an embodiment of the present invention is described below with reference to fig1 to fig7 . fig1 is a block diagram showing basic components of an information reading apparatus of an embodiment . this information reading apparatus photographs an information recording medium having information recorded thereon ( for example , a paper medium such as a document ) and reads the information . a control section 1 serving as the core of the apparatus operates with power supply from a power supply section 2 , and has a central processing unit which controls an entire operation of the information reading apparatus by following various programs in a storage section 3 , a memory , etc . the storage section 3 has , for example , a program memory 3 a where programs depicted in flowcharts of fig6 and fig7 described below , various applications , etc . are stored , and a work memory 36 which temporarily stores various information required for the information reading apparatus to operate ( for example , a flag ). the storage section 3 may be structured to include a recording medium such as an sd card , and may include a storage area on another server apparatus ( omitted in the drawing ) side . an operation section 4 in fig1 includes , although omitted in the drawing , a power supply key which is a press - button key for turning power supply on / off . the control section 1 performs processing in accordance with an input operation signal corresponding to an operation key which is outputted from the operation section 4 . a touch display section 5 is structured to have a display panel 5 a with a touch panel 5 b laminated thereon . an imaging section 6 , which constitutes an image reading function , is a digital camera section capable of photographing a subject with high definition by forming a subject image from an optical lens onto an imaging element ( such as a ccd ( charge - coupled device ) or a cmos ( complementary metal - oxide semiconductor ), and has an imaging lens , an imaging element , various sensors , an analog processing section , a digital processing section , and the like omitted in the drawing . a wireless lan ( local area network ) communicating section 7 is a wireless communication module capable of high - speed large - capacity communication , and is capable of being connected to the internet via a nearby wireless lan router ( omitted in the drawing ). fig2 is an external perspective view of the information reading apparatus , depicting a state in which a paper medium is read by the information reading apparatus . the information reading apparatus is structured to have a tablet device 11 and a paper medium 12 mounted on a double - open binder 10 , and is basically synonymous with the tablet device 11 . the binder 10 is structured to have a first housing 10 a and a second housing 10 b mounted thereon via a hinge section 10 c so as to be openable to be in an opened state . the first housing 10 a and the second housing 10 b are openable and closable from a state of being opened at 180 degrees to a state in which the second housing 10 b has been placed on the first housing 10 a ( completely closed state ). the touch display section 5 and the imaging section 6 of the tablet device 11 are placed to be positioned on the front surface side of the tablet device 11 . also , the imaging section 6 is placed to be positioned at the center of one end on the front surface side ( in the example depicted in the drawing , at the center of the left end on the front surface ). when an angle formed by the first housing 10 a and the second housing 10 b becomes in a predetermined angle range , the tablet device 11 obtains , as a read image , an image obtained by photographing the entire paper medium 12 mounted on the first housing 10 a . for example , in a state where the first housing 10 a has been placed on the surface of a table or the like , when an angle at which the second housing 10 b obliquely stands , that is , a standing angle of the second housing 10 b comes within a predetermined angle range , the paper medium 12 is photographed . specifically , when an optimum angle suitable for photographing the paper medium 12 is , for example , 70 degrees , and a standing angle of the second housing 10 b comes within a photographing angle range including predetermined angles ( 65 degrees to 75 degrees ) which are close ( plus or minus 5 degrees ) to the optimal angle , the paper medium 12 is photographed . also , conversely to the above - described case , it can be utilized such that the first housing 10 a obliquely stands with the second housing 10 b being placed on the surface of a desk and the like . the paper medium 12 is a medium having information written thereon from which characters , diagrams , tables , etc . are optically read out . for example , the paper medium 12 is a notebook , a report paper sheet , or a book . however , it is not limited to materials made of paper , and may be any photographic subject having information thereon , which includes electronic paper capable of electronically displaying information . fig3 a to fig3 d are diagrams each describing a judging method for judging whether the paper medium 12 is in a two - page spread layout . fig3 a is a diagram depicting a state in which a page of the paper medium 12 obtained by bundling a plurality of sheets and securing the upper - right corners of these sheets with a paper clip or the like ( hereinafter referred to as a one - point - secured - type document ) is being turned . in a live view image obtained by photographing this one - point - secured - type document whose one corner of the sheets has been secured and page is being turned , a change of the image at the time of page turning significantly appears in the vertical direction and the rightward direction . that is , as depicted in fig3 b , an image change area b where the image is partially straying off a sheet area a of the document by page turning ( a page being turned ) significantly changes in the vertical direction and the rightward direction . fig3 c is a diagram depicting a state where a page of a two - page - spread - type document having left and right pages such as a notebook and serving as the paper medium 12 is being turned . in a live view image obtained by photographing this two - page - spread - type document whose page is being turned , the image change area b where the image is partially straying off the sheet area a of the document by page turning ( a page being turned ) is hardly present in the horizontal direction , and is slightly large in the vertical direction , as depicted in fig3 d . thus , in the present embodiment , since a change of an image at the time of page turning varies according to the document format ( the one - point - secured - type document or the two - page - spread - type document ) and a change of the sheet area a in the rightward direction is significant , whether or not the image change area b is straying onto the right side of the sheet area a is used as a criterion for document format judgment . fig4 a and fig4 b are diagrams for describing another judging method for judging whether the paper medium 12 is in a two - page spread layout . fig4 a is a diagram depicting a state in which a page of a one - point - secured - type document is being turned , as with fig3 a . in a live view image obtained by photographing this one - point - secured - type document whose page is being turned , a change of the image at the time of page turning appears by a change of document content on the next page ( subsequent page ) in the diagonally upper direction ( the arrow direction in the drawing ). fig4 b is a diagram depicting a state in which a page of a two - page - spread - type document is being turned , as with fig3 c . in a live view image obtained by photographing this two - page - spread - type document whose page is being turned , a change of the image at the time of page turning appears by a change of document content on the next page ( subsequent page ) in the horizontally - straight rightward direction ( the arrow direction in the drawing ). thus , in the present embodiment , since a changing direction of document content on a next page ( subsequent page ) at the time of page turning varies according to the document format , the changing direction of the document content is used as a criterion for document format judgment . fig5 a and fig5 b are diagrams for describing still another method for judging whether the paper medium 12 is in a two - page spread layout . fig5 a is a diagram depicting a state when the page turning of a one - point - secured - type document is started . in a live view image obtained by photographing the state when the page turning of the one - point - secured - type document is started , since the entire page is slightly bent , warped , or shifted due to page turning , the image change area b where the document content is being changed is an area approximately similar to the sheet area a of the document ( the area surrounded by the broken line in the drawing ). fig5 b is a diagram depicting a state when the page turning of a two - page - spread - type document is started . in a live view image obtained by photographing the state when the page turning of the two - page - spread - type document is started , when the left page of the two page spread is started to be turned , the entire page is slightly bent , warped , or shifted , but this change does not occurs on the right page . therefore , the image change area b where the document content is being changed is the left - half area of the sheet area a of the document ( the area surrounded by the broken line in the drawing ). thus , in the present embodiment , since the size of the image change area b where document content is being changed at the start of page turning with respect to the sheet area a varies according to the document format , the size of the image change area b is used as a criterion for document format judgment . as described above , in the present embodiment , the control section 1 makes judgments according to the plurality of judgment methods , that is , the method of making a judgment based on whether the image change area b is straying onto the right side of the sheet area a , the method of making a judgment based on whether the changing direction of document content on a next page ( the subsequent page ) at the time of page turning is the horizontally - straight rightward direction , and the method of making a judgment based on whether the image change area b is the left - half area of the sheet area a . here , whether or not the paper medium 12 is in a two - page spread layout is judged by judgments being sequentially made according to the plurality of judging methods in a predetermined priority order . next , the operation concept of the information reading apparatus of the present embodiment is described with reference to flowcharts depicted in fig6 and fig7 . here , each function described in the flowcharts is stored in a readable program code format , and operations based on these program codes are sequentially performed . also , operations based on the above - described program codes transmitted over a transmission medium such as a network can also be sequentially performed . that is , the unique operations of the present embodiment can be performed using programs and data supplied from an outside source over a transmission medium , in addition to a recording medium . note that these flowcharts in fig6 and fig7 outline operations of the characteristic portion of the present embodiment from among all of the operations of the information reading apparatus . after exiting the flows in fig6 and fig7 , the procedure returns to the main flow ( not shown ) of the overall operation . fig6 is a flowchart for describing an operation ( characteristic operation of the embodiment of the present invention ) that is started when a document page - turning photographing mode is specified in response to the switching of an operation mode by a user operation . first , the control section 1 activates the imaging section 6 in response to the switching of the current mode to a document page - turning photographing mode so as to start a photographing operation ( step a 1 ), obtains a photographed image from the imaging section 6 , and temporarily stores the image in the work memory 3 b ( step a 2 ). then , the control section 1 obtains the photographed image as a preview ( live view ) image ( step a 3 ), and identifies the sheet area a of the document while detecting a contrast ratio and detecting a rectangular area by analyzing this preview image ( step a 4 ). then , the control section 1 obtains another preview image from the imaging section 6 ( step a 5 ), compares the previously - obtained preview image and the currently - obtained preview image ( step a 6 ), and thereby judges whether there is a change in the image content ( step a 7 ). when a change is detected in the images ( yes at step a 7 ), the control section 1 judges that the page is being turned , and temporarily stores the change detail in the work memory ( step a 8 ). next , the control section 1 judges whether or not the document page - turning photographing mode has been released and an instruction for ending the photographing has been provided ( step a 9 ). when the current mode is still the document page - turning photographing mode ( no at step a 9 ), the control section 1 returns to step a 5 above and obtains a preview image from the imaging section 6 . hereafter , the control section 1 repeats an operation of temporarily storing a change detail every time a change in images is detected ( until the page turning is over ) ( step a 5 to step a 8 ). when a change in the images is not detected ( no at step a 7 ), the control section 1 judges that the page turning is over , and proceeds to step a 10 . then , the control section 1 reads out the photographed image temporarily stored in the work memory 3 b as a previously photographed image , compares the currently obtained preview image and the previously photographed image , and judges whether there is a change in the image content ( step a 11 ). when there is no change in the image content ( no at step a 11 ), the control section 1 judges that there is not a change due to page turning in the images , and proceeds to step a 13 . then , the control section 1 performs processing for clearing the change detail temporarily stored in the work memory 3 b , returns to step a 9 , and judges whether the document page - turning photographing mode has been released . on the other hand , when a change of the image content is detected as a result of the currently - obtained preview image being compared with the previously photographed image ( yes at step a 11 ), the control section 1 judges that there is a change due to page turning in the images , and proceeds to processing for storing a page image according to a document format ( step a 12 ). then , after performing processing for clearing the temporarily stored change detail ( step a 13 ), the control section 1 returns to step a 9 , and judges whether the document page - turning photographing mode has been released . fig7 is a flowchart for describing the processing for storing a page image according to a document format ( step a 12 of fig6 ) in detail . first , the control section 1 refers to the work memory 3 b where details of a change in images at the time of read page turning are sequentially stored ( step b 1 ) so as to analyze the change state in the images , and thereby judges whether an area in the images ( the page being turned ), that is , the image change area b is straying onto the right side of the sheet area a of the document by an amount equal to or larger than a predetermined threshold , as depicted in fig3 a and fig3 b ( step b 2 ). when the image change area b is straying onto the right side of the sheet area a by an amount equal to or larger than the threshold ( yes at step b 2 ), as depicted in fig3 a and fig3 b , the control section 1 judges that a page of a one - point - secured - type document is being turned , and records and stores the entire photographed image as one - image - per - page data ( step b 3 ). then , after clearing the photographed images temporarily stored in the work memory 3 b ( step b 4 ), the control section 1 exits the flow of fig7 . on the other hand , when the image change area b is not significantly straying onto the right side of the sheet area a ( no at step b 2 ), the control section 1 judges that there is a possibility that a page of a two - page - spread - type document is being turned , and judges whether the changing direction of the document content is a horizontally - straight rightward direction ( step b 5 ), as depicted in fig4 b . when the changing direction is not a horizontally - straight rightward direction ( no at step b 5 ), the control section 1 judges that there is a possibility that a page of a one - point - secured - type document is being turned , and judges whether the change area of the document content is the left - half area of the sheet area a ( step b 6 ). when the changing direction is not a horizontally - straight rightward direction ( no at step b 5 ) and the image change area b is not the left - half area of the sheet area a ( no at step b 6 ), the control section 1 judges that a page of a one - point - secured - type document is being turned , and proceeds to processing for recording and storing the entire photographed image as data of one page ( step b 3 ). on the other hand , when the changing direction is a horizontally - straight rightward direction ( yes at step b 5 ) or the image change area b is the left - half area of the sheet area a ( yes at step b 6 ), the control section 1 judges that a page of two - page - spread - type document is being turned , and performs processing for dividing the sheet area a into left and right pages with the center line in the longitudinal direction as a boundary ( step b 7 ). with left and right areas obtained by this bisection as independent left and right pages , the control section 1 causes the left page and the right page to be independently stored and recorded ( step b 8 ). then , after clearing the photographed images temporarily stored in the work memory 3 b ( step b 4 ), the control section 1 exits this flow of fig7 . as described above , in the present embodiment , the control section 1 analyzes a photographed image obtained by photographing an entire document serving as the paper medium ( information recording medium ) 12 by the imaging section 6 , and thereby judges whether the paper medium 12 is in a two - page spread layout . when the paper medium 12 is in a two - page spread layout , the photographed image is divided into the pages of a two - page spread . as a result of this configuration , even when the entire paper medium 12 in a two - page spread layout is photographed at one time , one page can be processed as one image . this can save a bothersome editing work of dividing a photographed image of a two - page spread by a user operation , and can efficiently process continuously - photographed images of a book or the like for each page . also , the control section 1 compares images sequentially photographed when a page of the paper medium 12 is being turned , detects a change of the image content , and judges whether the paper medium 12 is in a two - page spread layout based on the change of the image content . as a result of this configuration , whether the paper medium 12 is in a two - page spread layout can be judged from the status of page turning . moreover , the control section 1 compares images sequentially photographed at the time of page turning , detects an area straying in a page - turning direction of the paper medium 12 as a change of the image content , and judges whether the paper medium 12 is in a two - page spread layout based on the stray area . as a result of this configuration , a two - page spread can be accurately and stably judged from the status of page turning . furthermore , the control section 1 judges that the paper medium 12 is in a two - page spread layout when the size of an area straying in the page - turning direction of the paper medium 12 is larger than a predetermined value . as a result of this configuration , a two - page spread can be further accurately judged . still further , the control section 1 compares images sequentially photographed at the time of page turning , detects whether there is a change in the page - turning direction as a change of the image content , and judges whether the paper medium 12 is in a two - page spread layout based on whether there is a change in the page - turning direction . as a result of this configuration , a two - page spread can always be accurately and stably judged from the status of page turning . yet still further , the control section 1 compares images sequentially photographed at the time of page turning , detects whether a change during the page turning has occurred in a substantially entire area or a substantially half area of the paper medium 12 , and judges whether the paper medium 12 is in a two - page spread layout based on the size of the change area . as a result of this configuration , a two - page spread can always be accurately and stably judged from the status of page turning . yet still further , the control section 1 sequentially makes judgments according to the plurality of judging methods in the predetermined priority order to judge whether the paper medium 12 is in a two - page spread layout . as a result of this configuration , a double - page spread can be further accurately judged . yet still further , the control section 1 divides a photographed image into two , that is , left and right pages with the center as a boundary along a folding portion ( longitudinal center line ) l 1 between pages . as a result of this configuration , right and left pages can be accurately obtained from a two - page spread . in the above - described embodiment , the plurality of judgment methods include , for example , the method of making a judgment based on whether the image change area b is straying onto the right side of the sheet area a , the method of making a judgment based on whether the changing direction of the document content of a next page ( subsequent page ) at the time of page turning is a horizontally - straight rightward direction , and the method of making a judgment based on whether the image change area b is the left - half area of the sheet area a . however , the present invention is not limited thereto . for example , the judging method depicted in fig8 may be used . that is , in the above - described embodiment , whether the paper medium 12 is in a two - page spread layout is judged based on the status of page turning . however , a configuration may be adopted in which a photographed image of the paper medium 12 is analyzed to detect the form and the warping status of the paper medium 12 and whether the paper medium 12 is in a two - page spread layout is judged based on the detected form and warping status . for example , a configuration may be adopted in which the paper medium 12 is judged to be in a two - page spread layout based on the fact that the folding portion ( longitudinal center line ) l 1 between pages in a two - page spread is present , the fact that the layout ( sheet form ) is such that a horizontal line l 2 is horizontally symmetrical with respect to the folding portion ( longitudinal center line ) l 1 , or the fact that a horizontally symmetrical warp l 3 with respect to the folding portion ( longitudinal center line ) l 1 is present . as a result of this configuration , a two - page spread can be judged even without page turning . also , in the above - described embodiment , when the paper medium 12 is judged to be in a two - page spread layout , the photographed image is divided into the pages of the two - page spread . however , in addition , the photographed image may be analyzed to further judge the orientation of the paper medium 12 and perform rotation control so that the orientation of each page data obtained by the division coincides with the orientation of the paper medium 12 . in this case , since there is a high possibility that the upper portion of the image of a two - page - spread - type document corresponds to the upper portions of the sheets as depicted in fig9 a and the upper or right portion of the image of a one - point - secured - type document whose upper - right corners of the sheets have been secured corresponds to the upper portions of the sheets as depicted in fig9 b , the orientation of sheets can be judged together with the document format . as a result of this configuration , for example , the entire processing efficiency can be improved as compared with a method of using a character recognition function to judge an orientation of the sheet from a character direction . moreover , in the above - described embodiment , judgments as to whether the paper medium 12 is in a two - page spread layout are sequentially made according to the plurality of judging methods in the predetermined priority order . however , a configuration may be adopted in which , when a desired judging method is selected by a user operation , this judging method is used to judge whether the paper medium 12 is in a two - page spread layout . by using this configuration where a judging method can be selected , even unique page turning can be supported , and a judgment can be accurately made . furthermore , in the above - described embodiment , a judgment is made according to whether the image change area b is straying onto the right side of the sheet area a . however , a configuration may be adopted in which a judgment is made according to whether the image change area b is straying onto the right side and the upper side of the sheet area a . still further , in the above - described embodiment , when the image change area b is not straying onto the right side of the sheet area a by an amount equal to or larger than the threshold , it is judged that there is a possibility that a page of a two - page - spread - type document is being turned , and it is judged whether the changing direction of the document content is a horizontally - straight rightward direction or whether the change area of the document content is the left - half area of the sheet area a . however , how these methods are combined for judgment may be arbitrarily changed . also , a configuration may be adopted in which a two - page spread is judged when all conditions of the plurality of judging methods are satisfied , or a configuration may be adopted in which a two - page spread is judged when at least one of the conditions of the plurality of judging methods is satisfied . yet still further , in the above - described embodiment , a photographed image is divided into left and right pages at the center of the sheet . however , a configuration may be adopted in which a photographed image is divided into upper and lower pages at the center of the sheet area . in addition , the number of the division is not limited to two . for example , the number of the division may be three , as long as the division is on a page basis . yet still further , in the above - described embodiment , a one - point - secured - type document obtained by bundling a plurality of sheets and securing the upper - right corners of these sheets with a clip or the like is exemplarily described . however , the position to be secured with a clip or the like is not limited to the upper - right corner of the sheet , and may be the upper - left corner or the center upper - end portion . yet still further , in the above - described embodiment , a photographed image is divided into left and right pages at the center of the sheet and these left and right pages are each recorded and stored . however , a configuration may be adopted in which , in the case of a two - page - spread - type document , when only one page is a printed page or a hand - written page and the other page is blank , the blank page is excluded and only the printed or hand - written page is extracted to be recorded and stored . yet still further , in the above - described embodiment , the information reading apparatus is structured such that the tablet device 11 and the paper medium 12 are mounted on the double - open binder 10 . however , the present invention is not limited thereto , and the structure may be arbitrarily determined . for example , a structure may be adopted in which the imaging section is mounted on a support pole or the like to photograph the paper medium 12 from diagonally above . yet still further , in the above - described embodiment , the tablet device 11 is described as an information reading apparatus of the present invention . however , the present invention is not limited thereto , and the information reading apparatus may be , for example , a personal computer , pda ( personal digital assistant ), or smartphone equipped with a camera , or a digital camera . yet still further , the “ devices ” or the “ sections ” described in the above - described embodiment are not required to be in a single housing and may be separated into a plurality of housings by function . in addition , the steps in the above - described flowcharts are not required to be processed in time - series , and may be processed in parallel , or individually and independently . while the present invention has been described with reference to the preferred embodiments , it is intended that the invention be not limited by any of the details of the description therein but includes all the embodiments which fall within the scope of the appended claims .