JP4629374B2 - Surface identification device, surface identification method, and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile machine, and more particularly to identification of used and unused surfaces such as print paper in the image forming apparatus and prevention of multiple printing.

  Patent Document 1 reads both sides of a sheet with a sensor such as a CCD, and detects whether each side of the sheet is a white side (an unused side) based on a read signal. An image forming apparatus that prevents multiple printing is described.

  Patent Document 2 includes means for printing a predetermined detection pattern at a predetermined position on the paper during printing on the paper, and detection means for such a detection pattern, and prevents multiple printing according to the detection result of the detection means. An image forming apparatus that performs the above control is described.

JP 10-97112 A JP 2002-323830 A

  In image forming apparatuses such as printers, copiers, and facsimile machines, printed paper (backing paper) may be used on one side for the purpose of reducing costs. In this case, when the paper is set up in the paper tray with the front and back sides reversed, there is a problem that the printed side is overlaid on the used side of the paper. Patent Documents 1 and 2 are intended to prevent such multiple printing.

  The technique described in Patent Document 1 will not have a problem if the paper is white. However, the paper used as the image forming medium is not limited to a white paper, and a paper having a low reflectance such as a colored paper or a half paper is often used as the image forming medium. When such an image forming medium other than blank paper is used, there is a risk that an unused surface is erroneously detected as a used surface unless the identification standard is changed. In addition, paper with a predetermined form printed in advance, such as standard forms, may be used. In this case, even though it is an unused surface, ruled lines etc. are printed, so the unused surface and used Face identification is extremely difficult.

  The image forming apparatus described in Patent Document 2 can prevent multiple printing when the printed paper is reused in the same kind of image forming apparatus. However, when reusing printed paper in another image forming apparatus, a specific detection pattern is not printed on the used side of the paper, so the used side cannot be identified and multiple printing is performed. It cannot be prevented.

  Therefore, an object of the present invention is to identify a used surface and an unused surface with high accuracy even with respect to image forming media other than white paper such as colored paper, cocoon paper, and a form on which a predetermined form is printed in advance. And providing a method.

  Another object of the present invention is to provide an image forming apparatus capable of preventing multiple printing on used surfaces of image forming media other than white paper such as colored paper, straw paper, and paper on which a predetermined form has been printed in advance. Is to provide.

According to the first aspect of the present invention, there is provided an image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image as image data.
Frequency conversion means for performing two-dimensional wavelet conversion on the image data input to the image input means;
Regarding the LH subband coefficient, the HL subband coefficient and the HH subband coefficient generated by the frequency conversion means, the sum of the absolute values of the LH subband coefficients, the sum of the absolute values of the HL subband coefficients, HH When none of the sum of the absolute values of the subband coefficients exceeds a predetermined value, the surface of the imaged image forming medium is determined as an unused surface, and the sum of the absolute values of the LH subband coefficients, the HL subband If any one of the sum of the absolute values of the coefficients and the sum of the absolute values of the coefficients of the HH subband exceeds the predetermined value, the sum of the absolute values of the coefficients of the LH subband and the absolute value of the coefficients of the HL subband The surface of the imaged image forming medium is determined to be an unused surface when the sum of the sums is larger than a predetermined degree compared to the sum of the absolute values of the HH subband coefficients, and the image is picked up otherwise. Image forming medium A determination processing unit and used surface plane,
It is the surface identification apparatus characterized by having.

According to a second aspect of the present invention, there is provided an image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image as image data.
Frequency conversion means for performing two-dimensional wavelet conversion on the image data input to the image input means;
Regarding the LH subband coefficient, the HL subband coefficient, and the HH subband coefficient generated by the frequency conversion means, coefficients of two or more predetermined subbands among the LH subband, the HL subband, and the HH subband When the sum of the absolute values of the two images does not exceed a predetermined value, the surface of the imaged image forming medium is determined as an unused surface, and the sum of the absolute values of the coefficients of the two or more subbands is When the predetermined value is exceeded, the sum of the absolute values of the LH subband coefficients and the sum of the absolute values of the HL subband coefficients is larger than a predetermined level compared to the sum of the absolute values of the HH subband coefficients. A determination processing means for determining the surface of the imaged image forming medium as an unused surface at times and determining the surface of the imaged medium as a used surface when not;
It is the surface identification apparatus characterized by having.

According to a third aspect of the present invention, there is provided an image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image data.
Compression processing means for performing two-dimensional wavelet transform on the image data input to the image input means, and encoding the generated wavelet coefficients for each subband;
When the code amount relating to the LH subband, the code amount relating to the HL subband, and the code amount relating to the HH subband of the encoded data generated by the compression processing unit does not exceed a predetermined value, If any one of the code amount related to the LH subband, the code amount related to the HL subband, and the code amount related to the HH subband exceeds the predetermined value, the code amount related to the LH subband and the HL The surface of the imaged image forming medium is determined to be an unused surface when the total code amount related to the subband is larger than a predetermined amount as compared with the code amount related to the HH subband. Determination processing means for determining the surface of the image forming medium as a used surface;
It is the surface identification apparatus characterized by having.

According to a fourth aspect of the present invention, there is provided an image input unit that captures an image of at least a part of one surface of an image forming medium and converts the image as image data.
Compression processing means for performing two-dimensional wavelet transform on the image data input to the image input means, and encoding the generated wavelet coefficients for each subband;
The image was taken when the sum of code amounts for two or more predetermined subbands of the LH subband, HL subband, and HH subband of the encoded data generated by the compression processing means does not exceed a predetermined value. When the surface of the image forming medium is determined to be an unused surface, and the sum of the code amounts related to the two or more predetermined subbands exceeds the predetermined value, the sum of the code amount related to the LH subband and the code amount related to the HL subband is When the code amount related to the HH subband is larger than a predetermined level, the surface of the imaged image forming medium is determined to be an unused surface. Otherwise, the surface of the imaged image forming medium is used. Determination processing means for determining a surface;
It is the surface identification apparatus characterized by having.

The invention according to claim 5 is an image forming apparatus for forming an image on an image forming medium;
5. The surface identification device according to claim 1, wherein a surface of the image forming medium on which an image is to be formed by the image forming device is determined to be a used surface or an unused surface. Have
In the image forming apparatus, the image forming apparatus does not form an image on the image forming medium when the surface identifying apparatus determines that the surface is a used surface.

The invention of claim 6 is an image forming apparatus for forming an image on an image forming medium;
5. The surface identification device according to claim 1, which determines whether a surface of an image forming medium on which an image is to be formed by the image forming device is a used surface or an unused surface;
An image forming apparatus comprising: means for reversing the front and back of the image forming medium when the surface identifying device determines that the surface is a used surface.

The invention according to claim 7 is a conveying device that conveys the image forming medium along a predetermined conveying path;
An image forming device for forming an image on the image forming medium conveyed by the conveying device;
An image forming apparatus comprising the surface identification device according to any one of claims 1 to 4.
The transport device has a reversing unit that reverses the front and back of the image forming medium in the middle of the transport path,
When the image forming medium on the conveyance path is again determined as a used surface by the surface identifying device, the image forming device does not form an image on the image forming medium. It is.

The coefficient of the high frequency component generated by frequency conversion of image data obtained by imaging one surface of the image forming medium, and the code of the high frequency component of the encoded data encoded after frequency conversion of such image data are: It reflects the amount of characters and lines on the image forming medium, and is hardly affected by differences in the ground color and reflectance of the image forming medium. Therefore, according to the surface identification apparatus or method of the first to fourth aspects of the present invention, the used surface and the unused surface are identified for various image forming media having different colors and reflectivities, such as colored paper and straw half paper as well as white paper. It is possible to identify with high accuracy, and it is possible to share a standard for identification (specifically, a threshold for determination described later) regardless of the type of image forming medium. In addition, a form or the like on which a predetermined form is printed in advance may be used as an image forming medium, but most of the forms printed in advance are like a table composed of vertical and horizontal ruled lines. On an unused surface where only such a form is printed, the sum or code amount of the absolute values of the coefficients of the LH subband (horizontal edge component) and the HL subband (vertical edge component) is relatively large. Although there is a possibility, the sum or code amount of the absolute values of the coefficients of the HH subband (edge components other than the vertical and horizontal directions) or the code amount is usually much smaller than that. Therefore, according to the surface identification device of the first to fourth aspects of the present invention, it is possible to identify a used surface and an unused surface even for an image forming medium preliminarily printed with a form like a table.

According to the image forming apparatus of the fifth aspect, the used surface and the unused surface of the image forming medium can be identified to prevent image formation on the used surface. According to the image forming apparatus of the invention of claim 6 to identify the used surfaces and unused surface of the imaging medium, by inverting the front and back of the image forming medium when the used surfaces, the spent surface preventing the image formation, Ru can perform image forming unused surface.

  The present invention identifies used and unused surfaces of image forming media such as paper used in various image forming apparatuses equipped with image forming means such as printers, copiers, facsimile machines, and multifunction machines having both functions. The present invention relates to a surface identification device that can be used for this purpose, and an image forming device that uses this surface identification device to prevent double formation of an image on an image forming medium. Hereinafter, embodiments of the surface identification device and the image forming apparatus will be described in order.

<Embodiment of Surface Identification Device of the Present Invention >
FIG. 1 is a block diagram for explaining an embodiment of a surface identification device of the present invention . The surface identification device according to this embodiment includes an image input unit 101, a frequency conversion unit 104, and a determination processing unit 105.

  An image input unit 101 captures at least a part of one surface of an image forming medium (not shown) such as print paper, and converts an image signal output from the imaging unit 102 into digital image data. Signal processing circuit 103. As the imaging means 102, a general one-dimensional image sensor or a two-dimensional image sensor can be used. The imaging unit 102 usually includes a light source for illuminating the imaging surface. This light source may be built in the image sensor or provided separately from the image sensor. In the case where an image sensor incorporating the function of the signal processing circuit 103 is used, it is not necessary to provide the signal processing circuit 103 separately. For the purpose of surface identification, it is generally sufficient that image data of luminance components is input. When an image sensor that outputs a color signal such as an RGB signal is used, the signal processing circuit 103 converts the color signal into a luminance signal.

  In the following description, it is assumed that image data having only a luminance component is input from the image input unit 101. However, it is also possible to input color image data, perform frequency conversion for each color by the frequency conversion unit 104, perform determination for each color by the determination processing unit 105, and make a final determination by combining the results.

  The frequency conversion unit 104 is a unit that performs frequency conversion of the image data input by the image input unit 101. Here, two-dimensional wavelet transformation is performed as frequency transformation, and wavelet transformation (discrete wavelet transformation) called 5 × 3 transformation defined by the international standard image encoding method JPEG2000 is used as wavelet transformation. explain. However, it is also possible to perform other wavelet transforms (for example, 9 × 7 transform specified in JPEG2000), discrete cosine transform (DCT), Fourier transform, Hadamard transform, and frequency transform using an edge extraction filter. It is.

  The determination processing unit 105 determines whether the surface of the image forming medium imaged by the imaging unit 102 is a used surface or an unused surface based on the coefficient of a specific high frequency component output from the frequency conversion unit 104. It is means to do. The reason why low-frequency component coefficients are not used for this determination is that, when color paper other than blank paper or paper half-paper is used as the image forming medium, the low-frequency component coefficients take reasonable values even on unused surfaces. This is because there is a risk of erroneously determining an unused surface as a used surface if the low-frequency component coefficient is used for the determination. In other words, the present invention uses the specific high-frequency component coefficient excluding the low-frequency component for determination, so that the unused surface and the used surface can be reliably identified even in the case of colored paper or paper half paper. Is.

  Here, a wavelet transform called a two-dimensional 5 × 3 transform defined in JPEG2000 will be described in detail with reference to FIGS. For a 16 × 16 pixel monochrome image as shown in FIG. 2, take XY coordinates as shown, and for a certain X coordinate, the pixel value of a pixel whose Y coordinate is y is P (y) (0 ≦ y ≦ 15).

  In JPEG2000, a coefficient C (2i + 1) is obtained by first applying a high-pass filter in the vertical direction (Y-coordinate direction) around an odd-numbered pixel (y = 2i + 1). Next, a low-pass filter is applied around the pixel whose Y coordinate is an even number (y = 2i) to obtain a coefficient C (2i) (this is performed for all X coordinates). The following equation (1) represents a high-pass filter, and equation (2) represents a low-pass filter.

C (2i + 1) = P (2i + 1) − | _ (P (2i) + P (2i + 2)) / 2_ | (1)
C (2i) = P (2i) + | _ (C (2i-1) + C (2i + 1) +2) / 4_ | (2) where _X_ | is the largest integer that does not exceed X To express.

  For simplicity, if the coefficient obtained by the high-pass filter is denoted by H and the coefficient obtained by the low-pass filter is denoted by L, the image in FIG. 2 is converted into an array of L and H coefficients as shown in FIG. Converted to.

  Subsequently, a high-pass filter is applied to the coefficient array of FIG. 3 in the horizontal direction centering on an odd-numbered (x = 2i + 1) coefficient, and then an even-numbered (x = 2i) coefficient. (This is performed for all y. In this case, P (2i) and the like in the equations (1) and (2) are read as representing coefficient values).

  For simplicity, LL is obtained by applying a low-pass filter centered on the L coefficient, HL is obtained by applying a high-pass filter centered on the L coefficient, and is obtained by applying a low-pass filter centered on the H coefficient. 3 is converted into a coefficient array as shown in FIG. 4, if the coefficient obtained is expressed as LH and the coefficient obtained by applying a high-pass filter around the H coefficient as HH. Here, coefficient groups with the same symbol are called subbands, and FIG. 4 is composed of four subbands.

  When one wavelet transform (one decomposition (decomposition)) is completed and only LL coefficients are collected (collected for each subband as shown in FIG. 5 and only the LL subband is extracted), the original image is obtained. An image having a resolution of 1/2 is obtained (classifying each subband in this way is called deinterleaving, and arranging in the state shown in FIG. 4 is interleaving). In JPEG2000, the conversion is performed in the order of the vertical direction and the horizontal direction, but in general, the conversion can also be performed in the order of the horizontal direction and the vertical direction. When one-dimensional wavelet transform is desired, the same filtering process may be performed only vertically or horizontally. A mode in which one-dimensional wavelet transform is performed is also included in the present invention.

  In the second wavelet transform, the LL subband may be regarded as an original image and the same transformation as described above may be performed. When the second wavelet transform is performed and the coefficients are rearranged, a schematic FIG. 6 is obtained. In FIGS. 5 and 6, prefixes 1 and 2 of the coefficient indicate how many times the wavelet transform has obtained the coefficient, and are called a decomposition level.

  In the case of the surface identification device according to the present invention, conversion up to decomposition level 1 may be performed, or conversion up to level 2 or more may be performed. In the present invention, the subband used for surface identification is a subband at a decomposition level 1 or a subband at a decomposition level 2 or higher. The LL, LH, HL, and HH subbands in the following description mean LL, LH, HL, and HH subbands at a certain composition level.

  As is apparent from the description of FIGS. 2 to 6, in the two-dimensional wavelet transform, the vertical and horizontal resolutions are halved every time the composition level (hierarchy) increases by one. Therefore, as the decomposition level (hierarchy) uses the upper subband, there is an advantage that the processing amount for obtaining the sum of the absolute values of the coefficients can be reduced.

  The wavelet transform described above can be easily performed using hardware such as a JPEG2000 encoder, but can also be executed as a program process using a computer. Since such hardware and programs are well known, further explanation is omitted. In JPEG2000, a wavelet transform called 9 × 7 transform is also defined. This wavelet transform may be used.

  FIG. 7 is a block diagram illustrating a specific configuration example of the determination processing unit 105. In FIG. 7, 201 is an arithmetic means, 202, 203 and 204 are comparators, and 205 is an OR gate. The computing unit 201 calculates the sum of the absolute values of the coefficients for each predetermined subband other than the LL subband that is a low frequency component among the wavelet coefficients output from the frequency conversion unit 104. In the example shown here, the computing means 201 calculates the sum sumLH of the absolute values of the coefficients of the LH subband, the sum sumHL of the absolute values of the coefficients of the HL subband, and the sum sumHH of the absolute values of the coefficients of the HH subband, respectively. Output. Comparators 202, 203, and 204 are means for comparing the sum of the absolute values of the calculated coefficients of each subband with a predetermined threshold corresponding to the subband. In the example shown here, the comparator 202 compares sumLH with the threshold value th1, and when sumLH> th1, the output is turned on. The comparator 203 compares sumHL with the threshold value th2, and when sumHL> th2, the output is turned on. The comparator 204 compares sumHH with the threshold th3, and when sumHH> th3, the output is turned on. The outputs of the comparators 202, 203, and 204 are ORed by an OR gate 205. The output of the OR gate 205 is the output of the determination processing unit 105. When this is on, it is determined that the surface has been used.

  The LH subband represents a vertical high-frequency component, that is, a horizontal edge component, the HL subband represents a horizontal high-frequency component, that is, a vertical edge component, and the HH subband represents a high-frequency component in the other direction. These high-frequency components reflect characters and lines on the image forming medium, and are hardly affected by differences in the ground color and reflectance of the image forming medium. Therefore, regardless of whether the image forming medium is a white paper, a colored paper, or a paper with low reflectivity such as a half paper, the sum of the absolute values of the coefficients of these subbands is used for the unused surface. Without exceeding th1, th2, th3, the outputs of the comparators 202, 203, 204 are in the off state, and the output of the OR gate is also in the off state. On the other hand, on the surface on which characters or the like are printed, the sum of the absolute values of the coefficients of all the subbands or at least some of the subbands exceeds the thresholds th1, th2, th3, and is output from the comparators 202, 203, 204. Are turned on, and therefore the output of the OR gate 205 is turned on.

  As described above, the common thresholds th1, th2, and th3 are used regardless of the type of the image forming medium, that is, the unused surface and the used surface are high without changing the identification condition according to the type of the image forming medium. Can be identified with accuracy.

  It is not always necessary to use all of the LH, HL, and HH subbands for the determination process. For example, only the LH and HL subbands can be used. Such an aspect is also included in the present embodiment.

  The determination processing unit 105 configured as shown in FIG. 7 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

  In step 1, the sum of absolute values of the LH subband coefficients sumLH is calculated, in step 2, the sum of absolute values of the HL subband coefficients sumHL is calculated, and in step 3, the sum of absolute values of the HH subband coefficients sumHH is calculated. . In step 4, comparison determination is made between sumLH and threshold value th1, and if sumLH> th1 (YES), the process proceeds to step 8, and a determination result of the used surface is output.

  If it is determined at step 4 that sumLH> th1 is not satisfied (NO), the comparison between sumHL and threshold value th2 is performed at step 5, and if sumHL> th2 (YES), the process proceeds to step 8. However, if it is determined that sumHL> th2 is not satisfied (NO), comparison determination is made between sumHH and threshold th3 in step 6, and if it is determined that sumHH> th3 (YES), the process proceeds to step 8, but sumHH> th3 is not satisfied. If it is determined (NO), the process proceeds to step 7 to output a determination result as an unused surface.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. It is possible to include the function of the frequency converter 104 (in the example described here, the function of wavelet transform) in such a program, and such a program is also included in the present invention.

  If step 4 is executed immediately after step 1 and the determination result is YES, step 8 is executed and the process is terminated. If the determination result of step 4 is NO, step 2 and step 5 are executed, and if the determination result is YES Step 8 is executed to end the processing. If the determination result of step 5 is NO, step 3 and step 6 are executed. If the determination result of step 6 is YES, step 8 is executed. If the determination result is NO, step 7 is executed. It can also be a flow. According to such a processing flow, the determination process can often be completed at an earlier stage.

  FIG. 9 is a block diagram illustrating another specific configuration example of the determination processing unit 105. In FIG. 9, the calculation means 201 is the same means as the calculation means 201 in FIG. An adder 210 calculates the sum Σ of sumLH, sumHL, and sumHH output from the computing unit 201. A comparator 211 compares the output value Σ of the adder 210 with the threshold value th4, and when Σ> th4, the output is turned on. The output of the comparator 211 is the output of the determination processing unit 105. When this is on, it is determined that the surface is used.

  As described with reference to FIG. 7, the coefficients of the LH, HL, and HH subbands do not take a large value when nothing is printed on the surface of the white paper as well as the surface of the colored paper or the half paper. The total sum Σ of the absolute values of the subband coefficients does not exceed the threshold th4, and the output of the comparator 211 is in the off state. On the other hand, since the total value Σ exceeds the threshold th4 on the surface on which characters or the like are printed, the output of the comparator 211 is turned on. In this way, regardless of the type of image forming medium, it is possible to identify the used surface and the unused surface with high accuracy using the common threshold th4, that is, based on the common identification condition.

  It is not always necessary to use all of the LH, HL, and HH subbands for the determination process. For example, only the LH and HL subbands can be used. Such an aspect is also included in the present embodiment.

  The determination processing unit 105 configured as shown in FIG. 9 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

In steps 11, 12, and 13, the sums sumLH, sumHL, and sumHH of the absolute values of the coefficients of the LH, HL, and HH subbands are respectively calculated. In step 14, the sum value Σ of sumLH, sumHL, and sumHH is calculated, and in step 15, comparison determination is performed between Σ and the threshold value th4. If Σ> th4 (YES), the process proceeds to step 17 to output a determination result as a used surface. If Σ> th4 is not satisfied (NO), a determination result as an unused surface is output at step 16.
A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit in accordance with such a determination processing algorithm is also included in the present invention. It is possible to include the function of the frequency converter 104 (in the example described here, the function of wavelet transform) in such a program, and such a program is also included in the present invention.

  FIG. 11 is a block diagram illustrating another specific configuration example of the determination processing unit 105. In this example, an adder 220, a multiplier 221, a comparator 223, and an AND gate 224 are added to the configuration shown in FIG. The adder 220 outputs a sum of sumLH and sumHL output from the computing unit 201. The multiplier 221 outputs a value obtained by multiplying sumHH output from the computing unit 201 by a predetermined multiplier n. When a power of 2 is used as the multiplier n, multiplication can be performed by a shift operation, so that the multiplier 221 can be realized by a shift register or the like. The comparator 223 compares the output value (sumLH + sumHL) of the adder 220 with the output value (n × sumHH) of the multiplier 221. When sumLH + sumHL> n × sumHH, the output is turned off. Turns on. The output of the comparator 223 and the output of the OR gate 205 are input to an AND gate 224, and a final determination result is output from the AND gate 224.

  In an image forming apparatus, a form on which a predetermined form is printed in advance may be used as an image forming medium. However, most of the forms printed in advance are like a table composed of vertical and horizontal ruled lines. . On an unused surface where only such a form is printed, the coefficients of the LH subband which is the horizontal edge component and the HL subband which is the vertical edge component may take a relatively large value. The output of the OR gate may be turned on. However, the HH subband coefficients are likely to take a much smaller value. Therefore, by appropriately selecting the multiplier n of the multiplier 221, the condition (sumLH + sumHL)> n × sumHH is satisfied and the output of the comparator 223 is turned off on such unused surfaces. In other words, even if the output of the OR gate 205 is turned on, the output of the AND gate 224 which is the final determination result is turned off, and it can be correctly determined as an unused surface.

  Thus, in this example, the sum of the absolute values of the LH subband coefficients and the sum of the absolute values of the HL subband coefficients is about a predetermined amount compared to the sum of the absolute values of the HH subband coefficients. If it is larger than the multiplier n), it is determined as an unused surface even if any of the absolute values of the coefficients of the LH, HL, and HH subbands exceeds the threshold.

  More generally, if the pattern of sumLH, sumHL, and sumHH matches the predetermined pattern prepared in advance, even if any of sumLH, sumHL, or sumHH exceeds the threshold, it is not used. It is judged as a surface.

  If it is sufficient to consider only one of the horizontal ruled line or the vertical ruled line, it is possible to omit the adder 220 and input sumLH or sumHL to the comparator 223, and this aspect is also included in this embodiment.

The determination processing unit 105 configured as shown in FIG. 11 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG .

  In steps 21, 22, and 23, the sum sumLH of the absolute values of the coefficients of the LH subband, the sum sumHL of the absolute values of the coefficients of the HL subband, and the sum sumHH of the absolute values of the coefficients of the HH subband are calculated. In step 24, comparison determination is made between sumLH and the threshold value th1. If sumLH> th1 (YES), the process proceeds to step 28. If it is determined that sumLH> th1 is not satisfied (NO), comparison determination is made between sumHL and threshold value th2 in step 25. If sumHL> th2 (YES), the process proceeds to step 28. If it is determined that sumHL> th2 is not satisfied (NO), comparison determination is made between sumHH and threshold th3 in step 26, and if it is determined that sumHH> th3 (YES), the process proceeds to step 28, but it is determined that sumHH> th3 is not satisfied. If it is (NO), the process proceeds to step 27, and the determination result of the unused surface is output.

  When the process proceeds to step 28, sumLH + sumHL is calculated in this step, and n × sumHH is calculated in the next step 29. Then, in step 30, comparison determination of sumLH + sumHL and n × sumHH is performed. If it is determined that sumLH + sumHL> n × sumHH (YES), the process proceeds to step 27, and the determination result of the unused surface is output. However, if it is determined that sumLH + sumHL> n × sumHH is not satisfied (NO), the process proceeds to step 31 to output a determination result as a used surface.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. It is possible to include the function of the frequency converter 104 (in the example described here, the function of wavelet transform) in such a program, and such a program is also included in the present invention. If it is sufficient to consider only the horizontal ruled lines or the vertical ruled lines, step 28 may be omitted, and the comparison of sumLH or sumHL and n × sumHH may be performed at step 30, and this aspect is also included in the present embodiment.

  It is also possible to change the processing flow so that step 24 is executed immediately after step 21, step 25 is executed immediately after step 22, and step 26 is executed immediately after step 23.

  FIG. 13 is a block diagram illustrating another specific configuration example of the determination processing unit 105. In this example, an adder 220, a multiplier 221, a comparator 223, and an AND gate 230 are added to the configuration shown in FIG. The adder 220 outputs a sum of sumLH and sumHL output from the computing unit 201. The multiplier 221 outputs a value obtained by multiplying sumHH output from the computing unit 201 by a predetermined multiplier n. When a power of 2 is used as the multiplier n, multiplication can be performed by a shift operation, so that the multiplier 221 can be realized by a shift register or the like. The comparator 223 compares the output value (sumLH + sumHL) of the adder 220 with the output value (n × sumHH) of the multiplier 221. When sumLH + sumHL> n × sumHH, the output is turned off. Turns on. The output of the comparator 223 and the output of the comparator 211 are input to the AND gate 230, and a final determination result is output from the AND gate 230.

  Also in this example, as is clear from the description related to FIG. 11, the output of the comparator 223 is turned off on an unused surface on which a form such as a table composed of vertical and horizontal ruled lines is printed in advance. Even if the output of the comparator 211 is turned on, the final determination output is not turned on, and it can be correctly determined as an unused surface.

  Note that only two of sumLH, sumHL, and sumHH can be input to the adder 210, and this aspect is also included in the present embodiment. Further, if it is sufficient to consider only the horizontal ruled lines or the vertical ruled lines, it is possible to omit the adder 220 and input sumLH or sumHL to the adder 223, and this aspect is also included in this embodiment.

The determination processing unit 105 configured as shown in FIG. 13 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

In steps 41, 42, and 43, the sum sumLH of the absolute values of the coefficients of the LH subband, the sum sumHL of the absolute values of the coefficients of the HL subband, and the sum sumHH of the absolute values of the coefficients of the HH subband are calculated. In step 44, the sum Σ of sumLH, sumHL, and sumHH is calculated. In step 45, Σ is compared with the threshold value th4, and if Σ> th4 (ES), the process proceeds to step 47. If it is determined that Σ> th4 is not satisfied (NO), the process proceeds to step 46 and the determination result of the unused surface is output.

  When the process proceeds to step 47, sumLH + sumHL is calculated in this step, and n × sumHH is calculated in the next step48. Then, in step 49, the comparison of sumLH + sumHL and n × sumHH is performed, and if it is determined that sumLH + sumHL> n × sumHH (YES), the process proceeds to step 46, and the determination result of the unused surface is output. However, if it is determined that sumLH + sumHL> n × sumHH is not satisfied (NO), the process proceeds to step 50 to output a determination result as a used surface.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. It is possible to include the function of the frequency converter 104 (in the example described here, the function of wavelet transform) in such a program, and such a program is also included in the present invention.

< Another Embodiment of Surface Identification Device of the Present Invention >
FIG. 15 is a block diagram for explaining another embodiment of the surface identification apparatus of the present invention . The surface identification apparatus according to this embodiment includes an image input unit 301, a compression processing unit 304, and a determination processing unit 305.

  Similar to the image input unit 101 in FIG. 1, the image input unit 301 includes an imaging unit 302 and a signal processing circuit 303, and the imaging unit 302 captures an image of at least a part of one surface of the image forming medium, Means for inputting the image data. Also here, it is assumed that the input image data is data of only the luminance component. However, as described with reference to FIG. 1, color image data is input, the compression processing unit 304 performs compression processing for each color, the determination processing unit 305 performs determination for each color, and the results are combined to obtain the final result. It is also possible to make a judgment.

  The compression processing unit 304 is a compression processing unit that performs compression encoding of the image data input from the image input unit 301 and outputs code data. Here, description will be made assuming that the compression processing unit 304 conforms to JPEG2000, which performs two-dimensional wavelet transform of image data and encodes wavelet coefficients for each subband (frequency band). However, the compression encoding method of the compression processing unit 304 is not limited to JPEG 2000 as long as the code amount related to a specific high frequency component can be calculated. Other compression encoding methods using wavelet transform, JPEG It is possible to use various compression encoding schemes that perform frequency conversion of image data and encode frequency conversion coefficients.

  The determination processing unit 305 calculates a code amount related to a specific high-frequency component from the code data output from the compression process 304, and the surface of the image forming medium imaged by the imaging unit 302 is a used surface or an unused surface. It is means for determining whether or not there is. The reason why the code amount related to the low frequency component is not used for this determination is that the color amount related to the low frequency component is appropriate even if it is an unused surface when a color paper other than white paper or a half paper is used as the image forming medium. This is because there is a risk of erroneously determining an unused surface as a used surface if the code amount of the low frequency component is used for determination. In other words, the present invention uses the code amount for a specific high frequency component excluding the low frequency component for determination, so that the unused surface and the used surface can be reliably identified even in the case of colored paper or paper half paper. To do.

  Among image forming apparatuses, there are many apparatuses such as a copying machine and a multi-function machine that have encoding for compressing and encoding image data, and having a function of compressing and encoding image data and storing it in a hard disk or the like. When the surface identification device according to the present embodiment is used in such an image forming apparatus, an encoder included in the image forming apparatus can be used as the compression processing device 304.

  Here, an outline of JPEG2000 will be described. FIG. 16 is an explanatory diagram of a basic processing flow of JPEG2000 compression encoding. In JPEG2000, image data is divided into non-overlapping rectangular areas called tiles, and compression encoding is performed in units of tiles.

  First, DC level shift and color conversion to YCrCb space are performed for each tile (step A). However, color conversion is unnecessary because image data of only the luminance component is handled here. Next, a two-dimensional wavelet transform is performed for each tile (step B). As the wavelet transform, 9 × 7 transform can be used in addition to the 5 × 3 transform described above.

  In the case of the surface identification device according to the present invention, conversion up to decomposition level 1 may be performed, or conversion up to level 2 or more may be performed. In the present invention, the subband used for surface identification is a subband at a decomposition level 1 or a subband at a decomposition level 2 or higher. The LL, LH, HL, and HH subbands in the following description mean LL, LH, HL, and HH subbands at a certain composition level.

  As is apparent from the description of FIGS. 2 to 6, in the two-dimensional wavelet transform, the vertical and horizontal resolutions are halved every time the composition level (hierarchy) increases by one. Therefore, as the decomposition level (hierarchy) uses the upper subband, there is an advantage that the processing amount for obtaining the code amount of the subband can be reduced.

  When the 9 × 7 transform is used, the wavelet transform coefficient is linearly quantized for each subband (step C). Next, bit-plane encoding is performed for each subband (step D). More specifically, the subband is divided into non-overlapping rectangles called precincts. One precinct consists of three rectangular regions spatially matching the LH, HL, and HH subbands having the same composition level. However, in the LL subband, one rectangular area constitutes one precinct. The precinct is divided into code blocks that are rectangular areas that do not overlap. Bit plane encoding is performed in units of this code block. FIG. 17 shows the size relationship among tiles, subbands, precincts, and code blocks.

  Unnecessary codes are discarded from the codes generated in this way (truncation), and necessary codes are collected to generate a packet (step E). A packet consists of a code and a packet header. Finally, by arranging packets in a predetermined order and adding a main header, tile part header, and other tags, code data (code stream) of a predetermined format is created (step F).

  Such an encoder compliant with JPEG2000 can be used as the compression processing unit 304. A compression encoding program based on JPEG2000 is also known, and the compression processing unit 304 can be realized on a computer by using such a program.

  Next, the determination processing unit 305 will be described. FIG. 18 is a block diagram illustrating a specific configuration example of the determination processing unit 305. In FIG. 18, 401 is an arithmetic means, 402, 403, 404 are comparators, and 405 is an OR gate. The calculation means 401 calculates a code amount related to a predetermined subband other than the LL subband which is a low frequency component, from the code data output from the compression processing unit 304. In JPEG2000 code data, the code amount for each subband can be easily calculated based on the information of the aggregate packet header of the main header and the information of the packet header of each packet.

  In the example shown here, the computing means 401 calculates and outputs a code amount related to the LH subband, a code amount related to the HL subband, and a code amount related to the HH subband. Comparators 402, 403, and 404 are means for comparing the calculated code amount of each subband with a predetermined threshold corresponding to the subband. In the example shown here, the comparator 402 compares the code amount of the LH subband with the threshold th11, and the output is turned on when the code amount> th11. The comparator 403 compares the code amount of the HL subband with the threshold value th2, and when the code amount> th12, the output is turned on. The comparator 404 compares the code amount of the HH subband with the threshold th13, and the output is turned on when the code amount> th13. The outputs of the comparators 402, 403, and 404 are ORed by an OR gate 405. The output of the OR gate 405 is the output of the determination processing unit 305. When this is on, it is determined that the surface is a used surface.

  As described above, the LH, HL, and HH subbands are high frequency components in the vertical direction, horizontal direction, and other directions, respectively. The code amount of each subband is approximately proportional to the sum of absolute values of the coefficients of the subband. Accordingly, when nothing is printed on the surface of the white paper as well as the surface of the colored paper or the half paper, the code amounts of these subbands do not exceed the thresholds th11, th12, and th13, so the comparators 402, 403, The output of 404 is in the off state, so the output of the OR gate is also in the off state. On the other hand, on the surface on which characters or the like are printed, the code amount of all of these subbands or at least some of the subbands exceeds the thresholds th11, th12, and th13, and all or one of the outputs of the comparators 402, 403, and 404. And the output of the OR gate 405 is turned on. In this way, regardless of the type of image forming medium, it is possible to identify the used surface and the unused surface with high accuracy using the common thresholds th11, th12, and th13, that is, using the common identification standard. it can.

Note that it is not always necessary to use all of the LH, HL, and HH subbands for the determination. For example, it is possible to perform the same determination process using only the code amount for the LH and HL subbands. It is included in this embodiment.

  The determination processing unit 305 configured as shown in FIG. 18 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

  In steps 61, 62, and 63, the code amount of the LH subband, the code amount of the HL subband, and the code amount of the HH subband are calculated. In step 64, the code amount of the LH subband is compared with the threshold value th11. If the code amount is greater than th11 (YES), the process proceeds to step 68 to output the determination result of the used surface.

  If it is determined in step 64 that the code amount> th11 is not satisfied (NO), in step 65, the code amount of the HL subband is compared with the threshold th12. If the code amount> th12 (YES), the process proceeds to step 68. However, if it is determined that the code amount> th12 is not satisfied (NO), a comparison determination is performed between the code amount of the HH subband and the threshold th13 in step 66, and if it is determined that the code amount> th13 (YES), step 68 is performed. The process proceeds, but if it is determined that the code amount is not greater than th13 (NO), the process proceeds to step 67 and the determination result of the unused surface is output.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. It is possible to include the function of the compression processing unit 304 in this program (in this example, the function of JPEG2000 compression encoding processing), and such a program is also included in the present invention.

  It should be noted that it is possible to have a processing flow in which step 61 is executed immediately after step 61, step 65 is executed immediately after step 62, and step 66 is executed immediately after step 63, and this aspect is also included in this embodiment.

  FIG. 20 is a block diagram illustrating another specific configuration example of the determination processing unit 305. In FIG. 20, a calculation means 401 is the same means as the calculation means 401 in FIG. Reference numeral 410 denotes an adder, which obtains the sum Σ of the code amounts of the LH, HL, and HH subbands output from the calculation means 401. Reference numeral 411 denotes a comparator that compares the output value Σ of the adder 410 with a threshold th14, and the output is turned on when Σ> th14. The output of the comparator 411 is the output of the determination processing unit 105. When this is on, it is determined that the surface has been used.

  The code amount of the LH, HL, and HH subbands does not take a large value when nothing is printed on the surface of the white paper as well as the surface of the colored paper or the half paper. Th14 is not exceeded, and the output of the comparator 411 is in the OFF state. On the other hand, on the surface on which characters or the like are printed, the total value Σ exceeds the threshold th14, and therefore the output of the comparator 411 is turned on.

  Note that it is not always necessary to use all of the LH, HL, and HH subbands. For example, it is possible to perform the same determination processing using only the code amounts of the LH and HL subbands. Included in the form.

  The determination processing unit 305 configured as shown in FIG. 20 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

In steps 71, 72, and 73, the code amounts of the LH, HL, and HH subbands are calculated. In step 74, the total value Σ of the code amounts of the LH, HL, and HH subbands is calculated, and in step 75, Σ is compared with the threshold th14. If Σ> th14 (YES), the process proceeds to step 77, and the determination result of the used surface is output. If Σ> th14 is not satisfied (NO), the determination result of the unused surface is output at step 76.
A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit in accordance with such a determination processing algorithm is also included in the present invention. It is possible to include the function of the compression processing unit 304 in this program (in this example, the function of JPEG2000 compression encoding processing), and such a program is also included in the present invention.

  FIG. 22 is a block diagram illustrating another specific configuration example of the determination processing unit 305. In this example, an adder 420, a multiplier 421, a comparator 423, and an AND gate 424 are added to the configuration shown in FIG. The adder 420 outputs a value obtained by summing up the code amounts of the LH and HL subbands output from the computing unit 401. The multiplier 421 outputs a value obtained by multiplying the code amount of the HH subband output from the computing unit 401 by a predetermined multiplier n. Note that when a power of 2 is used as the multiplier n, multiplication can be performed by a shift operation, so that the multiplier 421 can be realized by a shift register or the like. The comparator 423 compares the output value of the adder 420 (LH + HL code amount) with the output value of the multiplier 422 (n × HH code amount), and when (LH code amount + HL code amount)> n × HH code amount. The output is turned off, otherwise the output is turned on. The output of the comparator 423 and the output of the OR gate 405 are input to the AND gate 424, and a final determination result is output from the AND gate 424.

  In an image forming apparatus, a form on which a predetermined form is printed in advance may be used as an image forming medium. However, most of the forms printed in advance are like a table composed of vertical and horizontal ruled lines. . On an unused surface where only such a form is printed, there is a possibility that the code amount of the LH subband which is the horizontal edge component and the code amount of the HL subband which is the vertical edge component take a relatively large value. Therefore, the output of the OR gate 405 may be turned on. However, the code amount of the HH subband is likely to take a much smaller value. Therefore, by appropriately selecting the multiplier n of the multiplier 421, the condition of (LH + HL code amount)> n × HH code amount is satisfied and the output of the comparator 423 is turned off on such unused surfaces. That is, even if the output of the OR gate 405 is turned on, the output of the AND gate 424, which is the final determination result, is turned off, so that it can be correctly determined as an unused surface.

That is, in this example, when the sum of the code amount of the LH subband and the code amount of the HL subband is larger than a predetermined amount (which is determined by the multiplier n) as compared with the code amount of the HH subband. Even if any of the code amounts of the LH, HL, and HH subbands exceeds the threshold value, it is determined as an unused surface.
More generally, if the pattern of the magnitude relationship between the code amounts of the LH, HL, and HH subbands matches a predetermined pattern prepared in advance, any of the code amounts of the LH, HL, and HH subbands Even if the threshold value exceeds the threshold value, it is determined as an unused surface.

  If it is sufficient to consider only the horizontal ruled lines or the vertical ruled lines, the adder 420 can be omitted and the code amount of the LH or HL subband can be input to the comparator 423. This aspect is also included in this embodiment. included.

  The determination processing unit 305 configured as shown in FIG. 22 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

  In steps 81, 82, and 83, the code amounts of the LH, HL, and HH subbands are calculated, respectively. In step 84, the LH subband code amount is compared with the threshold value th11. If the code amount> th11 (YES), the process proceeds to step 88. If it is determined that the code amount> th11 is not satisfied (NO), the HL subband code amount is compared with the threshold th12 in step 85, and if the code amount> th12 (YES), the process proceeds to step 88. If it is determined that the code amount is not greater than th12 (NO), the HH subband code amount is compared with the threshold th13 in step 86, and if it is determined that the code amount is greater than th13 (YES), the process proceeds to step 88. If it is determined that the code amount is not greater than th13 (NO), the process proceeds to step 87, and the determination result of the unused surface is output.

  When the process proceeds to step 88, the total code amount of the LH and HL subbands is calculated in this step, and the n × HH subband code amount is calculated in the next step 89. In step 90, the LH and HL subband total code amount is compared with the n × HH subband code amount, and if it is determined that LH and HL subband total code amount> n × HH subband code amount (YES). Then, the process proceeds to step 87, and the determination result of the unused surface is output. However, if it is determined that the total code amount of LH and HL subbands is not greater than n × HH subband code amount (NO), the process proceeds to step 91 and the determination result of the used surface is output.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. Such a program can include the function of the compression processing unit 304 (in the example described here, the function of JPEG2000 compression encoding processing), and such a program is also included in the present invention.

  If it is sufficient to consider only the horizontal ruled lines or the vertical ruled lines, step 88 may be omitted, and the determination of the LH or HL subband code amount and the n × HH subband code amount may be performed at step 90. Aspects are also included in this embodiment.

  It is also possible to use a processing flow in which step 84 is executed immediately after step 81, step 85 is executed immediately after step 82, and step 86 is executed immediately after step 83. Such an aspect is also included in this embodiment.

  FIG. 24 is a block diagram illustrating another specific configuration example of the determination processing unit 305. In this example, an adder 420, a multiplier 421, a comparator 423, and an AND gate 430 are added to the configuration shown in FIG. The adder 420 outputs a value obtained by summing up the code amounts of the LH and HL subbands output from the computing unit 401. The multiplier 421 outputs a value obtained by multiplying the HH subband code amount output from the computing means 401 by a predetermined multiplier n. Note that when a power of 2 is used as the multiplier n, multiplication can be performed by a shift operation, so that the multiplier 421 can be realized by a shift register or the like. The comparator 423 compares the output value of the adder 420 (LH and HL subband total code amount) with the output value of the multiplier 421 (n × HH subband code amount), and when the former exceeds the latter, The output turns off, otherwise the output turns on. The output of the comparator 423 and the output of the comparator 411 are input to the AND gate 430, and a final determination result is output from the AND gate 430.

  Also in this example, as is clear from the description related to FIG. 22, the output of the comparator 423 is turned off on an unused surface on which a form such as a table composed of vertical and horizontal ruled lines is printed in advance. Even if the output of the comparator 411 is turned on, the final determination output is not turned on, and it can be correctly determined as an unused surface.

  Note that it is not always necessary to use all of the LH, HL, and HH subbands for the determination. For example, only the code amounts of the LH and HL subbands may be input to the adder 410. Are also included in this embodiment. If it is sufficient to consider only horizontal ruled lines or vertical ruled lines, it is possible to omit the adder 420 and input the code amount of the LH or HL subband to the comparator 423. This aspect is also included in this embodiment. included.

  The determination processing unit 305 configured as shown in FIG. 24 can be easily realized by a program using a computer. An example of the processing flow of such a program will be described with reference to FIG.

  In steps 101, 102, and 103, the code amounts of the LH, HL, and HH subbands are calculated, respectively. In step 104, the total value Σ of the LH, HL, and HH subband code amounts is calculated. In step 105, Σ is compared with the threshold value th14, and if Σ> th14 (YES), the process proceeds to step 107. If it is determined that Σ> th14 is not satisfied (NO), the process proceeds to step 106, and the determination result of the unused surface is output.

  When the process proceeds to step 107, the total code amount of the LH and HL subbands is calculated in this step, and the n × HH subband code amount is calculated in the next step 108. In step 109, the LH and HL subband total code amount is compared with the n × HH subband code amount. If it is determined that the former is larger than the latter (YES), the process proceeds to step 106 to determine the unused surface. Output the result. However, if it is determined that this is not the case (NO), the process proceeds to step 110 to output a determination result as a used surface.

  A program that causes a computer to execute such determination processing, in other words, a program that causes a computer to function as a determination processing unit according to the determination processing algorithm is also included in the present invention. It is possible to include the function of the compression processing unit 304 in such a program, and such a program is also included in the present invention.

It is clear that the above description of the processing content of the surface identification device is also an explanation of the processing procedure of the surface identification method of the present invention . The present invention also includes a program described in relation to the surface identification device, and various computer-readable information recording (storage) media such as a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor storage element on which such a program is recorded. Is included.

<Embodiment of Image Forming Apparatus of the Present Invention >
An image forming apparatus according to an embodiment of the present invention will be described by taking a printer as an example. However, it is obvious that the inventions of claims 13 to 15 can be similarly implemented in image forming apparatuses such as copying machines and facsimile machines, and such image forming apparatuses are also included in the present invention.

  FIG. 26 is a functional block diagram of the printer according to the present embodiment. This printer includes a transport device 503 that transports paper (image forming medium) along a predetermined transport path, an image forming device 502 that performs image formation (printing) on the paper transported by the transport device 503, an external computer, and the like. External interface 504 for transferring data and control signals to and from the device, and surface identification for identifying whether the surface of the paper to be printed by the image forming device 502 is a used surface or an unused surface The device 505, a forced print instruction input unit 506 for allowing a user to input an instruction to force printing even when the surface identification device 505 determines that the surface is a used surface, and control for controlling the entire device. The apparatus 501 is provided.

  The surface identification device 505 has the configuration shown in FIG. 1 or FIG. In the case of an image forming apparatus having an encoder for compressing and encoding image data, such as a copying machine, the encoder is used as the compression processing unit 304 (FIG. 15) of the surface identification device 505. Can do. Further, the frequency conversion function of the encoder can be used as the frequency conversion unit 104 (FIG. 1) of the image recognition apparatus 505.

  The control device 501 often takes a form realized by a computer such as a microcomputer and a program. In this case, the computer can be used to realize the determination processing unit 105 or 305 (FIGS. 1 and 15) of the surface identification device 505 by a program, and such an aspect is also included in the present embodiment. The determination processing unit 105 or 305 and the frequency conversion unit 104 or the compression processing unit 304 (FIGS. 1 and 15) of the surface identification device 505 can also be realized by a program, and this aspect is also included in the present embodiment. .

  The image forming device 502 forms an electrostatic latent image by, for example, scanning the surface of the uniformly charged photosensitive drum with a laser beam modulated according to print data, and develops the toner to develop a toner image. And an electrophotographic system in which this toner image is transferred directly or via a transfer roller to a paper, or an ink jet which forms an image by ejecting ink droplets onto a paper according to print data The recording method is arbitrary, and the recording method is arbitrary. Since such an image forming apparatus 502 is general, further detailed description is omitted.

  The transport device 503 is a device that transports the paper stored in the paper tray or the paper manually fed by the user along a predetermined transport path. There is an aspect provided with a reversing means for reversing the paper front and back in the middle of the conveyance path and an aspect not provided.

  FIG. 27 is a schematic structural diagram for explaining processing of paper conveyance, printing, and surface identification in this printer. The conveying path shown here is not provided with a reversing means.

  In FIG. 27, reference numerals 601 and 602 denote paper trays. The transport device 503 feeds and transports the paper stored in the paper trays 601 and 602 along the transport paths 603 and 604. The conveyance paths 603 and 604 merge with the conveyance path 605. In the middle of the conveyance path 605, an image pickup unit 607 (corresponding to the image pickup unit 102 in FIG. 1 and the image pickup unit 302 in FIG. 15) of the surface identification device 505 is provided. The conveyance path 605 branches into conveyance paths 608 and 609 on the downstream side. The transport device 503 includes a guide member that constitutes such a transport path, a mechanism that separates sheets from the paper trays 601 and 602 one by one, and takes them into the transport path, and moves the paper along the transport path. It comprises a roller, its drive motor, its drive circuit, and a sensor for detecting the position of the paper. Since such a conveying apparatus 503 is general, further explanation is omitted.

  For example, the image forming apparatus 502 prints on a sheet at a predetermined position on the conveyance path 608. When the image forming device 502 is of an electrophotographic type in which an electrostatic latent image is formed on a photosensitive drum and the toner image is directly transferred onto a sheet, the photosensitive drum 610 is positioned as shown in the drawing. Arranged. In this case, a fixing device 611 for fixing the toner image on the sheet is provided on the end side of the conveyance path 608. Reference numerals 612 and 613 denote sorters for receiving sheets discharged from the conveyance paths 608 and 609.

  FIG. 28 is a flowchart for explaining the operation of this printer. The flow of the operation shown here is controlled by the control device 501.

  First, the transport device 503 takes the paper from the paper tray 601 or 602 into the transport path 603 or 604 and transports it (step 201). The paper tray from which the paper is fed may be specified by the user, or may be automatically determined by the control device 501 based on the paper size or the like.

  The transport device 503 further transports the paper along the transport path 605. When the sheet passes through the imaging unit 607, at least a part of the surface to be printed is imaged by the imaging unit 607 of the surface identification device 505, and surface identification processing is performed in the surface identification device 505 (step 202). .

  When the surface identification device 505 determines that the surface is unused (step 203, YES), the control device 501 causes the conveyance device 503 to convey the sheet toward the conveyance path 608 and causes the image forming device 502 to perform a printing operation (step 204). ). Then, the printed paper is conveyed as it is and discharged to the sorter 612 (step 205).

  When the surface identification device 505 determines that the surface has been used (step 203, NO), the control device 501 stops the printing operation by the image forming device 502 (step 207), and causes the conveyance device 503 to feed the paper along the conveyance path 609. The sheet is conveyed and discharged to the sorter 613 (step 208). In step 207, the control device 501 sounds a buzzer (not shown) to warn the user, or notifies the external device connected to the printer via the external interface 504 of a warning message. Note that it is possible to take a warning method in which a warning message is transmitted to the user or administrator's mobile phone by e-mail or the like, and such a mode is also included in this embodiment.

  Further, when it is determined that the surface is a used surface, the control device 501 checks whether a forced print instruction (an instruction for forcibly forming an image) is input from the user (step 206). If this instruction is not input, the process proceeds to step 207. However, if an instruction is input, the process proceeds to step 204 to forcibly perform the printing operation on the paper.

  As described above, the surface identification device according to the present invention can accurately identify a used surface and an unused surface not only on white paper but also on paper such as colored paper and paper half paper. In the surface identification device having the configuration described with reference to FIGS. 11 to 14 and FIGS. 22 to 25, it is possible to identify a used surface and an unused surface even in a form or the like on which a ruled line form is printed in advance. . However, depending on the type of paper, the form of a preprinted form, etc., an unused surface may be erroneously determined as a used surface. In addition, there is a case where it is desired to print again even a used surface. In such a case, it is convenient to be able to instruct forced printing.

  Next, the aspect provided with the reversing means in the middle of the transport path will be described with reference to FIGS. 29 and 30. FIG. FIG. 29 is a schematic structural diagram for explaining a configuration of a conveyance path including a reversing unit. The difference from the configuration shown in FIG. 27 is that a reversing unit including conveyance paths 620 and 621 and a stacker 623 is added. Inversion is performed as follows. The sheet transported along the transport path 605 is transported to the stacker 623 along the transport path 620. The paper once stored in the stacker 623 is immediately transported along the transport path 621 and returned to the transport path 605. Since such inversion means is general, further description is omitted.

  Next, the operation of the printer will be described with reference to the flowchart of FIG. The flow of the operation shown here is controlled by the control device 501.

  First, the transport device 503 takes the paper from the paper tray 601 or 602 into the transport path 603 or 604 and transports it (step 211). The paper tray from which the paper is fed may be specified by the user, or may be automatically determined by the control device 501 based on the paper size or the like.

  The transport device 503 further transports the paper along the transport path 605. When the sheet passes through the imaging unit 607, at least a part of the surface to be printed is imaged by the imaging unit 607 of the surface identification device 505, and surface identification processing is performed in the surface identification device 505 (step 212). .

  When the surface identification device 505 determines that the surface is unused (step 213, YES), the control device 501 causes the conveyance device 503 to convey the sheet toward the conveyance path 608 and causes the image forming device 502 to perform a printing operation. (Step 214). Then, the printed paper is conveyed as it is and discharged to the sorter 612 (step 215).

  When the surface identification device 505 determines that the surface has been used (step 213, NO), the control device 501 causes the transport device 503 to perform the above-described paper front / back reversal operation (step 217). When the sheet passes through the imaging unit 607 again, at least a part of the surface to be printed (the surface opposite to the previous one) is imaged by the imaging unit 607 of the surface identification device 505, and the surface identification device 505 A second face identification process is performed on the sheet (step 218).

  When the surface identification device 505 determines that the surface is unused (step 219, YES), the control device 501 causes the conveyance device 503 to convey the sheet toward the conveyance path 608 and causes the image forming device 502 to perform a printing operation. (Step 214). Then, the printed paper is conveyed as it is and discharged to the sorter 612 (step 215). As described above, according to the aspect including the reversing unit, even when the used paper on one side is stored in the paper tray 601 or 602 in a state where the used side is printed, In contrast, printing can be performed normally.

  When the surface identification device 505 determines that the surface has been used again (step 219, NO), since both surfaces of the paper have been used, the control device 501 stops the printing operation by the image forming device 502 (step 220) and transports. The apparatus 503 transports the paper along the transport path 609 and discharges it to the sorter 613 (step 221). At step 220, the control device 601 sounds a buzzer (not shown) to warn the user, notifies the external device connected to the printer via the external interface 504, or sends the warning message to the user by e-mail or the like. Or send it to the administrator's mobile phone.

  Further, when it is determined that the used surface has been used in the first surface identification process (step 212) (step 213, NO), the control device 501 checks whether a forced print instruction is input from the user (step 216). If this instruction is not input (step 216, NO), the process proceeds to step 217. If the instruction is input, the process proceeds to step 214 to forcibly perform the printing operation on the sheet.

It is a block diagram for demonstrating embodiment of the surface identification apparatus of this invention. It is a figure which shows image data and its coordinate axis. It is a figure which shows the coefficient arrangement | sequence after filtering to a perpendicular direction. It is a figure which shows the coefficient arrangement | sequence after filtering to a horizontal direction. It is a figure which shows the coefficient arrangement | sequence which carried out the deinterleaving. It is a figure which shows the coefficient arrangement | sequence which carried out the deinterleaving after two-dimensional wavelet transformation twice. It is a block diagram which shows the structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 7 by a program. It is a block diagram which shows the other structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 9 by a program. It is a block diagram which shows the other structural example of the determination process part in FIG. It is a block diagram which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 11 by a program. It is a block diagram which shows the other structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 13 by a program. It is a block diagram for demonstrating other embodiment of the surface identification apparatus of this invention. It is explanatory drawing of the compression encoding algorithm of JPEG2000. It is a figure which shows the magnitude relationship of an image, a tile, a subband, a precinct, and a code block. It is a block diagram which shows the structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 18 by a program. It is a block diagram which shows the other structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 20 with a program. It is a block diagram which shows the other structural example of the determination process part in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 22 with a program. It is a block diagram which shows the other structural example of the determination process in FIG. It is a flowchart which shows an example of the processing flow in the case of implement | achieving the determination process part of FIG. 24 with a program. 1 is a block diagram for explaining an embodiment of an image forming apparatus of the present invention. 1 is a schematic structural diagram for explaining an embodiment of an image forming apparatus of the present invention. 3 is a flowchart for explaining an embodiment of the image forming apparatus of the present invention. 1 is a schematic structural diagram for explaining an embodiment of an image forming apparatus of the present invention. 3 is a flowchart for explaining an embodiment of the image forming apparatus of the present invention.

DESCRIPTION OF SYMBOLS 101 Image input part 102 Imaging means 103 Signal processing circuit 104 Frequency conversion part 105 Judgment processing part 301 Image input part 302 Imaging means 303 Signal processing circuit 304 Compression processing part 305 Judgment processing part 501 Control apparatus 502 Imaging apparatus 503 Conveyance apparatus 505 surface Identification device 506 Forced print instruction input unit 601 602 Paper tray 603 to 605 608 609 Transport path 607 Imaging means 612 613 Sorter 620 604 Transport path constituting reversing means 623 Stacker constituting reversing means

Claims (7)

  An image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image data as image data;
  Frequency conversion means for performing two-dimensional wavelet conversion on the image data input to the image input means;
  Regarding the LH subband coefficient, the HL subband coefficient and the HH subband coefficient generated by the frequency conversion means, the sum of the absolute values of the LH subband coefficients, the sum of the absolute values of the HL subband coefficients, HH When none of the sum of the absolute values of the subband coefficients exceeds a predetermined value, the surface of the imaged image forming medium is determined as an unused surface, and the sum of the absolute values of the LH subband coefficients, the HL subband If any one of the sum of the absolute values of the coefficients and the sum of the absolute values of the coefficients of the HH subband exceeds the predetermined value, the sum of the absolute values of the coefficients of the LH subband and the absolute value of the coefficients of the HL subband The surface of the imaged image forming medium is determined to be an unused surface when the sum of the sums is larger than a predetermined degree compared to the sum of the absolute values of the HH subband coefficients, and the image is picked up otherwise. Image forming medium A determination processing unit and used surface plane,
A surface identification device comprising:   An image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image data as image data;
  Frequency conversion means for performing two-dimensional wavelet conversion on the image data input to the image input means;
  Regarding the LH subband coefficient, the HL subband coefficient, and the HH subband coefficient generated by the frequency conversion means, coefficients of two or more predetermined subbands of the LH subband, the HL subband, and the HH subband When the sum of the absolute values of the two images does not exceed a predetermined value, the surface of the imaged image forming medium is determined as an unused surface, and the sum of the absolute values of the coefficients of the two or more subbands is When the predetermined value is exceeded, the sum of the absolute values of the LH subband coefficients and the sum of the absolute values of the HL subband coefficients is larger than a predetermined level compared to the sum of the absolute values of the HH subband coefficients. A determination processing means for determining the surface of the imaged image forming medium as an unused surface at times and determining the surface of the imaged medium as a used surface when not;
A surface identification device comprising:   An image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image data as image data;
  Compression processing means for performing two-dimensional wavelet transform on the image data input to the image input means, and encoding the generated wavelet coefficients for each subband;
  When the code amount relating to the LH subband, the code amount relating to the HL subband, and the code amount relating to the HH subband of the encoded data generated by the compression processing unit does not exceed a predetermined value, If any one of the code amount related to the LH subband, the code amount related to the HL subband, and the code amount related to the HH subband exceeds the predetermined value, the code amount related to the LH subband and the HL The surface of the imaged image forming medium is determined to be an unused surface when the total code amount related to the subband is larger than a predetermined amount as compared with the code amount related to the HH subband. Determination processing means for determining the surface of the image forming medium as a used surface;
A surface identification device comprising:   An image input unit that captures an image of at least a part of one surface of the image forming medium and converts the image data as image data;
  Compression processing means for performing two-dimensional wavelet transform on the image data input to the image input means, and encoding the generated wavelet coefficients for each subband;
  The image was taken when the sum of code amounts for two or more predetermined subbands of the LH subband, HL subband, and HH subband of the encoded data generated by the compression processing means does not exceed a predetermined value. When the surface of the image forming medium is determined to be an unused surface, and the sum of the code amounts related to the two or more predetermined subbands exceeds the predetermined value, the sum of the code amount related to the LH subband and the code amount related to the HL subband is When the code amount related to the HH subband is larger than a predetermined level, the surface of the imaged image forming medium is determined to be an unused surface. Otherwise, the surface of the imaged image forming medium is used. Determination processing means for determining a surface;
A surface identification device comprising: An image forming device for forming an image on an image forming medium;
  5. The surface identification device according to claim 1, wherein a surface of the image forming medium on which an image is to be formed by the image forming device is determined to be a used surface or an unused surface. Have
  2. An image forming apparatus according to claim 1, wherein an image is not formed on the image forming medium by the image forming device when the surface identifying device determines that the surface is a used surface. An image forming device for forming an image on an image forming medium;
  5. The surface identification device according to claim 1, which determines whether a surface of an image forming medium on which an image is to be formed by the image forming device is a used surface or an unused surface;
  An image forming apparatus comprising: means for reversing the front and back of the image forming medium when the surface identification device determines that the surface is a used surface. A transport device for transporting the image forming medium along a predetermined transport path;
  An image forming device for forming an image on the image forming medium conveyed by the conveying device;
  An image forming apparatus comprising the surface identification device according to any one of claims 1 to 4.
  The transport device has a reversing unit that reverses the front and back of the image forming medium in the middle of the transport path,
  When the image forming medium on the conveyance path is again determined as a used surface by the surface identifying device, the image forming device does not form an image on the image forming medium. .

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