JP4548368B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus.

  Conventionally, when a copying machine scans an original in the main scanning direction and the sub-scanning direction and reads an image, the image data obtained by reading the inclined original is corrected, and an image without inclination is recorded on the recording paper. The technology to form is considered.

  As one method of the document skew correction process, image data is regarded as a collection of linear data in the main scanning direction or a collection of linear data in the sub-scanning direction, and the lines in the main scanning direction constituting the image. Is performed by combining a main scanning shift process for shifting the image data in the main scanning direction (horizontal direction) and a sub scanning shift process for shifting line data in the sub scanning direction in the sub scanning direction (vertical direction). Yes (see, for example, Patent Document 1).

  Further, in the sub-scanning shift process, a configuration is considered in which a minimum required rectangular memory area is secured as an input buffer, and data in the input buffer is selected and corrected in accordance with an inclination angle (for example, Patent Documents). 2).

  FIG. 14 shows an outline of a conventional sub-scanning shift process. As shown in FIG. 14, a case where the tilted image data 200 after the main scanning shift process is sub-scan shifted is considered. Image data corresponding to a rectangular memory area 230 for a predetermined line is stored in a FIFO (First In First Out) memory, and the image data in the read area 231 in the memory area 230 is read from the stored image data. The inclination of the reading area 231 corresponds to the inclination of the image data 200. After reading the image data in the reading area 231, the memory area 230 is shifted by one pixel in the sub-scanning direction (downward in the figure). By repeating this process, one piece of image data with corrected inclination is obtained.

In the main scanning shift process and the sub scanning shift process, correction is performed in units of one pixel. For this reason, an error of one pixel or less is interpolated by interpolation processing after each shift processing.
JP 2000-59611 A JP-A-7-79321

  However, there is a demand for further reduction in the storage capacity of the FIFO memory used for the sub-scanning shift process in the conventional image data inclination correction.

  As illustrated in FIG. 14, the rectangular memory area 230 includes a read area 232 and a delay area 233 with the read area 231 as a boundary. The delay area 233 has image data before reading. The read area 232 includes image data that has been read from the read area 231. For this reason, the FIFO memory has a storage capacity enough to store the memory area 110 including the unnecessary read-out area 112. Therefore, there has been a demand for reducing the FIFO memory cost by reducing the storage capacity of the FIFO memory.

  Conventionally, in order to prevent an increase in the storage capacity of the FIFO memory, multilevel processing is performed before sub-scanning shift processing, and processing such as error diffusion is performed by reducing the number of bits of image data. For this reason, there is a demand not to perform multi-value processing at the time of sub-scan shift processing in order to accurately reproduce an error diffusion pattern even if FIFO memories having the same storage capacity are used.

  An object of the present invention is to reduce the storage capacity of a FIFO memory used for sub-scanning shift.

In order to solve the above problem, an image processing apparatus according to claim 1 is provided.
Stores image data of a plurality of line areas including a read area corresponding to the inclination of the image data out of the main scan shifted image data, and a line having a larger sub-scan shift amount of the read area has a smaller storage capacity. FIFO memory,
A control unit for reading out image data in the readout area from each of the FIFO memories;
It is characterized by providing.

The invention according to claim 2 is the image processing apparatus according to claim 1,
A selector for switching the output of each FIFO memory;
The control unit switches the selector and reads the image data in the reading area from each of the FIFO memories.

The invention according to claim 3 is the image processing apparatus according to claim 1 or 2,
The control unit reads the image data in the readout area, moves the multiple line area by one line in the sub-scanning direction, and stores the image data in the multiple line area after the movement in the multiple FIFO memories. It is characterized by making it.

The invention according to claim 4 is the image processing apparatus according to any one of claims 1 to 3,
A scanner that reads an image of a document and outputs image data;
And a main scanning shift processing section for main scanning shifting the read image data.

  According to the first aspect of the present invention, the storage capacity of the FIFO memory used for the sub-scan shift can be reduced.

  According to the second aspect of the present invention, the image data in the read area can be read from each FIFO memory by switching the selector.

  According to the third aspect of the present invention, the image data in the read area is read and the image data in the new multiple line area is written into the FIFO memory while moving the multiple line area in the sub-scanning direction. And can be done.

  According to the fourth aspect of the present invention, it is possible to read the original and acquire the image data to perform the main scanning shift and the sub scanning shift.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

  First, the apparatus configuration of the digital copying machine 1 according to the present embodiment will be described with reference to FIGS. FIG. 1 shows a mechanical configuration of a digital copying machine 1 according to the present embodiment.

  The digital copying machine 1 includes a copying machine main body 1 </ b> A and a document conveying unit 20. It is assumed that the document feeder 20 is formed and attached as a separate unit from the copier body 1A to the copier body 1A.

  The copying machine main body 1 </ b> A includes a scanner 10. The scanner 10 includes a document table 11, a document light source 12, a mirror 13, an imaging lens 14, and a line sensor 15. The copying machine main body 1A includes a main body control unit 60, an operation unit 70, a printer unit 50, and the like, as will be described later.

  The document placement table 11 forms a document passage and a document illumination position when a document to be scanned is placed and when a moving document is read. The document light source 12 outputs light movably along the document table 11. The mirror 13 is movable together with the document light source 12. The imaging lens 14 images incident light on the line sensor 15. The line sensor 15 is composed of a CCD (Charge Coupled Devices) or the like, and converts an incident optical signal into an electrical signal and outputs the electrical signal.

  The light output from the original light source 12 is reflected by the original and enters the line sensor 15 via the mirror 13 and the imaging lens 14.

  The document transport unit 20 includes a paper feed tray 21, a paper feed roller 22, a roller 23, a paper discharge roller 24, a paper discharge tray 25, and sensors 26a and 26b.

  The paper feed tray 21 places a document to be scanned. The paper feed roller 22 transports the originals placed on the paper feed tray 21 one by one. The roller 23 conveys the document conveyed by the paper supply roller 22 to the reading position, and conveys the document in a certain direction at the reading position. The paper discharge roller 24 discharges the original conveyed by the roller 23. The paper discharge tray 25 places the discharged original.

  Each of the sensors 26a and 26b includes a projector and a light receiver, and detects the passage of a document. The sensors 26a and 26b are provided immediately after the paper feed roller 22 and at a right angle to the document conveyance direction with the document conveyance path interposed therebetween.

  The originals on the paper feed tray 21 are separated one by one by a paper feed roller 22, pass through a roller 23 and a paper discharge roller 24, and transmitted to the paper discharge tray 25.

  A document moving system in which the line sensor 15 scans a document passing through a reading position formed by the document table 11 and the roller 23 in a main scanning direction that is the direction of the line and a sub-scanning direction that is a moving direction of the document. Is read.

  The digital copying machine 1 can also perform image reading by a document stationary method. That is, it is possible to read an image of a document placed on the document table 11 while moving the document light source 12 and the mirror 13.

  The sensors 26 a and 26 b detect the angle of the leading edge of the document conveyed along the document conveyance path, that is, the inclination of the document while the document is traveling in the document conveyance unit 20. Note that any known sensor can be used as a sensor for detecting the inclination of the document.

  FIG. 2 shows an electrical configuration of the image reading apparatus 2. As shown in FIG. 2, the image reading device 2 is a device that reads a document image, and is provided in the digital copying machine 1.

  As shown in FIG. 2, the image reading apparatus 2 includes a scanner 10, a document conveying unit 20, an image processing unit 30, and a tilt detection ROM (Read Only Memory) 40. In addition to the image reading apparatus 2, the digital copying machine 1 includes a printer unit 50, a main body control unit 60, and an operation unit 70.

  The scanner 10 reads an image of a document and outputs the image data. The scanner 10 includes an amplifier 16 and an A / D converter 17 in addition to the line sensor 15 and the like. The amplifier 16 amplifies the electric signal output from the line sensor 15. The A / D converter 17 converts the analog electric signal output from the amplifier 16 into digital image data and outputs the digital image data.

  The document transport unit 20 includes amplifiers 27a and 27b, comparators 28a and 28b, and a time difference measurement unit 29 in addition to the sensors 26a and 26b. The amplifiers 27a and 27b amplify the outputs of the sensors 26a and 26b. The comparators 28a and 28b compare the outputs of the amplifiers 27a and 27b with threshold values, and output signals corresponding to the passage time of the leading edge of the document. The time difference measuring unit 29 calculates and outputs the time difference between the outputs of the comparators 28a and 28b.

Information on the inclination angle θ of the conveyed document in the main scanning direction is detected by the sensors 26a and 26b, and the time difference measuring unit 29 calculates the time difference s. If the distance between the sensors 26a and 26b is d and the document transport speed is v, the inclination angle θ is expressed by the following equation (1).
θ = tan ⁻¹ (s · v / d) (1)

In the inclination detection ROM 40, the relationship between the time difference s, the inclination angle θ, and stairH and stairV expressed by the following equations (2) and (3) is stored in the inclination detection ROM 40.
stairH = (int) (1 / tan θ) (2)
stairV = (int) (1 / tan δ) (3)
In the expressions (1) and (2), (int) means an integer that rounds down the decimal part, δ is an angle obtained by converting the inclination angle θ of the document by the sub-scanning shift process described later. It is represented by (4).
δ = tan ⁻¹ {1 / (tan θ + 1 / tan θ)} (4)

  stairH is the number of pixels indicating how many pixels away from the origin in the sub-scanning direction need to be shifted by one pixel in the main scanning direction in order to eliminate the inclination of the image when a certain pixel is the origin. is there. The stairV is the number of pixels indicating how many pixels away from the origin in the main scanning direction need to be shifted by one pixel in the sub-scanning direction in order to eliminate the inclination of the image when a certain pixel is the origin. is there.

  The image processing unit 30 performs various image processes on the image data output from the scanner 10. The image processing unit 30 includes an image processing execution unit 31, an inclination correction processing unit 32, and an image processing control unit 33. Based on the control of the image processing control unit 33, the image processing execution unit 31 outputs, for the image data that is serially output from the scanner 10 for each pixel, data for one main scanning line in the sub-scanning direction. Performs filtering, scaling, etc. Based on the control of the image processing control unit 33, the tilt correction processing unit 32 performs tilt correction processing and interpolation processing in the main scanning direction and the sub-scanning direction on the image data after image processing output from the image processing execution unit 31. And output.

  The image processing control unit 33 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM. In the image processing control unit 33, various programs read from the ROM are expanded in the RAM, and various processes are executed in cooperation with the programs on the RAM and the CPU.

  The image processing control unit 33 controls the image processing execution unit 31 and the inclination correction processing unit 32 based on the control of the main body control unit 60. Further, the image processing control unit 33 calculates stairH and stairV based on the time difference s and angle θ output from the document conveying unit 20 and the information stored in the inclination detection ROM 40. The image processing control unit 33 controls the inclination correction processing unit 32 using the stairH and stairV.

  The printer unit 50 prints (image formation) on a recording medium such as recording paper based on the image data output from the image processing unit 30. The printing method of the printer unit 50 is an image photography method, an inkjet method, a thermal transfer method, or the like.

  The operation unit 70 includes various keys, receives user operation inputs, and outputs the input information to the main body control unit 60. The operation unit 70 includes a display unit such as an LCD (Liquid Crystal Display), and performs display based on display information input from the main body control unit 60. The operation unit 70 may be configured as a touch panel integrally with the display unit. The operation unit 70 accepts input of print condition settings such as image data scaling and image quality.

  The main body control unit 60 includes a CPU, a RAM, and a ROM. In the main body control unit 60, various processes are executed in cooperation with various programs read from the ROM and expanded in the RAM. The main body control unit 60 centrally controls each unit in the digital copying machine 1 such as the image processing control unit 33. In particular, the main body control unit 60 performs a copy process to be described later based on a copy program.

  FIG. 3 shows an internal configuration of the inclination correction processing unit 32. As shown in FIG. 3, the inclination correction processing unit 32 includes a main scanning interpolation processing unit 321, a main scanning shift processing unit 322, a sub scanning interpolation processing unit 323, and a sub scanning shift processing unit 324. Is done.

  The main scanning interpolation processing unit 321 performs main scanning interpolation processing on the image data output from the image processing execution unit 31 and outputs the result. The main scanning shift processing unit 322 performs main scanning shift processing on the image data output from the main scanning interpolation processing unit 321 and outputs the result. The main scanning shift processing unit 322 includes a line memory (not shown), stores each line data of the image data in the line memory, and shifts each line in the main scanning direction by adjusting the position of the line data in the line memory. .

  The sub-scanning interpolation processing unit 323 performs sub-scanning interpolation processing on the image data output from the main scanning shift processing unit 322 and outputs the image data. The sub-scanning shift processing unit 324 performs sub-scanning shift processing on the image data output from the sub-scanning interpolation processing unit 323 and outputs the image data.

  FIG. 4 shows the internal configuration of the sub-scanning shift processing unit 324. In the present embodiment, it is assumed that the sub-scanning shift processing unit 324 can shift a maximum of three pixels in the sub-scanning direction in the sub-scanning shift process. However, it is not limited to this shift amount configuration.

  As shown in FIG. 4, the sub-scan shift processing unit 324 includes a sub-scan shift control unit 3241 as a control unit, FIFO memories 3242 to 3244, and a selector 3245. The sub-scanning shift control unit 3241 generates the signal sel and the signals / EN1 to / EN3 based on the signal HVI and the signal ishy input from the image processing control unit 33, and outputs the signal sel to the selector 3245. EN1 to / EN3 are output to the FIFO memories 3242 to 3244, respectively. The storage capacity of each FIFO memory has a relationship of the storage capacity of the FIFO memory 3242> the storage capacity of the FIFO memory 3243> the storage capacity of the FIFO memory 3244.

  The signal HVI is a positive logic binary signal and is a signal indicating whether or not the data signal DI output from the image processing execution unit 31 is valid. The signal ishy is a signal indicating the shift amount in the sub-scanning direction. The signal sel is a control signal for switching the input of the selector 3245. Signals / EN1 to / EN3 are binary signals of negative logic, and are signals indicating whether data writing and reading of the FIFO memories 3242 to 3244 are valid, respectively. The data signal DO is a data signal output from the inclination correction processing unit 32.

  Next, the operation of the digital copying machine 1 will be described. First, an outline of the main scanning shift process and the sub scanning shift process will be described. FIG. 5 shows the concept of main scanning shift processing and sub-scanning shift processing. FIG. 5A shows the image data 100 after image reading. FIG. 5B shows the image data 200 after the main scanning shift process. FIG. 5C shows the image data 300 after the sub-scanning shift process.

  As shown in FIG. 5A, the scanner 10 reads a tilted original and acquires image data 100 as a collection of horizontal line data. Hereinafter, the x axis is taken in the main scanning direction and the y axis is taken in the sub scanning direction. An angle between the image data 100 and the x axis is defined as an angle θ.

  The main scanning shift process is a process for shifting the pixels of the image data 100 in the main scanning direction for each row, and is a correction process for eliminating the inclination of the vertical line of the image data 100. The shift amount differs depending on the position on the y-axis. As shown in FIG. 5B, the rectangular image data 100 is subjected to main scanning processing by the main scanning shift processing unit 322, and converted into parallelogram image data 200. An angle between the image data 200 and the x axis is an angle δ.

  The sub-scanning shift process is a process of shifting the pixels of the image data 200 in a direction (sub-scanning direction) perpendicular to the direction (main scanning direction) in which the pixels are shifted in the main scanning shift process. This is a correction process for setting the angle δ of image data tilted by δ to zero. As shown in FIG. 5C, the image data 200 is subjected to sub-scanning processing by the sub-scanning shift processing unit 324 and converted into image data 300 having an angle δ = 0.

  Next, the main scanning interpolation process, the main scanning shift process, the sub scanning interpolation process, and the sub scanning shift process will be described in detail in order.

  The main scanning interpolation processing is processing performed on the image data read out by the scanner 10 and output from the image processing execution unit 31 by the main scanning interpolation processing unit 321. Macroscopically, the vertical line of the image data subjected to the main scanning shift process seems to be connected with a single vertical line. However, in the pixel unit, a line inclined across two pixels is interrupted at a location where the shift amount is different. Due to such discontinuities, the outline looks jagged in the entire image. This is because the main scanning shift is performed in integer units as described above.

  The main scanning interpolation process is a process for correcting such image quality deterioration. In the main scanning interpolation processing, for example, the pixel value of the target pixel is obtained by weighting and averaging the pixel value of the target pixel and the pixel value of the adjacent pixel with weighting according to the shift amount after the decimal point discarded in the main scanning shift processing. The value is corrected. In the main scanning interpolation process, the main scanning interpolation amount is calculated using stairH.

  The main scanning shift process is a process performed on the image data output from the main scanning shift processing unit 322 by the main scanning shift processing unit 322. FIG. 6A shows the configuration of the image data 100. FIG. 6B shows the configuration of the image data 200. As shown in FIGS. 6A and 6B, consider a case in which image data 100 is subjected to main scanning shift processing to be image data 200.

  In the main scanning shift process, each line of the image data 100 is stored in the line memory by the main scanning shift processing unit 322 and is read out after being shifted in the main scanning direction. As indicated by the arrows in FIG. 6A, in order to shift the collection of pixels of the image data 100 in the main scanning direction as indicated by shx, the pixel values are changed on the line memory in the main scanning shift processing unit 322. Shifting in the scanning direction is performed.

Assuming that the value of how many pixels the y-line should be shifted in the main scanning direction when the document inclination is θ, shx is expressed by the following equation (5).
shx = y · tan θ (5)
By the way, the right or left of the shift is distinguished by a sign.

Actually, since the shift can be performed only in the unit of pixel, it is used in the form of the shift amount ishx of the pixel unit display defined as the following equation (6) with the fraction rounded down.
ishx = (int) shx (6)
Here, (int) means integerization.

When the coefficient stairH supplied from the inclination detection ROM 40 in FIG. 2 is used, Expression (6) is expressed as the following Expression (7).
ishx = (int) (y / stayH) (7)
By shifting the pixel value on the line memory according to the equation (7), the image data 100 shown in FIG. 6A is changed to the image data 200 shown in FIG. 6B, and the inclination in the main scanning direction is changed. Is corrected, for example, the inclination of the vertical line disappears.

  The sub-scan interpolation process is a process for correcting the pixel value of the image data whose continuity is cut by the sub-scan shift process, and weights the pixel value of the target pixel and the pixel value of the adjacent pixel using a weighting coefficient. On average, this is a process of correcting the pixel value of the target pixel. In the sub-scan interpolation process, the sub-scan interpolation amount is calculated using stairV.

  The sub-scanning shift process is a correction for shifting the pixels of the image data 200 in the sub-scanning direction so that the image data 200 inclined by the angle δ with respect to the y-axis is set to the angle δ = 0. The shift amount of the sub-scanning shift process varies depending on the position on the x axis.

  Data processing for sub-scanning shift processing is performed by storing image data in a memory area within a rectangular area for a plurality of lines in a FIFO memory (FIFO memories 3242 to 3244), with a delay according to a position on the x-axis, Image data is output to obtain image data for one line.

  FIG. 7A shows a rectangular area 201 in the sub-scanning shift process. FIG. 7B shows a read area 202 in the rectangular area 201. FIG. 7C shows a reading procedure in the reading area 202. FIG. 7D shows read data 301. In the example of FIG. 7, the rectangular area 201 is represented as 3 lines.

  For example, a rectangular area 201 is set in the image data 200 as shown in FIG. Then, as shown in FIG. 7B, a readout area 202 corresponding to the inclination in the sub-scanning direction is specified from the 3-line rectangular area 201. Each line in the read area 202 is read with a larger delay amount as the x-axis value is smaller. Then, as shown in FIG. 7D, it is read as read data 301 of one line with no inclination. A rectangular area 201, a part of which is stored in the FIFO memory, moves downward one image at a time. For this reason, the read data 301 of all lines is collected to form the image data 300 shown in FIG.

  When the inclination of the image data 200 with respect to the x-axis is an angle δ, for the pixel in the x-th column, the pixel value of the pixel below (or above) the shy line from the target line is output. shy is a shift amount in the sub-scanning direction. The relationship between the coordinate value x and the shift amount shy is expressed by the following equation (8).

shy = x · tan δ (8)
Again, processing is performed in integer units. Therefore, an ishy obtained by converting shy into an integer is used as the shift amount, and the ishy is expressed by the following equation (9).

ishy = (int) (x / stayV) (9)
By this sub-scanning shift process, the inclination of the original is corrected as shown in FIG. 5C, and a correct image is reproduced.

  8A to 8C show how the memory area 210 is moved. As shown in FIGS. 8A to 8C, the rectangular area 203 is moved downward by one pixel. The rectangular area 203 has a read area 211, a delay area 212, and a read area 204. In the present embodiment, only the read area 211 and the delay area 212 below the read area 211 are stored in the FIFO memories 3242 to 3244. The read area 211 and the delay area 212 are referred to as a memory area 210.

  This is because the image data in the read area 204 becomes unnecessary data after reading. Therefore, the storage capacity required for the FIFO memory when storing the image data in the memory area 210 is about half that in the case where all the image data in the rectangular area 203 is stored. As described above, the storage capacity of the FOFO memory can be suppressed to a value suitable for incorporation into a practical device.

  Further, since the memory area 210 is small, the multi-value processing for reducing the number of bits of the image data is not executed in the previous process of the sub-scanning shift processing. The multi-value processing is processing for reducing the number of bits of pixel values so as to convert 8-bit image data into 2- or 4-bit image data, for example, and is performed by a known processing method such as an error diffusion method or a dither method. For this reason, it is possible to prevent the image data from being deteriorated due to the multi-value processing.

  Further, as described in Japanese Patent Application No. 9-138402, the image undergoes scaling with different magnifications in the main scanning direction and the sub scanning direction by the main scanning shift process and the sub scanning shift process. In order to faithfully reproduce not only the angle but also the shape of the original image, it is theoretically necessary to perform zooming correction. However, in practice, since the inclination of the document generated in the reading is small, the magnification that is received in the shift processing is extremely small, and this correction need not be performed.

  Next, with reference to FIG. 9, the copying process executed by the digital copying machine 1 will be described. FIG. 9 shows the flow of the copying process.

  A document is set in the document transport unit 20 in advance. Also, it is assumed that a setting input such as zooming from the user is accepted via the operation unit 70. For example, the copying process is executed by the main body control unit 60 triggered by the input of a copy instruction from the user via the operation unit 70. In the main body control unit 60, the copying process is executed in cooperation with the copying program read from the ROM and expanded in the RAM.

  First, the scanner 10 is controlled by the main body control unit 60. With this control, the original is read by the scanner 10 and image data is acquired (step S11). At this time, the document transport unit 20 is similarly controlled by the main body control unit 60, and the time difference s is calculated by the time difference measuring unit 29.

  Then, the image processing control unit 33 is controlled by the main body control unit 60. The image processing control unit 33 controls the image processing execution unit 31. With this control, image processing such as filtering and scaling is performed on the image data output from the scanner 10 by the image processing execution unit 31 (step S12).

  In parallel with step S12, the image processing control unit 33 detects the inclination angle θ of the document based on the equation (1) and the time difference s output from the document conveying unit 20 (step S13).

  Then, the image processing control unit 33 reads the above expressions (2) to (4) from the inclination detection ROM 40, and based on the relational expression and the angle θ, the inclination angles δ, stairH, and stairV after the main scanning shift. Is calculated. Then, the main scanning interpolation processing unit 321 performs main scanning interpolation processing on the image data output from the image processing execution unit 31 using stairH (step S14).

  Then, the main scanning shift processing unit 322 calculates the ishx based on the above formulas (5) to (7), and the main scanning shift processing is performed on the image data output from the main scanning interpolation processing unit 321 using the ishx. (Step S15).

  Then, the sub-scan interpolation processing unit 323 performs sub-scan interpolation processing on the image data output from the main scan shift processing unit 322 using the stair V (step S16). The sub-scan shift processing unit 324 calculates the ishy based on the above formulas (8) to (9), and the image data output from the sub-scan interpolation processing unit 323 is subjected to the sub-scan shift process using the ishy. (Step S17).

  Then, the printer unit 50 is controlled by the main body control unit 60. The printer unit 50 records an image of the image data output from the sub-scanning shift processing unit 324 on a recording sheet (step S18). Then, the copying process ends.

  Next, with reference to FIGS. 10 to 13, sub-scanning shift processing classified according to the inclination angle δ of the image data 200 will be described.

  First, consider a case where the angle δ is positive and maximum (the angle when the read area is included in the memory area is maximum). FIG. 10A shows the memory area 210 when the tilt angle δ is positive and maximum. FIG. 10B shows each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is positive and maximum.

  As shown in FIG. 10A, a rectangular area 203 has a memory area 210 including a read area 211 when the inclination angle δ is maximum. Then, as shown in FIG. 10B, data reading is enabled when the signal HVI output from the image processing control unit 33 is in a high state. The sub-scanning shift control unit 3241 generates and outputs signals sel, / EN1, / EN2, and / EN3 in accordance with the signal ishy output from the image processing control unit 33.

  First, when the signal HVI is in the high state, the selector 3245 selects the data signal DI (D0) by the signal sel and outputs it as the data signal DO. The output data signal DI corresponds to the bottom line of the read area 211. Also,

  Then, the signal / EN1 is turned on to a low state. When the signal / EN1 is in the on state, data reading and writing of the FIFO memory 3242 are enabled. When the signal / EN1 is on, the selector 3245 outputs the data signal D1 read from the FIFO memory 3242 as the data signal DO by the signal sel. The output data signal D1 corresponds to the second line from the bottom of the read area 211. Further, the data signal D0 is written to the FIFO memory 3242 at the same time when the data D1 is read from the FIFO memory 3242 while the signal / EN1 is in the ON state.

  Then, the signal / EN2 is turned on to a low state. When the signal / EN2 is on, data reading and writing of the FIFO memory 3243 are enabled. When the signal / EN2 is on, the selector 3245 outputs the data signal D2 read from the FIFO memory 3243 as the data signal DO by the signal sel. The output data signal D2 corresponds to the third line from the bottom of the read area 211. Further, the data signal D0 is written to the FIFO memory 3242 at the same time when the data D1 is read from the FIFO memory 3242 while the signal / EN1 is in the ON state. In addition, while the signal / EN 2 is in an ON state, the data D 1 read from the FIFO memory 3242 is written into the FIFO memory 3243 along with the reading of the data D 2 from the FIFO memory 3243.

  Then, the signal / EN3 is turned on to a low state. When the signal / EN3 is on, data reading and writing of the FIFO memory 3244 are permitted. When the signal / EN3 is in the on state, the selector 3245 outputs the data signal D3 read from the FIFO memory 3244 as the data signal DO by the signal sel. The output data signal D3 corresponds to the fourth line from the bottom of the read area 211. Further, the data signal D0 is written to the FIFO memory 3242 at the same time when the data D1 is read from the FIFO memory 3242 while the signal / EN1 is in the ON state. In addition, when the signal / EN 2 is in an ON state, the data signal D 1 read from the FIFO memory 3242 is written into the FIFO memory 3243 along with the reading of the data D 2 from the FIFO memory 3243. In addition, when the signal / EN3 is in the ON state, the data signal D2 read from the FIFO memory 3243 is written to the FIFO memory 3244 along with the reading of the data D3 from the FIFO memory 3244.

  By this series of data reading operations, the image data in the reading area 211 is output as one line of image data. Then, the memory area 210 is moved down by one pixel, the series of data reading operations are executed, and the process is repeated until image data of all lines is output.

  Next, consider a case where the angle δ is positive and an intermediate value between 0 and the maximum. FIG. 11A shows the memory area 210 when the tilt angle δ is positive and intermediate. FIG. 11B shows each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is positive and intermediate.

  As shown in FIG. 11A, the rectangular area 203 has a memory area 210 including a reading area 211A when the inclination angle δ is intermediate. Since the inclination angle δ is intermediate, the readout region 211A is formed on three lines.

  Therefore, as shown in FIG. 11B, the data signal D0 and the data signals D1 and D2 stored in the FIFO memories 3242 and 3243 are output from the selector 3245 as the data signal DO.

  Further, the area above the read area 211A in the memory area 210 is read image data. For this reason, the read image data is discarded without being read from the FIFO memories 3242, 3243, 3244. The other operations of the sub-scanning shift processing unit 324 are the same as in the case where each degree δ is positive and maximum.

  Next, consider the case where the angle δ is negative and maximum. FIG. 12A shows the memory area 220 when the tilt angle δ is negative and maximum. FIG. 12B shows each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is negative and maximum.

  As shown in FIG. 12A, the rectangular area 205 has a memory area 220 including a reading area 221 when the inclination angle δ is negative and maximum. The read area 221 has a slope opposite to that of the read area 211. Since the inclination angle δ is the maximum, the read area 221 is formed on four lines.

  Therefore, as shown in FIG. 12B, the data signal D0 and the data signals D1, D2, and D3 stored in the FIFO memories 3242, 3242, and 3243 are output from the selector 3245 as the data signal DO. Further, the data signals D0, D1, D2, and D3 are finally output as the data signal DO on the time axis while the signals / EN1, / EN2, and / EN3 are turned on. The other operations of the sub-scanning shift processing unit 324 are the same as in the case where each degree δ is positive and maximum.

  Next, consider the case where the angle δ is negative and intermediate. FIG. 13A shows the memory area 220 when the tilt angle δ is negative and intermediate. FIG. 13B shows each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is negative and intermediate.

  As shown in FIG. 13A, the rectangular area 205 has a memory area 220 including a read area 221A when the inclination angle δ is intermediate. Since the inclination angle δ is intermediate, the read area 221A is formed on three lines.

  Therefore, as shown in FIG. 13B, the data signal D0 and D1 and D2 stored in the FIFO memories 3242 and 3243 are output from the selector 3245 as the data signal DO. Further, the data signals D0, D1, and D2 are finally output as the data signal DO on the time axis with the signals / EN1, / EN2, and / EN3 being turned on. Further, the area above the read area 221A in the memory area 220 is discarded without being read from the FIFO memories 3242, 3243, 3244 as read image data. The other operations of the sub-scanning shift processing unit 324 are the same as in the case where each degree δ is positive and intermediate.

  As described above, according to the present embodiment, the image data in the memory area including the reading area and the memory area having about half the storage capacity is included in the FIFO memory 3242 without storing all the image data in the rectangular area in the FIFO memory in the sub-scanning shift process. Store to ~ 3244. For this reason, the storage capacity of the FIFO memories 3242 to 3244 used for the sub-scanning shift process can be reduced. In addition, since the storage capacity of the FIFO memories 3242 to 3244 is reduced, multilevel conversion is not performed before the sub-scanning shift processing. For this reason, it is possible to prevent deterioration of the image data due to the multi-value processing. In addition, sub-scanning shift processing (including tilt correction processing) and image processing such as error diffusion processing can be made independent.

  Further, by switching the selector 3245, the image data in the read area can be read from each of the FIFO memories 3242 to 3244. Further, it is possible to read out image data in the read area and write image data in a new memory area to the FIFO memories 3242 to 3244 while moving the memory area pixel by pixel in the sub-scanning direction.

  Further, image data can be acquired from the document by the scanner 10, and shift processing and interpolation processing in the main scanning direction and the sub-scanning direction can be performed by the image processing unit 30.

  Note that the description in the above embodiment is an example of a suitable image processing apparatus according to the present invention, and the present invention is not limited to this.

  For example, the memory area in the sub-scanning shift process in the above embodiment is a maximum of 4 lines, but is not limited to this. It is good also as a structure made into a memory area | region of a maximum of 2, 3 or 5 lines or more. If the number of lines in the memory area is increased, the sub-scanning shift process can be performed on image data having a large maximum inclination angle δ. Reducing the number of lines in the memory area can further reduce the storage capacity of the FIFO memory.

  Further, although the digital copying machine 1 has been described as the image information processing apparatus in the above embodiment, the present invention is not limited to this. The image information processing apparatus may be a scanner apparatus having an image reading unit, a facsimile apparatus, an MFP (Multi Function Printer), or the like, and has only a function of performing image processing on image data read by the image reading unit. It is good also as an apparatus. The present invention can also be used for correcting the installation inclination of a printer head in a printer apparatus having a solid scanning printer head such as an LED (Light Emitting Diode) array or a PLZT optical shutter array.

  Further, the detailed configuration and detailed operation of each part constituting the digital copying machine 1 in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

1 is a diagram showing a mechanical configuration of a digital copying machine 1 according to an embodiment of the present invention. 3 is a block diagram showing an electrical configuration of the image reading apparatus 2. FIG. 3 is a block diagram showing an internal configuration of an inclination correction processing unit 32. FIG. It is a figure which shows the internal structure of the subscanning shift process part 324. (A) is a figure which shows the image data 100 after image reading. (B) is a diagram showing the image data 200 after the main scanning shift processing. (C) is a diagram showing the image data 300 after the sub-scanning shift process. (A) is a figure which shows the structure of the image data 100. FIG. FIG. 4B is a diagram showing the configuration of the image data 200. (A) is a figure which shows the rectangular area | region 201 in a subscanning shift process. (B) is a diagram showing a read area 202 in the rectangular area 201. (C) is a diagram showing a reading procedure in the reading area 202. (D) is a diagram showing read data 301. (A)-(c) is a figure which shows the mode of the movement of the memory area 210. FIG. It is a flowchart which shows a copy process. (A) is a diagram showing the memory area 210 when the inclination angle δ is positive and maximum. (B) is a diagram showing each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is positive and maximum. (A) is a diagram showing the memory area 210 when the tilt angle δ is positive and intermediate. (B) is a diagram showing each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is positive and intermediate. (A) is a diagram showing the memory area 220 when the tilt angle δ is negative and maximum. (B) is a diagram showing each signal of the sub-scanning shift processing unit 324 when the tilt angle δ is negative and maximum. (A) is a diagram showing the memory area 220 when the inclination angle δ is negative and intermediate. (B) is a diagram showing each signal of the sub-scanning shift processing unit 324 when the inclination angle δ is negative and intermediate. It is the schematic which shows the conventional subscanning shift process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital copying machine 1A Copying machine main body 2 Image reader 10 Scanner 11 Original mounting stand 12 Original light source 13 Mirror 14 Imaging lens 15 Line sensor 16 Amplifier 17 A / D converter 20 Original conveyance part 21 Paper feed tray 22 Paper feed roller 23 Roller 24 Paper discharge roller 25 Paper discharge tray 26a, 26b Sensors 27a, 27b Amplifiers 28a, 28b Comparator 29 Time difference measurement unit 30 Image processing unit 31 Image processing execution unit 32 Inclination correction processing unit 321 Main scanning interpolation processing unit 322 Main scanning shift processing Unit 323 sub-scanning interpolation processing unit 324 sub-scanning shift processing unit 3241 sub-scanning shift control units 3242 to 3244 FIFO memory 3245 selector 33 image processing control unit

Claims (4)

Stores image data of a plurality of line areas including a read area corresponding to the inclination of the image data among the image data shifted in the main scan, and a line having a larger sub-scan shift amount of the read area has a smaller storage capacity. FIFO memory,
A control unit for reading out image data in the readout area from each of the FIFO memories;
An image processing apparatus comprising: A selector for switching the output of each FIFO memory;
The image processing apparatus according to claim 1, wherein the control unit reads the image data in the read area from each FIFO memory by switching the selector.   The control unit reads the image data in the readout area, moves the multiple line area by one line in the sub-scanning direction, and stores the image data in the multiple line area after the movement in the multiple FIFO memories. The image processing apparatus according to claim 1, wherein: A scanner that reads an image of a document and outputs image data;
The image processing apparatus according to claim 1, further comprising: a main scanning shift processing unit that performs main scanning shifting on the read image data.

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