JP2011062922A - Method and apparatus for recording in multi-gradation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form binary data for more smoothly expressing change in gradation. <P>SOLUTION: A printer driver 50 is provided which constitutes one pixel with matrix of a plurality of dots to form binary data ϕ2 for recording in multi-gradations. The printer driver 50 possesses a distribution unit 56 for distributing the plurality of dots, which are contained in a first matrix comprising the first pixel and which expresses a gradation value of the first pixel, in the first direction based on the ratio of the gradation values of the pixel that is adjacent in the first direction relative to the first pixel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and apparatus for recording one pixel with a matrix of a plurality of dots.

  In Japanese Patent Laid-Open No. 2004-260, multi-tone recording is performed using a dither matrix to improve the quality of a recorded image, and in order to reduce duty and power consumption, recording of one pixel is performed. A dither matrix composed of a plurality of dots is used, and among these pixels, the dither matrix pattern of odd-numbered pixels and the dither matrix pattern of even-numbered pixels are different from each other.

JP 2001-322314 A

  When recording or printing an image by generating dots on paper using heat or ink with a dot generation element included in a thermal head, etc., pixels with the same gradation value are recorded in the same dot array matrix. Then, it cannot be said that the image quality is sufficient, for example, a linear pattern is conspicuous, and it is desired to further improve the image quality. In Patent Document 1, when pixels with the same gradation value are continuously recorded by changing the pattern of the odd-numbered pixel matrix and the even-numbered pixel matrix, the gradation value is low. Dots are continuously arranged, and a matrix pattern is prevented from appearing in the image. However, the matrix including the odd-numbered pixels and the even-numbered pixels is common, and as the repeated pattern becomes larger, the matrix pattern may be more visible.

  One embodiment of the present invention is a method for forming a single pixel by a matrix of a plurality of dots and performing multi-gradation recording, and a plurality of matrices each including a plurality of pixels arranged adjacent to each other in the first direction. Generating a dot distribution in the first direction. The generation of the dot distribution in the first direction (the step of generating the dot distribution) means that a plurality of dots representing the gradation value of the first pixel included in the first matrix constituting the first pixel. Is distributed in the first direction based on the ratio of the gradation values of the pixels adjacent to the first pixel in the first direction.

  In this method, a dot distribution of a plurality of matrices constituting each of a plurality of pixels to be recorded is generated for each pixel. For this reason, pixels having the same gradation value are expressed not only by a matrix including the same or two limited dot arrays, but also by a wide variety of matrices including a large number of dot arrays that can be arranged in the matrix. there is a possibility. Therefore, it can suppress that a linear pattern is conspicuous.

  A dot distribution that represents a certain pixel (first pixel) is generated based on the gradation values of pixels that move back and forth in the first direction. By selecting a random dot arrangement, it is possible to further suppress the possibility of occurrence of a pattern, but by generating a dot distribution based on the gradation values of pixels that move back and forth in the first direction, the change in the gradation value is included. The image can be recorded more smoothly as an image in which the shade of color (including black and white) changes, and can be recorded as an image in which the contour appears more sharply at a location where the gradation value changes greatly.

When a matrix constituting one pixel includes a dot array of 2 n (n is an integer of 1 or more) in the first direction, one algorithm for generating a dot distribution is as follows. That is, it is desirable that the step of distributing in the first direction includes the following steps.
A plurality of dots representing the first level gradation value of the first pixel included in the first matrix of the first level constituting the first pixel are changed to the first matrix of the first level. Distributing to the second level matrix divided into two in one direction based on the ratio of the gradation values of the first level of adjacent pixels within a range that can be arranged in the second level matrix.
The third level matrix that divides the second level matrix into two in the first direction is converted into a third level matrix that includes a plurality of dots representing the second level gradation value included in one second level matrix. Distributing based on the ratio of the second level tone values of the second level matrix adjacent in the first direction to one second level matrix within a range that can be arranged in the level matrix.

  A pixel unit matrix in which 2 n dots can be arranged is a first level matrix, and according to the above algorithm, the dot distribution is repeated n times from the first level to the (n + 1) level matrix, It is possible to generate data that has a distribution that reflects the previous and subsequent gradation values, and in which the multi-value data is binarized. Furthermore, by treating the on dots and off dots equivalently, the number of times the process is repeated can be reduced to about half.

  The method of distributing gradation values (dots) may be a linear interpolation method, that is, a distribution of a primary spline curve. Further, the method of distribution may provide a distribution of higher order, eg, quadratic or cubic spline curves.

  The matrix constituting one pixel may have a spread in the scan direction and the sub-scan direction, and has a spread only in the scan direction or the sub-scan direction, that is, a matrix that is linear in the first direction. It may be. The above method can also be applied to a recording method in which a plurality of dot generation elements are arranged in the scan direction and a multi-tone pixel is expressed by a plurality of dots to be recorded in the sub-scan direction, such as a line thermal head. .

  One of the other aspects of the present invention is a method for generating binary data for performing multi-gradation recording, in which one pixel is constituted by a matrix of a plurality of dots. The plurality of dots representing the gradation value of the first pixel included in the matrix are distributed in the first direction based on the ratio of the gradation values of the pixels adjacent to the first pixel in the first direction. It is a method that has that. From the multi-value data, binary data including a dot distribution reflecting the change in the gradation value of the preceding and succeeding pixels can be generated.

  One of further different aspects of the present invention is an apparatus for generating binary data for performing multi-gradation recording, in which one pixel is constituted by a matrix of a plurality of dots, and constitutes the first pixel. The plurality of dots representing the gradation value of the first pixel included in the first matrix are changed in the first direction based on the ratio of the gradation values of the pixels adjacent to the first pixel in the first direction. A device having a distribution unit that distributes to This apparatus can be installed in a printer driver that supplies image data to a recording device such as a printer or a host device such as a personal computer as a part thereof.

  One of the other different aspects of the present invention is an image generation apparatus having the above-described apparatus and a plurality of dot generation elements that form dots based on binary data. From the image data supplied from the host device, binary data including dot distribution reflecting the fluctuation of the gradation value of the preceding and succeeding pixels is generated, and dots are formed by the binary data to record the image on a printing paper or the like. By recording on a medium, a higher quality image can be recorded (printed).

  According to another aspect of the present invention, there is provided a program for generating a binary data for performing multi-gradation recording, in which one pixel is configured by a matrix of a plurality of dots, The plurality of dots representing the gradation value of the first pixel included in the first matrix constituting the pixel are determined based on the ratio of the gradation values of the pixels adjacent to the first pixel in the first direction. A program having distribution in a first direction. This program can be provided by being recorded on a recording medium such as a CD-ROM or via a computer network such as the Internet.

1 is a diagram illustrating a schematic configuration of a system including a printer and a PC. It is a flowchart which shows the method of producing | generating binary data. FIG. 3A is a diagram for illustrating an example in which the dot array is generated based on the gradation values of the previous and subsequent pixels, and FIG. 3B is a diagram for illustrating an example in which the dot array is fixed.

  FIG. 1 shows an example of an image recording system. The image recording system 1 includes a personal computer (PC) 10 as a host device and a printer 30 that prints binary data φ2 supplied from the PC 10. The printer 30 includes a line-type thermal head 37 in which a plurality of heating elements 36 are arranged in a line, a platen roller 32 for feeding a medium (recording medium) 31, a motor 33 for driving the platen roller 32, and these. And a control device 20 for controlling. If the medium 31 is thermal paper, the printer 30 forms dots on the surface of the medium 31 by the thermal energy supplied from the heating element 36 and records (prints) an image on the medium 31. The printer 30 may be a sublimation type (thermal transfer, sublimation transfer), and a color (may be monochrome) ink ribbon 35 is set between the medium 31 and the head 37, and the heating element 36. Multicolor dots are formed on the medium 31 by thermal energy, and a color image is recorded on the medium 31.

  The PC 10 that supplies data φ2 for forming an image to the printer 30 includes hardware resources for realizing a general-purpose computer such as a processor, a memory, and an input / output device. An OS 11 and an application program 12 that runs on the OS 11 are installed in the PC 10 so that contents including documents, images, and the like can be viewed, created, and edited. The PC 10 is further installed with a printer driver 50 including a function of converting multi-value data φ1 such as characters and images included in the content into binary data φ2 when the content is printed by the printer 30. In the PC 10, the printer driver 50 is provided as a program recorded in a recording medium such as a hard disk or ROM (not shown), and the function as the printer driver 50 is realized by a processor (not shown) executing the program. Is done.

  The printer driver 50 includes a function 52 that generates image data φ2 so that image data φ1 supplied from the application 12 or the like is output from the printer 30. The data generation function 52 generates a command and the like for controlling the printer 30 and outputs it, and a binarization unit 55 that converts the multi-value data φ1 supplied from the application 12 into binary data φ2. including. In the printer 30, an image is recorded by on / off dots. For this reason, the binarization unit 55 generates binary data φ2 for expressing the gradation value in binary from the multi-value data φ1 in which the gradation value is given in multiple values. The binarization unit 55 of this example generates binary data φ2 for so-called area gradation display (recording and printing) in which one pixel is constituted by a matrix of a plurality of dots, and multi-gradation recording is performed. To do.

  The binarization unit 55 includes a distribution unit 56 for distributing the gradation values included in the multi-value data φ1 into binary values of on / off (1, 0). The distribution unit 56 of this example has a plurality of units 57.1 to 57... That distribute the gradation values included in the upper matrix linearly with the ratio of the gradation values included in the adjacent matrix. n (n is an integer of 1 or more). For the sake of simplicity, if the matrix constituting one pixel is a line or row-like one-dimensional matrix (first level matrix) including a dot array of 2 n in the first direction, the first unit 57.1 Determines the gradation value (number of dots) included in the second level matrix (sub-matrix) including the 2 (n-1) th power dot array.

  That is, the first unit 57.1 includes a plurality of first level gradation values of the first pixel included in the first level first matrix constituting the target pixel (first pixel). Adjacent to the first pixel within a range that can be arranged in the second level matrix in a second level matrix that divides the first level first matrix into two in the first direction. Distribution based on the ratio of the gradation values of the first level of the pixels (two pixels) to be performed. At this stage, the number of dots contained in the two second level matrices is determined.

  The next unit 57.2 is a third unit that divides the second level matrix into two in the first direction for a plurality of dots representing the second level gradation value included in one of the second level matrices. Based on the ratio of the gradation values of the second level of the second level matrix adjacent in the first direction to one of the second level matrices within a range that can be arranged in the third level matrix. Distribute.

  A plurality of units 57.1 to 57. 5 included in the distribution unit 56. n repeats the above process from the first level matrix to the nth level matrix. Nth unit 57. n outputs a matrix of the (n + 1) level, but the (n + 1) level becomes binary data φ2, and the multi-value data φ1 is converted into binary data φ2.

  FIG. 2 is a flowchart showing an outline of the processing of the distribution unit 56. FIG. 3A schematically shows an example in which a matrix (first level matrix) M1 constituting one pixel generates binary data φ2 of 8 bits (n = 3). When the distribution unit 56 receives the multi-value data φ1 in step 61, the distribution unit 56 performs initial processing in step 62. In the initial processing, for example, the color information given by the multi-value data φ1 is converted into color information that can be expressed by the printer 30, or the multi-value data φ1 is converted into data having a resolution that can be expressed by the printer 30. Such processing is included. If the multi-value data φ1 is data of 256 gradations, the printer 30 is 8 gradations in this example, so the 256 gradation data is converted in advance to 8 gradation data.

  In step 63, first, the first unit 57.1 calculates the tone value of the target pixel (the tone value (number of dots) of the target matrix) and the tone value of the adjacent pixel (the tone of the adjacent matrix). Value (the number of dots)) and the gradation value (the number of dots) of the lower matrix is set. In FIG. 3A, pixels Pa, Pb, and Pc are arranged in the sub-scan direction X, and the respective gradation values are “2”, “6”, and “4”. When the first unit 57.1 processes the first-level first matrix M1b representing the target pixel Pb, the number of dots (first-level gradation value) “6” included in the first matrix M1b. Is proportionally distributed by the gradation values “2” and “4” of the adjacent pixels Pa and Pc, and distributed to the second level matrices M2b1 and M2b2. That is, the gradation value (number of dots) of the second level matrix M2b1 on the left is “2” (= (2 × 6) / (2 + 4)), and the gradation value (number of dots) of the second level matrix M2b2 on the right side ) Is set to “4” (= (4 × 6) / (2 + 4)).

  Furthermore, the first unit 57.1 performs fraction processing in step 64 and performs excess processing in step 65. When the upper level gradation value (number of dots) is distributed to the lower level in the ratio of the gradation value (dot number) of the adjacent matrix, the lower level gradation value often includes a fractional part. Therefore, units 57.1 to 57. It is desirable to incorporate in n. For example, when the proportionally distributed value includes a fractional part, it is converted to an integer by rounding off, and when the decimal part is “0.5”, the value of the left matrix M2b1 is rounded up and the value of the right matrix M2b2 is rounded down. The left and right may be reversed.

  Further, the proportionally distributed lower level gradation values may exceed the maximum value of the lower level matrix, for example, the matrix M2b2. In such a case, the gradation value cannot be expressed in the lower level matrix, and therefore, in step 65, the excess value is transferred to the other matrix M2b1.

  In step 66, the above processing is repeated for all the first level matrices M1, that is, all the pixels, to generate a second level matrix M2. In step 67, the lower level matrix continues to be generated until the final level is completed. If the final level has not been reached, the matrix conditions for the next level are set in step 68, and the process returns to step 63 to repeat the distribution process. If the final level has been reached, since the binarized data φ2 has been generated, in step 69, the binary data φ2 is transmitted to the printer 30 for printing.

  In this example, after obtaining the gradation value (second level gradation value) of the second level matrix M2, it is necessary to obtain the third level matrix M3. Therefore, the second unit 57.2 determines the gradation value (number of dots) of the third level matrix M3 from the second level matrix M2. For example, in the case of processing the second level matrix M2b2, the gradation value (second level gradation value) “4” of the second level matrix M2b2 is set to the adjacent (adjacent) second level matrix M2b1. And the gradation values (second level gradation values) “2” and “3” with the matrix M2c1. When the fraction processing is performed in step 64, the third level gradation values (number of dots) of the third level matrices M3b21 and M3b22 become “2” and “2”, respectively.

  Further, since it is necessary to obtain the fourth level matrix M4, the third unit 57.3 (57.n) determines the gradation value (number of dots) of the fourth level matrix M4 from the third level matrix M3. To decide. In this example, the fourth level is the final level, and the matrix M4 of the fourth level is “0” or “1”, that is, binary data φ2. For example, when processing the third-level matrix M3b21, the gradation value (third-level gradation value) “2” of the third-level matrix M3b21 is replaced with the adjacent third-level matrix M3b12. And the gradation values (second level gradation values) “1” and “2” with the matrix M3b22. When fraction processing is performed in step 64, the fourth level gradation values (number of dots) of the fourth level matrices M4b211 and M4b212 become “1” and “1”, respectively. Thus, the gradation value of the final level becomes “0” or “1”, and binary data φ2 is generated.

  The dot output of the binary data φ2 generated in this way is shown in FIG. The plurality of dots constituting the pixel Pa having the gradation value “2” are arranged on the pixel Pb side having the gradation value “6”, and the plurality of dots constituting the pixel Pb having the gradation value “6” Most of the plurality of dots constituting the pixel Pc having the tone value “4” are concentrated on the boundary between the pixels Pb and Pc. As a result, binary data φ2 can be generated in which the shade of an image expressed by a plurality of pixels is expressed more smoothly by the distribution of a plurality of dots that express those pixels. Furthermore, the dot distribution in the matrix tends to gather in the dark direction so that the dots of the pixel Pa gather on the pixel Pb side. For this reason, it is possible to generate binary data φ2 that can easily emphasize a boundary between edges expressed by a plurality of pixels, and can express a sharper image.

  FIG. 3B shows an example in which the dot arrangement in the matrix forming each pixel is fixed in advance by the gradation value. As shown in FIG. 3B, when an arrangement in which dots are left-justified in the matrix is set in advance, the dot arrangements constituting the adjacent pixels Pa to Pc are not connected, and the density of the image Appears as a streak, or the boundary between light and shade is blurred.

  As described above, in the system 1 of this example, the dot arrangement for representing individual pixels included in the binary data φ2 for printing an image by the printer 30 is changed in the gradation value of adjacent pixels. Is generated each time so as to reflect. Therefore, the dot arrangement included in the matrix that constitutes each pixel may change depending on the gradation value of the adjacent pixel even if the gradation value of the pixel is the same, and the shading is even smoother. It is possible to generate binary data φ2 that can be printed with a higher quality image that is less likely to notice a linear pattern. The printer 30 can record a higher quality image on the recording medium. In the binary data φ2, the dots constituting the portion where the gradation value of the image changes are concentrated on the dark side, so that an image with a sharper outline appears on the recording medium. Can record.

  In the system 1 described above, an example in which the binary data φ2 is generated by the printer driver 50 installed in the PC 10 has been described. However, the multivalue data φ1 is transmitted from the PC 10 to the printer 30, and the printer 30 side It is also possible to binarize with. For example, the data generation unit 21 including the binarization unit 55 may be mounted on the control device 20 of the printer 30.

  In the above example, the sub-scan direction X is the first direction, and the pixels are represented by a matrix extending in a line in that direction. However, even when pixels are represented by a matrix extending in a line in the scan direction, binarization can be performed using the same algorithm as described above. Furthermore, even when one pixel is formed of a two-dimensional matrix such as 4 × 4, it can be binarized by applying the above algorithm. When applied to a two-dimensional matrix, the gradation values are distributed to the lower level matrix based on the ratio of the gradation values of adjacent pixels in either the scan direction or the sub-scan direction, and then in the reverse direction. An algorithm that distributes gradation values to a lower level matrix based on the ratio of gradation values of adjacent pixels or matrices can be employed.

  Further, the distribution unit 56 of the binarization unit 55 distributes the gradation values included in the upper matrix in a linear manner, that is, a linear spline curve, based on the ratio of the gradation values included in the adjacent matrix. To do. The distribution unit 56 may alternatively distribute the tone values and / or the distribution of dots in a higher order, for example a quadratic or cubic spline curve.

  The above description is based on a line thermal type printer in which the head does not move in the scanning direction. However, the present invention can also be applied to a serial printer in which the head moves in the scanning direction. Furthermore, although the thermal printer has been described above, it can be applied to a system including other types of printers such as an ink jet printer and a laser printer. Further, the printer is not limited to a personal printer, and may be a multifunction machine or a business printing machine.

1 Printing system 10 Personal computer (PC, host device)
30 Printer

Claims (9)

A method in which one pixel is constituted by a matrix of a plurality of dots and performs multi-gradation recording,
Generating a dot distribution in the first direction of a plurality of matrices respectively constituting a plurality of pixels arranged adjacent to each other in the first direction;
The generation of the dot distribution in the first direction means that the plurality of dots representing the gradation value of the first pixel included in the first matrix constituting the first pixel are converted into the first pixel. Distributing in the first direction based on a ratio of gradation values of pixels adjacent to the pixel in the first direction. In Claim 1, the matrix constituting one pixel includes a dot array of 2 n powers in the first direction,
Distributing in the first direction means that a plurality of first level gradation values of the first pixel included in the first matrix of the first level constituting the first pixel are expressed. The first pixels of the adjacent pixels are within a range in which dots can be arranged in a second level matrix that divides the first matrix of the first level into two in the first direction. Distributing based on the ratio of one level of gradation values;
A plurality of dots representing a second level gradation value included in one of the second level matrices is converted into a third level matrix that divides the second level matrix into two in the first direction. Distribution within the range that can be arranged in the third level matrix based on the ratio of the second level gradation values of the second level matrix adjacent to the one second level matrix in the first direction. And a method comprising:   3. The method according to claim 1, wherein the matrix constituting the one pixel is a plurality of dots arranged in a line in the first direction. A method in which one pixel is constituted by a matrix of a plurality of dots and binary data for performing multi-gradation recording is generated,
A plurality of dots representing a gradation value of the first pixel included in a first matrix constituting the first pixel are represented by gradations of pixels adjacent to the first pixel in a first direction. Distributing in said first direction based on a ratio of values. 5. The matrix according to claim 4, wherein the matrix constituting one pixel includes a dot array of 2 n in the first direction,
Distributing in the first direction means that a plurality of first level gradation values of the first pixel included in the first matrix of the first level constituting the first pixel are expressed. The dots of the adjacent pixels are within a range in which dots can be arranged in a second level matrix that divides the first matrix of the first level into two in the first direction. Distributing based on the ratio of one level of gradation values;
A plurality of dots representing a second level gradation value included in one of the second level matrices is converted into a third level matrix that divides the second level matrix into two in the first direction. Distribution within the range that can be arranged in the third level matrix based on the ratio of the second level gradation values of the second level matrix adjacent to the one second level matrix in the first direction. And a method comprising: An apparatus for generating binary data in which one pixel is constituted by a matrix of a plurality of dots and multi-tone recording is performed,
A plurality of dots representing a gradation value of the first pixel included in a first matrix constituting the first pixel are represented by gradations of pixels adjacent to the first pixel in a first direction. An apparatus having a dispensing unit that dispenses in the first direction based on a ratio of values. In Claim 6, the matrix constituting one pixel includes a dot array of 2 n in the first direction,
The distribution unit includes a plurality of dots representing a first level gradation value of the first pixel included in the first matrix of the first level constituting the first pixel. The first level gradation values of the adjacent pixels in a range that can be arranged in the second level matrix into a second level matrix that divides the first matrix of levels into two in the first direction A first unit that distributes based on the ratio of
A plurality of dots representing a second level gradation value included in one of the second level matrices is converted into a third level matrix that divides the second level matrix into two in the first direction. Distribution within the range that can be arranged in the third level matrix based on the ratio of the second level gradation values of the second level matrix adjacent to the one second level matrix in the first direction. And a second unit. An apparatus according to claim 6 or 7, and
An image recording apparatus comprising: a plurality of dot generation elements that form dots based on the binary data. A program for generating a binary data for forming one pixel by a matrix of a plurality of dots and performing multi-tone recording,
A plurality of dots representing a gradation value of the first pixel included in a first matrix constituting the first pixel are represented by gradations of pixels adjacent to the first pixel in a first direction. A program comprising distributing in the first direction based on a ratio of values.

Images