Image processing device and printing apparatus for performing bidirectional printing

• US 7,965,419 B2
• Filed: 02/07/2006
• Issued: 06/21/2011
• Est. Priority Date: 02/09/2005
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kakutani, Toshiaki
• Primary Examiner(s): Poon; King Y
• Assistant Examiner(s): Tran; Dung D
• Application Number:
  US11/350,374
• Publication Number:
  US 20060193010A1
• Time in Patent Office: 1,960 Days
• Field of Search: 347/15, 347/19, 347/41, 358/1.9, 358/1.18, 358 303- 306, 358/3.13, 358/3.19, 382/162, 382/237
• US Class Current: 358/3.06
• CPC Class Codes: H04N 1/4015 of the reproducing head
• CPC Class Codes: H04N 1/4051 producing a dispersed dots halftone pattern, the dots having substantially the same size different sizes H04N1/4057

Abstract

This invention provides a printing apparatus that performs printing on a print medium. The printing apparatus includes: a dot data generator that performs a halftone process on image data, wherein the print image is formed by mutually combining print pixels belonging to each of a plurality of pixel position groups for which a physical difference is assumed at a formation of dots by the print image generator, in a common print area, and the halftone process is configured to determine the status of dot formation on each of the print pixels on an assumption of the physical difference.

Claims

1. A printing apparatus that performs printing on a print medium, comprising:

a dot data generator that performs a halftone process on image data representing a tone value of each of pixels constituting an original image to determine a status of dot formation on each of print pixels of a print image to be formed on the print medium, for generating dot data representing the determined status of dot formation, and

a print image generator that forms a dot on each of the print pixels for generating the print image according to the dot data, wherein

the print image generator is configured to generate the print image by mutually combining dots formed on print pixels belonging to each of a plurality of pixel position groups in a common print area,

the print image generator has a printing head and generates the print image by forming dots on each of the print pixels during forward scan and backward scan of the printing head, while performing a main scan of the printing head,

the plurality of pixel position groups includes a first pixel position group for which dots are formed during the forward scan of the printing head and a second pixel position group for which dots are formed during the backward scan of the printing head,

the dot data generator is set such that the halftone process is configured to provide each of dot patterns with a predetermined characteristic, each of the dot patterns including dot patterns formed on the print pixels belonging to each of the plurality of pixel position groups,

the predetermined characteristic is either one of blue noise characteristics and green noise characteristics, and

the halftone process is configured such that any first correlation coefficients are higher than any of second correlation coefficients at least for tone levels with relatively low dot density, wherein

the first correlation coefficients are coefficients between each of spatial frequency distributions of the dot patterns formed on the print pixels belonging to each of the plurality of pixel position groups and spatial frequency distribution of the print image, and

the second correlation coefficients are correlation coefficients between each of spatial frequency distributions of dot patterns formed on print pixels belonging to each of any of other plurality of the pixel position groups that form print images by mutually combining in a common print area and the spatial frequency distribution of the print image.

2. The printing apparatus according to claim 1, wherein

the halftone process is further configured to provide a hypothetical print image on an assumption of none of the relative shift of dot position with the predetermined characteristic.

3. The printing apparatus according to claim 1, wherein

the halftone process is further configured to provide both of a plurality of hypothetical print images with the predetermined characteristic, the plurality of hypothetical print images including a first hypothetical print image on an assumption of the relative shift of dot position and a second hypothetical print image on an assumption of none of the relative shift of dot position.

4. The printing apparatus according to claim 1, wherein

the print image generator generates the print image by forming dots on each of the print pixels while repeating a main scan cycle of the printing head N times (N is an integer of 2 or more), according to the dot data, and

the plurality of pixel position groups includes a plurality of pixel position groups divided according to a remainder from a numerical value representing an order of a sub-scan direction of the main scan line divided by the aforementioned N.

5. The printing apparatus according to claim 1, wherein

the print image generator has a plurality of printing heads and generates the print image by forming dots on each of the print pixels according to the dot data, while performing a main scan of the plurality of printing heads, and

the plurality of pixel position groups includes a plurality of pixel position groups for which each of the plurality of printing heads in charge of the dot formation of each of the plurality of pixel position groups.

6. The printing apparatus according to claim 1, wherein

the print image generator has a plurality of printing heads and generates the print image by forming dots on each of the print pixels according to the dot data, while performing a sub-scan of the print medium, and

the plurality of pixel position groups includes a plurality of pixel position groups for which each of the plurality of printing heads in charge of the dot formation of each of the plurality of pixel position groups.