Image processing system determining dot formation for each pixel group and method for the same

• US 7,813,007 B2
• Filed: 11/20/2006
• Issued: 10/12/2010
• Est. Priority Date: 05/20/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kakutani, Toshiaki
• Primary Examiner(s): Zimmerman; Mark K
• Assistant Examiner(s): HON, MING Y
• Application Number:
  US11/602,677
• Publication Number:
  US 20070070423A1
• Time in Patent Office: 1,422 Days
• Field of Search: None
• US Class Current: 358/3.13
• CPC Class Codes: H04N 1/4057 the pattern being a mixture of differently sized sub-patterns, e.g. spots having only a few different diameters multi-toning H04N1/40087

Abstract

The present invention provides a dot data processing apparatus for generating data of dots to be formed on a printing medium. The apparatus includes: a decoding preparation unit that prepares a decoding table for pixel groups, each of the pixel groups grouping together a plurality of pixels that constitute a unit of dot formation, the table containing output dot arrangements and code values in a number of identifiers assigned to the pixel groups, the output dot arrangements and code values being associated, the output dot arrangements representing the dot on-off states for the pixels in the pixel groups, the code values assuming a prescribed range of values; a code value receiving unit that receives code values derived as a result of encoding of image data representing an image with a prescribed tone number, the encoding being performed for the each pixel group as an encoding unit; a decoding unit that acquires the output dot arrangement based on the received code value and the identifier assigned to the pixel group, by means of lookup in the decoding table; and a dot data output unit that outputs dot data which represents an arrangement of dots to be formed on a printing medium, in accordance with the acquired output dot arrangement.

Claims

1. A dot data processing method of generating data of dots to be formed on a printing medium, comprising the steps of:

a decoding preparation step of preparing a decoding table for pixel groups, each of the pixel groups grouping together a plurality of pixels that constitute a unit of dot formation, the table containing output dot arrangements and code values in a number of identifiers assigned to the pixel groups, the output dot arrangements and code values being associated, the output dot arrangements representing the dot on-off states for the pixels in the pixel groups, the code values assuming a prescribed range of values;

a code value receiving step of receiving code values derived as a result of encoding of image data representing an image with a prescribed number of tones, the encoding being performed for each pixel group as an encoding unit;

a decoding step of acquiring the output dot arrangement based on the received code value and the identifier assigned to the pixel group, by means of lookup in the decoding table; and

a dot data output step of outputting dot data which represents an arrangement of dots to be formed on a printing medium, in accordance with the acquired output dot arrangement,

wherein the decoding table associates the code values and the output dot arrangements depending on arrangements of selected threshold values, the threshold values being associated with pixels contained in the pixel groups while sequentially changing extraction locations from a dither matrix having threshold values of different values allocated according to a prescribed characteristic, and

wherein the dither matrix is a global dither matrix containing threshold values in greater number than a tone number of the image.

2. The dot data processing step according to claim 1, wherein

the decoding table is constituted as a two-dimensional table that stores the output dot arrangements, with the code values and the identifiers as parameters.

3. The dot data processing step according to claim 1, wherein

the decoding preparation step includes the step of preparing correspondence relationships as the table, the correspondence relationships associating multi-value quantization result values derived by multi-value quantization of tone values of the pixel groups, and output dot arrangements that are arrangements of dots to be formed in the pixel groups, on an individual basis of the identifier;

and

the code value receiving step includes the step of receiving the multi-value quantization result values as the code values.

4. The dot data processing step according to claim 1, wherein

the decoding preparation step includes the step of defining the identifiers that order the output dot arrangements and the code values, as classification numbers associated with locations of the pixel groups in the image;

and

the decoding step includes the step of determining the classification number depending on the location in the image of the pixel group whose code value has been received, and looks up the table.

5. The dot data processing step according to claim 4, wherein

the classification numbers include at least 100 types of numbers.

6. The dot data processing step according to claim 4, wherein

the product of the number of pixels grouped in the pixel groups, and the number of types of classification numbers assigned to the pixel groups, is at least 1000.

7. The dot data processing step according to claim 1, wherein

the decoding preparation step includes the step of preparing the output dot arrangements as data in which values representing dot on-off states for individual pixels are lined in a prescribed sequence depending on pixel locations within the pixel group in the table.

8. The dot data processing step according to claim 1, wherein

the decoding preparation step includes the step of preparing a first type code values specifying the output dot arrangements using a dot generation methodology specified in common for individual identifiers, and a second type code values specifying the output dot arrangements without reference to the methodology, in distinguishable form in the table;

and

the decoding step includes the step of distinguishing whether the code value is the first type code value or the second type code value, and the step of determining the output dot arrangement according to the type of the code value.

9. The dot data processing step according to claim 8, wherein

the decoding step includes the step of distinguishing whether the received code value is the first type code value or the second type code value, by means of comparison of magnitudes of the code value and a prescribed threshold value.

10. The dot data processing step according to claim 9, wherein

the decoding preparation step includes the step of representing the first type code values by means of data of bit counts representable the number of types of combinations of numbers of dots formed within the pixel groups, and the step of associating the second type code values with a portion in which the number of combinations representable by the data of prescribed bit count is surplus relative to the number of types.

11. The dot data processing step according to claim 8, wherein

the first type code values prepared by the decoding preparation step are specified as values that represent numbers of dots to be formed according to a sequence specified on an individual basis of the identifier;

and the second type code values are specified as code values associated with locations for forming dots within the pixel groups.

12. The dot data processing step according to claim 11, wherein

the sequence of dot formation specified on an individual basis of the identifier is specified as an order of ranking of magnitude of a plurality of collected threshold values associated with a plurality of pixels contained in a the pixel group, from a dither matrix wherein characteristics of generated dots are defined by the arrangement of the plurality of threshold values with different values.

13. The dot data processing step according to claim 11, wherein

the decoding step comprises:

an intermediate data generating step of generating intermediate data composed of composed of M items of sequential data signifying dot formation and (N-M) items of sequential data signifying no dot formation based on the received code value when the received code value is distinguished as the first type code value, where the number of pixels contained in the pixel group is denoted N and the number of dots to be formed in the pixel group is denoted M; and

a step of determining output dot arrangement of the pixel group by means of identifying an order for forming dots on N pixels within the pixel group based on the identifier, and reading out data of locations corresponding to the order, from the intermediate data.

14. The dot data processing step according to claim 1, further comprising a dot forming step of forming one or more types of dot on the printing medium, wherein

the dot data output step includes the step of controlling the dot forming step for forming dots according to the dot data at locations on the printing medium corresponding to the locations of the pixel groups in the image, by outputting the dot data.

15. The dot data processing step according to claim 1, wherein

the decoding preparation step includes the step of arranging the code values and the output dot arrangements in association with each other, for a plurality of types of dots of different tone values representable per single dot as the decoding table;

and

the dot data output step includes the step of outputting the dot data, as data representing locations for forming the plurality of types of dots.

16. The dot data processing step according to claim 15, further comprising dot forming step of forming one or more types of dot on the printing medium, wherein

the dot data output step includes the step of controlling the dot forming step for forming dots of the plurality of types according to the dot data at locations on the printing medium corresponding to the locations of the pixel groups in the image, by outputting the dot data.

17. An image processing system comprising:

an image data processing apparatus for processing image data indicative of an image represented with a prescribed number of tones, by each of pixel groups composed of a plurality of pixels; and

a dot data processing apparatus for receiving the processed result and converting the result to data indicating dots to be formed on a printing medium, wherein

the image data processing apparatus comprises;

a code value preparation unit that prepares correspondence relationships of pixel group tone values which are tone values representative of the pixel groups, with prescribed code values, the correspondence relationships being prepared in a number of identifiers assigned to the pixel groups;

a pixel group tone value determining unit that extracts groups of pixels corresponding to the pixel groups from the image data representing the image, and determines the pixel group tone values on an individual basis for the pixel groups;

an encoding unit that acquires the code values by means of lookup the correspondence relationships specified based on the identifier assigned to the pixel group on an individual basis for the pixel groups, based on the determined pixel group tone value;

a code value output unit that outputs the code values derived for each of the pixel groups; and

wherein

the dot data processing apparatus comprises;

a decoding preparation unit that prepares a decoding table containing output dot arrangements that represent a dot on-off state for each pixel in the pixel groups, and code values that assume a prescribed range of values, in an arrangement associated with the identifiers;

a code value receiving unit that receives the code value of each pixel group;

a decoding unit that acquires the output dot arrangements by means of lookup in the decoding table, based on the received code value and the identifier assigned to the pixel group; and

a dot data output unit that outputs dot data that represents an arrangement of dots to be formed on a printing medium, in accordance with the acquired output dot arrangement,

wherein the decoding table associates the code values and the output dot arrangements depending on arrangements of selected threshold values, the threshold values being associated with pixels contained in the pixel groups while sequentially changing extraction locations from a dither matrix having threshold values of different values allocated according to a prescribed characteristic, and

wherein the dither matrix is a global dither matrix containing threshold values in greater number than a tone number of the image.

18. The image processing system according to claim 17, wherein

the dot data processing apparatus comprises dot forming unit that forms one or more types of dot on a printing medium;

and

the dot data output unit controls the dot forming unit to form dots according to the dot data at locations on the printing medium corresponding to the locations of the pixel groups in the image, by outputting the dot data.

19. The image processing system according to claim 17, wherein

the image data processing apparatus and the dot data processing apparatus are housed in different cases, with the two apparatus connected by wires or wirelessly, and thereby connected directly or over a network.

20. The image processing system according to claim 17, wherein

the image data processing apparatus and the dot data processing apparatus are constituted as a single apparatus, and the code value output unit and the aforementioned code value receiving unit are integrally constituted.

21. The image processing system according to claim 17 wherein

the code value preparation unit of the image data processing apparatus prepares an encoding table having the correspondence relationships of the pixel group tone values and the code values are arranged in the number of the identifiers;

and

the encoding unit acquires the code values through lookup in the encoding table, based on the identifiers and the pixel group tone values for the pixel groups.

22. The image processing system according to claim 17, wherein

the code value preparation unit of the image data processing apparatus prepares a first type code values associated with a predetermined dot generation methodology as the prescribed code values associated with the pixel group tone values on an individual identifier basis, and prepares a second type code values associated with output dot arrangements specified without reference to the methodology in the event that the pixel group tone value is in a prescribed value range, wherein

the decoding preparation unit prepares the decoding table having the first type code values and the second type code values, in distinguishable form;

and

the decoding unit distinguishes whether the code value is the first type code value or a second type code value based on the received code value, and specifies the output dot arrangement according to the type of the code value.

23. A dot data processing apparatus for generating data of dots to be formed on a printing medium, comprising:

a decoding preparation unit that prepares a decoding table for pixel groups, each of the pixel groups grouping together a plurality of pixels that constitute a unit of dot formation, the table containing output dot arrangements and code values in a number of identifiers assigned to the pixel groups, the output dot arrangements and code values being associated, the output dot arrangements representing the dot on-off states for the pixels in the pixel groups, the code values assuming a prescribed range of values;

a code value receiving unit that receives code values derived as a result of encoding of image data representing an image with a prescribed number of tones, the encoding being performed for each pixel group as an encoding unit;

a decoding unit that acquires the output dot arrangement based on the received code value and the identifier assigned to the pixel group, by means of lookup in the decoding table; and

a dot data output unit that outputs dot data which represents an arrangement of dots to be formed on a printing medium, in accordance with the acquired output dot arrangement,

wherein the decoding table associates the code values and the output dot arrangements depending on arrangements of selected threshold values, the threshold values being associated with pixels contained in the pixel groups while sequentially changing extraction locations from a dither matrix having threshold values of different values allocated according to a prescribed characteristic, and

wherein the dither matrix is a global dither matrix containing threshold values in greater number than a tone number of the image.

24. An image processing method of processing image data indicative of an image represented with a prescribed number of tones, by each of pixel groups composed of a plurality of pixels;

and receiving the processed result and converting the result to data indicating dots to be formed on a printing medium, the method comprising the steps of;

preparing correspondence relationships of pixel group tone values which are tone values representative of the pixel groups, with prescribed code values, the correspondence relationships being prepared in a number of identifiers assigned to the pixel groups;

preparing a decoding table containing output dot arrangements that represent a dot on-off state for each pixel in the pixel groups, and code values that assume a prescribed range of values, in an arrangement associated with the identifiers;

extracting groups of pixels corresponding to the pixel groups from the image data representing the image, and determines the pixel group tone values on an individual basis for the pixel groups;

acquiring the code values by means of lookup the correspondence relationship specified based on the identifier assigned to the pixel group based on the determined pixel group tone value for each of the pixel groups;

acquiring the output dot arrangements by means of lookup in the decoding table, based on the received code value and the identifier assigned to the pixel group; and

outputting dot data that represents an arrangement of dots to be formed on a printing medium, in accordance with the acquired output dot arrangement,

wherein the decoding table associates the code values and the output dot arrangements depending on arrangements of selected threshold values, the threshold values being associated with pixels contained in the pixel groups while sequentially changing extraction locations from a dither matrix having threshold values of different values allocated according to a prescribed characteristic, and

wherein the dither matrix is a global dither matrix containing threshold values in greater number than a tone number of the image.