06052205 is referenced by 26 patents and cites 2 patents.

Image data encoding/decoding method and apparatus uses a first data divider for dividing image data into--by n-pixel blocks, two data encoders for encoding an--by n-pixel block into a first data block including frequency data elements and into a second data block including an image density, locations of pixels, and a flag, respectively. A first image type determiner is also included for determining a number of different image density values included in the--by n-pixel block, as is a first data selector for selecting the first data block when the first image type determiner determines that the--by n-pixel block includes a number of different image density values different from a first predetermined value and the second data block when the first image type determiner determines that the--by n-pixel block includes a first predetermined number of the different image density values. Two data decoders are included for decoding the first data block into a block substantially similar to the block previously divided by the first data divider and the second data block into a block substantially similar to the block previously divided by the first data divider, respectively. A second image type determiner is used for determining the flag. A second data selector selects the block obtained by decoding the first data block when the flag is different from a second predetermined value and the block obtained by decoding the second data block when the flag is equal to the second predetermined value.

Title
Image data encoding/decoding method and apparatus configured to compress both natural gray scale images and binary images
Application Number
9/24708
Publication Number
6052205
Application Date
February 17, 1998
Publication Date
April 18, 2000
Inventor
Nekka Matsuura
Tokyo-to
JP
Agent
Oblon Spivak McClelland Maier & Neustadt P C
Assignee
Ricoh Company
JP
IPC
H04N 1/41
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