Image analysis – Image compression or coding – Parallel coding architecture
Reexamination Certificate
1999-03-02
2002-03-12
Johnson, Timothy M. (Department: 2623)
Image analysis
Image compression or coding
Parallel coding architecture
C375S240100
Reexamination Certificate
active
06356662
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 87117110, filed Oct. 15, 1998, the fill disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to handling digitized data, and more particularly, to a method of handling digitized data, such as digitized video data, in a digital information system, such as a personal computer in conjunction with a digital camera, which allows the handling of the digitized data in the digital information system to be more efficiently carried out to help reduce the load on the CPU (central processing unit) of the computer.
2. Description of Related Art
The digital camera has recently become a popular peripheral device for personal computers (PC) due to breakthrough development in digital signal processing (DSP) technologies. To make the digital camera acceptable to the consumers, it must be cheap to purchase and easy to install and use. To achieve these objectives, most manufacturers use standard components to build their digital camera products. For instance, the data communication interface between the digital camera and the PC employs typically a standard data communication interface, such as ECP (Extended Capabilities Port), EPP (Enhanced Parallel Port), or USB (Universal Serial Bus).
Presently, an ECP/EPP interface can provide a data transmission rate of from 5 Mbps to 12 Mbps (megabits per second), while a full-speed USB interface can provide 12 Mbps. However, in the case of transmitting CIF (Common Interchanged Format) formatted video data at 30 frames per second, the required data rate is 352×288×2×8×30=48.66048 Mbps. In order to transmit such a great amount of digitized video data over an ECP, EPP, or USB interface, the data should be compressed.
FIG. 1
is a schematic block diagram showing the system configuration of a digital camera used in conjunction with a PC. As shown, the digital camera includes a video unit
10
and a compression unit
20
, with the compression unit
20
being coupled via a peripheral communication interface
50
, such as an ECP, an EPP, or a USB interface, to a PC
30
. The PC
30
is further coupled to a communication network line
60
and a data storage unit
40
. The video unit
10
includes a video image sensor
11
, a CDS/AGC (Correlation Duplex Sampling & Auto Gain Control) unit
12
, an ADC (Analog to Digital Converter) unit
13
, and a signal processor
14
. The analog video signal captured by the video image sensor
11
is processed successively by the CDS/AGC unit
12
, the ADC unit
13
, and the signal processor
14
to obtain a set of digitized video data. The digitized video data output from the signal processor
14
are then compressed by the compression unit
20
through a compression process into compressed data of a specific video compression format, which can be either a proprietary video compression format or a standard video compression format such as MPEG, H.261, or H.263. A proprietary video compression format is typically low in compression ratio, whereas a standard video compression format is typically high in compression ratio.
In the case of using a proprietary video compression format, the compressed video data are transferred via the peripheral communication interface
50
to the PC
30
. To allow the compressed video data to be displayed and edited, the PC
30
should first perform a decompression process on these data. This decompression process is the inverse of the compression process performed by the compression unit
20
. The decompressed video data can be then displayed on the monitor screen (not shown) of the PC
30
. Owing to the limitation of the storage capacity of the data storage unit or the limitation of a bandwith of the communication network line, the decompressed video data stored in the data storage unit
40
or transmitted over the communication network line
60
must be again compressed, typically into a high-compression-rate video compression format, such as MPEG, H.261, or H.263. The data storage unit
40
can be either a hard disk, a magnetic tape, a writable optical disc as a CD (compact disc) or DVD a (digital versatile disc), or a flash memory unit.
One drawback to the use of the low-compression-rate proprietary video compression format, however, is that the captured video data from the video unit
10
should undergo a compression-decompression-compression process before they are stored into the data storage unit
40
or transmitted over the communication network line
60
, and therefore the subsequently decompressed data from the data storage unit
40
or the communication network line
60
is significantly poor in fidelity. Moreover, since the PC
30
needs to perform many decompression and compression steps, the load on the PC
30
is very heavy, making the overall system performance of the PC
30
low.
In the case of using a high-compression-rate video compression format such as MPEG, H2.261, or H.263, the compressed video data are transferred via the peripheral communication interface
50
to the PC
30
. To allow the compressed video data to be displayed and edited, the PC
30
must first perform a decompression process on these data. This decompression process is the inverse of the previous compression process performed by the compression unit
20
. The decompressed video data can be then displayed on the monitor screen (not shown) of the PC
30
. One advantage of using high-compression-rate video compression format over low-compression-rate one is that the received data from the peripheral communication interface
50
can be directly stored into the data storage unit
40
or transmitted over the communication network line
60
without having to perform an additional compression as in the foregoing case. Therefore, the PC
30
needs to perform just one decompression process to make the received data displayable and editable. The load on the PC
30
is thus reduced. One drawback to the use of high-compression-rate video compression format, however, is that it typically requires a high-end CPU to allow satisfactory processing speed. Moreover, in application, in order to satisfy the limitation of the storage capacity of the data storage unit or the limitation of a bandwith of the communication network line, the video data must be compressed by the compression unit
20
with a high-compression ratio. However, the performance of the decompressed video data becomes poor while being re-decompressed and being shown in the monitor of the personal computer.
SUMMARY OF THE INVENTION
It is therefore an objective of the present invention to provide a method for handling digitized data through compression/decompression and utilization in a more efficient manner than the prior art.
In accordance with the foregoing and other objectives of the present invention, a new method is provided for use in a digital information system to handle digitized data through compression/decompression and utilization.
When used to handle digitized video data, the method includes compressing the original digitized video data concurrently into a first set of compressed data through a first compression process and a second set of compressed data through a second compression process. The first compression process has a lower compression ratio than the second compression process. The first and second sets of compressed data via a data transmission interface are transferred to an information processing unit. The first set of compressed data is decompressed through a decompression process to obtain a set of decompressed data representing the original digitized video data for output of the original digitized video data at an output device. The second set of compressed data remains in compressed form for storage into a data storage unit and transmission over a communication network line.
Since the information processing unit needs to perform just a simple decompression process to decompress the low-compression-rate set o
Huang Jiawei
J. C. Patents
Johnson Timothy M.
Winbond Electronics Corp.
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