Method and apparatus for creating less amount of compressd image data from compressed still image data and system for transmitting compressed image data through transmission line

• US 5,666,161 A
• Filed: 04/26/1994
• Issued: 09/09/1997
• Est. Priority Date: 04/26/1993
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Tomokane, Takeo, Nakata, Junji, Kohiyama, Tomohisa, Kamo, Munekazu, Yamada, Takahiro, Tomita, Taminori, Yamagishi, Masami, Kawahara, Tetsuya
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/233,702
• Time in Patent Office: 1,232 Days
• Field of Search: 358/403, 358/261.3, 358/432, 358/433, 358/439, 348/400, 348/405, 348/408
• US Class Current: 375/240.18
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/164 Feedback from the receiver or from the transmission channel
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 21/236 Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream multiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/434 Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream demultiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/6377 directed to server one-way streaming services wherein the source is controlled by the destination H04L65/613
• CPC Class Codes: H04N 21/658 Transmission by the client directed to the server

Abstract

Compressed image data of a desired picture is read out from a memory having compressed image data of a sequential format stored therein and then subjected to an examination with respect to a plurality of frequency components of the read-out compressed image data. Part of the plurality of frequency components is deleted to obtain compressed image data of a quality lower than an original quality of the compressed image data. The obtained compressed image data of the lower quality is decoded and displayed on a display. The plurality of frequency components are deleted in a stepwise manner according to a traffic state of a transmission line through which the compressed image data is to be transmitted. For maintaining a picture frame rate to be constant, the plurality of frequency components may be deleted in a stepwise manner. For obtaining a desired decoding rate, the plurality of frequency components may be deleted in a stepwise manner.

Claims

1. A method for creating compressed image data, said method comprising the steps of:

reading out compressed image data of a desired picture from a memory having compressed image data of a sequential format stored therein, said image data of the sequential format having been compressed by using at least an orthagonal transform and Huffman coding;

examining a plurality of frequency components of said read-out compressed image data;

deleting part of said plurality of frequency components without altering the size of the coded image data; and

obtaining compressed image data of a quality lower than an original quality of said compressed image data.

2. A device for creating compressed image data as set forth in claim 1, wherein at least a D.C. component of said read-out compressed image data remains after said step of deleting part of said frequency components.

3. A device for creating compressed image data, comprising:

means for reading out compressed image data of a desired picture from a memory having compressed image data of a sequential format stored therein, said image data of the sequential format having been compressed by using at least an orthagonal transform and Huffman coding;

means for examining a plurality of frequency components of said read-out compressed image data;

means for deleting part of said plurality of frequency components by directly editing the Huffman coding without altering the size of the coded image data; and

means for obtaining compressed image data of a quality lower than an original quality of said compressed image data by utilizing the frequency components other than said deleted frequency components.

4. A device for creating compressed image data as set forth in claim 3, wherein at least a D.C. component of said read-out compressed image data is left in said frequency component deletion means.

5. A method for displaying compressed image data, said method comprising the steps of:

reading out compressed image data of a desired picture from a memory having compressed image data of a sequential format stored therein, said image data of the sequential format having been compressed by using at least an orthagonal transform and Huffman coding;

examining a plurality of frequency components of said read-out compressed image data;

deleting part of said plurality of frequency components by directly editing the Huffman coding without altering the size of the coded image data in a stepwise manner according to a specified picture quality to obtain compressed image data of the sequential format of a quality lower than an original quality of said compressed image data;

decoding said compressed image data of the lower quality with use of a decoder; and

displaying said decoded picture of the lower quality on display means.

6. A method for displaying compressed image data as set forth in claim 5, wherein at least a D.C. component of said read-out compressed image data is left in said frequency component deletion step.

7. A device for displaying compressed image data, comprising:

means for reading out compressed image data of a desired picture from a memory having compressed image data of a sequential format stored therein, said image data of the sequential format having been compressed by using at least an orthagonal transform and Huffman coding;

means for examining a plurality of frequency components of said read-out compressed image data;

means for deleting part of said plurality of frequency components by directly editing the Huffman coding without altering the size of the coded image data in a stepwise manner according to the specified picture quality to obtain compressed image data of the sequential format of a quality lower than an original quality of said compressed image data;

a decoder for decoding said compressed image data of the lower quality; and

display means for displaying thereon said decoded picture of the lower quality.

8. A device for displaying compressed image data as set forth in claim 7, wherein at least a D.C. component of said read-out compressed image data is left in said frequency component deletion means.