US 7,612,911 B2
Image processing device and image processing method for performing conversion of color image data
Toshiaki Kakutani, Nagano-ken (Japan)
Assigned to Seiko Epson Corporation, Tokyo (Japan)
Appl. No. 10/549,663
PCT Filed Mar. 17, 2004, PCT No. PCT/JP2004/003603
§ 371(c)(1), (2), (4) Date Sep. 16, 2005,
PCT Pub. No. WO2004/084540, PCT Pub. Date Sep. 30, 2004.
Claims priority of application No. 2003-076071 (JP), filed on Mar. 19, 2003.
Prior Publication US 2006/0181720 A1, Aug. 17, 2006
Int. Cl. H04N 1/40 (2006.01)
U.S. Cl. 358—1.9  [382/243] 17 Claims
OG exemplary drawing
 
1. An image processing device for converting color image data expressed by a first color system to image data expressed by a second color system representing each pixel data as a dot on/off state for each color, the image processing device comprising:
a color conversion unit that converts color image data expressed by the first color system to color image data expressed by the second color system;
an edge detection unit that detects whether or not an edge exists in a first type of block into which specified adjacent pixels are grouped;
a compressed data storage unit that compresses the color image data of pixels contained in the first type of block and stores the compressed color image data in a memory when the edge detection unit detects that no edge exists in the first type of block;
a data decompression unit that decompresses the compressed color image data read from the memory to color image data of each pixel and groups specified adjacent pixels into a second type of block; and
a dot formation judgment unit that judges in block units for each color of the second color system the dot on/off state for each pixel contained in the block based on the decompressed color image data of pixels grouped into the second type of block.