JP4905294B2 - Image processing circuit, printing apparatus, and image processing program - Google Patents

Description

  The present invention relates to an image processing circuit that can embed information in image data as a digital watermark, a printing apparatus that can perform printing with information embedded as a digital watermark, and image processing for reading out information embedded as a digital watermark from image data Related to the program.

  Among existing printing apparatuses, image data generated from print data by a CPU in the apparatus (or image data sent from a PC) is a halftoning circuit having a configuration shown in FIG. There is an apparatus (see, for example, Patent Document 1) configured to perform printing after being converted into image data (halftone data in the figure) composed of pixel data having a smaller number of gradations, as will be described later.

  Among such printing apparatuses, there is an apparatus that can embed a digital watermark at the time of printing. However, the printing apparatus can embed a digital watermark separately from the processing by the halftoning circuit. Since relatively complicated processing is performed by a CPU (software), it is a device that takes time to print with an embedded digital watermark.

JP 2006-352837 A

  Therefore, an object of the present invention is to provide an image processing circuit that does not require a CPU to perform complicated processing for embedding a digital watermark, and a printing apparatus that can perform printing with embedded digital watermark at high speed.

  Another object of the present invention is an image processing program capable of extracting embedded information from image data generated by the image processing circuit of the present invention and image data of a printed matter printed by the printing apparatus of the present invention. Is to provide.

In order to solve the above problems, an image processing circuit according to the present invention stores embedding information, which is information to be embedded in image data, and embedding position information for designating a position where the embedding information is to be embedded. An information storage circuit for storing data, a cell unit data output circuit for decomposing and outputting image data into a plurality of cell unit data that is a set of pixel data relating to a predetermined number of pixels having a predetermined positional relationship, and a cell The number of gradations for a predetermined number of pixels from the unit data and the position information indicating the pixel position in the cell unit data (information indicating the position of a certain pixel in the pixel group indicated by the cell unit data) there a cell unit halftone data which is a set of smaller pixel data, and generating circuit for generating a cell unit halftone data with gradation value centroid position to a position corresponding to the position information An embedding in which the cell unit data is stored in the information storage circuit based on the position in the image data of the cell unit data output from the cell unit data output circuit and the embedding position information stored in the information storage circuit. It is determined whether or not information is to be embedded. If the cell unit data is to be embedded, the cell unit data is sent to the generation circuit together with position information corresponding to the embedded information. The first process of supplying is performed. If not, the position information generated by generating position information indicating the gravity center position of the gradation value of the cell unit data is supplied to the generation circuit together with the cell unit data. In addition to the circuit that performs the two processes, as the first process, in the image data composed of the cell unit halftone data group generated by the generation circuit, the level is set at a position corresponding to the specific position information. A circuit that performs processing for supplying specific position information and cell unit data to a generation circuit when a condition defined for including cell unit halftone data having a value centroid position in a predetermined pattern is satisfied A supply circuit.

  In other words, the image processing circuit of the present invention is a circuit that performs an embedding process of a digital watermark (embedding information) when image data is converted to halftone data. Therefore, if the image processing circuit of the present invention is used, a device that does not require the CPU to perform complicated processing for embedding a digital watermark (printing with embedded digital watermark can be performed at high speed). Device, etc.) can be manufactured.

  Image data generated by the image processing circuit of the present invention (cell unit halftone data group for one image data generated by the generation circuit in the image processing circuit) and scan results of printing results by the printing apparatus of the present invention The image processing program of the present invention (image data given as a processing target is a plurality of cell unit data (cell unit data according to claims 1 to 3), which is a set of pixel data relating to a predetermined number of pixels having a predetermined positional relationship. Whether or not the image data is embedded information-containing image data in which cell unit data having a gradation value gravity center position at a predetermined position is included in a predetermined pattern. A determination step for determining image data, and when the determination step determines that the image data is embedded information-containing image data, Embedding to specify the gradation value centroid position of each cell unit data having a predetermined positional relationship with the cell unit data included in a predetermined pattern in the data, and to restore the embedding information from the specified gradation value centroid position group Embedded information can be extracted by a program that causes a computer to execute an information restoration step. However, since the image data obtained by scanning the printing result is not usually the same as the image data (cell unit halftone data group) used for printing, the supply circuit in the image processing circuit of the present invention As a first process, no matter how many times it is executed, position information indicating adjacent pixel positions is not supplied to the generation circuit (arbitrary two position information indicates adjacent pixel positions). It is desirable to employ a process that performs processing for supplying any one of a plurality of predetermined position information groups to the generation circuit.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the printing apparatus 10 according to the present embodiment is an apparatus (so-called multi-function machine) that includes a scanner 11, an operation panel 12, a controller 13, and a print engine 14.

  The operation panel 12 is a unit provided in the printer 10 in order to obtain various instructions from the user (and to present the status of the printer 10 to the user). The operation panel 12 is a unit composed of an LCD, a plurality of LEDs, a plurality of push button switches, and the like.

  The print engine 14 is a unit for printing on paper. The scanner 11 is a unit that generates image data of a document by scanning the document set on the scanner 11.

  The controller 13 is a unit for controlling each part in the printer 10 in an integrated manner (making the printer 10 function as a multifunction machine). The controller 13 is a unit (unit consisting of CPU, ROM, RAM, halftoning circuit, various interface circuits, etc.) having the same hardware configuration as the existing controller, but the halftone having the configuration shown in FIG. This is a unit on which the halftoning circuit having the configuration shown in FIG.

  Before describing the function of this halftoning circuit, the function common to each halftoning circuit and the function of the center of gravity calculation unit 23 in the existing halftoning circuit will be described.

  The input raster buffer 21 (FIGS. 2 and 8) in the halftoning circuit is a buffer for temporarily storing image data for a predetermined number of lines. The cell data read control unit 22 reads 10 × 10 pixel data (pixel data group related to 10 × 10 pixel groups arranged in a matrix) from the input raster buffer 21 and supplies the read data to the centroid calculation unit 23. It is a circuit which has. Hereinafter, the data that the cell data read control unit 22 supplies to the centroid calculation unit 23 (or the centroid calculation unit 28) is referred to as cell data.

  The centroid calculation unit 23 (FIG. 8) calculates the gradation value centroid coordinates of the cell data supplied from the cell data read control unit 22 and the total value of the gradation values of the cell data, and calculates the calculated total value. This is a circuit that supplies the pixel number corresponding to the gradation value barycentric coordinates and the cell data supplied from the cell data read control unit 22 to the gradation value calculation unit 24. Note that the tone value barycentric coordinate of the cell data is an average value of the coordinates of each pixel weighted by the tone value (pixel data value). The pixel number is numerical information assigned to each pixel (pixel position), and the pixel number corresponding to the gradation value centroid coordinate is the calculated gradation value centroid coordinate. It is the pixel number of the closest pixel.

  The gradation value calculation unit 24 is a set of pixel data corresponding to the cell data and having a smaller number of gradations based on the cell data, the pixel number, and the total value supplied from the centroid calculation unit 23 (or the centroid calculation unit 28). This is a circuit for generating cell unit halftone data. This gradation value calculation unit 24 is a cell unit halftone in which the gradation value centroid is located at the pixel of the supplied pixel number, and the total value of the gradation values matches the supplied total value. It is a circuit that generates data.

  Specifically, the gradation value calculation unit 24 is a circuit (a circuit including a RAM in which various information can be written) in which a pixel growth order table, a dither matrix, and a plurality of gamma tables can be set.

  Here, the pixel growth order table is pixel growth order defining information (information in which pixel numbers are arranged in the processing order in this embodiment) that defines the processing order of each pixel data in the cell data. It is a table that has been. The gamma table is a table identified by a table number for defining the correspondence between the input gradation value and the output gradation value. The dither matrix is information in which the table number of the gamma table to be used is set for each pixel position, as shown in a simplified manner in FIG. As schematically shown in FIG. 3, the gamma table is a table whose contents are determined so that the output gradation value for the same input gradation value increases as the table number increases. The dither matrix (FIG. 4) is information that is used after being shifted so that the table number relating to the pixel identified by the pixel number from the centroid calculation unit 23 (or centroid calculation unit 28) becomes zero.

  When the cell data, the pixel number (hereinafter referred to as a target pixel number), and the total value (referred to as a target total value) are supplied, the gradation value calculation unit 24 is associated with the target pixel number. In the order indicated by the pixel growth order defining information in the pixel growth order table, “select pixel data in cell data (gradation value related to a certain pixel) and shift the amount according to the target pixel number. The table number related to the selected pixel data is read from the applied dither matrix, and the output gradation value associated with the selected pixel data (input gradation value) in the gamma table identified by the read table number is read. When the total output gradation value is equal to or greater than the total attention value, the total output gradation value is equal to the total attention value. Adjust the value of final output values has a circuit to end the process from to.

  The writing control circuit 23 writes the cell unit halftone data generated by the gradation value calculation unit 24 to an appropriate position in the output raster buffer 26 that is a buffer for temporarily storing a predetermined amount of image data. Circuit. The read control circuit 27 is a circuit for outputting the data in the output raster buffer 26 to the outside.

  Returning to FIG. 2, instead of the centroid calculating unit 23 described above, the centroid calculating unit 28 and the embedded data storage unit 29 provided in the halftoning circuit according to the present embodiment will be described.

  The embedded data storage unit 29 in the halftoning circuit according to the present embodiment includes embedded data that is data to be embedded in the print result [in this embodiment, an alphabetic character string that does not include one specific character (such as Z). ] And area designation information for designating a rectangular area in which the embedded data is to be embedded. The embedded data storage unit 29 is a circuit (a circuit accessible by an external circuit) in which the CPU can set embedded data and region designation information.

  If the cell unit data to be processed is related to a region outside the region indicated by the region designation information stored in the embedded data storage unit 29, the centroid calculation unit 23 It is a circuit that performs the same processing.

  However, the center-of-gravity calculation unit 28 is a circuit capable of setting a character / pixel number table. Here, the character / pixel number table is a table for associating a pixel number with each of a plurality of characters, as shown in FIGS. 5 and 6, and does not include pixel numbers of adjacent pixels. This is the table whose contents are determined.

  Further, when the cell unit data to be processed relates to the boundary portion of the region indicated by the region designation information stored in the embedded data storage unit 29, the centroid calculating unit 28 The total value and a predetermined pixel number (55 in the present embodiment) are supplied to the gradation value calculation unit 24, and the cell unit data to be processed relates to the portion in the region indicated by the region designation information. In this case, it is associated with the character to be processed this time (the first character or the character next to the previously processed character) in the embedded data stored in the storage unit 29 such as embedded data. The pixel number is read from the character / pixel number table, and the read pixel number is supplied to the gradation value calculation unit 24 together with the cell data and the total value.

  Then, the printing apparatus 10 according to the present embodiment prints print data (designated embedded data / embedded data already set in the printing apparatus 10) instructing that printing should be performed with a digital watermark embedded. Received), a part of the image data with the contents corresponding to the print data (the part where there is no information to be printed) has a predetermined floor size corresponding to the size of the part. An image embedding image data (hereinafter, referred to as image embedding image data) having tone values (tone values that are hardly printed) is prepared on a RAM, and then an information embedding image. The apparatus is programmed to perform printing by setting area designation information (and embedding data) indicating the size and position of data and then operating the halftoning circuit.

  In addition, when the character / pixel number table (FIG. 5) is set in the centroid calculating unit 28 (halftoning circuit), the printing apparatus 10 uses the pixel number / character for specifying the character from the pixel number. The table is a device set on a non-volatile memory (flash ROM in this embodiment) in the controller 13. This pixel number / character table has substantially the same contents as the character / pixel number table, but each character has a plurality of pixel numbers (the pixel number associated with the character / pixel number table, the upper left, The upper and left pixel numbers (see FIG. 6) are associated with each other.

  Further, the printing apparatus 10 is an apparatus programmed to perform the copying process of the procedure shown in FIG. 7 when the execution of copying is instructed.

  That is, the printing apparatus 10 (controller 13 / CPU in the controller 13) instructed to perform copying first generates image data of a document (prepared on a RAM) by controlling the scanner 11 (step S1). S101) is performed. Thereafter, the printing apparatus 10 determines whether or not the embedded data is embedded in the image data. If the embedded data is embedded in the image data, the printing apparatus 10 specifies the embedded data. The embedded data specifying process (step S102) is performed.

  In this embedded data specifying process, first, image data is handled as a set of cell data composed of 10 × 10 pixel data, so that the pixel number of the pixel at the gradation value gravity center position is 55, 44, 45. Or 54 [the above-mentioned “predetermined pixel number” and any one of the upper left, upper, left pixel numbers (see FIG. 6)] and surrounded by the cell data, The process of checking whether there is an area where the cell data in which the pixel number of the pixel at the center of gravity is different from the pixel number exists is a process performed while changing the reference position of the cell data. Yes. Then, if such an area does not exist, the embedded data specifying process is terminated by determining that the embedded data is not embedded in the image data, and such an area exists. In this case, the pixel number of the pixel at the gradation value centroid position of each cell data in the area is obtained, and the character associated with each obtained pixel number is read out from the pixel number / character table to fill in the pixel number. It is a process to specify the embedded data.

  The printing apparatus 10 that has completed the process of step S102 prints the contents according to the generated image data (embedded data) if the embedded data cannot be specified by the process (step S103; NO). After performing a print control process (step S104) for causing the print engine 14 to perform (print without embedding), this copy process is terminated. In addition, when the embedded data can be identified in the process of step S102 (step S103; YES), the printing apparatus 10 performs a process with a previously specified content (such as an error message display process) in step S106. The copying process is terminated.

<Deformation>
The printing apparatus 10 and the halftoning circuit described above can be variously modified. For example, the halftoning circuit can be configured (or used) as a circuit for performing color reduction of image data. Further, the program used in the printing apparatus 10 (a program for causing the printing apparatus 10 to perform the processing in FIG. 7) can be transformed into a computer program or a scanner program.

1 is a configuration diagram of a printing apparatus according to an embodiment. 1 is a configuration diagram of a halftoning circuit used in a printing apparatus according to an embodiment. Explanatory drawing of a gamma table. Explanatory drawing of a dither matrix. Explanatory drawing of a character and pixel number table. The figure for demonstrating the setting content of a character and pixel number table. 6 is a flowchart of copy processing executed by the printing apparatus according to the embodiment. The block diagram of the conventional halftoning circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printing apparatus, 11 Scanner, 12 Operation panel, 13 Scanner 14 Print engine, 21 Input raster buffer 22 Cell data reading control part, 23,28 Gravity calculation part 24 Gradation value calculation part, 26 Output raster buffer 27 Reading control circuit, 29 Embedded data storage

Claims (4)

An information storage circuit for storing embedding information, which is information to be embedded in image data, and embedding position information for designating a position where the embedding information is to be embedded;
A cell unit data output circuit for decomposing and outputting image data into a plurality of cell unit data that is a set of pixel data relating to a predetermined number of pixels having a predetermined positional relationship;
And a position information indicating a pixel position in the cell unit data and the cell unit data, said predetermined number of pixels relating to, the number of gradations is a cell unit halftone data which is a set of smaller pixel data, said positional information A generation circuit for generating half-tone data in cell units having a gradation value gravity center position at a corresponding position;
The cell unit data is stored in the information storage circuit based on the position of the cell unit data output from the cell unit data output circuit in the image data and the embedded position information stored in the information storage circuit. It is determined whether or not the embedded information to be embedded is to be embedded. If the cell unit data is to be embedded, the cell unit data is included in the embedded information. The first process of supplying to the generation circuit together with the corresponding position information is performed, and if not, the position information generated by generating the position information indicating the gravity center position of the gradation value of the cell unit data is displayed in the cell. It is a circuit that performs a second process to be supplied to the generation circuit together with unit data, and includes a cell unit halftone data group generated by the generation circuit as the first process. In the image data, when a condition defined for including cell unit halftone data having a gradation value centroid position at a position corresponding to specific position information in a predetermined pattern is satisfied, the specific data A supply circuit that is a circuit for performing processing for supplying position information and the cell unit data to the generation circuit;
An image processing circuit comprising: The first process performed by the supply circuit includes:
The image processing circuit according to claim 1, wherein the processing is such that no positional information indicating adjacent pixel positions is supplied to the generation circuit, no matter how many times it is executed. The image processing circuit according to claim 1 or 2,
A printing apparatus comprising: a print engine that performs printing on a sheet based on a cell unit halftone data group for one image data generated by the image processing circuit. On the computer,
By treating the image data given as the processing target as a plurality of cell unit data that is a set of pixel data relating to a predetermined number of pixels having a predetermined positional relationship, the gradation value gravity center position of the image data becomes a predetermined position. A step of determining whether or not the cell unit data is embedded image-containing image data included in a predetermined pattern;
When it is determined by the determination step that the image data is the embedded information-containing image data, each cell unit data having a predetermined positional relationship with the cell unit data included in the predetermined pattern in the image data An image processing program characterized by specifying a gradation value centroid position and executing an embedding information restoring step for restoring embedding information from the specified gradation value centroid position group.