Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-09-11
2003-12-16
Britton, Howard (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C382S248000
Reexamination Certificate
active
06665343
ABSTRACT:
2. FIELD OF THE INVENTION
The present invention relates to multimedia images and digital communications, and more particularly to methods and arrangements for converting a high definition picture or image to a lower definition image using wavelet transforms.
3. DESCRIPTION OF THE RELATED ART
Many different image and/or video sampling techniques are used in the coding, transmission and reproduction of multimedia images and/or signals such as, for example, still and moving pictures, video, and other related data signals such as audio. These techniques allow multimedia information to be properly coded, transmitted and reproduced by known hardware currently in use. Examples of such techniques are well known in the art and many are presented in the
Revised Text for ITU
-
T Recommendation H.
262
ISO/IEC
13818-2:1995,
Information technology—Generic coding of moving pictures and associated audio information: Video
dated Mar. 31, 1995.
On Nov. 4, 1994, the ISO (International Organization for Standards) Motion Picture Experts Group (MPEG) adopted a standard for audio/video digital compression known as MPEG-2. This standard allows for consistent digital signal sampling, coding, transmission and reception throughout the world and is well known in the art.
U.S. Pat. No. 5,262,854 issued to Ng on Nov. 16, 1993, entitled Lower Resolution HDTV Receivers, shows a receiver which decimates compressed HDTV digital video signal data to provide lower resolution NTSC images. This system allows high definition signals to be used on lower definition receivers which are currently more commonly in use than high definition receivers.
Similarly, there are many different types of video sampling techniques and digital component video formats commonly used in MPEG video coding. By way of example, there is a high definition 4:4:4 video format which defines the relative relationship between the luminance and chrominance components in a transmitted digital video color signal. In lower definition video sampling formats such as 4:2:2 and 4:2:0 there are less chrominance components per samples of luminance in the digital signal. All three of these sampling techniques are well known in the art. The higher definition sampling techniques and contain more information and therefore produce higher resolution images.
Regardless of the sampling technique, an appropriate display apparatus, such as a monitor or flat panel display, is required to effectively reproduce the encoded image. Given the current development of higher resolution systems and apparatii, a display that is capable of reproducing and displaying a higher resolution image can be very expensive. For example, a high definition television (HDTV) apparatus can cost several thousands of dollars. For many consumers, the cost of a HDTV can be prohibitive when compared to that of a standard definition television, such as, for example, a NTSC compatible apparatus which often costs less than a few hundred dollars.
There are similar cost issues for the producers and broadcasters of the video signals. Producing higher resolution images requires state of the art image recording and generating systems, and often requires that additional bandwidth be provided within the transmission channels in order to handle the increase in information (data) being provided to the consumers.
Broadcasters and consumers are also presented with the concern that there may be a period of time in which only a few consumers have higher resolution display apparatii. This is especially a concern as the technology moves to the next generation of imagery which will incorporate HDTV as the standard.
Thus, there is a need for methods and arrangements that allow the remaining consumers, which possess lower definition television and imaging equipment, to receive the higher definition image data and convert this data to lower definition image data that can be displayed on the lower resolution displays.
HDTV digital video signal decoders are also well known in the art. In conventional MPEG-compatible decoders, there is typically an inverse discrete cosine transform (IDCT) process that is used to decode video-related data that was previously encoded using a discrete cosine transform (DCT) process.
The image data that is encoded/decoded by conventional encoders and decoders typically includes three (3) components per pixel. The components are luminance data (Y
c
), chrominance data (U
c
) and chrominance data (V
c
). For example, to display a high definition image, such as, for example, a 1920 by 1080 pixel image, a typical decoder would output 1920 by 1080 pixels of luminance-related data, and 960 by 540 pixels of chrominance-related data. In this example, the resulting data provides a 4:2:0 image having 1920 by 1080 pixels.
The known methods and arrangements for decimating or otherwise reducing the amount of image data attempt to create a subset of the image data that can then be displayed on a lower resolution display. To accomplish this “downscaling”, the known methods and arrangements typically pre-parse or filter the received encoded image data. For example, these methods use masking techniques that eliminate particular data. The remaining portions of the encoded image data are then decoded, for example using a decoder having an IDCT process. The decoded image data is then filtered and/or decimated to further reduce the image for display on a lower resolution display.
By way of example, the amount of information used for a low definition image in certain decoders is ¼ the amount of information used for the original higher definition image. Thus, for a 1920 by 1080 pixel high definition image, the lower resolution image is 960 by 540 pixels.
It is important to note that this type of known decoder essentially loses video-related information before and after the IDCT process. One result of losing video-related information is that the symmetry of the resulting decoded image can be adversely affected. The loss of symmetry in the resulting decoded image from this type of known decoder can result in a lower quality image, for example, a non-symmetrical 4:2:0 lower-resolution image.
FIGS. 1 and 2
show block diagram depictions of conventional digital video encoding/decoding transmission systems.
FIG. 1
is a block diagram depicting a conventional system
100
having an encoder
102
that encodes an image file
104
containing image data
114
. The output of encoder
102
, i.e., encoded image data, is transmitted or otherwise provided to a decoder
108
through a transmission link
106
.
Transmission link
106
can include one or more communication media and/or systems and supporting apparatii that are configured to carry the encoded image data from encoder
102
to decoder
108
. Examples of transmission link
106
may include, but are not limited to, a telephone system, a cable television system, a direct or an indirect broadcast television system, a direct or an indirect satellite broadcast system, one or more computer networks and/or buses, the Internet, an intranet, and any software, hardware and other communication systems and equipment associated therewith.
Decoder
108
decodes the received encoded image data and outputs an image
110
that is suitable for reproduction through a display
112
. In certain conventional systems, encoder
102
and/or decoder
108
may include one or more processors that each are coupled to a memory. The processor(s) respond to computer implemented instructions stored within the memories to encode or decode image data
114
, as required. In other conventional systems, encoder
102
and/or decoder
108
include logic that is configured to encode or decode image data
114
, as required.
FIG. 2
is a block diagram depicting a conventional encoding/decoding/transmission system
100
that reduces a higher definition image
114
to a lower definition image
124
that can be displayed on a lower resolution display (not shown). System
100
includes an encoder
102
which implements a DCT algorithm
116
that encodes image data
114
using a DCT algorithm. Decoder
Chaney Jack
Jahanghir Musa
Kaufman Michael A.
Aiello Jeffrey P.
Britton Howard
Samsung Electronics Co,. Ltd.
Sherman Kenneth L.
Sherman & Sherman
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