Television – Camera – system and detail – Remote control
Reexamination Certificate
1997-03-12
2002-05-07
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Remote control
C348S211130
Reexamination Certificate
active
06384862
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to an electronic imaging system and method, particularly, to an improved imaging system and method for customizing the images to the viewer's specifications, and, more particularly, to an imaging system and method allowing the viewer, via a backchannel, to adjust the spatial and temporal resolution and quantization parameters of an image.
2. Background and Objects of the Present Invention
With the rise of the consumer electronics industry over the past few decades, a variety of electronic imaging systems of increasing complexity have emerged, e.g., video recorders, camcorders and the like. Additionally, video teleconferencing communications are becoming increasingly important as our society becomes increasingly and interactively interconnected.
As is understood in this art, video, i.e., moving, images undergo encoding to reduce the amount of information needed to represent a given image. Encoding affects both the spatial resolution, i.e., the detail within a particular image frame, and temporal resolution, i.e., the number of such image frames per second. These parameters are typically fixed within a conventional video system, such as the one shown in
FIG. 1
of the Drawings and generally referred to herein as numeral
10
. The video system
10
in the figure includes a sending device
12
which receives signals from a camera
14
. It should be understood that various portions of camera
14
which are not related to the present invention, for example, the diaphragm, shutter and the like, are not illustrated. Accordingly, as is understood in this art, the optical image before the camera
14
, such as the individual depicted, is received by a camera lens
16
and converted into an analog video signal, e.g., by a conventional charge coupled device. It should be understood that camera
14
may be a digital camera forwarding digital data to a subsampler device
18
within the sending device
12
. If camera
14
is not digital, however, and analog-to-digital conversion is required, then device
18
may also function as an A/D converter, as is understood in the art. The subsampler
18
determines pixel values representing the captured video image at a particular spatial resolution, i.e., pixels per line and lines per image, and temporal resolution, i.e., images per second. Another parameter related to both spatial and temporal resolution is quantization, i.e., a measure of the amount of distortion present in the video signal, as will be discussed in more detail hereinafter.
An encoder
20
encodes the aforedescribed digital image data into a video signal stream which flows into a buffer
22
. As is understood in the art and discussed further herein, the rate of the flow of information from the encoder
20
into buffer
22
varies in accordance with the degree of encoding. Additionally, the video signal stream typically includes compressed signals, in which image information has been condensed or compressed by the encoder
20
to facilitate transmission or storage. One set of formats using such compression technologies are those specified by the Moving Picture Experts Group (MPEG), a standard in accord with the International Organization for Standardization/International Electro-technical Commission (ISO/IEC). Other compression technologies are the H.261, H.262 and H.263 standards of the International Telecommunications Union, Teleconferencing Section (ITU-T) for use in video teleconferencing, for example.
In conjunction with these image data formatting standards and techniques, by which the encoder
20
provides a syntax for the subsequent bitstream, the encoder
20
also employs compression algorithms, such as Discrete Cosine Transforms (DCT), Huffman coding and other mechanisms, whereby the amount of data needed to represent the image is drastically reduced while substantially retaining image integrity. As is well understood by those skilled in the art, these and other techniques eliminate or reduce the transmission of frame-to-frame redundancies and other information which are unnecessary or repetitive, and exploit various physiological and psychological aspects of human perception to present a coherent image to the viewer's eye.
With further reference to
FIG. 1
, the subsampler
18
, encoder
20
and buffer
22
are controlled by a control unit
24
, which also controls other functions of the imaging system
10
. For example, control unit
24
controls the sequencing of the afore-described operations, i.e., image pickup by camera
14
through a connection thereto (not shown), pixel conversion in subsampler
18
, compression in encoder
20
, recording the encoded images on a magnetic or electronic recording medium (not shown), and other operations. Control unit
24
supplies encoder
20
with a plurality of operating parameters to govern the aforementioned transformation of pixel data into a corresponding compressed bitstream. As discussed, control unit
24
also governs the variable bit rate of the information flow into buffer
22
to maintain a particular data level and avoid both overflow and underflow therein.
As is understood in this art, the primary purpose of buffer
22
is to regulate the flow of data from the encoder
20
and forward that data at a fixed rate across a transmission channel
26
to a receiver device
28
, particularly, to another buffer
30
therein, which like buffer
22
acts as a reservoir storing the data and regulating its use. It should, of course, be understood that channel
26
may transfer data at a variable rate, e.g., a variable rate service of an Asynchronous Transfer Mode (ATM) network. Nonetheless, the variable flow rate of data from encoder
20
does not generally agree with that of channel
26
, fixed or variable.
Buffer
30
forwards the received image data, at a fixed or variable rate as needed, to a decoder
32
. Similarly to the encoding process, the decoder
32
reverses the aforedescribed compression algorithms to expand the image pursuant to the aforementioned operating parameters. In other words, the decoder
32
decompresses the compressed information in the bit stream and reconstitutes the image pursuant to the relevant image format used, e.g., the ITU-R/601 Digital Studio Standard, and the operating parameters. The reconstituted image is then placed within an image storage device
34
, the contents of which may be continuously displayed on a video display
36
, the circuitry of which is understood in the art.
As discussed, the aforedescribed compression technologies employ various techniques to condense the image information. The decoder
32
is configured to interpret the format and operating parameters by which the image information was encoded by encoder
20
. As is understood in the art, much of the decoding process performed within the decoder
32
may be called “normative”, i.e., fixed by the particular standard used, e.g., MPEG. Consequently, the decoder
32
readily recognizes these normative parts of a signal from encoder
20
, i.e., how to interpret the transmitted bits in the bit stream.
In conventional apparatus employing the above technology, the aforementioned operating parameters are fixed within the video system
10
. Usually, encoder
20
utilizes fixed spatial and temporal resolution values, which comports well with the requirements of buffer
22
, guaranteeing a fixed-rate bitstream across transmission channel
26
. Nonetheless, buffer
22
in an effort to maintain the transmission rate required by the channel
26
adjusts the quantization or distortion of the pertinent images. Quantization then becomes a function of the fullness of buffer
22
, which, in turn, is a function of the complexity of the subject video images, i.e., how bit-consuming the images are during compression. Some encoders
20
have fixed spatial resolution only and the buffer
22
adjusts quantization and temporal resolution to maintain the constant bit-rate. The balance between quantization and temporal resolution is governed b
Brusewitz Harald
Burman Bo
Roth Göran
Garber Wendy R.
Jenkens & Gilchrist P.C.
Moe Aung S.
Telefoaktiebolaget L M Ericsson
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