JP3807349B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine or a facsimile machine.
[0002]
[Prior art]
In recent years, the recording resolution of printers has increased, and when printing image data received by facsimile or image data read by a scanner, it is necessary to convert the resolution of the image data to match the resolution of the printer. Conventionally, for this resolution conversion, (1) the resolution is converted with binary data (smoothing is applied at the same time), (2) binary image data is converted into multivalued data in a pseudo manner, and linear interpolation calculation is performed. There are two methods of converting the resolution using the above.
[0003]
[Problems to be solved by the invention]
Of the conventional conversion methods described above, the first conversion method has no problem in the case of images such as characters and ruled lines, but in the case of a pseudo halftone image such as a photograph, white lines and black lines are included, and moire patterns. Is not preferable. The second conversion method can perform resolution conversion of pseudo halftone image data without generating lines or moire. However, since it involves linear interpolation, the circuit scale increases when the degree of resolution conversion is large. There's a problem.
[0004]
The present invention has been made paying attention to the above problems, and does not deteriorate the image quality of the recorded image even if the resolution is converted, and increases the circuit scale even if the resolution conversion degree is increased. It is an object of the present invention to provide an image forming apparatus that does not occur.
[0005]
[Means for Solving the Problems]
The image forming apparatus according to the present invention includes a first resolution converting unit that converts resolution of input binary image data as binary, and binary image data that has been converted in resolution by the first resolution converting unit. A second resolution converting means for converting to multi-valued image data, converting the resolution back to binary data, and a selecting means for selecting one of the outputs of the first resolution converting means and the second resolution converting means And image recording means for recording the image data selected by the selection means on a sheet . When the resolution conversion is not necessary, the selection means outputs the input binary image data as it is, and the image data is character data. Is selected from the output of the first resolution conversion means, and when the image data is pseudo halftone image data, the output of the second resolution conversion means is selected .
[0006]
In the image forming apparatus according to the present invention, when the output of the second resolution conversion unit is selected by the selection unit, the scaling factor R is represented by N (integer) × M, and the first resolution conversion unit converts the resolution by N times. And the second resolution conversion means may perform M-fold resolution conversion .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0008]
FIG. 1 shows the configuration of a multifunction peripheral (having multiple functions such as a copy function, a fax function, and a reading function) as an embodiment of the image forming apparatus of the present invention.
[0009]
The MFP according to this embodiment includes an MPU 1, an NCU 2, a MODEM 3, a ROM 4, a RAM 5, an image memory 6, a LAN I / F 7, a scanner 8, a scanner image processing circuit 9, a reading / communication CODEC 10, A display unit 11, a keypad 12, a printer CODEC 13, a resolution conversion circuit 14, a memory management circuit 15, a page memory 16, a printer I / F 17, and a printer 18 are provided.
[0010]
The MPU 1 has a function of controlling the entire MFP according to this embodiment. An NCU (Network Control Unit) 2 and MODEM 3 are connected to the MPU 1. The NCU 2 is controlled by the MPU 1 to control the connection between the line L and the MFP, and has a function of sending a dial pulse corresponding to the telephone number of the communication partner and a function of detecting an incoming call. The line L is connected to a general public telephone network (PSTN).
[0011]
MODEM 3 modulates / demodulates transmission / reception data, specifically, modulates transmission data, which is a digital signal, into an analog audio signal, and sends it to the line L via the NCU 2, and conversely, from the line L via the NCU 2, The received analog audio signal is demodulated into a digital signal.
[0012]
The ROM 4 stores in advance a program and the like for controlling the operation of the entire multifunction machine. The RAM 5 stores data necessary for control by the MPU 1 and data that needs to be temporarily stored during the control operation. The RAM 5 also has a FAT (File Allocation Table) 5a for registering the number of pages of image data, the storage start address of each page, the number of codes of each page (added value), and the data amount of each page. The image memory 6 stores image data read by the scanner 8 and also stores image data received from the outside via the line L and the MODEM 3.
[0013]
The LAN I / F 7 is connected to the server 21 from the LAN 20, the client PC 22, and further to the Internet 25 from the router 24 via this.
[0014]
The scanner 8 reads an original image using, for example, a CCD image sensor. The scanner image processing circuit 9 performs image processing such as shading correction and binarization processing on the document image read by the scanner 8.
[0015]
The reading / communication CODEC 10 encodes image data to be transmitted, encodes the read image data, and stores the encoded image data in the image memory 6.
[0016]
The display unit 11 displays various information such as a telephone number, a FAX number, and a toner remaining amount of the printer 18 input by operating the keypad 12. In addition to the start key, the keypad 12 includes a mode switching key for setting various modes, a numeric keypad for inputting numbers such as a telephone number and a FAX number, operation keys for instructing various operations, and the like.
[0017]
The printer CODEC 13 decodes the image data to be printed stored in the image memory 6. The resolution conversion circuit 14 converts the input binary image data into a binary resolution, and converts the binary resolution-converted binary image data into multi-valued image data in a pseudo manner to convert the resolution. And a function for selecting either a resolution conversion output for binary processing or a resolution conversion output for binary processing or a resolution conversion output for photo processing. Since the resolution conversion circuit 14 performs the above functions, a binary processing resolution conversion circuit (first resolution conversion means) 14a, a photo processing resolution conversion circuit (second resolution conversion means) 14b, and a selection circuit (selection means). 14c. The memory management circuit 15 stores the decoded data to be printed in the page memory 16 and manages the data to be printed. The printer 18 prints the received image data, the image data read by the scanner 8 or the image data stored in the image memory 6 by printing on paper, and performs hard copy output. The printer 18 used here has a high resolution.
[0018]
A feature of this embodiment is the resolution conversion circuit 14. The resolution conversion circuit 14 is configured as shown in FIG. 5 along the flow of image processing. The photo processing resolution conversion unit 14 b includes a buffer memory 31, a multilevel resolution conversion unit 32, a multilevel memory 33, an error buffer 34, and an error diffusion unit 35.
[0019]
When image data decoded by the printer CODEC 13 is input to the resolution conversion circuit 14, the input image data is input to the selection circuit 14c. The binary processing resolution conversion unit 14a performs binary enlargement smoothing on the input image data to perform simple enlargement. The binary image data whose resolution has been converted is input to the selection circuit 14 c and stored in the buffer memory 31. The binary image data stored in the buffer memory 31 is converted into multi-value image data in a pseudo manner by the multi-value conversion circuit 32, and the resolution of the multi-value image data is converted by applying linear interpolation or the like. The multi-value image data is stored in the multi-value memory 33. The multilevel image data stored in the multilevel memory 33 is returned to binary data using the error buffer 34 and the error diffusion unit 35.
[0020]
The selection circuit 14c outputs the input image data as it is in the case of no resolution conversion, selects the output of the binary processing resolution conversion circuit 14a in the case of resolution conversion in the case of characters and ruled lines, and in the case of a halftone such as a photograph Selects the output of the photo processing resolution conversion circuit 14b.
[0021]
Next, the processing operation at the time of reception of the multifunction machine (facsimile apparatus) will be described with reference to the flowchart shown in FIG. In step ST1, it is determined whether there is a calling signal. When a call signal is received from the line L to the NCU 2 and MODEM 3, the process proceeds to step ST2. In step ST2, line connection is performed. Subsequently, the process proceeds to step ST3. In step ST3, a pre-procedure is executed. The pre-procedure here is to send the capability of the multifunction device to the partner and to receive the specification of the capability level from the partner in order to match the capability level with the partner. Next, the process proceeds to step ST4.
[0022]
In step ST4, the transmitted encoded image data is received. Next, the process proceeds to step ST5. In step ST5, the received encoded image data is decoded by the reading / communication CODEC 10. Then, the process proceeds to step ST6. In step ST6, it is determined whether or not decoding has been correctly performed. If the decoding is correctly performed, the process proceeds to step ST7. On the other hand, if the decoding cannot be performed correctly, error processing is performed.
[0023]
In step ST7, the decoded image data is re-encoded by the CODEC 10. Subsequently, the process proceeds to step ST8. In step ST8, the number of codes is added. Then, the process proceeds to step ST9. In step ST9, the re-encoded image data is stored in the image memory 6. Next, the process proceeds to step ST10. In step ST10, it is determined whether or not one page ends. If it is not the end of one page, the process returns to step ST4, the encoded image data is received, and the processing of steps ST4 to ST10 is continued up to the processing means for one page. On the other hand, when one page is completed, the process proceeds to step ST11.
[0024]
In step ST11, the number of pages, the resolution start address, the number of codes, and the data amount are registered in the FAT 5a of the RAM 5. Next, the process proceeds to step ST12. In step ST12, it is determined whether or not there is a next page in the received image data. If there is a next page, the process returns to step ST4. On the other hand, if there is no next page, the process proceeds to step ST13. In step ST13, the line is released. Next, the bit image development processing will be described with reference to the flowchart shown in FIG. In step ST21, it is determined whether or not an unprinted page is registered by referring to the FAT 5a of the RAM 5. If an unprinted page is registered, the process proceeds to step ST22. In step ST22, the printer 18 is activated. Then, the process proceeds to step ST23.
[0025]
In step ST23, it is determined whether or not resolution conversion is necessary. When resolution conversion is necessary as in the case where the resolution of the printer is higher than that of the image data, the process proceeds to step ST24. On the other hand, when the resolution of the received image data is high and resolution conversion is not necessary, the process proceeds to step ST29. In step ST24, code number data is read from the FAT 5a. Next, the process proceeds to step ST25. In step ST25, it is selected whether or not the number of codes is a predetermined value or more. If the number of codes is greater than or equal to the predetermined value, it is determined that photo resolution conversion is to be selected, and the process proceeds to step ST26. On the other hand, if the number of codes is not greater than or equal to the predetermined value, it is determined that the binary resolution conversion selection is OK, and the process proceeds to step ST30. In step ST26, photo resolution conversion is selected. The selection of the photo resolution conversion is performed by selecting the output of the photo processing resolution conversion circuit 14b by the selection circuit 14c. Subsequently, the process proceeds to step ST27. In step ST27, CODEC (printer CODEC 13) is activated. Next, the process proceeds to step ST28. In step ST28, the bit image is developed in the image memory 16. Then, the process proceeds to step ST31. In step ST31, it is determined whether or not the bit image development has ended. If the bit image development is not finished, the process returns to step ST28 and the bit image development is continued. On the other hand, if the bit image development has ended, the process proceeds to step ST32. In step ST32, the CODEC of the printer CODEC 13 is stopped.
[0026]
In step ST30, binary resolution conversion is selected. In the selection of binary resolution conversion, the selection circuit 14c selects the output of the binary processing resolution conversion circuit 14a. Then, the process proceeds to step ST27. The subsequent processing is the same as when the photo resolution conversion is selected in step ST26. In step ST29, resolution conversion is not necessary, and through is selected. The through selection selects that the input image data decoded by the selection circuit 14c is output as it is. Then, the process proceeds to step ST27. The subsequent processing is the same as when photo resolution conversion or binary resolution conversion is selected.
[0027]
Next, transfer processing of a bit image to the printer 18 will be described with reference to a flowchart shown in FIG. When this processing routine is entered, in step ST41, the page memory 16 is referenced to determine whether or not a bit image for one page has been developed. When the bit image is developed, the process proceeds to step ST42.
[0028]
In step ST42, the bit image of the page memory 16 is read from the memory management unit 15, and is output via the printer I / F 17. Next, the process proceeds to step ST43. In step ST43, image data is transferred to the printer 18 in synchronization with the transfer clock. Subsequently, the process proceeds to step ST44. In step ST44, it is determined whether or not image data transfer for one page is completed. If the transfer for one page is completed, the process returns to step ST41. On the other hand, if the transfer of one page is not completed, the process returns to step ST42, until the transfer of one page is completed, reading of the bit image of step ST42,..., ST44, transfer to the printer, and transfer for one page. Repeat the end determination. The printer 18 performs a print process every time data is received.
[0029]
【The invention's effect】
According to this invention, the first resolution conversion means suitable for the resolution conversion processing of the image data of characters and ruled lines and the second resolution conversion means suitable for the resolution conversion processing of the pseudo halftone, the selection means includes: When the resolution conversion is not necessary, the input binary image data is output as it is. When the image data is character data, the output of the first resolution conversion means is selected. When the image data is pseudo halftone image data, Since the output of the second resolution conversion means is selected, it is possible to prevent deterioration of the image quality of the image recorded on the paper. Further, in the case of pseudo halftone, first, the first resolution conversion means performs an integer multiple N resolution conversion, and then the second resolution conversion means performs M resolution conversion, so that the second resolution conversion means The degree of resolution conversion can be reduced, and the circuit scale can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a multifunction machine as an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a flowchart illustrating a reception process of the MFP according to the embodiment.
FIG. 3 is a flowchart illustrating a bit image development process of the MFP according to the embodiment.
FIG. 4 is a flowchart illustrating transfer processing to the printer of the multifunction machine according to the first embodiment.
FIG. 5 is a flowchart illustrating a flow of resolution conversion processing performed by the MFP according to the embodiment.
[Explanation of symbols]
1 MPU
2 NCU
3 MODEM
4 ROM
5 RAM
5a FAT
6 Image memory 7 LAN I / F
8 Scanner 9 Scanner Image Processing Circuit 10 Reading / Communication CODEC
11 Display 12 Keypad 13 CODEC for Printer
14 resolution conversion circuit 14a binary processing resolution conversion circuit 14b photo processing resolution conversion circuit 14c selection circuit 15 memory management unit 16 page memory 17 printer I / F
18 Printer

Claims (2)

First resolution conversion means for converting the resolution of the input binary image data as binary, and binary image data whose resolution has been converted by the first resolution conversion means is converted into multi-value image data in a pseudo manner. The second resolution conversion means for converting the resolution back to binary data, the selection means for selecting one of the outputs of the first resolution conversion means and the second resolution conversion means, and the selection means. Image recording means for recording image data on paper ,
The selection means outputs the input binary image data as it is when resolution conversion is not necessary, and selects the output of the first resolution conversion means when the image data is character data, and the image data is pseudo halftone image data. In this case, the output of the second resolution conversion means is selected . When the output of the second resolution conversion means is selected by the selection means, the scaling factor R is represented by N (integer) × M, the first resolution conversion means performs N times resolution conversion, and the second resolution conversion 2. The image forming apparatus according to claim 1 , wherein said means performs M times resolution conversion.

Images