Title:
IMAGE DATA COMPRESSION METHOD, COMPRESSION/EXPANSION METHOD, RECORDING MEDIUM, COMPRESSION DEVICE, IMAGE STORAGE DEVICE, IMAGE READER AND IMAGE FORMING DEVICE
Document Type and Number:
Japanese Patent JP3821422
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a compression device that converts image data into fixed length compressed data the position of which on an image surface can easily be identified, suppresses deterioration in the image quality of a reproduced image, suppresses block distortion, sharply reproduces characters and smoothly reproduces a photograph.
SOLUTION: The compression device for image data is provided with means (124d, 124e: 22-25 in Figure 17) that calculate density differences (H1-H3) in parts (b0-b3) on the basis of image data of the division parts (b0-b3) in an image data group representing an image in an area, sequentially read a threshold value from a threshold value group (PTD) by one or a plurality of number of selection times of the parts, and discriminate whether each part is an edge or a non-edge on the basis of the density differences (H1-H3) in each part and the read threshold value (Thij) and with a compression data generating means (124d, 124g: 21, 26-35 in Figure 17, Figure 21) that compresses (21 in Figure 17) the image of the non-edge parts while conversion the entire density of the parts, compresses (26-35 in Figure 17) the image data of the edge parts while conserving the density difference, and synthesizes the compressed data of each part to have a fixed length format (Figure 26 (c)).
Inventors:
Oyama Maki
Application Number:
JP2000274381A
Publication Date:
September 13, 2006
Filing Date:
September 11, 2000
Export Citation:
Assignee:
株式会社リコー
International Classes:
B41J5/30; H04N1/413; G06F3/12; H04N1/00; H04N1/40; H04N19/115; H04N19/134; H04N19/14; H04N19/157; H04N19/172; H04N19/196; H04N19/60; H04N19/70; H04N19/86; (IPC1-7): H04N1/413; B41J5/30; G06F3/12; H04N1/00; H04N7/30
Domestic Patent References:
| JP1231582A | ||||
| JP6334855A | ||||
| JP1169150A | ||||
| JP2000134472A | ||||
| JP2262764A |
Attorney, Agent or Firm:
Nobuoki Sugi