JP4345865B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus.

Conventionally, a scanner that outputs image data obtained by reading a document placed on a document placement surface by a reading unit to a computer, or a copier that supplies image data from the reading unit to a printing unit and performs printout Such image processing apparatuses are widely provided. In such an image processing apparatus, since reading accuracy and document reproducibility have improved due to recent technological advances, techniques for preventing counterfeiting of banknotes, securities, and the like are also regarded as important. As a method for preventing forgery, generally, it is determined whether or not specific image data that should be prohibited from being output is included in image data acquired from a document, and it is determined that specific image data is included in the image data. In such a case, processing such as stopping output is performed.
Japanese Patent Laid-Open No. 2002-300355

However, particularly in an apparatus using a reading unit with a shallow depth of focus, such as a CIS (Contact Image Sensor), when the document is lifted from the document placement surface, the focus position of the reading unit and the reading surface of the document are displaced. Since the image quality of the read image data deteriorates, the determination may not be performed with high accuracy. For this reason, although it is not determined that specific image data is included in the determination for certain image data, there is a risk that a person may mistakenly be genuine when viewing the printed image.

  As a countermeasure against this problem, for example, as disclosed in Patent Document 1, a thickness detection unit that detects the thickness of the document is provided, and the reading unit is moved in accordance with the detected thickness of the document, so that the focal position of the reading unit is detected. It is conceivable to eliminate the deviation between the original and the reading surface of the original. However, since the document floating amount (distance between the document placement surface and the document reading surface) may vary within the detected thickness range of the document, even when such a configuration is employed, the focus is not necessarily obtained. The positional shift cannot be eliminated, and another measure for improving the accuracy of determination has been demanded.

  The present invention has been completed based on the above circumstances, and an object of the present invention is to accurately determine a specific image even when a document is lifted from a document placement surface.

  As means for achieving the above object, an image processing apparatus according to the invention of claim 1 includes a reading unit that reads a document placed on a document placing surface to obtain image data, the reading unit, and the document. Detecting means for detecting the distance between the image data and a determination means for determining whether or not the image data includes specific image data based on a determination condition that changes according to a detection result of the detection means. The determination unit uses the match rate between the image data and the reference data as the determination condition, and determines that the specific image data is included as the distance detected by the detection unit increases. It has a feature in that the threshold value of the match rate is lowered.

  According to a second aspect of the present invention, in the first aspect of the present invention, the document pressing portion includes a document pressing portion that sandwiches the document with the document placement surface, and the document pressing portion is provided with a distance detection chart. The detecting means is characterized in that the distance between the reading unit and the document pressing unit is detected by reading the chart by the reading unit.

<Invention of Claim 1>
Whether or not the image data includes specific image data is determined based on a determination condition according to the distance between the reading unit and the document. As a result, when the document is lifted from the document placement surface or when the document is supposed to be lifted, if the distance between the reading unit and the document increases, the image of the image data deteriorates. Thus, by lowering the threshold value of the match rate for determining the specific image data, it is easier to determine that the specific image is included, thereby suppressing the output of the specific image.

<Invention of Claim 2>
The distance between the reading unit and the document pressing unit can be detected with a simple configuration.

<Reference form 1>
Next, Reference Embodiment 1 of the present invention will be described with reference to FIGS.

1. Overall Configuration FIG. 1 is a perspective view showing an appearance of a multifunction machine 1 as an example of an image processing apparatus of the present invention, and FIG. 2 is a perspective view of the multifunction machine 1 showing a state in which a document cover 35 is raised. The multifunction device 1 is a multi-function peripheral device having various functions such as a printer function, a scanner function, and a copy function. The multi-function device 1 includes a main body 2 that houses an image forming unit 10 that forms an image on a sheet 5 and a document reading unit 3 that is provided above the main body 2 and reads a document image.

(Main body)
FIG. 3 is a cross-sectional view showing a schematic configuration of the main body 2. In the following description, the left side in FIG.

  The main body 2 includes a substantially box-shaped main body casing 4, and a paper feed tray 6 on which a plurality of sheets 5 for forming an image are stacked can be drawn forward at the bottom of the main body casing 4. Is provided. A paper feed roller 7 is provided above the front end of the paper feed tray 6, and a single sheet 5 stacked on the top of the paper feed tray 6 by the rotation of the paper feed roller 7 is fed to the paper feed roller 6. 7 is sent out to a registration roller 8 provided above 7. The registration roller 8 feeds the paper 5 onto the rear belt unit 11 at a predetermined timing.

  An image forming unit 10 is provided above the paper feed tray 6 in the main casing 4. The image forming unit 10 includes a belt unit 11, four process units 12 </ b> M, 12 </ b> C, 12 </ b> Y, and 12 </ b> K, four exposure units 13, and a fixing device 14.

  The belt unit 11 has a conveying belt 18 installed horizontally between a pair of front and rear support rollers 16, 17. The belt unit 11 circulates and moves when the rear support roller 17 is driven to rotate, and the paper 5 placed on the upper surface thereof. To the rear. Inside the conveyance belt 18, four transfer rollers 19 are provided in the front and rear side so as to face each photosensitive drum 26 of the process unit 12 described later.

  The exposure unit 13 emits laser light L corresponding to one color of image data from the light source, and the laser light L is rotated on the surface of the photosensitive drum 26 via a polygon mirror or the like that is rotationally driven by the polygon motor 21. Irradiate with high-speed scanning.

The process units 12M, 12C, 12Y, and 12K respectively include a toner storage chamber 23 that stores magenta (M), cyan (C), yellow (Y), and black (K) toner, a supply roller 24, and a development roller 25. A photosensitive drum 26, a scorotron charger 27, and the like.

  The toner discharged from the toner storage chamber 23 is supplied to the developing roller 25 by the rotation of the supply roller 24, and at this time, the toner is positively frictionally charged between the supply roller 24 and the developing roller 25. As the surface of the photosensitive drum 26 rotates, the surface of the photosensitive drum 26 is first uniformly charged positively by the scorotron charger 27 and then exposed by the laser light L from the exposure unit 13 to form an image to be formed on the paper 5. A corresponding electrostatic latent image is formed. Next, as the developing roller 25 rotates, the toner on the developing roller 25 is supplied to the surface of the photosensitive drum 26, and the electrostatic latent image is visualized. Thereafter, the toner image carried on the surface of the photosensitive drum 26 is applied to the paper 5 by the transfer bias voltage applied to the transfer roller 19 while the paper 5 passes between the photosensitive drum 26 and the transfer roller 19. Transcribed.

  The fixing device 14 includes a heating roller 28 having a heat source and a pressure roller 29 that presses the paper 5 toward the heating roller 28, and heat-fixes the toner image transferred onto the paper 5 on the paper surface. The paper 5 thermally fixed by the fixing device 14 is conveyed upward and discharged onto a discharge tray 30 provided on the upper surface of the main body casing 4.

(Original reading section)
As shown in FIGS. 1 and 2, the document reading unit 3 includes a document placement unit 33 (document placement surface) made of a transparent glass plate. An original is placed on the original placement portion 33 when the original is read by a so-called flat bed method. Further, the upper surface of the document placing portion 33 is covered with a document cover 35 having an ADF 34 so as to be opened and closed. The ADF 34 includes a document tray 36 on which a plurality of documents can be stacked. The document tray 36 is provided with a document detection sensor (not shown) using a photo sensor or the like for detecting whether or not a document is placed. The ADF 34 conveys the originals placed on the original tray 36 one by one, and discharges the originals after they are read by the CIS 37 described below.

  In addition, a rectangular plate-shaped document pressing portion 38 is provided on the lower surface of the document cover 35 so as to sandwich the document with the document placement portion 33. A distance detection chart 40 for detecting the position of the document pressing unit 38 is provided at one end (left end) of the document pressing unit 38 as will be described later.

  A CIS 37 (Contact Image Sensor, see FIG. 4, an example of a reading unit and a detection unit) is provided below the document placing unit 33. The CIS 37 includes photodiodes arranged in a line in the front-rear direction, and receives reflected light from each light source when a strong light is applied to the document from the light source, and reflects the reflected light for each pixel of the document. Is converted into an electrical signal. The document reading unit 3 converts this into digital data by an A / D converter (not shown), thereby reading an image formed on the document as image data.

  The reading of the original is performed by placing the original on the original placing portion 33 or using the ADF 34. In the former case, the CIS 37 is moved in the left-right direction along the plate surface of the document placement unit 33, and the document on the document placement unit 33 is read line by line. In the latter case, the CIS 37 is fixed at the left end position of the document placing portion 33, and the document is conveyed to a position where the document can be read by the CIS 37 by the ADF 34, whereby the document is read line by line. .

An operation unit 39 including various buttons is provided on the upper surface of the front end of the document reading unit 3. The operation unit 39 allows the user to input various commands for operating the multi-function device 1 such as a print command for executing a document printing process.

2. Next, the electrical configuration of the multifunction machine 1 will be described. FIG. 4 is a block diagram conceptually showing the electrical configuration of the multifunction machine 1. The multi function device 1 includes a control device 50 that includes a CPU 51, a ROM 52, a RAM 53, a nonvolatile memory 54, a control unit 55, a network interface 56, and the like.

  The ROM 52 stores various control programs, various settings, initial values, and the like for controlling the multifunction machine 1. The RAM 53 is used as a work area from which various control programs are read or as a storage area for temporarily storing image data.

  The CPU 51 controls each component of the multifunction device 1 via the control unit 55 while storing the processing result in the RAM 53 or the nonvolatile memory 54 according to the control program read from the ROM 52.

  An external computer 58 (an example of an information processing apparatus) is connected to the network interface 56, and mutual data communication is possible via the network interface 56.

The control unit 55 includes an application specific integrated circuit (ASIC), and is electrically connected to each unit such as the document reading unit 3, the image forming unit 10, and the operation unit 39 described above. The control unit 55 is connected to the common correction unit 60 connected to the document reading unit 3, the determination correction unit 61 and the generation correction unit 62 connected to the common correction unit 60, and the determination correction unit 61. A determination unit 63 and a generation unit 64 connected to the generation correction unit 62 are provided.

  The common correction unit 60 receives image data from the document reading unit 3 and performs correction processing such as gamma correction, shading correction, and black correction on the image data. The determination correction unit 61 and the generation correction unit 62 each receive image data that has been subjected to correction processing by the common correction unit 60, and perform processing such as edge enhancement processing (such as an unsharp mask) on the image data.

  The determination unit 63 (an example of a determination unit) receives the image data corrected by the determination correction unit 61, and whether or not the image content of the image data includes a specific image (such as banknotes or securities). Is determined based on a predetermined determination condition. As a determination item of this determination condition, for example, a match rate between image data and reference data stored in advance is used. That is, in this case, the determination unit 63 calculates a match rate between the image data and the reference data stored in advance, and when the match rate is equal to or higher than a predetermined threshold, the image data includes the specific image data. When the image data is less than the threshold, it is determined that the image data does not include the specific image data.

  The generation unit 64 receives the image data corrected by the generation correction unit 62, and uses the image data (RGB image data) as image data (MCYK image data) corresponding to each color of magenta, cyan, yellow, and black. By performing processing such as color conversion processing for conversion into image data, output image data is generated, and the output image data is stored in the RAM 53.

  Further, the control unit 55 includes an image formation control unit 65 connected to the image forming unit 10. The image formation control unit 65 reads the output image data generated by the generation unit 64 stored in the RAM 53 under the control of the CPU 51 and controls the image formation unit 10 to control the image formation unit 10 based on the image data. Print and output the image.

3. As described below, the control device 50 executes a floating amount detection operation for detecting the floating amount of the document pressing unit 38 from the document placement unit 33 under the control of the CPU 51.

  FIG. 5 shows a distance detection chart 40 provided in the document pressing portion 38. As shown in the figure, the chart 40 includes a black correction unit 41, a white correction unit 42, and a measurement region unit 43. The measurement region unit 43 includes a white line and a black line. , CIS 37 are arranged alternately at a constant pitch (a constant spatial frequency) in the main scanning direction.

  The CPU 51 first reads the black correction unit 41 of the chart 40 using the CIS 37 and stores an output value based on the output signal of the CIS 37 in the RAM 53 as a black reference value. Subsequently, the white correction unit 42 is read by the CIS 37, and the output value is similarly stored as a white reference value. The CPU 51 further reads the measurement area 43 by the CIS 37. At this time, the maximum value and the minimum value appear alternately in the output signal of the CIS 37 corresponding to the white lines and the black lines that are alternately arranged. CPU51 calculates MTF (Modulation Transfer Function) by following Formula (1) using these values.

MTF = (maximum value−minimum value) / (white reference value−black reference value) (1)
FIG. 6 is a characteristic diagram showing the relationship between the MTF at the spatial frequency corresponding to the measurement area 43 of the chart 40 and the floating amount of the reading object (original or original pressing portion 38) from the original placement portion 33. is there. As shown in the figure, the MTF is maximum when the reading object is slightly lifted from the document placing portion 33 (that is, in a state where the focus is the best), and the floating amount of the reading object increases from there. It decreases with it. Characteristic data corresponding to this characteristic diagram is stored in the nonvolatile memory 54, and the CPU 51 refers to the characteristic data and detects the floating amount of the document pressing portion 38 from the MTF obtained as described above. .

4). Printing Process FIG. 7 is a flowchart showing the flow of the printing process executed by the CPU 51. When the user places a document on the document placement unit 33 and inputs a print command for instructing printing (copying) from the operation unit 39, the CPU 51 receives the print command and starts the printing process shown in FIG. The CPU 51 first reads the chart 40 by the CIS 37 according to the procedure described above, and detects the floating amount of the document pressing portion 38 (S11).

  Next, the CPU 51 sets a correction coefficient used by the determination correction unit 61 when performing edge enhancement processing on image data (S12). As the correction coefficient, three values β1, β2, and β3 are stored in the nonvolatile memory 54 and the like. β1 <β2 <β3, and the degree of edge enhancement increases as the value of the correction coefficient increases. Here, the CPU 51 selects one of the three correction coefficients β1 to β3 according to the floating amount of the document pressing unit 38, and sets it as the correction coefficient used by the determination correction unit 61. That is, as shown in FIG. 6, if the floating amount of the document pressing portion 38 is in the range of 0 to L1, the correction coefficient is set to β1, and if the floating amount is in the range of L1 to L2, the correction coefficient is set to β2. When is equal to or greater than L2, the correction coefficient is set to β3. For this reason, the degree of edge enhancement of the image data supplied to the determination unit 63 increases as the floating amount of the document pressing unit 38 increases.

  The correction coefficients β1 to β3 are adjusted so that the determination unit 63 can make an optimal determination according to the floating amount (of the reading surface) of the document. In other words, the document on the document placement unit 33 is assumed to float between the document placement unit 33 and the document pressing unit 38, but the correction unit 61 for determination uses a document that is assumed for the image data. By performing the edge enhancement processing according to the range of the floating amount, the determination accuracy in the determination unit 63 can be increased.

It should be noted that when the document floating amount is L3 or more, the MTF is extremely small, and the reproducibility of the document image when image data is printed out is low. Therefore, when a specific image is included in the original document image, even if it is not determined that the acquired image data includes the specific image, the image printed by a person is regarded as genuine. There is very little possibility of mistakes. For this reason, when the floating amount of the original is L3 or more, it is not necessary to increase the accuracy of determination by the determination unit 63, and therefore the correction coefficient remains constant at β3.

  The correction coefficient in the edge emphasis process of the generation correction unit 62 is set to a constant value β4 regardless of the floating amount (or MTF) of the document pressing unit 38. The correction coefficient β4 is smaller than the correction coefficients β1 to β3 used by the determination correction unit 61 (β4 <β1). That is, the degree of edge enhancement for the image data in the generation correction unit 62 is made smaller than the degree of edge enhancement in the determination correction unit 61. As a result, the generation unit 64 generates output image data that is faithful to the original image (highly reproducible).

  After setting the correction coefficient as described above, the CPU 51 executes a determination / output parallel process in which the determination by the determination unit 63 and the print output by the image forming unit 10 are performed in parallel (S13). In this determination / output parallel processing, first, an original image reading operation is executed by the original reading unit 3. The image data obtained by the document reading unit 3 is supplied to the determination correction unit 61 and the generation correction unit 62 after passing through the common correction unit 60. The determination correction unit 61 and the generation correction unit 62 perform edge enhancement processing on the image data using the set correction coefficients.

  The determination unit 63 determines whether or not the image data processed by the determination correction unit 61 includes specific image data. In parallel with this, the generation unit 64 generates output image data based on the image data processed by the generation correction unit 62, and the output image data is sequentially stored in the RAM 53.

  When the converted image data stored in the RAM 53 reaches a predetermined amount, print output by the image forming unit 10 is started. That is, the image data for output stored in the RAM 53 is sequentially read by the image formation control unit 65, and an image based on the image data is printed on the paper 5 and output by the image formation unit 10.

  If the determination unit 63 determines that the image data includes the specific image data during the determination / output parallel processing, the CPU 51 executes a prohibition process for preventing the print output based on the image data from being executed. To do. In this prohibition process, for example, the mechanical operation of the image forming unit 10 is stopped, and the print output of the image data is stopped. Alternatively, in this prohibition process, invalidation processing for modifying the image data stored in the RAM 53 is performed, and the image forming unit 10 executes print output of an image based on the image data subjected to the invalidation processing. . Note that the image based on the invalidated image data may be, for example, a pattern or characters superimposed on the original image, or may be an image completely different from the original image ( Including fill).

5. Effects of the Present Embodiment As described above, according to the present embodiment, the determination correction unit 61 performs edge enhancement processing according to the distance between the CIS 37 and the document on the image data obtained by the CIS 37. The determination unit 63 performs determination based on the image data. As a result, when the document is floating from the document placement unit 33 or when the document is supposed to be lifted, it is possible to perform a highly accurate determination in consideration thereof.

  In addition, since the edge enhancement processing in the determination correction unit 61 changes in multiple steps according to the distance detected by the CIS 37, it is possible to perform accurate determination according to the degree of deterioration of the image quality of the image data. Become.

  Also, as the distance between the CIS 37 and the document increases, the image quality of the image data tends to deteriorate. Therefore, the degree of edge enhancement on the image data is increased accordingly, thereby suppressing a decrease in determination accuracy in the determination unit 63. Can do.

  In addition, since the process applied to the image data supplied to the determination unit 63 and the process applied to the image data supplied to the generation unit 64 are different, it is possible to realize a process suitable for each purpose. . That is, the image data supplied to the generation unit 64 is subjected to a process for generating output image data faithful to the original image, and the image data supplied to the determination unit 63 is It is possible to perform a process so that the determination is appropriately performed even when the document is lifted.

  In addition, when it is determined that the specific image data is included in the image data, the output is stopped or invalidated to prevent the specific image from being output and misused. Can do.

  Further, by detecting the distance between the CIS 37 and the document pressing unit 38 by reading the chart 40 provided on the document pressing unit 38 with the CIS 37, the distance can be detected with a simple configuration.

<Reference form 2>
Next, Reference Embodiment 2 of the present invention will be described with reference to the flowchart of FIG. The configuration of the multifunction machine 1 is the same as that in the first embodiment.

  When starting the printing process, the CPU 51 first detects the floating amount of the document pressing portion 38 as in the first embodiment (S21). Then, it is determined whether or not the floating amount of the document pressing portion 38 is L1 or more (S22). When the floating amount of the document pressing unit 38 is less than L1 (S22: No), the correction coefficient used for the edge enhancement processing by the determination correction unit 61 is set to β1 (S23), and the determination / output parallel processing is performed. Start (S24).

  Here, the correction coefficient β1 is a value optimized so that the determination unit 63 can perform highly accurate determination when the document floating amount is in the range of 0 to L1 (same as in the first embodiment). (The same is true for the other correction coefficients β2 to β4.) Note that the correction coefficient used for the edge enhancement processing by the generation correction unit 62 is always constant at β4. In this determination / output parallel processing, when the determination unit 63 determines that the image data includes the specific image data, the prohibition processing is executed as in the first embodiment.

  Further, when the floating amount of the document pressing portion 38 is L1 or more (S22: Yes), the CPU 51 subsequently determines whether or not the floating amount of the document pressing portion 38 is L2 or more (S25). . When the floating amount of the document pressing unit 38 is less than L2 (S25: No), the correction coefficient used in the determination correction unit 61 is set to β2 (S26), and the determination process is executed (S27). Here, the correction coefficient β2 is a value optimized so that the determination unit 63 can perform highly accurate determination when the document floating amount is in the range of L1 to L2. In this determination process, first, a document image reading operation is executed by the document reading unit 3, and each process is performed on the obtained image data by the common correction unit 60 and the determination correction unit 61. The determination unit 63 determines the subsequent image data. Here, the generation process of the output image data by the generation unit 64 and the print output by the image formation control unit 65 are not executed.

Subsequently, the CPU 51 determines whether or not the determination unit 63 determines that the image data includes the specific image data (S28), and when the determination is made that the specific image data is included (S28). : Yes), the process is terminated without printing. If it is not determined that the specific image data is included (S28: No), the process proceeds to S23, the correction coefficient is set to β1, and the determination / output parallel processing is executed in S24.

  As described above, when the floating amount of the document pressing portion 38 is in the range of L1 to L2, the correction coefficient optimized by the determination correction unit 61 when the floating amount of the document is in the range of 0 to L1. Edge enhancement processing using β1 and edge enhancement processing using correction coefficient β2 optimized when the amount of floating of the document is in the range of L1 to L2 are performed. Since the determination unit 63 performs determination on each of the image data on which each edge enhancement processing has been performed, determination with high accuracy is performed regardless of whether the document floating amount is 0 to L1 or L1 to L2. It can be carried out.

  In S25, when the floating amount of the document pressing unit 38 is L2 or more (S25: Yes), the correction coefficient used in the determination correction unit 61 is set to β3 (S29), and the determination process is executed (S30). ). Here, the correction coefficient β3 is a value optimized so that the determination unit 63 can perform highly accurate determination when the document floating amount is in the range of L2 to L3. In this determination process, first, an original image reading operation is executed by the original reading unit 3, and various correction processes are performed on the obtained image data by the common correction unit 60 and the determination correction unit 61, respectively. The determination unit 63 determines the processed image data.

  Subsequently, the CPU 51 determines whether or not the determination unit 63 determines that the image data includes the specific image data (S31), and when the determination is made that the specific image data is included (S31). : Yes), the process is terminated without printing. If it is not determined that the specific image data is included (S31: No), the process proceeds to S26, the correction coefficient is set to β2, and the determination process is executed in S27. The following operations are the same as described above.

  As described above, when the floating amount of the document pressing portion 38 is L2 or more, the correction unit 61 for determination uses the correction coefficient β1 optimized when the floating amount of the document is in the range of 0 to L1. The edge enhancement processing using the correction coefficient β2 optimized when the document floating amount is in the range of L1 to L2, and the edge enhancement processing optimized when the document floating amount is in the range of L2 to L3. And edge enhancement processing using the correction coefficient β3. Since the determination unit 63 performs determination for each of the image data subjected to each edge enhancement process, it is possible to perform highly accurate determination regardless of the value of the document floating amount in the range of 0 to L3.

  According to the present embodiment, since the document floating amount cannot always be accurately grasped by the CIS 37, the content of the edge emphasis processing in the determination correction unit 61 is changed a plurality of times, and each processing result is obtained. By making a determination, the reliability of the determination can be increased.

  Furthermore, as the distance detected by the CIS 37 increases, the actual document floating amount can be widened. Accordingly, by increasing the number of times of edge enhancement processing in the determination correction unit 61 accordingly, the reliability of determination can be increased. Can be increased.

<Reference form 3>
Next, Reference Embodiment 3 of the present invention will be described with reference to the flowchart of FIG. Note that most of the configuration of the multifunction machine 1 is the same as that of the first embodiment.

In the reference form 1, the CIS 37 is used as the detection means of the present invention and the floating amount of the document pressing portion 38 is detected. However, in this embodiment, a distance sensor (not shown) that measures the distance between the CIS 37 and the document as the detection means. Z). This distance sensor is provided adjacent to the CIS 37 and can move integrally with the CIS 37. The distance sensor irradiates a document with laser light, etc., receives the reflected light with a light receiving unit such as a CCD, and measures using the fact that the light incident position on the light receiving unit changes depending on the distance to the document The distance to the document is measured by the triangulation method that performs.

  When starting the printing process, the CPU 51 first measures the distance from the CIS 37 to the document using a distance sensor, and detects the amount of lift of the document based on the measured distance (S41).

  Subsequently, the CPU 51 sets the correction coefficient used by the determination correction unit 61 in accordance with the amount of floating of the document (S42), and then executes determination / output parallel processing (S43).

  When the floating amount of the document pressing portion 38 is detected as in the above-described Reference Mode 1, since the expected document floating amount (actual document floating amount) can be widened, the correction coefficient is set in the range of the floating amount. It was only set to an appropriate value. On the other hand, according to the present embodiment, since the floating amount of the document itself is detected, the correction coefficient value can be finely adjusted according to the actual floating amount of the document. This makes it possible to make a more accurate determination.

<Embodiment 1>
Next, Embodiment 1 of the present invention will be described with reference to the flowchart of FIG. The configuration of the multifunction machine 1 is the same as that in the first embodiment.

  When starting the printing process, the CPU 51 first detects the floating amount of the document pressing portion 38 as in the first embodiment (S51). Subsequently, the determination condition used by the determination unit 63 for determination is set according to the amount of floating of the document pressing unit 38 (S52). For example, the determination unit 63 uses the determination condition 1 if the floating amount of the document pressing unit 38 is in the range of 0 to L1, the determination condition 2 if the floating amount is in the range of L1 to L2, and the determination condition 63 if the floating amount is L2 or more. Set to make a decision.

  Here, the determination conditions 1, 2, and 3 are conditions that make it easier to determine that the image data includes the specific image data in this order. Specifically, for example, when the determination is performed using the above-described match rate, the threshold value of the match rate for determining that the determination condition 2 includes the specific image data is lower than the determination condition 1; In the determination condition 3, the threshold value of the matching rate is further lowered than the determination condition 2.

  After setting the determination conditions as described above, the CPU 51 executes determination / output parallel processing (S53).

  According to the present embodiment, whether or not the image data includes specific image data is determined based on the determination condition corresponding to the distance between the CIS 37 and the document. As a result, when the document is floating from the document placement unit 33 or when the document is supposed to be lifted, it is possible to perform a highly accurate determination in consideration thereof.

  Further, when the distance between the CIS 37 and the original increases, the image of the image data deteriorates. Accordingly, the threshold of the matching rate for determining the specific image data is lowered accordingly, thereby determining that the specific image is included. As a result, the output of the specific image can be suppressed.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the first embodiment and the first and second embodiments, the MTF with respect to the document pressing unit is measured, the floating amount of the document pressing unit is calculated from the measured value, and correction factors and determination conditions are calculated based on the floating amount. Although what is set is shown, it is also possible to set the correction coefficient and the like directly based on the value of MTF without calculating the floating amount in processing. In this case, the measurement of the MTF corresponds to “detection relating to the distance between the reading unit and the document” of the present invention.
(2) In the above reference embodiments 1 and 2, the relationship between the correction coefficient β4 used by the generation correction unit and the correction coefficients β1 to β3 used by the determination correction unit satisfies β4 <β1, β2, β3. However, these correction coefficients may have a relationship satisfying, for example, β4 = β1 <β2, β3, β1 <β4 <β2, β3, or other relationships.
(3) In the above-described embodiment and the reference embodiment, the correction coefficient in the determination correction unit is switched in three stages, or the determination condition is switched in three stages. However, the switching is performed in two stages, Or you may make it carry out 4 steps or more.
(4) In the above-described embodiment and the reference embodiment, the image data acquired from the original is printed on the recording medium (paper 5). However, the present invention electrically outputs the image data via the network interface. The present invention can also be applied to a signal output to an external information processing apparatus (computer) or the like as a signal. The present invention can also be applied to a case where, for example, a USB interface or other media connection unit is provided and the acquired image data is output and stored in an external medium such as a flash memory. The present invention can also be applied to an apparatus having a facsimile function in which image data acquired by a reading unit is transmitted and output to the outside via a telephone line.
(5) The present invention can also be applied to an image processing system including an image reading device (scanner) including a reading unit and an information processing device (computer) connected to the image reading device. In this case, the information processing apparatus may receive image data from the image reading apparatus, and various correction processes and determination processes may be performed on the image data by software of the information processing apparatus.

1 is a perspective view showing an external appearance of a multifunction peripheral that is an example of an image processing apparatus according to the present invention. Perspective view of the MFP showing the document cover raised Sectional drawing which shows schematic structure of a main-body part. A block diagram conceptually showing the electrical configuration of the MFP The figure which shows the chart for the distance detection provided in the document pressing part A characteristic diagram showing the relationship between the MTF and the floating amount of the reading object (original or original pressing portion) The flowchart which shows the flow of the printing process in the reference form 1. The flowchart which shows the flow of the printing process in the reference form 2 The flowchart which shows the flow of the printing process in the reference form 3 7 is a flowchart showing a flow of printing processing in the first embodiment.

Explanation of symbols

1 ... Multifunction machine (image processing device)
5... Paper 10... Image forming unit 33... Document placement unit (document placement surface)
37 ... CIS (reading unit, detection means)
38 ... Document holding unit 40 ... Chart 51 ... CPU
56 ... Network interface 61 ... Correction unit for determination 62 ... Correction unit for generation 63 ... Determination unit (determination means)
64 ... generating unit

Claims (2)

A reading unit that reads a document placed on a document placing surface and obtains image data;
Detecting means for detecting a distance between the reading unit and the document;
Determination means for determining whether or not specific image data is included in the image data, based on a determination condition that changes according to a detection result by the detection means;
With
The determination unit uses the matching rate between the image data and the reference data as the determination condition, and determines that the specific image data is included as the distance detected by the detection unit increases. An image processing apparatus characterized by lowering a threshold value of a match rate. A document pressing portion that sandwiches the document between the document placement surface and
The document pressing portion is provided with a distance detection chart,
The image processing apparatus according to claim 1, wherein the detection unit detects a distance between the reading unit and the document pressing unit by reading the chart with the reading unit.