JP2009182850A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure sufficient confidentiality, to save toner, to prevent deterioration of consumable components and to reduce paper feed troubles by appropriately determining the shape and a printing position of a see through prevention pattern which makes image data of an original hard to be visible. <P>SOLUTION: This image forming apparatus includes: an image reading part which reads an image formed in the original; a selection part which performs area separation of an area where effective information on the read image exists, and selects an area which should be considered as an area to be kept secret among each area to which the area separation is performed; a pattern determination part which determines the shape of the see through prevention pattern to the selected area and a forming position of the see through prevention pattern; and an image printing part which prints the read image on the rear surface of a first sheet and at the same position as the one where the image is formed, and prints the determined see through prevention pattern on a second sheet based on information on the determined forming position of the see through prevention pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus having a function of analyzing the information type of an image to be printed on a recording sheet and determining the shape and print position of a watermark prevention pattern corresponding to the image to be printed.

  In a copying machine which is a kind of image forming apparatus, when a copy copied on a blank paper is enclosed in an envelope or the like, the contents of the copy may be seen through the envelope from the outside. Therefore, in order to prevent the act of seeing the inside information of the envelope through the light, and to increase the confidentiality of the copy, a method using a specially processed envelope, a method using thick paper, a special pattern on the back Various methods are used, such as a method using a special paper with a mark and a method of printing the entire back surface of a normal recording paper with ink or toner.

  For example, Patent Document 1 proposes an adhesive sheet for overlaying that uses special paper and devise the position of anti-perspective printing in order to increase the secrecy of print information and further reduce paper feeding troubles. Yes. This overlapping sheet is a three-fold concealed postcard in which three pieces of paper are connected. Of the three pieces of paper, the second piece at the center is not subjected to fluoroscopic prevention printing, and the first and third pieces on both sides. By performing anti-perspective printing on the back side different from the information print side of the paper piece, both confidentiality and paper feedability are achieved.

JP 2001-171264 A

  However, the method using a special envelope or paper reduces the degree of freedom in selecting the envelope or paper. Furthermore, the cost of the envelope and the paper itself is high, which causes the cost to increase. Further, in the method of printing in a form in which the entire back surface of ordinary paper is painted, more ink and toner are consumed than printing on the front surface, and deterioration of consumable parts of the printing apparatus is accelerated, resulting in an increase in maintenance cost. Further, in the case of printing with the back surface being filled with ink or toner, the friction between the paper feeding roller and the paper increases after printing on the back surface, which is likely to cause a paper jam due to winding around the roller.

  Further, the sheet described in Patent Document 1 is an effective method for a special paper called tri-fold paper, and it is difficult to apply this method to, for example, a general A4 size white paper. . Further, when the A4 paper is put in the envelope without being folded, it is unclear which position on the back side of the A4 paper should be printed for prevention of fluoroscopy, and the position and shape of the printing for prevention of fluoroscopy to reduce paper feeding troubles. (Size) cannot be determined.

  Therefore, the present invention has been made in view of the above circumstances, and has sufficient confidentiality and consumes even when using commercially available paper without using special envelopes and paper. It is an object of the present invention to provide an image forming apparatus that can save toner, prevent deterioration of consumable parts, and minimize paper feeding trouble.

  The present invention focuses on the fact that document data printed by a digital copying machine is printed after image processing for printing, and mainly distinguishes the character print area and image print area of the document data. The image forming apparatus includes an image printing unit that prints the read image and the determined watermarking prevention pattern on different sheets by performing separation processing. Also, an image analysis unit that generates analysis data of the image information, and a mask image generation that determines the shape and printing position of the watermarking prevention pattern to be printed on the back side opposite to the printing side of the document data based on the analysis data An image forming apparatus including a printing unit.

  According to the present invention, an image reading unit that reads an image formed on a document and a region where valid information of the read image exists are separated into regions, and a region to be concealed among the separated regions. A selection unit for selecting an area; a pattern determination unit for determining a shape of a watermark prevention pattern for the selected area; a formation position of the watermark prevention pattern; and the back side of the first sheet of the read image. The image is printed at the same position where the image was formed, and based on the information on the formation position of the determined watermarking prevention pattern, the determined watermarking prevention pattern is applied to the second sheet. An image forming apparatus including an image printing unit for printing is provided.

  According to this, since the watermarking prevention pattern is printed only on the position of the paper corresponding to the area where the valid information of the document exists, it is sufficiently concealed even with a commercially available paper regardless of the type of the recording paper. Therefore, it is possible to save the amount of toner used to print the watermark prevention pattern, suppress deterioration of consumable parts, and reduce paper feeding troubles.

A binding processing unit that binds the first sheet and the second sheet so that a back surface of the first sheet and a printing surface of the watermark prevention pattern of the second sheet face each other; And a paper discharge unit for discharging the bound sheet bundle.
According to this, since a sheet bundle having sufficient secrecy can be automatically created, the work efficiency of concealing the document can be improved.

Further, the image printing unit generates a mirror image pattern of the watermarking prevention pattern determined by the pattern determination unit, and prints the mirror image pattern on a second sheet.
According to this, the confidentiality of information can be further improved.

  Further, the watermarking prevention pattern is formed in a size including the concealment target area. According to this, secrecy is more reliable.

Further, the cover, the first sheet, and the second sheet are overlapped in this order so that the image printing surface of the first sheet and the printing surface of the watermark prevention pattern of the second sheet face each other. And a binding processing unit for binding and a paper discharge unit for discharging the bound paper bundle.
According to this, it is possible to further enhance the confidentiality of information to be concealed printed on the first sheet, and it is possible to automatically create a sheet bundle having sufficient concealment.

  Further, when the concealment target area is a character area, the watermark viewing prevention pattern is a checkered pattern.

  According to this, it is possible to further save the amount of toner consumed for printing the watermark viewing prevention pattern.

  Further, the present invention provides an image reading step for reading an image formed on a document, and a region where valid information of the read image exists is separated into regions, and a concealment target region among the separated regions A selection step for selecting an area to be performed, a pattern determination step for determining the shape of the watermark prevention pattern for the selected area, and the formation position of the watermark prevention pattern, and the read image on the first sheet Printing on the back surface at the same position where the image was formed, and based on the information on the formation position of the determined watermarking prevention pattern, the determined watermarking prevention pattern is An image forming method characterized by comprising an image printing step for printing on a sheet.

According to the present invention, when copying by a copying machine, a watermark is placed at a specific position determined on a sheet (second sheet) different from a sheet (first sheet) on which an original image is printed. Since the anti-viewing pattern is printed, the toner dielectric amount can be saved, and it is not necessary to use a specially processed paper for preventing the see-through of the watermark.
Further, since the watermarking prevention pattern is printed only on the position of the paper corresponding to the area where the valid information of the document exists, sufficient confidentiality can be ensured by stacking and binding the two sheets. it can.

  In addition, it is rare that an area where valid information exists exists in the entire document, and therefore the watermarking prevention pattern is printed only on a part of the paper, so that toner consumption can be saved and the photosensitive member can be saved. It is possible to reduce deterioration of consumable parts such as drums and to reduce maintenance costs.

  Further, a watermark viewing prevention pattern is printed only on a predetermined area of the second sheet, the cover is overlaid on the front surface of the first sheet, and the surface on which the original of the first sheet is printed (back surface); Since the three sheets are bound together so as to face the surface of the second sheet on which the watermarking prevention pattern is printed, it is possible to create a sheet bundle with better secrecy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by description of the following examples.
<Configuration of image forming apparatus>
FIG. 1 is a block diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus shown in FIG. 1 includes a portion (3, 4) corresponding to a printer that is connected to a computer and forms an image based on image data input from the computer, and a copy that reads image data formed on a document. This is a multifunction machine having the functions of the parts (1, 2) corresponding to the machine (scanner).

The image forming apparatus mainly includes an image data reading unit 1 that reads image data formed on a document, and an image that is stored in the image storage unit 23 after image processing is performed on the image data read by the image data reading unit 1. The processing unit 2, an image printing unit 3 that reads image data from the image storage unit 23 and forms an image on a recording sheet, a user interface (input unit) 5 that inputs information for image processing, and a stapler 6. Consists of including.
The stapler 6 is an apparatus attached to a conventional copying machine or the like, and binds a plurality of printed sheets together.
The stapler 6 corresponds to a binding processing unit, and performs staple processing (binding processing) described later.

The image data reading unit 1 is, for example, an optical document scanning unit that optically scans an image of an original document placed on the original document placement unit on which an original document on which an image is previously formed is placed, and reads image data. Can be used. The image data of the original read by the image data reading unit 1 is transferred to the image analysis unit 21 of the image processing unit 2 and subjected to region separation processing as will be described later. For the reason described later, the document image data is preferably stored in the image storage unit 23 of the image processing unit 2.
Here, the image data formed on the document includes not only so-called image information such as graphics, graphs, and photographs, but also character information such as alphabets, numbers, and kanji, and symbol information.
That is, after reading, the character is also handled as one of the image data.

The image processing unit 2 mainly includes an image analysis unit 21, a mask image generation unit 22, and an image storage unit 23.
The image processing unit 2 performs region separation on regions where valid information of the read image data exists, and determines the shape of the watermark viewing pattern and the formation position of the watermark viewing prevention pattern for each region separated. Part.
Here, the area where valid information exists means an area where characters, symbols, figures, graphs, photographs, etc. exist, and means an area where information that can be visually recognized is printed. In addition, among areas where valid information exists, an area where a large number of character strings are mainly described is referred to as a character area, and an area where a graphic or a photograph is printed is referred to as an image area.
Also, a document portion that is mainly left in the same color as that of the recording paper, in other words, a portion where there is no valid information such as characters and images, is referred to as a background region. The character area and the image area are candidates for the concealment target area, and the background area is a non-confidential area.

The image analysis unit 21 performs a region separation process on the image data read by the image data reading unit 1, and generates analysis data indicating the information type (for example, character region, image region) of the image data for each pixel. It is.
The information type refers to the type of information mainly included in the area separated by the area separation process, and is represented by a numerical value as will be described later. For example, a character area in which character information mainly exists has an information type “1”.
The analysis data is data for each pixel that can identify what type of information of an area where valid information exists, and includes at least an area where a character exists, an area where an image exists, a background area, It is represented by a numerical value (information type value) indicating the information type with distinction. For example, the analysis data of each pixel belonging to the character area is represented by “1”.

The mask image generation unit 22 is a part that generates a watermarking prevention pattern by selecting the shape of the watermarking prevention pattern and determining the arrangement position of the pattern based on the analysis data generated by the image analysis unit 21.
Here, the shape of the watermarking prevention pattern is determined as a set of watermarking prevention pattern generation basic patterns (hereinafter also referred to as basic patterns) previously associated with information types.
This basic pattern is defined in advance for each numerical value of the information type, and the generated analysis data is converted into a basic pattern associated with the numerical value (information type) of the analysis data.
In addition, among the generated analysis data, an area where analysis data indicating a specific information type such as a character area or an image area exists is determined as a formation area of the watermark viewing prevention pattern. In other words, in principle, a watermarking prevention pattern is formed in an area portion where valid information such as a character area exists. However, as will be described later, even in a region where valid information exists, a watermarking prevention pattern is not formed in a region that is not subject to concealment.
Here, an area where analysis data having a numerical value different from the information type value indicating the background area exists is referred to as a concealment target area in which a watermarking prevention pattern is to be formed.
The image printing unit prints the watermark viewing prevention pattern in this concealment target area.

  The image storage unit 23 is a part that stores the watermark viewing prevention pattern generated by the mask image generation unit 22 and the image data of the original read by the image reading unit 1.

  For example, for each pixel of the image data, the image analysis unit 21 determines whether the pixel of interest is a pixel included in the character area or the image area based on the correlation of density information between the pixel of interest and a plurality of adjacent pixels. It is determined whether the pixel is included or a pixel included in another region, and digitized information indicating which region is included for each pixel is generated as analysis data. As a result, the document is separated into several secret areas.

The mask image generation unit 22 mainly includes a table 221, a selector 222, and a select signal generation unit 223.
Here, the table 221 is a portion that stores a basic pattern that is minimum structural unit data of a watermarking prevention pattern. The selector 222 is a part that selects the shape of the watermarking prevention pattern by referring to the basic pattern of the table based on the information of the analysis data generated by the image analysis unit 21.

Selection information indicating which separation region should be a concealment target region is input from the user interface 5 described later. With reference to this selection information, a watermarking prevention pattern is assigned to only a region requiring concealment. The part that generates the select signal is the select signal generator 223. This select signal is given to the selector 222, and the position where the watermarking prevention pattern is to be arranged and the basic pattern to be selected are determined. The select signal is the same as the analysis data in principle, but the analysis data included in the area not to be concealed is converted into other predetermined data and given to the selector 222.
Based on the select signal, the selector 222 generates a watermarking prevention pattern for printing on the back side opposite to the information print side of the recording paper. Thereby, the shape and position of the watermark viewing prevention pattern are determined.

Further, the selection signal generation unit of the mask image generation unit may perform a thinning process of the analysis data before generating the selection signal. In particular, when the shape of the basic pattern corresponding to the analysis data for one pixel is defined with a size corresponding to the size of two or more pixels, the basic pattern is set to the same size as the original document. This is because it is necessary to select.
In this case, when converting the analysis data into the basic pattern, some analysis data is thinned out in consideration of the pixel size of the predetermined basic pattern. Then, the analysis data after the thinning is given to the selector, and only the analysis data after the thinning is converted into the basic pattern for generating the watermark prevention pattern. As a result, the shape of the watermarking prevention pattern having a size corresponding to the size of the area where valid information of the original document exists is determined.

  The image storage unit 23 mainly includes a memory 232 and a memory control unit 231 that controls the memory 232. The memory 232 can be a non-volatile storage element that stores image data. For example, a random access memory (RAM) or a flash memory can be used. The memory 232 controlled by the memory control unit 231 stores the watermark viewing prevention pattern generated by the mask image generation unit 22 and the image data read by the image data reading unit 1.

  Here, the image storage unit 23 is mainly used as a buffer for absorbing a speed difference between the reading speed of the image data reading unit 1 and the printing speed of the image printing unit 3. When there is no speed difference between the two speeds or when the reading speed is surely faster, it is not necessary to store the image data read by the image data reading unit 1 in the image storage unit 23, but the printing speed is faster. In some cases, the printing may pass over the reading of the document. Therefore, it is preferable to store the image data read by the image data reading unit 1 in the image storage unit 23.

The image printing unit 3 mainly includes a memory read control unit 31 that reads out image data to be printed from the image storage unit 23 and a laser writing control unit 32.
The laser writing control unit 32 transfers the image data read from the memory reading control unit 31 to the LSU 4 at an appropriate timing, controls charging of a photosensitive drum (not shown), and writes an electrostatic latent image by an exposure unit. This is a part that executes operation control for forming an image on the photosensitive drum, such as image control and control related to development of the electrostatic latent image.
Further, when reading the watermark viewing prevention pattern for printing in the concealment target area from the image storage unit, the image printing unit 3 reads while generating a mirror image pattern of the watermark viewing prevention pattern determined by the mask image generation unit. Then, using this mirror image pattern, a watermark prevention pattern is printed on the back surface of the recording paper.

  The LSU 4 is a part that performs operation control such as transfer of an image formed on the photosensitive drum to the recording paper and fixing of the image transferred to the recording paper based on an operation command of the laser writing control unit 32. is there.

The user interface 5 corresponds to an input unit through which an operator of the image forming apparatus inputs an operation command or an operation condition. The user interface 5 is, for example, a keyboard and an input button 51 that is set so that each operation command can be input, A touch panel display device 52 including a display is provided.
In particular, the user interface 5 is used to input selection information for selecting a region to be a concealment target region among regions where valid information exists.
Here, the selection information is information given to the mask image generation unit, and is given as a value corresponding to a numerical value indicating the information type. The mask image generation unit uses this selection information to determine the concealment target area. That is, an area where analysis data having an information type that matches the given selection information exists is determined as a concealment target area.

<Outline of Forming Process of Watermarking Prevention Pattern of the Invention>
FIG. 3 is a schematic explanatory diagram of the watermarking prevention pattern forming process according to the present invention.
First, the document image 101 of FIG. 3 is read by the image data reading unit 1 and given to the image analysis unit 21. As described above, the image analysis unit 21 analyzes which part of the document has effective information from the density information for each pixel, recognizes the character area and the image area for each pixel, and divides the area. Analysis data 102 is generated by this region division processing. The generated analysis data 102 is given to the mask image generation unit 22.

The mask image generation unit 22 generates a watermarking prevention pattern 102 at a position corresponding to an area (character area, image area) recognized as an area where valid information exists. The watermark seeing prevention pattern 103 is generated by placing the basic pattern corresponding to the numerical value of the analysis data at the position of the numerical value while referring to the basic pattern stored in the table 221.
However, since the watermarking prevention pattern is actually printed on the back side opposite to the surface on which the document image information is printed, a pattern 104 that mirrors the watermarking prevention pattern 103 is generated. . This mirror image pattern 104 is an actual pattern printed on the back side of the paper.
For example, the mirror image pattern 104 of the watermarking prevention pattern 103 generated in the image area is printed on the back surface of the area where the image data of the document image 101 is printed.

As described above, since the mirror image pattern of the watermarking prevention pattern is printed at a position corresponding to an area where valid information exists, sufficient confidentiality can be ensured.
In general, there are few areas where valid information exists over the entire surface of the document, and some background areas exist. Therefore, by preventing the watermark viewing pattern from being printed in the background area, the amount of toner used for printing the watermark viewing prevention pattern can be reduced, the deterioration of consumable parts can be suppressed, and paper feeding troubles can be reduced. can do.

<Explanation of analysis data>
Here, analysis data generated by the image analysis unit 21 will be described.
The analysis data is digitized data indicating the area where character or image information exists and the type of information of the area in the original image 101 as shown in 102 of FIG. It is data held as numerical information corresponding to each.
FIG. 4 shows a specific example of analysis data.
The analysis data is, for example, numerical information such as 102a in FIG. 4. Here, the background where there is no character or image is indicated by 0, and the area where the characters (A to L) exist is indicated by 1. In addition, a value of 2 is assigned to an area where an image exists, and a value of 3 is assigned to another area, for example, an area where neither a character nor an image is discriminated.

<Description of basic pattern of table>
FIG. 5 shows an example of the basic pattern of the watermark seeing prevention pattern stored in the table 221.
FIG. 5 shows pattern shapes 105 of four basic patterns defined corresponding to four analysis data (0, 1, 2, 3).
For example, the entire surface of the analysis data 0 (background) is a white pattern, and this means that a watermarking prevention pattern is not printed at this position. For analysis data 1 (characters), a pattern is used in which the upper left and lower right basic rectangular portions are black patterns. For the analysis data 2 (image), a pattern in which three regions as shown in the figure are black patterns is used. Further, for the analysis data 3 (others), a black filling pattern is used on the entire surface.
While referring to these four basic patterns, the basic pattern corresponding to the analysis data is selected for each pixel, and the position where the watermarking prevention pattern is arranged and the shape of the watermarking prevention pattern are determined.

  As described above, by using a different basic pattern for each information type value of analysis data, an appropriate watermarking prevention pattern can be formed for each area where valid information exists, and it is effective for the information type. Secrecy is possible. For example, a character portion with a small amount of information can be hidden even with a pattern with a relatively small amount of black, and an image portion with a large amount of information can be hidden by using a pattern with a relatively large amount of black. Become.

<Description of generation and thinning processing of watermarking prevention pattern>
Next, generation of a watermarking prevention pattern and thinning processing will be described.
The selector 222 of the mask image generation unit 22 has a table 221 according to the numerical values (background region 0, character region 1, image region 2, other region 3) indicated by the analysis data (selector signal) generated by the image analysis unit 21. The basic pattern of the corresponding watermarking prevention pattern stored in is selected. As a result, the analysis data is converted into a basic pattern.

FIG. 6 shows an embodiment of processing for selecting a basic pattern of a table from analysis data.
Here, attention is focused on only six pieces of analysis data in the dotted line region among the many pieces of analysis data 102b in the left diagram. Further, the thinning process described later is not considered. It is assumed that 0 and 1 analysis data exist in the dotted line area.
Since the table 221 includes a basic pattern A corresponding to the analysis data 0 and a basic pattern B corresponding to the analysis data 1, the basic pattern A corresponding to the analysis data 0 in the dotted line region is included. And the basic pattern A is arranged at the position of the analysis data 0.
For the analysis data 1 in the dotted line area, the corresponding basic pattern B is selected, and the basic pattern B is arranged at the position of the analysis data 1. As a result, the six pieces of analysis data 102b in the dotted line region in FIG.

By the way, the shape of the basic pattern 105 is composed of a plurality of pixels. For example, if the image data is rectangular image data composed of 4 horizontal pixels × 4 vertical pixels, the data size after conversion to the basic pattern increases. Resulting in. For example, when one pixel of analysis data generated by the image analysis unit 21 is simply replaced with the basic pattern shape 105 of 4 pixels × 4 pixels, the size is increased by 4 times for each length and 16 times as a whole. Image data. This prevents the watermarking prevention pattern from being printed at the intended position. Therefore, a thinning process for deleting some data is performed.
For example, the analysis data 102C generated by the image analysis unit 21 is thinned by the select signal generation unit 223 every 4 pixels horizontally and every 4 lines vertically as shown in FIG. As a result, the necessary number of analysis data (selector signals) to be given to the selector 222 is thinned out, so that a watermark seeing prevention pattern having the same size as the document size can be generated at a position corresponding to the character region of the original document. it can.

FIG. 7 shows a schematic explanatory diagram of an embodiment of the thinning process according to the present invention.
FIG. 7A shows a thinning process for the analysis data in the horizontal direction.
Here, it is assumed that attention is paid to only one horizontal line and eight “1” analysis data corresponding to eight pixels are arranged. In this case, only the first and fifth analysis data from the left are left, and the other six analysis data are deleted. As a result, the eight analysis data are thinned out into two “1” analysis data.
Thereafter, basic pattern selection processing is performed on the two pieces of analysis data “1” after thinning. In this case, each analysis data of “1” is converted into a corresponding basic pattern (4 pixels × 4 pixels), and the original eight analysis data portions have two basic patterns as shown in the figure. This is converted into a watermark prevention pattern arranged in the horizontal direction. Accordingly, a watermark viewing prevention pattern for 8 pixels of the same size in the horizontal direction is formed corresponding to the analysis data for 8 pixels arranged in the horizontal direction.

FIG. 7B shows a thinning process for the analysis data in the vertical direction. Here, it is assumed that only one line in the vertical direction is focused and eight “1” analysis data corresponding to eight pixels are arranged. Here, the thinning-out process is performed in the same way as in FIG.
That is, only the first and fifth analysis data from the upper side are left, and the other six analysis data are deleted.
Thereafter, a basic pattern selection process is performed on the two “1” analysis data after thinning. Thereby, as shown in the figure, a watermarking prevention pattern composed of two basic patterns (4 pixels × 4 pixels) arranged in the vertical direction is formed. Also in this case, in the vertical direction, a watermarking prevention pattern for 8 pixels having the same size as the analysis data for 8 pixels is formed.

<Determination of the area to be concealed>
By the area separation process, areas (character area, image area, etc.) where valid information printed in the document exists are recognized, and these areas are distinguished by the numerical value of the generated analysis data.
In the case where secret information is described in all the recognized areas in this way, all the recognized areas may be concealed and a watermarking prevention pattern may be formed at the positions of those areas.
However, confidential information is not always described in all areas where information exists, and there are areas where there is information that does not have any problem even if known to third parties, such as advertisement texts and design patterns of manuscript paper. In some cases, such a region does not need to be concealed.
Thus, it is considered that it is not necessary to generate a watermarking prevention pattern at the position of the back surface corresponding to the region that does not need to be concealed clearly.
In other words, for areas that are not concealed, it is possible to suppress the consumption of toner and deterioration of consumable parts by preventing the generation of watermark viewing prevention patterns, and to feed paper by reducing the number of patterns printed on the back side. Trouble can be minimized.

Therefore, the select signal generation unit 223 determines whether or not the information existence area (separation area) distinguished by the generated analysis data is to be a concealment target area. The determination of the concealment target area is performed using selection information given from the user interface 5.
As described above, the selection information is information indicating which separation region should be a concealment target region, and the selection information is set by the user using the user interface 5 with his / her own intention. For example, when the user inputs a numerical value (1, 2, or 3) of an area desired to be a concealment target area, this numerical value is set as selection information.
This selection information is given from the user interface 5 to the select signal generation unit 223 as the numerical value of the analysis data to be set as the concealment target area. The select signal generation unit 223 supplies analysis data having the same numerical value as the given selection information to the selector 222 as it is as a select signal.

On the other hand, the analysis data having a numerical value different from the selection information is data corresponding to the non-confidential area, and is therefore replaced with the same value 0 as that indicating the background area and given to the selector 222. The position of the analysis data having the same value 0 as that of the background area is treated as a position where the watermarking prevention pattern is not printed during the printing process of the image printing unit 3. Thereby, even if it is an area | region where valid information exists, according to the selection information given from the user interface 5, it is divided into a confidential object area | region and a non-confidential area.
Since the watermark viewing prevention pattern is not printed on the back surface corresponding to the non-confidential area, it is possible to save toner, prevent deterioration of consumable parts, and reduce paper feeding troubles.

<Mirror image pattern generation processing>
For example, when a watermark prevention pattern 103 as shown in FIG. 3 generated by the mask image generation unit 22 is printed as it is on the back side of the recording paper, the position where the information on the front side exists and the position opposite to the horizontal direction are placed. A watermark prevention pattern is printed. Accordingly, in order to print the watermark prevention pattern on the back surface corresponding to the position where the information on the front surface exists, the mirror image pattern 104 of FIG. 3 must be generated.
Therefore, the memory reading control unit 31 of the image printing unit 3 reads the watermarking prevention pattern from the memory 232 while performing mirror image processing for generating a mirror image pattern.
In the mirror image processing, as will be described later, for example, the watermark viewing prevention pattern may be read from the rear end in the horizontal direction. As a result, a mirror image pattern 104 is generated.
If such a mirror image pattern 104 is generated, the position where the surface information exists and the position where the watermarking prevention pattern is printed can be matched.

  The mirror image pattern 104 of the watermark prevention pattern generated in this way is printed on the back side of the recording paper for copying the original image by the LSU 4 so that the information of the document put in the envelope or the like is seen through the light. Can be protected from threats.

<An Example of Watermarking Prevention Pattern Printing Processing>
Here, a processing flow for printing the watermark prevention pattern will be described.
FIG. 2 shows a schematic flowchart of an embodiment of the printing process of the present invention.
First, in step s1, the image data reading unit 1 reads image data from the document 101 on which information has already been recorded. As a result, digitized document image data having density information is generated, supplied to the image analysis unit 21, and stored in the memory 232 of the image storage unit 23.

  In step s2, the image analysis unit 21 performs region separation processing on the document image data generated in step s1. The region separation process may be performed using the density information of adjacent pixels as described above, but for example, the separation process described in JP-A-10-84482 may be used. By this region separation process, analysis data 102 corresponding to one pixel of the original image data generated in step s1 is generated.

The analysis data is generated as follows, for example.
If it is determined by the region separation processing that a certain pixel is a pixel in the background portion where no information exists, a numerical value of 0 is assigned to that pixel. In addition, a numerical value 1 is assigned to a pixel determined to be character information, a numerical value 2 is assigned to a pixel determined to be image information such as a photograph or a figure, and a pixel determined to be other information such as noise or a ruled line. Assigns the number 3. In this case, since the digitized analysis data is data indicating four information types, it may be stored as 2-bit information per pixel.

  Next, in step s3, the select signal generation unit 223 performs a thinning process on the analysis data generated in step s2. As a thinning method, for example, a simple thinning method can be used in which analysis data is acquired every four pixels in the horizontal direction and every four lines in the vertical direction and other data is discarded. By this thinning process, the analysis data has a data amount of 1/16.

Next, in step s4, whether the value (any one of 1, 2 and 3) indicated by the analysis data generated by thinning out in step s3 matches the value of the confidential object desired by the operator of the image forming apparatus. Judgment is made. That is, the process for determining the concealment target area is performed. This process is also performed by the select signal generator 223.
The value of the target of concealment desired by the operator of the image forming apparatus corresponds to the selection information described above, and is 1 for text information, 2 for image information, and 2 for other information. 3 is a numerical value set in advance by the user interface 5.

In step s4, the numerical value of the analysis data is compared with the numerical value set by the user interface 5. If they match, the value of the analysis data is output as it is, and if they do not match, the value is replaced with a numerical value 0 representing the background and output.
Here, when the concealment target area (numerical value: 2) is input as only the image area, the numerical values (0, 1, 3) other than the image area are replaced with 0.
The output numerical value (numerical value: 2) corresponds to the select signal described above. By this processing, the concealment target area intended by the operator is extracted, and the area where the watermarking prevention pattern is to be printed is specified.
The output select signal is given to the selector 222.

Next, in step s5, processing for converting the analysis data into a watermarking prevention pattern is performed.
Here, the basic pattern shape 105 corresponding to the numerical information indicated by the analysis data output in step s4 is selected from the table 221 storing the basic pattern, which is the minimum structural unit data of the shape of the watermark prevention pattern, The analysis data is converted into the pattern shape 105.
However, the position where the numerical value indicated by the analysis data output in step s4 is 0 is regarded as unnecessary for the watermark viewing prevention pattern, and the pattern data (original image data) having the same color as the background is output without selection from the table. Therefore, only the positions where the numerical values of the analysis data (select signal) given to the selector 222 are 1, 2, and 3 are converted into the corresponding pattern shapes 105. The basic pattern 105, which is the minimum structural unit data of the shape of the see-through prevention pattern, is, for example, a size of 4 horizontal pixels and 4 vertical pixels as shown in FIG. This is image data having a density value composed of pixels.

  Next, in step s 6, the shape data of the watermarking prevention pattern selected and output in step s 5 is written in the memory 232.

  Next, in step s7, it is checked whether printing on the surface of the document on which information is recorded is completed. If the printing has not been completed, the check in step s7 is repeated. After the printing on the front side is completed, the process proceeds to step S8, and printing of the watermark prevention pattern on the reverse side on the opposite side is started.

  Next, in step s8, the shape data of the watermarking prevention pattern recorded in the memory in step s6 is read while performing mirror image processing. The mirror image processing may be performed by a method of reading in reverse order from the rear end of each line that is generally performed. By this mirror image processing, the shape data of the watermark viewing prevention pattern recorded in the memory in step s6 becomes a mirrored pattern that is horizontally reversed like the pattern 104 in FIG.

When the concealment target area is a character area, the watermarking prevention pattern may be a checkered pattern.
According to this, toner consumption can be reduced.

Next, in step s9, all the data read from the original is printed on the back surface of the first sheet 200, and the watermark using the mirrored pattern 104 of the watermark prevention pattern read on the second sheet 201 is used for watermarking. The anti-viewing pattern is printed (see FIG. 9).
The watermarking prevention pattern is formed larger than the selected concealment target area. By doing so, it is possible to sufficiently cover the data printed on the first sheet.

Next, in step s10, when a stapling process (binding process) is instructed, as shown in FIG. 9, the first sheet 200 and the second sheet 201 are stapled by the stapler 6 (step S11). Thereafter, the stapled sheet bundle 202 is discharged.
Here, the first sheet 200 is one in which the data read from the document is printed at the same position as the original document, but the side on which the document data of the first sheet 200 is printed. The first sheet 200 and the second sheet 201 are bound so that the surface (back surface) of the second sheet 201 faces the surface of the second sheet 201 on which the watermark seeing prevention pattern is printed (see FIG. 9).

As another method, a cover sheet may be added, the cover sheet, the first sheet 200, and the second sheet 201 may be stapled, and then the stapled sheet bundle may be discharged.
In this case, the front cover is arranged on the front side different from the image print side of the original of the first sheet 200, and the image print side (back side) of the first sheet and the watermark seeing prevention pattern of the second sheet are set. In order to face the printing surface, the three sheets are overlapped and stapled together.

  By executing the above processing, a watermarking prevention pattern is printed at a position that needs to be concealed, so that sufficient concealment can be secured, toner amount can be saved, and paper feeding trouble can be reduced.

1 is a configuration block diagram of an embodiment of an image forming apparatus of the present invention. It is a schematic flowchart of one Example of the printing process of the watermark prevention pattern of this invention. It is an outline explanatory drawing of formation processing of a watermark seeing prevention pattern of this invention. It is explanatory drawing of one Example of the structure of the analysis data of this invention. It is explanatory drawing of one Example of the basic pattern memorize | stored in the table of this invention. It is explanatory drawing of one Example of the process which forms a watermark seeing prevention pattern from the analysis data and basic pattern of this invention. It is explanatory drawing of one Example of the thinning-out process of the analysis data of this invention. It is explanatory drawing of one Example of the process which determines a watermark seeing prevention pattern from analysis data. It is explanatory drawing of one Example of the paper binding process of this invention.

Explanation of symbols

1 Image Data Reading Unit 2 Image Processing Unit 3 Image Printing Unit 4 LSU
5 User Interface 6 Stapler 21 Image Analysis Unit 22 Mask Image Generation Unit 23 Image Storage Unit 31 Memory Read Control Unit 32 Laser Write Control Unit 51 Input Button 52 Touch Panel Type Display Device 221 Table 222 Selector 223 Select Signal Generation Unit 231 Memory Control Unit 232 memory

Claims (7)

An image reading unit that reads an image formed on a document;
Separate the area where valid information of the read image exists,
A selection unit for selecting a region to be a concealment target region among the separated regions;
A pattern determining unit that determines the shape of the watermarking prevention pattern for the selected region, and the formation position of the watermarking prevention pattern;
Printing the read image on the back side of the first paper at the same position where the image was formed;
An image forming apparatus, comprising: an image printing unit that prints the determined watermarking prevention pattern on a second sheet based on the determined watermarking prevention pattern formation position information. A binding processing unit that binds the first sheet and the second sheet such that the back surface of the first sheet and the printing surface of the watermark prevention pattern of the second sheet face each other;
The image forming apparatus according to claim 1, further comprising a paper discharge unit that discharges the bound sheet bundle.   The image forming apparatus according to claim 1, wherein the image printing unit generates a mirror image pattern of the watermarking prevention pattern determined by the pattern determination unit, and prints the mirror image pattern on a second sheet.   The image forming apparatus according to claim 1, wherein the watermarking prevention pattern is formed in a size including the concealment target area. The cover sheet, the first sheet, and the second sheet are overlapped in this order so that the image printing surface of the first sheet and the printing surface of the watermark prevention pattern of the second sheet face each other. A binding processing unit for binding,
The image forming apparatus according to claim 1, further comprising a paper discharge unit that discharges the bound sheet bundle.   2. The image forming apparatus according to claim 1, wherein when the concealment target area is a character area, the watermark viewing prevention pattern is a checkered pattern. An image reading step for reading an image formed on a document;
Separate the area where valid information of the read image exists,
A selection step of selecting a region to be a concealment target region among the separated regions;
A pattern determining step for determining the shape of the watermarking prevention pattern for the selected region and the formation position of the watermarking prevention pattern;
The read image is printed on the back side of the first paper at the same position as the image is formed, and the determined image is determined based on the determined information on the formation position of the watermarking prevention pattern. And an image printing step for printing the watermark prevention pattern on the second sheet.

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