KR20200089074A - Method for skew compensation based on block - Google Patents

Abstract

Disclosed is an image reading device. The image reading device comprises: an image sensor reading a manuscript; a memory storing a scan image corresponding to the manuscript; and a processor reading the scan image stored in the memory in units of a block size with a preset first block size, generating a correction image of a second block size by correcting the scan image of the first block size, and storing the generated correction image of the second block size in the memory. The processor calculates a quadrilateral skew angle of the scan image, and sets a first block size based on the second block size and the calculated skew angle.

Description

Block-based skew correction method {METHOD FOR SKEW COMPENSATION BASED ON BLOCK}

The image reading device is a device that scans an original image such as a document, picture, or film and converts it into digital data. In this case, the digital data can be displayed on a computer monitor or printed by a printer to generate an output image. Examples of such an image reading apparatus include a scanner, copier, facsimile, or a multifunction peripheral (MFP) that implements these functions in a complex manner through a single device.

In the image reading device, the printing paper may not be aligned due to the arrangement characteristics of the sensor or the mechanical characteristics such as the movement of the roller and the motor, and accordingly, the scanned image may be distorted differently from the original.

1 is a block diagram showing a simple configuration of an image reading apparatus according to an embodiment of the present disclosure,
2 is a block diagram showing a specific configuration of an image reading apparatus according to an embodiment of the present disclosure,
3 is a view showing an example of a quadrilateral skew,
4 is a view showing a specific configuration according to an embodiment of the processor of FIG. 1,
5 is a view showing the configuration of a skew correction device according to an embodiment of the present disclosure,
6 is a view showing the configuration of a skew correction device according to another embodiment of the present disclosure,
7 and 8 are diagrams for explaining a method for determining a block size and position for skew processing according to an embodiment of the present disclosure;
9 is a view showing a specific configuration of the RST core 220 according to an embodiment of the present disclosure,
10 is a diagram showing the number of surrounding pixels required for a bicubic interpolation method,
11 is a view for explaining a data storage method according to an embodiment of the present disclosure, and
12 is a view for explaining a skew correction method according to an embodiment of the present disclosure.

Hereinafter, various embodiments will be described in detail with reference to the drawings. The embodiments described below may be implemented by being modified in various different forms. In order to more clearly describe the characteristics of the embodiments, detailed descriptions of the matters well known to those of ordinary skill in the art to which the following embodiments belong will be omitted.

Meanwhile, in the present specification, when a component is "connected" to another component, this includes not only "directly connected" but also "connected with other components in between". In addition, when it is said that a configuration "includes" another configuration, this means that other configurations may be included and not excluded, unless specifically stated to the contrary.

In this specification, “image forming job” may mean various jobs (eg print, scan, or fax) related to images, such as image formation or image file creation/save/transfer. (job)” may mean not only an image forming job, but also a series of processes necessary for performing the image forming job.

In addition, the "image reading device" refers to a device that reads an image of a manuscript and generates a scanned image. Examples of such image reading apparatuses include scanners, copiers, facsimile machines, or multi-function printers (MFPs) that implement their functions in a complex manner through a single device. Meanwhile, when the image reading apparatus is a copying machine, facsimile machine, multifunction machine, or the like capable of forming an image, the image reading apparatus may be referred to as an image forming apparatus.

Also, “hard copy” means an operation of outputting an image to a print medium such as paper, and “soft copy” means an operation of outputting an image to a display device such as a TV or monitor. can do.

In addition, "scan data" refers to a scanned image created using an image reading device, and may be a black and white image or a color image, and may include various types of file formats (eg, BMP, JPG, TIFF, PDF, etc.). Can have

Also, the term “user” may refer to a person who performs an operation related to an image forming operation using an image reading device or a device connected to the image reading device by wire or wireless. In addition, "administrator" may mean a person who has the authority to access all functions and systems of the image reading device. "Administrator" and "User" may be the same person.

1 is a block diagram showing a simple configuration of an image reading apparatus according to an embodiment of the present disclosure.

Referring to FIG. 1, the image reading apparatus 100 may include an image sensor 110, a memory 120, and a processor 130.

The image sensor 110 reads the manuscript. Specifically, the image sensor 110 may read image information of the original from light (or light) reflected from the original. The image sensor 110 may include a CCD (Charge Coupled Device) or CIS (CMOS image sensor) arranged in a line in the main scanning direction. The image sensor 110 may be disposed at the bottom of a flatbed, and may be disposed in an automatic feeding device (ADF).

The memory 120 may store data for image processing. Specifically, the memory 120 stores a program necessary to perform image processing of the processor 130 to be described later, or a signal read from the image sensor 110 or data processed by the processor 130 (eg, skew Calibrated image).

The memory 120 may be a volatile memory such as DRAM or SRAM, or a non-volatile memory such as an HDD, SSD, or flash memory, or a combination of volatile memory and non-volatile memory.

The processor 130 controls each component in the image reading device 100. Specifically, the processor 130 may be implemented with a CPU, an ASIC, or the like, and detect whether a scan command is input from a user. Here, the scan command may be input through the manipulation input device 160 provided in the image reading apparatus 100, or may be input through an communication device 140 from an external device (for example, a PC, a smartphone, etc.).

When a scan command is input, the processor 130 may control the image sensor 110 to generate a scanned image. In addition, the processor 130 may generate a scanned image using the signal output from the image sensor 110. In addition, the processor 130 may store the generated scan image in the memory 120.

In addition, the processor 130 may determine whether image processing is necessary. Here, the image processing may be an operation of adjusting the skew of the scanned image, an operation of adjusting the color and brightness, an operation of removing the back background of the paper included in the scanned image, and the like.

If a quadrilateral skew is detected in the manuscript, the processor 130 calculates the angle of the quadrilateral skew, and when the calculated quadrilateral skew angle is within a preset range (eg, -5 degrees to +5 degrees), the quadrilateral It may be decided to perform image processing for skew correction. Even when a quadrilateral skew is detected in the document, if the calculated skew angle is outside a preset range, it may be determined that the quadrilateral skew correction process is not performed, or the skew correction process may be performed with an extreme value of the preset range. On the other hand, in the implementation, it may be determined that skew correction is not performed if the angle is small enough to recognize the quadrilateral skew.

The angle range may be provided by the manufacturer, or the user or administrator may set or modify the range.

For such an operation, the processor 130 may perform an operation of confirming whether a quadrilateral skew exists in an original image and an operation of confirming the angle of the maritime quadrilateral skew. On the other hand, in the above, it has been described that the quadrilateral skew is checked and the skew angle is calculated thereafter. However, in the implementation, the skew angle may be calculated first and the quadrilateral skew may be checked accordingly.

The processor 130 may sequentially read image data stored in the memory 120 in units of one line corresponding to the horizontal size of the image, and perform image processing, or divide the image into a plurality of blocks and read the image in block size units. Processing may be performed.

The processor 130 implemented as a device such as an ASIC or SoC has no choice but to read and process in a block size unit due to limitations of internal memory. Hereinafter, an operation of the present disclosure for reading an image block in block units will be described. .

First, in order to perform image processing by reading data in block size units, the processor 130 may determine an image block size required for image processing. For example, when performing skew correction, the processor 130 may calculate a skew angle of the scanned image and determine a block size (hereinafter, a first block size) required for image processing based on the calculated skew angle. . In this case, the processor 130 may determine the first block size by additionally considering the number of surrounding pixels required for image processing.

For example, in the case of using a bicubic interpolation method using 4x4 peripheral pixels for skew correction, the processor 130 may include an extended partition that is larger than the targeted partition by 4x4 pixels in the scanned image. One block size can be determined.

On the other hand, when the processor 130 needs to perform a plurality of image processing, the block size to be read from the memory 120 based on the image block size and the final output image block required for each image processing (ie, the first block size) Can be calculated. The more detailed operation of determining the block size by the processor 130 will be described later with reference to FIG. 6.

In addition, the processor 130 may perform image processing on the generated scanned image. Specifically, the processor 130 may read the scanned image stored in the memory 120 in the first block size unit. More specifically, the processor 130 divides the original area into the second block size, and for the'block area having the first block size and including the divided area in the scanned image' for sequentially generating a plurality of divided areas. The coordinates are calculated, and the scanned image of the first block size can be read based on the calculated coordinates.

In other words, the processor 130 calculates vertex coordinates on the original region for the divided region and the expanded partition including a preset number of pixels around the partition, converts the calculated vertex coordinates to vertex coordinates on the scanned image, and The first block size scan image may be read by calculating coordinates in a first block size block area including an area defined by vertex coordinates on the scanned image.

Thereafter, the processor 130 may perform image processing on the scanned image having the first block size. When performing a plurality of image processing on the scanned image, the processor 130 may sequentially perform a plurality of image processing on the scanned image having the first block size. For example, the processor 130 first performs skew correction on the scanned image of the first block size, and sequentially performs operations such as edge correction on the skew corrected image block and color correction on the edge corrected image block. It can be done.

In the image processing process, the processor 130 may divide the read first-block sized scan image into pixel blocks of a predetermined size, and temporarily store the divided plurality of pixel blocks in a form that can be read at once. . Accordingly, the processor 130 may read a plurality of pixel values required in the interpolation process for a specific pixel at a time. This will be described later with reference to FIGS. 9 to 11.

When the image processing is completed, the processor 130 may store the corrected image having the second block size in the memory 120.

On the other hand, in the above, only a simple configuration constituting the image reading apparatus is illustrated and described, but in the implementation, various configurations may be additionally provided. This will be described below with reference to FIG. 2.

2 is a block diagram showing a specific configuration of an image reading apparatus according to an embodiment of the present disclosure.

Referring to FIG. 2, the image reading device 100 includes an image sensor 110, a memory 120, a processor 130, a communication device 140, a display 150, an operation input device 160, and a print engine ( 170).

The operation of the image sensor 110 and the memory 120 has been described with reference to FIG. 1, and duplicate description is omitted. Also, since the processor 130 has been described in connection with FIG. 1, the contents described in FIG. 1 are not described repeatedly, and only the contents related to the configuration added to FIG. 2 will be described below.

The communication device 140 is connected to a terminal device (not shown) such as a mobile device (Smart Phone, Tablet PC), PC, notebook PC, PDA, digital camera, and the scanned image or the corrected scan stored in the memory 120 The image can be transmitted to another terminal device.

Specifically, the communication device 140 is formed to connect the image reading device 100 with an external device, and is connected to a terminal device through a local area network (LAN) and an Internet network, as well as USB ( Universal Serial Bus) port or wireless communication (eg, WiFi 802.11a/b/g/n, NFC, Bluetooth) port is also available. The communication device 140 may be referred to as a communication interface, a transceiver, or the like.

The display 150 displays various information provided by the image reading device 100. Specifically, the display 150 may display a user interface window for selecting various functions provided by the image reading device 100. The display 150 may be a monitor such as an LCD, CRT, OLED, or the like, and may also be implemented as a touch screen capable of simultaneously performing the functions of the manipulation input device 160 to be described later.

In addition, the display 150 may display a control menu for performing functions of the image reading apparatus 100. This allows the user to enter scan commands on the displayed user interface window. Here, the scan command may be a command for performing only the scan operation, or may be a scan-to-server, scan-to-DLNA, scan-to-cloud command for transmitting the scanned operation to a specific server.

In addition, when the image reading apparatus 100 is a multifunction machine (MFP) capable of printing and copying, the scan command may be a copy command using a scan function. On the other hand, in the present exemplary embodiment, only receiving a scan command through the operation input device 160 is described, but in the implementation, the scan command may be received from a terminal device (not shown) through the communication device 140.

Also, the display 150 may display the generated scanned image and information about the scanned image. In this case, the displayed scanned image may be the scanned image itself or a preview image for the scanned image.

In addition, the display 150 may display a user interface window for selecting an image processing method to be performed after scanning the original. At this time, the user interface window may include an input area for receiving an angle range for performing skew correction.

The manipulation input device 160 may receive a function selection and a control command for the corresponding function from a user. Here, the functions may include a print function, a copy function, a scan function, and a fax transmission function. The manipulation input device 160 may be implemented with a plurality of buttons, keyboard, mouse, or the like, and may also be implemented with a touch screen capable of simultaneously performing the functions of the display 150 described above.

The print engine 170 prints the corrected scanned image. The print engine 170 may form an image on an image forming medium such as a photosensitive drum, an intermediate transfer belt, and a paper transfer belt, and finally transfer the image formed on the image forming medium to the printing paper to perform a print job.

When the processor 130 receives a copy command from the user, the processor 130 controls the image sensor 110 to perform a scan operation, generates a scanned image, performs image correction on the generated scanned image, and prints the corrected scanned image The print engine 170 can be controlled as much as possible.

Alternatively, if a command such as a scan-to-server, scan-to-DLNA, scan-to-cloud, or the like is received from the user, the processor 130 may transmit the corrected scan image to a storage corresponding to the command. Can be controlled.

In addition, although only the general functions of the image reading apparatus 100 are illustrated and described in FIGS. 1 and 2, a fax transmitting and receiving unit performing a fax sending and receiving function according to functions supported by the image reading apparatus 100 as well as the above-described configuration. It may further include.

As described above, the image reading apparatus according to the present embodiment can correct a quadrangle skew, and thus can output a higher quality scanned image. In addition, since the skew correction is performed in a hardware manner based on a block, skew correction is possible at a faster speed.

3 is a view showing an example of a quadrilateral skew.

Referring to FIG. 3, when the loaded document is moved to the scan area, if the feeding or moving roller left/right speed (or force) is different, it may be distorted in a quadrilateral shape.

The skew of the quadrilateral shape cannot use a method of correcting a general skew (ie, skew by rotation), and RST (Rubber Sheet Transform) must be used.

The RST method detects four vertices of the input image 310 corresponding to four vertices of the output image 320 to be obtained when the original is distorted in a quadrilateral shape, and corresponds to pixels of the output image 320 Quadrangle distortion can be corrected by using backward mapping, which finds the pixel location of the input image 310 and calculates the pixel value at that location.

Equation 1 below is an equation used to calculate the pixel position of the input image 310 corresponding to the pixel of the output image 320 to correct quadrature distortion.

Here, x, y are the coordinate values in the input image, u, v are the coordinate values in the output image, and a0, a1, a2, a3, bo, b1, b2, b3 are constants, X _LT , Y _LT , X _RT , Y _RT , X _LB , Y _LB , X _RB , and Y _RB are vertex coordinates on the input image, and W and H are length information in the output image.

On the other hand, in order to correct the quadrilateral skew in a hardware manner in a device such as an ASIC or SoC, not a software, a method for reading an image in a block unit and processing an image is required. Specifically, in a processor such as an ASIC or SoC, the size of data that can be processed at one time corresponds to the size of the SRAM or line memory.

Accordingly, in the present disclosure, image processing is performed in units of blocks so that quadrilateral skew can be corrected even when a general small size SRAM (or line memory) is used.

4 is a diagram illustrating a specific configuration according to an embodiment of the processor of FIG. 1.

Referring to FIG. 4, the processor 130 includes a scanner interface 131, a CPU 132, an RST processor 200, a memory controller 134, a scan image processor 135, a print image processor 136, and a video controller It can be composed of (137). The processor 130 may be an application specific integrated circuit (ASIC) or a system on chip (SoC).

The scanner interface 131 communicates with the image sensor 110 to receive a scanned image.

The CPU 132 controls the overall operation of the processor 130. Specifically, the scanner interface 131 may be controlled to read information of the image sensor 110 in response to the scan speed, and the memory controller 134 may be controlled to store the read information in the memory 120. In addition, when the quadrilateral skew correction is required, the CPU 132 may control the RST processor 200 to perform skew correction.

The RST processor 200 performs image processing related to quadrilateral skew. The specific configuration and operation of the RST processor 200 will be described later with reference to FIGS. 5 and 6.

The memory controller 134 communicates with the memory 120. Specifically, the memory controller 134 may transmit data to the memory 120.

The scanned image processor 135 performs image processing on the scanned image. On the other hand, in the illustrated example, although the RST processor 200 is illustrated and described as having a separate configuration distinct from the scan image processor 135, the RST processor 200 implements some functions of the scan image processor 135 in implementation. The RST processor 200 and the scan image processor 135 may be integrated into one processor.

The print image processor 136 performs an operation related to a print job. Specifically, when print data is received, the print image processor 136 may perform an operation of generating a bitmap image by performing a rendering operation on the received print data.

The video controller 137 controls the print engine 170. Specifically, the video controller 137 may convert the generated bitmap image into a video signal, and transmit the converted video signal to the print engine 170. Here, the video signal is a signal provided to a laser scanning unit (LSU) of the print engine 170.

5 is a view showing the configuration of a skew correction device according to an embodiment of the present disclosure.

Referring to FIG. 5, the RST processor 200 may include a DMA RX 210, an RST core 220, and a DMA TX 230.

The DMA RX 210 may read the scanned image stored in the memory 120 (specifically, DRAM) to a block size having a first block size (IBW, IBH). Specifically, the DMA RX 210 may calculate a block position of the first block size to be read, and read the scanned image of the calculated position from the memory 120.

A detailed method of calculating the first block size will be described later with reference to FIGS. 6 to 8.

In addition, the RST core 220 may generate an output image having a second block size (OBW, OBH) using the scanned image data. Here, since the RST processor 200 performs skew correction only, the second block size is the same as the final block size (CHW, CBH). Meanwhile, when the RST processor 200 performs additional image processing, the second block size may be different from the final block sizes (CHW, CBH). The specific configuration and operation of the RST core 220 will be described later with reference to FIG. 9.

The DMA TX 230 stores the image-processed image in the memory 120.

In the illustrated example, the RST processor is shown and described as performing only skew correction, but in implementation, the RST processor may simultaneously perform a plurality of different image processing as well as skew correction. The operation of the RST processor in this case will be described below with reference to FIG. 6.

6 is a view showing the configuration of a skew correction device according to another embodiment of the present disclosure. The embodiment of FIG. 6 includes a skew correction process as well as another additional plurality of image processes.

Referring to FIG. 6, the RST processor 200' is composed of a DMA RX 210, an RST core 220, a DMA TX 230, an A core 240, a B core 250, and a C core 260. Can be.

The DMA RX 210, the RST core 220, and the DMA TX 230 have been described with reference to FIG. 5, and duplicate description is omitted.

The A core 240, the B core 250, and the C core 260 perform image processing using different algorithms. For example, A core is an image processing algorithm that performs image processing using 9x9 peripheral pixels during image processing, B core is an image processing algorithm that performs image processing using 7x7 peripheral pixels, and C core Is an image processing algorithm that performs image processing using 5x5 surrounding pixels.

On the other hand, in FIG. 6, for convenience of description, it has been described that cores for performing three image processing of A, B, and C are disposed, but in implementation, one or two image processing cores may be included in the configuration of FIG. In addition, four or more image processing cores may be added.

As described above, in the present disclosure, multiple image processing is performed in units of blocks, that is, image processing is performed by constructing a plurality of image processing cores in a pipeline to perform block processing.

Image processing usually performs image processing in consideration of the number of pixels around it, so an input image larger than the size of the output image is required. Therefore, for the size (CBW,CBH (256, 128)) of the final block 105 to be finally output as shown, the C core 260 using 5x5 peripheral pixels is an input image of (260, 132) size (104) is required. In addition, the B core 250 using 7x7 peripheral pixels requires an input image 103 of (266, 138) size, and the A core 240 using 9x9 peripheral pixels has an input image 102 of (274, 146). Is needed.

Thus, finally, the RST core 220 can determine the size of the input block 101 in which the output block 102 can be (274, 146). For example, based on the skew angle, the first block size at which the size of the output block can be (274, 146) can be determined. Hereinafter, a method of determining a block size for skew processing will be described with reference to FIGS. 7 and 8.

7 and 8 are diagrams for explaining a method of determining a block size and a block location for skew processing according to an embodiment of the present disclosure.

Referring to FIGS. 7 and 8, if the four vertices of the original image or the output image are Q0, Q1, Q2, Q3, the four vertices on the distorted scanned image correspond to P0, P1, P2, and P3.

In FIG. 7, the output image D(u,v) is divided into block units having (CBW, CBH) size.

In addition, for processing a plurality of images, the size of an extended divided region including pixels around a divided region is referred to as a second block size (OBW, OBH), and four vertices are referred to as q0, q1, q2, and q3.

When only skew correction is processed as shown in FIG. 5, the second block sizes OBW and OBH have image blocks having the same size as the final block sizes CBW and CBH.

When there are cores for processing a plurality of images as shown in FIG. 6, the second size blocks OBW and OBH have image blocks having a size larger than the final size blocks CBW and CBH.

Meanwhile, when the RST core 220 needs to output an image block of the second block size (OBW, OBH) through one block processing, the input block is an image block of a size larger than the second block size (OBW, OBH) Should be entered. Specifically, when it is necessary to perform image processing in an interpolation manner, for example, a 4x4 pixel value is needed around a specific pixel.

If the vertices of a block having a size determined according to this process are q0, q1, q2, and q3, the four vertices on the distorted scanned image may have p0, p1, p2, and p3 values as shown in Equation 2 below. have.

Here, p0, p1, p2, and p3 are coordinates on the scanned image corresponding to q0, q1, q2, and q3 of the original image, and f() and g() are RST calculation equations as in Equation 1.

Accordingly, the RST core 220 may calculate four vertices on the scanned image, and may calculate vertices r0, r1, r2, and r3 of a square block including all four vertices as shown in FIG. 8. Here, blocks defined by r0, r1, r2, and r3 may have the above-described first block size.

Specifically, in order to calculate the minimum rectangle surrounding p0, p1, p2, and p3, the following equations 3 to 12 are calculated, and on the basis of this, vertices r0, r1, r2, r3 as in equation 13 are calculated. can do.

Where ┕ ┚ is the floor.

Where ┎ ┑ is the raised value (ceil).

Here, IBW is the width of the first block.

Where IBH is the height of the first block.

On the other hand, in the above, the form of calculating the IBH and IBW has been described, but in implementation, it is possible to use a value determined based on the skew angle.

Specifically, the larger the skew angle is, the larger the blocks composed of r0, r1, r2, and r3 become, so that the data to be read from the memory 120 becomes larger. However, the typical skew angle has a range of -5 to +5 degrees, for example, and the SRAM inside the processor also has a fixed size. Taking this into consideration, when the skew angle is determined, IBW and IBH can be fixed and used accordingly. In this case, r0 is calculated using Equations 2 to 6 described above, and r1, r2, and r3 may be directly calculated through Equation 13 using fixed IBW and IBH.

And RST core 220 in the above-described calculation process, Q ₀ , Q ₁ , Q ₂ , Q ₃ P ₀ , P ₁ , P ₂ , and P ₃ corresponding to the value are the same or if the difference is not large, that is, the skew angle In very small cases, RST may not be performed. In addition, the RST core 220 uses the values of P ₀ , P ₁ , P ₂ , and P _{3 when} the angle of the quadrilateral and the length of the quadrilateral exceed the pre-designed range, that is, when the skew angle is very large, RST It may or may not be performed with extreme values in the range.

9 is a view showing a specific configuration of the RST core according to an embodiment of the present disclosure.

The RST core 900 may include an input block interface 910, an SRAM interface 920, an interpolation 930, and an output block interface 940.

The input block interface 910 controls the DMA RX 210 to read an image of a preset size. Specifically, the input block interface 910 may receive a scanned image of a first block size (IBW x IBH).

The SRAM interface 920 reads and writes data to the SRAM 190. Here, the SRAM 190 is a volatile memory, and may be a line memory in the processor 130 or a dedicated memory of the RST processor 200 or an image processor. In addition, the SRAM 190 may have an IBW size horizontally and an IBH size vertically corresponding to the first block size, but the SRAM may have a size smaller than the first block size (IBW x IBH2) (where IBH2 <IBH). .

Specifically, the SRAM interface 920 may divide the first block-sized scanned image read from the input block interface 910 into pixel blocks of a predetermined size and store the scanned image in the SRAM 190.

In addition, in the interpolation operation, the SRAM interface 920 may perform an operation of reading only some pixel blocks required for the interpolation operation from the SRAM 190. The write read operation will be described later with reference to FIGS. 10 and 11.

The interpolation unit 930 performs an interpolation operation using the read image. Specifically, the interpolation unit 930 may calculate a value for a specific pixel by using pixel values of a plurality of pixel blocks. For example, the interpolation unit 930 may perform correction using various interpolation methods such as Bilinear, Quadratic, and Bicubic.

Hereinafter, in order to facilitate the description, it will be described on the assumption that the Bicubic interpolation method using 4x4 peripheral pixels is applied.

For example, as illustrated in FIG. 10, 16 peripheral pixel values are required to calculate a pixel value at a specific location. If the pixel values of each line are stored in different SRAM lines in the SRAM 190, it takes 4 clocks to read 16 pixel values.

Therefore, the interpolation unit 930 may read a first block sized scanned image in a plurality of pixel blocks (for example, four, even if it is read by the input block interface 910) so that data necessary for interpolation can be read for a time of one clock. Pixel), and the plurality of pixel blocks required for one interpolation may be controlled by the SRAM interface 920 to be stored in one line of the SRAM.

For example, as illustrated in FIG. 11, the interpolation unit 930 divides the SRAM 190 into four pieces horizontally, and stores the scanned image of the first block size, which is individually configured and read in the vertical direction. , It becomes possible to read 16 pixel values needed for interpolation at once.

The output block interface 940 performs an operation of outputting the corrected image output from the interpolation unit 930 to the outside. In this case, the outputted correction image may have a second block size (OBW, OBH). If the RST processor 200 performs additional image processing together, the image output by the output block interface 940 may have a size corresponding to the size required for the subsequent image processing.

12 is a view for explaining a skew correction method according to an embodiment of the present disclosure.

Referring to FIG. 12, a first block size is set (S1210). Specifically, the quadrilateral skew angle of the scanned image may be calculated, and the first block size may be set based on the second block size and the calculated skew angle. In this case, the first block size may be set by further considering the number of neighboring pixels corresponding to the interpolation method to be performed for skew correction. In addition, when performing additional image processing as well as skew correction, the first block size may be set by additionally considering the number of surrounding pixels required for additional image processing.

Then, the scanned image stored in the memory is read in a set first block size unit (S1220). Specifically, in order to divide the original region into a second block size and sequentially generate a plurality of divided regions, coordinates for'a block region having a first block size and including a divided region in a scanned image' are calculated and calculated. The scanned image of the first block size can be read based on the coordinates.

Here, the coordinate calculation calculates vertex coordinates on the original area for the extended partition including the partition and a preset number of pixels around the partition, converts the calculated vertex coordinates to vertex coordinates on the scanned image, and scans the image. It may be performed by calculating coordinates in a block area having a first block size including an area defined by vertex coordinates of the image.

Then, the first block-size scanned image is image-corrected to generate a second block-size corrected image (S1230). Meanwhile, when additional image processing is performed, additional image processing may be performed in a pipeline form for the skew corrected corrected image.

Then, the corrected image of the generated second block size is stored in the memory (S1240). In addition, the above-described operation may be repeatedly performed to perform a corrected image for the entire scanned image.

As described above, the skew correction method according to an exemplary embodiment can correct a quadrangle skew, and thus can output a higher-quality scanned image. In addition, since the skew correction is performed in a hardware manner based on a block, skew correction is possible at a higher speed.

Meanwhile, the skew correction method described above may be implemented as a program and provided to the management server. In particular, a program including a skew correction method may be stored and provided in a non-transitory computer readable medium.

The preferred embodiments of the present disclosure have been described and described above, but the present disclosure is not limited to the specific embodiments described above, and it is not limited to the specific embodiments described above, without departing from the gist of the present disclosure claimed in the claims. Of course, various modifications can be made to any person skilled in the art, and such changes are within the scope of the claims.

100: image reading device 110: image sensor
120: memory 130: processor
140: communication device 150: display
160: operation input device 170: print engine

Claims (15)

In the image reading device,
An image sensor that reads the manuscript;
A memory for storing the scanned image corresponding to the original; And
The scanned image stored in the memory is read in block size units having a predetermined first block size, and the first block size scanned image is image corrected to generate a second block size corrected image, and the generated second block size Includes a processor for storing the corrected image of the memory;
The processor,
An image reading apparatus for calculating a quadrangle skew angle of the scanned image, and setting a first block size based on the second block size and the calculated skew angle. According to claim 1,
The processor,
In order to divide the original region into the second block size, and sequentially generate a plurality of divided regions, coordinates for'a block region having the first block size and including the divided region in the scanned image' are calculated, and the An image reading apparatus for reading a scanned image of a first block size based on the calculated coordinates. According to claim 2,
The processor,
Calculate vertex coordinates on the original area for the extended partition including the partition and a preset number of pixels around the partition, convert the calculated vertex coordinates to vertex coordinates on the scanned image, and scan An image reading apparatus for calculating coordinates in a block area of a first block size including an area defined by vertex coordinates on an image. According to claim 1,
The processor,
An image reading apparatus for setting the first block size by further considering the number of surrounding pixels corresponding to an interpolation method to be performed for skew correction. According to claim 1,
The processor,
Skew-correcting the scanned image of the first block size to generate a corrected image of the third block size, and performing additional image correction processing on the corrected image of the third block size to generate a corrected image of the second block size Image reading device. The method of claim 5,
An image reading apparatus for setting the first block size by further considering the size of the number of surrounding pixels required for the additional image correction processing. According to claim 1,
The processor,
An image reading apparatus for dividing the scanned image of the first block size into pixel blocks having a predetermined size, and performing image processing on the specific pixel by simultaneously using a plurality of pixel blocks required for image processing of a specific pixel in units of pixels. . According to claim 1,
The processor,
An image reading apparatus that performs skew correction when the calculated skew angle is within a preset size range. In the skew correction method of the image reading device,
Calculating a quadrangle skew angle of the scanned image and setting a first block size based on the second block size and the calculated skew angle;
Reading the scanned image stored in the memory in the set first block size unit;
Image-correcting the scanned image of the first block size to generate a corrected image of the second block size; And
And storing the generated second block sized correction image in the memory. The method of claim 9,
The reading step,
Dividing the original area into the second block size;
Calculating coordinates for'a block area having the first block size and including a divided area in the scanned image' in order to sequentially generate a plurality of divided areas; And
And reading a scanned image of a first block size based on the calculated coordinates. The method of claim 10,
Step of calculating the coordinates,
Calculate vertex coordinates on the original area for the extended partition including the partition and a preset number of pixels around the partition, convert the calculated vertex coordinates to vertex coordinates on the scanned image, and scan A skew correction method for calculating coordinates in a block area of a first block size including an area defined by vertex coordinates on an image. The method of claim 9,
The setting step,
The skew correction method of setting the first block size by further considering the number of surrounding pixels corresponding to the interpolation method to be performed for skew correction. The method of claim 9,
The step of generating the corrected image,
Skew correcting the scanned image of the first block size to generate a corrected image of the third block size; And
And performing a second image correction process on the third block sized correction image to generate a second block sized correction image. The method of claim 13,
The setting step,
The skew correction method of setting the first block size by further considering the size of the number of surrounding pixels required for the additional image correction processing. The method of claim 9,
And determining whether the calculated skew angle is a preset size range.

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