JP4318027B2 - Image processing apparatus and method, and printer system - Google Patents

Description

  The present invention relates to a technique for performing image processing using a plurality of gradation modes.

  Conventionally, various tone expression methods have been proposed in order to improve the printing quality of printer apparatuses.

  For example, in Japanese Patent Laid-Open No. 2000-335014, an operator selects a key attribute from a coordinate area, a density area, a hue area, and a spatial frequency, and is suitable for each of a plurality of areas divided for the key. A configuration is disclosed in which a halftone dot group combining a plurality of halftone dot types composed of a binary halftone dot and a larger multivalued dot network is selected to output a halftone dot image signal with a halftone dot type suitable for the region. (Patent Document 1).

With the development of network technology, printer systems in which a computer and a printer device are connected via a network have become widespread. The user can obtain a desired print result by transmitting the print data created by the host device to the printer device via the network.
JP 2000-33014 A

  By the way, in a so-called host print system in which a host device has a function of developing a print target into a print image, the host device needs to transmit the developed print image to a printer via a network or the like. The data amount of the developed print image depends on the gradation expression at the time of image processing. Therefore, the data amount is large when the gradation is large, and the data amount is small when the gradation is small. Is. For example, if 3 bits are assigned to each pixel of the image, 8 gradations can be expressed, but the data amount also increases. On the other hand, if 1 bit is assigned to each pixel, only two gradations can be expressed, but the data amount is small.

  However, in the conventional host print system, the host device has only one gradation mode. Therefore, if you want to prioritize high image quality, that is, image gradation, it is necessary to adopt a mode in which the bit length of each pixel is large, so you can obtain a high-quality image, but the data transfer time becomes longer and printing There has been a problem that the throughput of the entire process is reduced. On the other hand, when it is desired to prioritize the data transfer time, it is necessary to adopt a mode in which the bit length of each pixel is small. Therefore, although the data amount of the print image is small, there is a problem that the image quality is deteriorated.

  SUMMARY An advantage of some aspects of the invention is that it provides a printer system that takes into consideration the balance between required image quality and print processing speed.

  Another object of the present invention is to provide a printer system in which a user can arbitrarily select a plurality of gradation expressions.

  An image processing apparatus according to the present invention includes a selection unit that selects a gradation mode, an image processing unit that generates image data from print target data according to the gradation mode selected by the selection unit, and the image processing unit Transfer means for transferring image data to a printer.

  According to the configuration of the present invention, the image processing apparatus can select a predetermined gradation mode from among a plurality of gradation modes.

  Preferably, the gradation mode is a plurality of gradation modes having different bit length configurations used for gradation expression.

  According to such a configuration, when image quality is given priority over print processing speed, it is possible to obtain high image quality by selecting a gradation mode with a large bit length used for gradation expression. On the other hand, when the print processing speed is given priority over the image quality, the print processing speed can be kept fast by suppressing the data size of the print image by selecting the gradation mode with a small bit length used for gradation expression. .

  The plurality of gradation modes include a first gradation mode in which the bit length of each pixel is a constant value and a second gradation mode in which the bit length of each pixel is not a constant value. To do.

  The image processing means generates image data by expressing the gradation of each pixel with a bit length configuration according to the gradation mode selected by the selection means.

  Furthermore, the transfer means transfers gradation identification information indicating the gradation mode selected by the selection means to the printer.

  The selection unit may select the gradation mode in accordance with an instruction input by a user.

  A printer control apparatus according to the present invention includes a plurality of gradation conversion means for converting an input gradation value on print target data into an output gradation value on a print image, and a predetermined gradation conversion from the plurality of gradation conversion means. An image processing unit that generates image data from print target data using a selection unit that selects a unit, a predetermined gradation conversion unit selected by the selection unit, and the image data generated by the image processing unit to a printer Transfer means for transferring.

  Further, the plurality of gradation converting means are different in the bit length configuration of the output gradation value.

  Further, the plurality of gradation conversion means include first gradation conversion means in which the bit length of each pixel is a constant value, and second gradation conversion means in which the bit length of each pixel is not a constant value. Is desirable.

  Further, it is desirable that the transfer means transfers gradation identification information indicating the predetermined gradation conversion means selected by the selection means to the printer.

  Furthermore, it is desirable that the selection means selects the predetermined gradation conversion means in accordance with an instruction input from a user.

  According to another aspect of the present invention, there is provided a control method for a printer control apparatus comprising a plurality of gradation modes having different bit length configurations used for gradation expression, wherein the control method includes: A step of selecting a predetermined gradation mode, a step of generating image data in accordance with the gradation mode selected by the selection unit based on print target data, and transferring the image data generated by the image processing unit to a printer. And a process.

  The program of the present invention includes a plurality of gradation conversion means for converting an input gradation value on print target data into an output gradation value on a print image, and a predetermined gradation conversion from the plurality of gradation conversion means. An image processing unit that generates image data from print target data using a selection unit that selects a unit, a predetermined gradation conversion unit selected by the selection unit, and the image data generated by the image processing unit to a printer This is a program for causing a printer control device to function as a transfer means for transferring.

  According to another aspect of the invention, there is provided a printer device that receives image data and gradation identification information that indicates a gradation mode of the image data; and according to the gradation identification information received by the reception means, the plurality of gradation modes. A selection means for selecting a gradation mode from among; a print execution means for executing printing on a print recording medium based on image data; and the image data received by the reception means in accordance with the gradation mode selected by the selection means. Transfer means for transferring to the print execution means.

  Further, the transfer means specifies the bit length of each pixel in accordance with the gradation mode selected by the selection means, and supplies information for each pixel to the print execution means.

  The printer system of the present invention includes a host device having a plurality of gradation modes having different bit length configurations used for gradation expression, and a printer device configured to be communicable with the host device. The host system includes a selection unit that selects a predetermined gradation mode from the plurality of gradation modes, and image data according to the gradation mode selected by the selection unit based on print target data. Image processing means to be generated; and transfer means for transferring image data generated by the image processing means and gradation identification information indicating a gradation mode of the image data to a printer. Receiving means for receiving gradation identification information indicating the gradation mode of the image data, and according to the gradation identification information received by the receiving means, Selection means for selecting a gradation mode from a plurality of gradation modes, print execution means for executing printing on a print recording medium based on image data, and selection means for selecting image data received by the reception means Transfer means for transferring to the print execution means in accordance with the gradation mode.

  The image processing method and the printer apparatus control method of the present invention can be implemented by a computer, and a computer program therefor is installed in the computer through various media such as a CD-ROM, a magnetic disk, a semiconductor memory, and a communication network. Or can be loaded. It also includes the case where a computer program is recorded and distributed on a printer card or printer option board.

  According to the present invention, it is possible to realize a printer system that takes into consideration the balance between required image quality and print processing speed.

(First embodiment)
In the first embodiment, one bit is used as the bit length of each pixel as an example of a plurality of gradation modes (hereinafter referred to as “bit gradation modes”) having different bit length configurations used for gradation expression. Two bit gradation modes, a 1-bit fixed gradation mode that expresses 2 gradations and a 2-bit fixed gradation mode that expresses 4 gradations using 2 bits as the bit length of each pixel, The case where it is adopted will be described.

(Printer system configuration)
First, the configuration of the printer system according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing a hardware configuration of a printer system 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the functional configuration of the printer driver means and printer controller according to the embodiment of the present invention.

  As shown in FIG. 1, the printer system 1 may be any of a host device 10 and a communication network (LAN, Internet, dedicated line, packet communication network, a combination thereof, etc., and includes both wired and wireless. The printer device (image processing device) 20 is configured so as to be communicable with the host device 10 via the network.

  The host device 10 includes hardware such as a CPU, ROM, RAM, user interface, and communication interface. Further, the host apparatus 10 includes a printer driver unit 16 shown in FIG. 2 as a normal control function necessary for causing the printer apparatus 20 to execute printing.

  The printer driver unit 16 has the same functional configuration as that of a normal printer driver, and is described in a predetermined printer control language such as a postscript in response to a print request from an application program operating on the host device 10, for example. RIP unit 160 that generates a raster image based on print target data, image processing unit 162 that generates a print image by performing predetermined image processing (halftone processing, etc.) on the raster image generated by the RIP unit 160, A compression control unit 163 that compresses the print image generated by the image processing unit 162, a transfer unit 165 that transfers the print image compressed by the compression control unit 163 to the printer 20, and the like.

  However, as will be described later, the printer driver unit 16 of the present embodiment includes a gradation mode selection unit 161 that selects a bit gradation mode, and the image processing unit 162 prints an input gradation value on a raster image. A plurality of gradation conversion means (first gradation conversion means and second gradation conversion means) for converting into output gradation values on the image are provided. The transfer unit 165 is different from the conventional configuration in that the compressed print image and the gradation identification signal indicating the bit gradation mode are transferred to the printer 20. The image processing unit 162 selects a gradation conversion unit corresponding to the bit gradation mode selected by the gradation mode selection unit 161, and generates gradation data for each pixel using the selected gradation expression unit.

  Here, the gradation converting means will be described. Each gradation conversion means includes a table (hereinafter referred to as “gradation conversion table”) that stores the correspondence between the input gradation value on the raster image and the output gradation value on the print image. Using this gradation conversion table (not shown), the input gradation value on the raster image is converted into the output gradation value on the print image.

  Here, the first gradation conversion means corresponds to the 1-bit fixed gradation mode, and the second gradation conversion means corresponds to the 2-bit fixed gradation mode. For example, when the 1-bit fixed gradation mode is set, the gradation value of one pixel on the raster image is converted into a gradation value having a bit length of 1 bit by the first gradation converting means. . In this case, since the print image is expressed by two levels of gradation, the image quality is low, but the data size can be kept small. On the other hand, when the 2-bit fixed gradation mode is set, the gradation value of one pixel on the raster image is converted into a gradation value having a bit length of 2 bits by the second gradation converting means. . In this case, since the print image is expressed by four levels of gradation, the image quality is high but the data size is also large.

  Each of these means is functionally realized by the CPU executing a program stored in a ROM or RAM in the host device 10 or an external storage medium.

  The printer device 20 includes a power mechanism unit and a printer controller 26.

  The power mechanism unit includes a paper feed mechanism that supplies paper into the printer, a print engine that performs printing, and a paper discharge mechanism that discharges paper outside the printer. As the print engine, for example, a serial printer that prints in units of characters, such as an inkjet printer or a thermal transfer printer, a line printer that prints in units of lines, a page printer that prints in units of pages, and the like are used. it can.

  The printer controller 26 includes a CPU, a ROM, a RAM, a user interface, a communication interface, and the like. The power mechanism unit may be provided with a CPU independently. In that case, the CPU of the power mechanism unit communicates with the CPU of the information processing unit via a parallel interface or the like to control the print engine. A printing operation is performed.

  The printer controller 26 has the same functional configuration as that of a printer controller in a normal printer. As shown in FIG. 2, for example, a receiving unit 260 that receives commands and data from the host device 10 and stores them in a receiving buffer, a power mechanism An engine control unit 262 that controls the printing unit to execute printing, an expansion control unit 263 that executes expansion processing, a transfer unit 265 that transfers the expansion processing result to the print engine in the order used for printing, and the like.

  However, the printer controller 26 of the present embodiment includes gradation mode selection means 261 for selecting the bit gradation mode, and the transfer means 265 performs the decompression processing result according to the bit gradation mode selected by the gradation mode selection means 261. This is different from the conventional configuration in that data having a predetermined bit length (gradation data of each pixel) is taken out from the image data and transferred to the print engine.

  The gradation mode selection unit 261 according to the present embodiment selects the bit gradation mode according to the gradation identification signal indicating the bit gradation mode received by the reception unit 260. For example, in the case of the 1-bit gradation mode, the transfer unit 265 extracts 1-bit data as the gradation data of each pixel from the beginning of the expansion result, and in the case of the 2-bit gradation mode, the expansion result. 2 bits of data can be extracted from the head of each pixel as gradation data of each pixel.

  Each of these means is realized by the CPU executing a program stored in a ROM or RAM in the printer device 20, an external storage medium, or the like.

(Print processing in the printer system)
Hereinafter, the printing process in the printer system 1 will be described with reference to the flowcharts shown in FIGS. 3 and 5 and the screen configuration diagram shown in FIG. 4. In addition, each process (including the partial process to which the code | symbol is not provided) can be arbitrarily changed in order within the range which does not produce contradiction in the processing content, or can be performed in parallel.

  In the present embodiment, as described above, two types of bit gradation modes, ie, a 1-bit fixed gradation mode and a 2-bit fixed gradation mode, are employed as an example of a plurality of bit gradation modes. However, the bit gradation modes are not limited to these two types, and can be added or changed as appropriate according to the specifications. For example, instead of or in addition to these, a gradation mode in which all pixels have a gradation signal having a 3-bit length and thereby perform gradation expression in eight stages may be employed.

(Processing in the host device 10)
First, processing in the host device 10 will be described with reference to FIG.

  FIG. 3 is a flowchart showing the flow of processing in the host device. The user inputs an instruction for selecting the bit gradation mode to the host device 10 via the user interface. The gradation mode selection means 161 outputs and displays a gradation selection screen as shown in FIG. 4 on a display (display device) according to the input instruction (STEP 300).

  FIG. 4 is a diagram illustrating an example of the gradation selection screen displayed on the display. As shown in the figure, a plurality of bit gradation modes 4b are displayed on the gradation selection screen 4a. The gradation selection screen has a function for the user to specify a desired bit gradation mode. For example, the user can designate a desired bit gradation mode by clicking a button corresponding to each bit gradation mode. Hereinafter, in the present embodiment, it is assumed that the 2-bit fixed gradation mode is designated as shown in FIG.

  When a predetermined bit gradation mode is designated by the user (Yes in STEP 301), the gradation mode selection unit 161 sets a bit gradation mode to be applied to image processing based on the designated content (STEP 302). For the bit gradation mode setting, for example, a bit gradation flag indicating whether the bit gradation mode is the 1-bit fixed gradation mode or the 2-bit fixed gradation mode is prepared, and each mode is set in the flag. Information for identification (“1” for 1-bit fixed gradation mode, “2” for 2-bit fixed gradation mode, etc.) can be stored. In the present embodiment, since the 2-bit fixed gradation mode is designated, “2” is stored in the bit gradation flag.

  Next, when the printer driver unit 16 receives a print request from an application program operating on the outside or the host device 10 (YES in STEP 303), the printer driver unit 16 transmits a print instruction command to the printer device 20 (printer controller 26). At the same time, it instructs the RIP unit 160 and the like to start processing.

  Upon receiving the processing start instruction, the RIP unit 160 generates a raster image based on print target data described in a predetermined printer control language such as a postscript received from the application program (STEP 304). If the print target data can be received from the application program or the like in the form of a raster image, the processing by the RIP unit 160 can be omitted.

  The image processing unit 162 performs predetermined image processing on the generated raster image in accordance with the bit gradation mode set by the gradation mode selection unit 161, generates a print image, and stores it in a predetermined area of the RAM. Store (STEP 305).

  Specifically, the image processing unit 162 selects a gradation conversion unit corresponding to the bit gradation mode. The selected gradation conversion means refers to the gradation conversion table corresponding to itself, converts the input gradation value on the raster image into the output gradation value on the print image, and has a predetermined bit length for each pixel. Tone data is generated. The image processing unit 162 stores the generated gradation data as a print image in a predetermined storage area of the RAM. Here, since “2” is stored in the bit gradation flag, the image processing means 162 selects the second gradation converting means. The second gradation conversion unit generates gradation data having a 2-bit length for each pixel.

  Next, the compression control means 163 reads out the print image generated from the predetermined area of the RAM, executes predetermined compression processing on the read print image, and generates compressed data (step S306). As the predetermined compression processing, various conventional compression algorithms can be adopted depending on the design. For example, if the print image is binary data, JBIG (Joint Bi-level Image Experts Group). It is conceivable to adopt an algorithm.

  Next, when the printer device 20 (printer controller 26) can receive the compressed data, the transfer unit 165 sends the gradation identification signal indicating the bit gradation mode and the compressed data to the printer device 20 (printer controller 26). (Step S307). The transfer unit 165 executes transfer processing for the generated print image until all the compressed data is transferred.

  Since the gradation identification signal is for detecting the bit information mode in the printer device 20, the gradation identification signal may be transferred at a timing different from the timing at which the compressed data is transferred. For example, after receiving a print request, it may be transferred when a print instruction command is transmitted to the printer device 20 (printer controller 26). Further, it may be transferred in response to an acquisition request from the printer device 20.

  According to such a configuration, the user can designate a desired gradation via the gradation selection screen, so that the host apparatus can implement a gradation mode according to the required image quality. In addition, since the user can designate the gradation mode in consideration of the required image quality, printing speed, network traffic state, and the like, it is possible to improve user convenience in the printing system. .

(Processing in the printer 20: FIG. 5)
Next, processing in the printer device 20 will be described with reference to FIG.

  FIG. 5 is a flowchart showing the flow of printing processing in the printer device 20. If the command received by the receiving unit 260 is a print instruction command (Yes in STEP 500), the printer controller 26 controls the power mechanism unit by the engine control unit 262 to prepare for printing. Further, when receiving the compressed data 7 and the gradation identification signal transferred from the host device 10, the receiving means 260 stores the compressed data 7 and the gradation identification signal in the reception buffer, and also sends them to the gradation mode selection means 261 and the expansion control means 263. The start of processing is instructed (STEP 501).

  When receiving the instruction to start processing, the gradation mode selection unit 261 selects the bit gradation mode based on the gradation identification signal (STEP 502). Here, the 2-bit fixed gradation mode is selected.

  In addition, when the decompression control unit 263 receives an instruction to start processing, the decompression control unit 263 reads the compressed data stored in the data reception buffer (step S503), and executes predetermined decompression processing on the read compressed data (step S503). S504). The decompression process needs to employ the decompression process corresponding to the compression algorithm employed by the compression control means 163 of the host device 10.

  When the transfer means 265 specifies the bit length of each pixel according to the bit gradation mode selected by the gradation mode selection means 261 (STEP 505), the transfer means 265 takes out data of that bit length in order from the beginning of the decompression result according to this bit length. Thus, gradation data for each pixel is extracted (STEP 506). Here, since the 2-bit gradation mode is selected, 2-bit information is extracted as gradation data for each pixel.

  When the transfer unit 265 extracts the gradation data for the pixels of one scanning line (Yes in step S507), the transfer unit 265 transfers the extracted gradation data of each pixel to the print engine (step S508).

  According to such a configuration, since the printer apparatus determines the bit gradation mode of the received print image according to the gradation identification signal, even when a print image according to a plurality of bit gradation modes is transferred from the host apparatus 10. The gradation data of each pixel can be extracted in the bit gradation mode corresponding to the print image.

  Further, according to the above configuration, the printer system can be selected by selecting the 1-bit fixed gradation mode when the data to be printed does not particularly require gradation or when it is desired to prioritize the data speed over the image quality. Can reduce the data communication load. On the other hand, if the data to be printed requires gradation, or if you want to prioritize image quality over data speed, select the 2-bit fixed gradation mode to obtain high-quality printing results. Will be able to. As a result, it is possible to realize a printer system that can select both requested image quality and data communication according to the situation.

(Second Embodiment)
In the first embodiment, by selecting the 1-bit fixed gradation mode or the 2-bit fixed gradation mode according to the purpose, a printer system that takes into account the balance between gradation expression and data transfer time is realized. However, when it is desired to reduce the data transfer time while maintaining high image quality, it is not easy to select one of the gradation modes.

  Therefore, in the second embodiment, by providing a variable gradation mode in which the bit length can be specified in units of pixels, a printer system that satisfies the user's request to maintain the high image quality and suppress the data transfer time is provided. It aims to be realized.

  The variable gradation mode is configured to take one of a plurality of types of bit lengths in units of pixels, and the bit length for all pixels as in the 1-bit fixed gradation mode and the 2-bit fixed gradation mode. Is different from the fixed gradation mode in which is a constant value. In the present embodiment, in addition to the 1-bit fixed gradation mode and the 2-bit fixed gradation mode, each pixel can be configured to specify either 1-bit length, 2-bit length, or 3-bit length. Adopted variable gradation mode. The bit length configuration in the variable gradation mode can be changed as appropriate according to the specifications.

(Functional configuration of printer system)
FIG. 6 is a block diagram illustrating a functional configuration of the printer system 1 according to the second embodiment. The function realizing means corresponding to the functions shown in FIG. The printer driver unit 16 ′ includes a pack processing unit 164 that executes a process of grouping bit-wise print images generated according to the variable gradation mode into a byte unit, and a table (hereinafter referred to as “bit”) that specifies an arrangement of the bit length of each pixel. Bit information table storage means 166 for storing the information table. Further, the image processing unit 162 includes a third gradation conversion unit corresponding to the variable gradation mode.

  Each of these means is functionally realized by the CPU executing a program stored in a ROM or RAM in the host device 10 or an external storage medium. The bit information table storage unit 166 is constructed in a ROM or RAM in the host device 10, an external storage medium, or the like.

On the other hand, the print controller 26 ', unpacking means 2 64 to run back to the bit basis (unpacked) processing the print image are combined into bytes by packing means 164, the data unpacked by the unpacking unit 2 64 Position control means 267 for controlling the position of the isolated dot and bit information table storage means 266 for storing the bit information table are provided.

  Each of these means is realized by the CPU executing a program stored in a ROM or RAM in the printer device 20, an external storage medium, or the like. The bit information table storage unit 266 can be constructed in a ROM or RAM in the printer device 20, an external storage medium, or the like.

(Bit information table)
FIG. 7 is a diagram illustrating an example of the data configuration of the screen table and the bit information table. An example of screen table shown in FIG. 7 (A), showing an example of a bit information table in FIG. 7 (B). The bit information table associates a bit length with a position in the screen table. When one pixel on the raster image is converted to 9 × 9 pixels on the print image, each gradation value of 9 × 9 pixels on the print image is represented on the bit information table corresponding to the position in the screen table. Is converted to a gradation value having a bit length of.

  The variable gradation mode is based on the 2-bit gradation, and a place where a small amount of gradation is sufficient is expressed by a 1-bit gradation, and a part where more gradations are required is expressed by a 3-bit gradation. Composed. For example, the human eye is said to be sensitive to density changes in low density areas, but insensitive to density changes in high density areas. The 2-bit fixed gradation mode can express smoother gradation than the 1-bit fixed gradation mode, so it is suitable for halftone and high-density images, but it is smooth for thin areas such as human skin. It is difficult to express a smooth gradation.

  From the above, in this embodiment, in the variable gradation mode, the larger value (for example, 27 or 24) of the screen table is set to 1-bit gradation, and the smaller value (for example, 6 or 3). By adopting 3 bit gradation, the gradation of the dark part of the printed image is reduced and the gradation of the thin part is increased. In addition, by combining the number of pixels in the portion to which 1-bit gradation is assigned and the number of pixels in the portion to which 3-bit gradation is assigned, the total data amount is the same as that in the 2-bit fixed gradation mode. It is composed.

  The bit information table can be transferred from the printer driver means 16 'to the printer controller 26', and conversely from the printer controller 26 'to the printer driver means 16'. Thereby, even when the printer driver, the target engine, the screen table, etc. are changed, the bit information table can be easily updated.

(Print processing in the printer system)
Hereinafter, the printing process in the printer system 1 will be described with reference to the flowcharts shown in FIGS. In addition, each process (including the partial process to which the code | symbol is not provided) can be arbitrarily changed in order within the range which does not produce contradiction in the processing content, or can be performed in parallel.

  FIG. 8 is a flowchart showing the flow of processing in the host device. Since the process from the selection of the gradation mode and the process start instruction by the user to the generation of the raster image is basically the same as the process flow in FIG.

  It is assumed that the user has selected the bit variable gradation mode from the gradation selection screen as shown in FIG. Since the bit variable gradation mode is designated, the gradation mode selection unit 161 stores “3” indicating the mode in the bit gradation flag.

The RIP unit 160 generates a raster image based on the print target data (STEP 800). When the raster data is generated by the RIP unit 160, the image processing unit 162 determines whether or not the set gradation mode is the variable gradation mode (STEP 801).
In the case of the variable gradation mode, the image processing means 162 reads out the bit information table corresponding to the variable gradation mode from the bit information table storage means 166 using the third gradation conversion means (STEP 802). . On the other hand, when it is not the variable gradation mode, the image processing means 162 generates a print image using the gradation converting means corresponding to the designated bit gradation mode (STEP 803).

  In the present embodiment, since the variable gradation mode is designated, the image processing unit 162 (third gradation conversion unit) reads the bit information table corresponding to the variable gradation mode. When there are a plurality of variable gradation modes, the corresponding bit information table is read out because the corresponding bit information table is stored in the bit information table storage means 166.

  The image processing means 162 acquires the bit length of the target pixel from the bit information table (STEP 804). Then, gradation data is generated according to the acquired bit length for each target pixel (STEP 805). The image processing unit 162 delivers the generated gradation data to the pack processing unit 164.

Next, the pack processing unit 164 starts a process of collecting the gradation data of each pixel from the bit unit to the byte unit (STEP 8 07). Specifically, 1-bit, 2-bit, and 3-bit data are connected to form 1-byte (8-bit) data (pack processing). The pack processing unit 164 transfers the data packed in byte units to the compression control unit 163.

  The compression control unit 163 performs a predetermined compression process on the packed data to generate compressed data (step S807). Then, when the printer device 20 (printer controller 26) can receive the compressed data, the transfer unit 165 sends the gradation identification signal indicating the bit gradation mode and the compressed data to the printer device 20 (printer controller 26). Transfer (step S808).

  When the variable gradation mode is designated and the same bit information table does not exist in the printer device 20, the transfer unit 165 also transfers the bit information table together. The timing for transferring the bit information table is not limited to this timing. For example, after receiving a print request, it may be transferred when a print instruction command is transmitted to the printer device 20 (printer controller 26), or may be transferred in response to an acquisition request from the printer device 20. May be.

  Next, processing on the host device side will be described.

  FIG. 9 is a flowchart showing the flow of processing in the host device. The processing until the compressed data is stored in the reception buffer is basically the same as the processing flow in FIG.

  The decompression control means 263 reads the compressed data from the reception buffer and decompresses it (STEP 901). The decompression process needs to employ the decompression process corresponding to the compression algorithm employed by the compression control means 163 of the host device 10. Next, the gradation mode selection unit 261 determines whether or not the bit gradation mode is a variable gradation (STEP 902). In the case of variable gradation, the unpack processing means 264 is instructed to start processing.

  The unpack processing means 264 refers to the bit information table based on the head position and acquires the bit length of the target pixel (STEP 903). As the bit information table used in the unpacking process, a bit information table corresponding to the bit length information table employed by the pack processing unit 164 of the host device 10 needs to be employed. In the present embodiment, the bit information table uses the information transferred from the printer device 10, but may be stored in the printer device 20 in advance. The unpack processing means 264 extracts the data of each pixel from the packed data according to the acquired bit length (STEP 904).

  Next, the position control means 267 executes processing for controlling the position of the isolated dot (STEP 905). In the case of a laser printer, a plurality of gradations are expressed using a plurality of partial dots obtained by dividing one pixel in the main inspection direction. For example, in the case of the 2-bit gradation mode, one dot is divided into four partial dots (first partial dot, second partial dot, third partial dot, and fourth partial dot) in the main scanning direction. A laser is irradiated on these partial dots in a pattern determined in (1) and toner is placed thereon.

  However, when there are a plurality of partial dots that are not irradiated with laser before and after the partial dots that are irradiated with laser (for example, when laser is irradiated only to the third partial dots, the portions other than the third partial dots The problem is that toner is not easily applied to the target partial dot. Such partial dots are called isolated dots.

  In view of this, the printer system 1 is configured such that such isolated dots are subjected to position control so as to approach either the main inspection direction or the reverse direction of the main inspection direction. When the position control unit 267 detects an isolated dot, the position control unit 267 adds information indicating whether to approach the main inspection direction or the main inspection direction.

  When the gradation data of the pixels for one scanning line are all expanded (in the case of the variable gradation mode, the transfer unit 265 further unpacks and performs position control) (Yes in step S906), The pixel gradation data is transferred to the print engine (step S9007).

  According to such a configuration, the printer system 1 employs the variable gradation mode, so that gradation expression with different levels can be realized on a pixel-by-pixel basis.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be variously modified and applied. For example, the present invention can be applied to a system other than a printer system as long as the system performs gradation processing on image data.
(1) For example, in the above-described embodiment, the case where the 1-bit fixed gradation mode, the 2-bit fixed gradation mode, and the variable gradation mode are adopted as the bit gradation mode has been described. It is possible to add or change as appropriate according to the situation. For example, a 3-bit fixed gradation mode that expresses 8 gradations using a bit length of 3 bits may be added.
(2) Further, for example, in the above embodiment, the gradation mode selection means 161 of the printer driver means 16 sets a bit gradation mode to be applied to image processing, but the present invention does not necessarily have such a structure. Not limited. For example, the bit controller mode may be set on the printer controller 26 side. In this case, the user can designate via the user interface of the printer 20, and the printer controller 26 transfers a gradation identification signal indicating the bit gradation mode to the host device 10 at a predetermined timing. For example, it is transferred at the timing when a print instruction command is received from the host device or when a tone identification signal acquisition request is received. According to this, the setting on the host side can be matched with the bit gradation mode on the printer side.
(3) In the above embodiment, the user designates the bit gradation mode. However, the present invention is not necessarily limited to such a configuration. For example, the printer driver unit 16 and the print controller 26 may be configured to automatically specify the bit gradation mode according to a predetermined condition.
(4) In the above embodiment, in the variable gradation mode, the pack / unpack process is performed and the position control process is performed. However, the present invention is not necessarily limited to such a structure. For example, even in the 2-bit fixed gradation mode, the pack / unpack process and the position control process may be executed.

2 is a block diagram illustrating a hardware configuration of the printer system 1 according to the first embodiment. FIG. FIG. 2 is a block diagram illustrating a functional configuration diagram of a printer driver unit 16 and a printer controller 26 according to the first embodiment. 3 is a flowchart showing processing contents of a printer driver unit 16 in the first embodiment. It is a figure which shows an example of the gradation selection screen in 1st Embodiment. 4 is a flowchart illustrating processing contents of the printer controller according to the first embodiment. It is a block diagram which shows the function block diagram of the printer driver means 16 and the printer controller 26 in 2nd Embodiment. It is a figure which shows an example of a data structure of the bit length information table in 2nd Embodiment. It is a flowchart which shows the processing content of the printer driver means 16 in 2nd Embodiment. 6 is a flowchart illustrating processing contents of a printer controller according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer system, 10 Host apparatus, 16 Printer driver means, 160 RIP means, 161 Gradation mode selection means, 162 Image processing means, 163 Compression control means, 164 Pack processing means, 165 Transfer means, 166 Bit information table storage means, 20 printer device 260 reception means 261 gradation mode selection means 262 engine control means 263 decompression control means 264 unpack processing means 265 transfer means 266 bit information table storage means

Claims (4)

A host device connected to a printer device via a network,
Selecting means for selecting one gradation mode in accordance with an instruction input by a user from a plurality of gradation modes having different bit length configurations used for gradation expression ;
By expressing a gray scale of each pixel in the configuration of the slave power sale bit length tone mode selected by the selecting unit, image processing means for generating image data from the print data,
Transfer means for transferring image data generated by the image processing means and gradation identification information indicating the gradation mode selected by the selection means to the printer device ;
The plurality of gradation modes include a fixed gradation mode in which the bit length of each pixel is a constant value and a variable gradation mode in which the bit length of each pixel is not a constant value,
When the selection means selects the variable gradation mode, the image processing means prints according to the bit information table stored in the variable gradation mode in association with the bit length of each pixel in correspondence with the position in the screen table. Generate image data according to the variable gradation mode from the target data,
The transfer unit transfers the same bit information table to the printer device when the same bit information table as the bit information table used by the image processing unit does not exist in the printer device;
The bit length of each pixel in the bit information table is based on 2-bit gradation, and when the screen table position value indicates high density, the bit length is 1 bit gradation, and the screen table position value indicates low density. In the case shown , a host apparatus is characterized in that a 3-bit gradation is assigned, and the number of pixels to which the 1-bit gradation is assigned coincides with the number of pixels to which the 3-bit gradation is assigned . An image processing method in a host device that is connected to a printer device via a network and has a plurality of gradation modes having different bit length configurations used for gradation expression,
Selecting one gradation mode in accordance with an instruction input by the user from the plurality of gradation modes;
By representing the gray level of each pixel in the sub sales of bit length configuration to the selected gradation mode, and generating image data from the print data,
Transferring the generated image data and gradation identification information indicating the selected gradation mode to a printer device , and
The plurality of gradation modes include a fixed gradation mode in which the bit length of each pixel is a constant value and a variable gradation mode in which the bit length of each pixel is not a constant value,
In the generating step, when the variable gradation mode is selected, the variable gradation mode is changed from the print target data according to the bit information table that stores the bit length of each pixel in association with the position in the screen table for the variable gradation mode. Generate image data according to the gradation mode,
In the transferring step, when the same bit information table as the bit information table does not exist in the printer device, the same bit information table is transferred to the printer device,
The bit length of each pixel in the bit information table is based on 2-bit gradation, and when the screen table position value indicates high density, the bit length is 1 bit gradation, and the screen table position value indicates low density. In the case shown, an image in the host device is assigned with a 3-bit gradation, and the number of pixels to which the 1-bit gradation is assigned matches the number of pixels to which the 3-bit gradation is assigned. Processing method. A host device connected to the printer device via a network
Selecting means for selecting one gradation mode in accordance with an instruction input by a user from a plurality of gradation modes having different bit length configurations used for gradation expression ;
Image processing means for generating image data from print target data by expressing the gradation of each pixel in a bit length configuration according to the gradation mode selected by the selection means;
Transfer means for transferring image data generated by the image processing means and gradation identification information indicating the gradation mode selected by the selection means to the printer device ;
The plurality of gradation modes include a fixed gradation mode in which the bit length of each pixel is a constant value and a variable gradation mode in which the bit length of each pixel is not a constant value,
When the selection means selects the variable gradation mode, the image processing means prints according to the bit information table stored in the variable gradation mode in association with the bit length of each pixel in correspondence with the position in the screen table. Generate image data according to the variable gradation mode from the target data,
The transfer unit transfers the same bit information table to the printer device when the same bit information table as the bit information table used by the image processing unit does not exist in the printer device;
The bit length of each pixel in the bit information table is based on 2-bit gradation, and when the screen table position value indicates high density, the bit length is 1 bit gradation, and the screen table position value indicates low density. In the case shown, a program is made to function as a host device to which 3-bit gradation is assigned and the number of pixels to which the 1-bit gradation is assigned matches the number of pixels to which the 3-bit gradation is assigned . A printer system comprising: a host device having a plurality of gradation modes each having a different bit length configuration used for gradation expression; and a printer device configured to be able to communicate with the host device,
The host device
A selection unit that selects one predetermined gradation mode from the plurality of gradation modes according to an instruction input by a user ;
By expressing a gray scale of each pixel in the configuration of the slave power sale bit length tone mode selected by the selecting unit, image processing means for generating image data from the print data,
Transfer means for transferring image data generated by the image processing means and gradation identification information indicating a gradation mode of the image data to a printer device ;
The printer device
Receiving means for receiving image data and gradation identification information indicating a gradation mode of the image data;
Selection means for selecting a gradation mode from the plurality of gradation modes according to the gradation identification information received by the receiving means;
Print execution means for executing printing on a print recording medium based on image data;
Transfer means for transferring the image data received by the receiving means to the print execution means in accordance with the gradation mode selected by the selection means ,
In the host device,
The plurality of gradation modes include a fixed gradation mode in which the bit length of each pixel is a constant value and a variable gradation mode in which the bit length of each pixel is not a constant value,
When the selection means selects the variable gradation mode, the image processing means prints according to the bit information table stored in the variable gradation mode in association with the bit length of each pixel in correspondence with the position in the screen table. Generate image data according to the variable gradation mode from the target data,
The transfer unit transfers the same bit information table to the printer device when the same bit information table as the bit information table used by the image processing unit does not exist in the printer device;
The bit length of each pixel in the bit information table is based on 2-bit gradation, and when the screen table position value indicates high density, the bit length is 1 bit gradation, and the screen table position value indicates low density. In the printer system, a 3-bit gradation is assigned, and the number of pixels to which the 1-bit gradation is assigned coincides with the number of pixels to which the 3-bit gradation is assigned .

Images