanner 120, and inverse discrete cosine transformer 140
performs an inverse discrete cosine transform function on the
output of dequantizer 130, to output decoded data.
[0032] The original image signal is reconstructed at a remote
station by performing the appropriate inverse scanning of the
runlength coded signal in accordance with the multiplexed scanning
pattern selection data.
[0033] FIGS. 3A to 3H show possible scanning patterns employed by
the multi-scanner 80. Additional scanning patterns will be apparent
to those skilled in the art. However, if the number of patterns
becomes too large, the coding efficiency is degraded as the
selection data word becomes longer.
[0034] As described above, according to the present invention, the
quantized image signal is scanned according to various scanning
patterns, and then the most efficient pattern is selected.
[0035] A suitable measure of efficiency is the number of bits
required to runlength code the image signal.
* * * * *