JP2008072753A - Image reading apparatus, method for detecting black pixel, and method for detecting blank sheet of original - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein blank sheets of an original cannot be detected efficiently and highly precisely, depending on the utilization environment. <P>SOLUTION: Thresholds corresponding to respective line density levels are stored in a RAM 9, in advance; the line density level set in reading an original is discriminated by a line density level discriminating section 14; and the blank sheet detection is performed, switching to the threshold corresponding to the line density level by a threshold selecting section 15 and a setting section 16. The thresholds, corresponding to the line density levels and stored in the RAM 9, are changed by a change instruction by a user or automatically changed, based on the number of black pixels read from an original having a large number of white parts which the user would have liked them to be regular originals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that scans a document and reads image data from the document, such as a facsimile machine, a scanner connected to a computer, or a copying machine with an automatic document feeding function. The present invention relates to an image reading apparatus suitable for efficient and highly accurate detection, a black pixel search method, and a blank document detection method.

  In an image reading apparatus such as a facsimile machine, a scanner connected to a computer, or a copying machine with automatic document feeding function, when setting a document to be read, the front and back sides of the document are determined according to the reading position of the image sensor. ing. In the following, a blank manuscript with information on the front side and nothing on the back side is targeted. When such a document is set upside down, blank image information and a copy are output. As a result, communication costs and recording paper are wasted.

  As a prior art for solving such a problem, for example, there is one described in Patent Document 1 or the like. However, in the technique described in Patent Document 1, in an image reading apparatus such as a facsimile machine, when it is determined whether or not a read document is blank, one line of image data is composed of white for one page. The original is determined to be blank. For this reason, if the data read from the image sensor includes dust-like data due to the performance of the image sensor, it cannot be determined to be blank even though it is actually a blank document.

  For example, the technique described in Patent Document 2 as a conventional technique is such that, in a facsimile apparatus or the like, in the case of memory transmission, the number of effective dots (black pixels) of each image information once stored in the memory is less than a predetermined value. If the number of effective dots (black pixels) in the image information is not more than a predetermined value, the message is judged to be set upside down, and in the case of real-time transmission Is output.

  However, in this technique, when a large number of originals are set in the facsimile apparatus, it takes time to decide whether or not to transmit. That is, even in the case of real-time transmission, the predetermined number of pages may be reached on the last page, and in this case, the same time as memory transmission is required. As a result, the user of the facsimile apparatus must monitor without leaving the facsimile apparatus until the reading operation for all the originals is completed in order to confirm whether or not the normal reading has been performed. Is not efficient.

  Japanese Patent Application Laid-Open No. 2004-228867 describes a technique for counting the number of black pixels for each line or the like to determine whether or not the document is a blank document, and deleting the image data if the document is a blank document. . The blank document detection mechanism of the image reading apparatus, including such a blank document detection technique, is conventionally fixed, and the user can select any blank document detection mechanism according to the usage environment of the apparatus. Is not efficient.

Japanese Patent Laid-Open No. 5-48835 JP-A-6-261168 JP-A-10-229484

  The problem to be solved is that the conventional technique cannot detect a blank original document with high accuracy and efficiency.

An object of the present invention is to solve these problems of the prior art, improve the performance and reliability of a facsimile apparatus, a scanner apparatus, etc., and improve the convenience, and its black pixel search And a blank document detection method.

  In order to achieve the above object, the image reading apparatus of the present invention stores a threshold value associated with each line density in advance, discriminates a document reading line density, and a threshold value corresponding to the line density. To detect a blank document. In this image reading apparatus, a threshold value associated with each line density stored in the storage unit is displayed, and the displayed threshold value for each line density is changed based on an instruction from the user.

  At this time, the threshold value changing operation of the user is facilitated by displaying the counted number of black pixels of the document. Alternatively, the user reads a document with many white portions that he wants to use as a normal document, and the threshold value corresponding to the line density is automatically changed by the number of black pixels.

  Further, the threshold value is stored in association with not only the line density but also the reading mode selected when the document is composed of a line drawing or a halftone, and based on the optimum threshold value for the selected reading mode, Perform detection.

  In the black pixel search method of the image reading apparatus of the present invention, one main scanning line is divided into four blocks, and one block is set as a reading target range of each line, and the next line is a block next to the previous line. A black pixel is searched for every other byte in each block, and the search start address of each block is alternately set to odd and even every four lines. A black pixel is detected for. It should be noted that isolated dots of 1 dot and 2 dots in one byte to be searched are regarded as erroneous detection due to dust of the image sensor and are not counted as black pixels.

  In addition, there are a plurality of procedures for counting (counting) the number of black pixels for each line density and each document reading mode, and the number of black pixels is counted by switching the procedure according to the selected line density and reading mode.

  Further, even when it is determined that the document is a blank document, if the user supports forced transmission, the threshold value is changed to a new threshold value based on the number of black pixels at that time. For example, after a predetermined number of forced transmissions, the average value is changed. This change is made based on user confirmation.

In addition, the image reading apparatus and its blank document detection method according to the present invention have a first detection function (outputting a detection result if even one sheet is determined to be a blank document), a second detection function (a predetermined number of sheets). Wait until output of detection results until a blank document is determined), and a third detection function (the detection result is not output unless all documents are determined as blank documents). Is selected. As a result, the user can select an optimal blank document detection function according to the document, and the performance and convenience of the apparatus are improved. Further, when notifying the user, the operation is stopped, and the user is made to select whether to repeat the operation or continue the process, and perform a process according to the selection.
This further improves the convenience of the apparatus.

  According to the present invention, by automatically changing the threshold value according to the line density, it is possible to detect a blank document with high accuracy according to the use environment of the apparatus.

  Also, in an image reading apparatus equipped with an automatic double-sided document feeder, it is possible to detect a blank document with high accuracy according to the usage environment of the apparatus by automatically changing the threshold value according to the line density. Therefore, it is possible to avoid re-reading the image data by erroneously detecting a blank original and inverting the original.

  Further, it is possible to avoid useless output of a blank original in the image reading apparatus provided with the automatic duplex original feeder.

  In addition, since the user can change the threshold value for each line density, it is possible to detect a blank document with an optimum threshold value according to the type of document used by the user.

  Further, since the threshold value for each set linear density is displayed, the user can make the change more accurately and easily.

  Further, it is possible to automatically change the threshold value for each type of document and for each linear density.

  Further, not only the line density but also the threshold value for each reading mode such as halftone can be changed and set, so that a more accurate blank document can be detected.

  In addition, by making it possible for the user to perform a judgment operation, it is possible to avoid useless output of a blank document and useless rereading operation in the image reading apparatus, and to read and Output is possible.

  In addition, the threshold value can be automatically changed to the number of black pixels when the user forcibly outputs, and subsequent reading and output of a similar document is facilitated.

  Further, by obtaining the change of the threshold value based on the forced output by an average over a plurality of times, accurate detection of a blank original can be stabilized.

  In addition, by allowing the user to select and instruct execution of the threshold value change based on the forced output, it is possible to avoid a bad influence on the detection of a blank document with respect to a normal document by a special document.

  In addition, by allowing the user to select a blank document detection decision timing from a plurality of options, the user can select the optimal blank document detection function according to the document, improving the performance and convenience of the device. To do.

  Further, when the user detects a blank document, the operation of the apparatus can be stopped and the user can select whether to repeat the operation or continue, further improving the convenience of the apparatus.

  Further, the processing time can be shortened, and the black pixel search in the image reading apparatus can be made efficient.

  Further, the calculation of dust-like black pixels can be avoided, and the black pixel search in the image reading apparatus can be further improved in accuracy and efficiency.

  Further, the black pixel search in the image reading apparatus can be performed with high accuracy by performing the black pixel search according to the procedure for each reading mode.

  Further, the black pixel search in the image reading apparatus can be performed with high accuracy by performing the black pixel search according to the procedure for each line density.

  Further, by allowing the user to select a blank document in the image reading apparatus from a plurality of procedures, it is possible to detect a blank document with high accuracy for each document.

  In addition, when detecting a blank document in the image reading apparatus and notifying the user, it is possible to stop the operation of the apparatus so that the user can select whether to repeat the operation or continue the processing, thereby improving the convenience of the apparatus. It becomes.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a configuration according to the present invention of an image reading apparatus of the present invention.

  The image reading apparatus of this example is a facsimile machine, and includes a scanner 1, an encoding / decoding unit 2, an image memory 3, a plotter 4, an operation display unit 5, a switch (denoted as “SW” in the figure) 6, a CPU (Central A processing unit (ROM) 7, a read only memory (ROM) 8, a random access memory (RAM) 9, a modem 10, and a network control unit 11 are connected via a bus 12.

  The scanner 1 is composed of a CIS (Contact-type Image Sensor) or the like and reads a document. The encoding / decoding unit 2 encodes image data of a document read by the scanner 1 and decodes received image data. The image memory 3 stores image data read by the scanner 1 and received image data.

The plotter 4 prints out the received image data, the image data read for copying by the scanner 1, and the like. The operation display unit 5 includes a one-touch key, an LCD (Liquid Crystal Display), and the like, and is used for interactive input / output processing with the user.
The switch 6 includes a power switch and a cover switch.

The CPU 7 controls the overall operation of the facsimile apparatus including processing related to the blank original detection operation of the present invention.
The ROM 8 stores an operation program of the CPU 7 and the like.
The RAM 9 stores data generated by the CPU 7 and the like.

The modem 10 performs modulation processing and demodulation processing of image data transmitted and received by the facsimile apparatus.
The network control unit 11 performs connection control with a partner apparatus via a telephone line.
In the facsimile apparatus having such a configuration, the blank document detection system according to the present invention as shown in FIG.

FIG. 2 is a block diagram showing a first system configuration example of the portion of the facsimile apparatus shown in FIG. 1 that performs blank document detection according to the present invention.
The blank document detection system of the first example includes a scanner 1, an operation display unit 5, a RAM 9, a threshold control processing unit 13 including a CPU 7, a ROM 8, a RAM 9, and the like, and a document determination unit 17.

  The threshold control processing unit 13 includes a line density determination unit 14, a threshold selection unit 15, and a setting unit 16, and the line density determination unit 14 determines the line density designated by the user via the operation display unit 5. Then, the threshold selection unit 15 is notified. The threshold selection unit 15 refers to a list of threshold values of the number of black pixels for each line density registered in the RAM 9 in advance, and the number of black pixels corresponding to the line density notified from the line density determination unit 14 Is specified and notified to the setting unit 16. The setting unit 16 stores the threshold value of the number of black pixels notified from the threshold value selection unit 15 using the RAM 9.

  The document discriminating unit 17 includes a pixel number counting unit 18 and a comparison / discrimination unit 19. The pixel number counting unit 18 counts the number of black pixels of the image data read by the scanner 1 and compares the result with the comparison / discrimination unit 19. Notify The comparison / determination unit 19 compares the number of black pixels notified from the pixel number counting unit 18 with the threshold value of the number of black pixels stored by the setting unit 16, and the image data read by the scanner 1 is a blank document. It is determined whether or not.

A processing operation according to the present invention of the facsimile apparatus of FIG. 1 having such a blank sheet original detection system will be described with reference to FIG.
FIG. 3 is a flowchart showing an example of blank document detection processing operation according to the present invention of the facsimile apparatus in FIG.

When starting to read a document, the user selects one line density from several types of read line densities (step 301).
From the selected line density, the blank sheet detection threshold value corresponding to each line density registered in advance in the RAM 9 of FIG. 1 is read (step 302), the document is read (step 303), and the number of black pixels is detected. (Step 304).

  When the reading is finished (step 305), the detected number of black pixels is compared with the threshold value read from the RAM 9 at step 302 (step 307), and the number of black pixels of the read original is compared. Is smaller than the threshold value read from the RAM 9, a blank sheet detection flag is set in the RAM 9 (step 308), and it is determined that a blank document has been read (step 309). If the read document black pixel count is larger than the threshold value read from the RAM 9, the blank sheet detection flag in the RAM 9 is reset (step 310), and it is determined that a normal document is read (step 311).

  When the flag in the RAM 9 is set, the CPU 7 in FIG. 1 notifies the user that the blank document has been read via the display unit and the buzzer of the operation display unit 5, and reads from the document. Storage of image data in the image memory 3 and communication via the modem 10 and the network control unit 11 are interrupted. Alternatively, such interruption is not performed, and it is only necessary to warn the user that a blank original has been read via the display unit or buzzer of the operation display unit 5.

Next, the black pixel search technique according to the invention will be described with reference to FIGS.
4 and 5 are explanatory diagrams showing an example of black pixel search processing according to the invention.
The original is read line by line by CIS or the like, and black pixels in the image transferred to the line buffer are sampled (searched) as follows.

First, one block obtained by dividing one main scanning line into four is set as a sampling target range of the line, and sampling is performed every other byte in the target block.
For the next line, the block next to the block that is the target range in the previous line is the target range.

In FIG. 4A, in the first line, the block “A” indicated by the double broken line in the figure is the target range, and in the second line, it is indicated by the next double broken line. The block is the target range.
Further, as shown in FIG. 4B, the sampling start address of the target range is alternately performed with an odd start and an even start every four lines.

  That is, in the target range of A, sampling starts from the first address, that is, an odd address (asterisk “*” in the figure), and in the target range of B, sampling starts from the second address, that is, an even address (asterisk “*” in the figure). Start sampling.

Further, 10 mm from the leading edge of the original and 8 mm (8 bytes) on both sides in one line are cut (deleted) and not sampled.
With the above sampling, black pixels are sampled (searched) for about 1/8 of the entire area of the document, and the processing amount is reduced and the processing speed is increased.

Specifically, the number of search bytes in one line of read width is as follows.
For A4 width: ((216 bytes-16 bytes) / 4) / 2 = 25 bytes For B4 width: ((256 bytes-16 bytes) / 4) / 2 = 30 bytes As shown in FIG. An isolated point of 1 dot or 2 dots in one byte to be sampled is not counted as the number of black pixels.

Next, a second example of the blank document detection system according to the present invention will be described with reference to FIGS.
FIG. 6 is a block diagram showing a second system configuration example of the portion of the facsimile apparatus shown in FIG. 1 that performs blank document detection according to the present invention.

  The blank document detection system of this example includes an operation display unit 5, a RAM 9, and a threshold update unit 20 configured by the CPU 7, ROM 8, RAM 9 and the like in FIG. A density-specific threshold value display unit 21 and a threshold value changing unit 22 are provided.

  This example further improves the operability of the blank document detection system configured as shown in FIG. In other words, when one blank sheet detection threshold is fixed at each reading line density, when many users use it, the degree of blank sheets of the document that the user wants to recognize as an image differs. Therefore, in the blank page original detection system of this example, the user can easily change the blank page detection threshold.

  That is, the line density threshold value display unit 21 reads each read line density registered in the RAM 9 and the corresponding blank page detection threshold value, and displays the threshold value change screen 5b on the LCD 5a of the operation display unit 5. indicate. By referring to this threshold value change screen 5b, the user changes the blank sheet detection threshold value at each line density to a threshold value suitable for the user's usage environment by operating the key on the operation display unit 5, and presses the enter key. Press (“Yes” or the like).

  Based on the key operation result on the operation display unit 5, the threshold value changing unit 22 rewrites the registered content in the RAM 9. Note that the RAM 9 is connected to a backup power source, and maintains the current value even if the power switch is turned off and the power is turned off unless such a value is rewritten.

The blank threshold value changing process operation will be described with reference to FIG.
FIG. 7 is a flowchart showing an example of processing operation according to the present invention of the facsimile apparatus having the blank document detection system in FIG.
A threshold for each line density is displayed on the operation display unit 5 (step 701).

  If there is a change (threshold value change) instruction from the operation display unit 5 for this display content (step 702), the change corresponding to the change instruction is temporarily stored (step 703). Is waited for the confirmation key to be pressed (step 704). If the confirmation key is pressed, the registered contents of the RAM 9 are rewritten with the temporarily stored changed contents (step 705).

Next, a third example of the blank document detection system according to the present invention will be described with reference to FIGS.
FIG. 8 is a block diagram showing a third system configuration example of the portion of the facsimile apparatus in FIG. 1 that performs blank document detection according to the present invention.

  The blank document detection system of this example includes a scanner 1, an operation display unit 5, a RAM 9, and a document determination unit 17 in FIG. 2 and a threshold value update unit in FIG. 6 configured by the CPU 7, ROM 8, RAM 9 and the like in FIG. 20 and a pixel number display unit 23 are provided.

The blank page original detection system of this example further facilitates the user's operation of changing the threshold value for each line density in the blank page original detection system in FIG.
That is, the user first causes the scanner 1 to read a document that is desired to be determined as an image at least so far. The number of pixels of the document is counted by the pixel number counting unit 18 of the document discrimination unit 17, and the result is displayed on the pixel number detection screen 5 c of the LCD 5 a of the operation display unit 5 by the pixel number display unit 23.

  The user can easily set the threshold value, that is, the number of black pixels, to the desired threshold value through the threshold value change screen 5b with reference to the display content of the pixel number detection screen 5c. Can be changed. The change result is reflected in the RAM 9 via the threshold update unit 20.

Such threshold value changing operation will be described with reference to FIG.
FIG. 9 is a flowchart showing an example of the processing operation according to the present invention of the facsimile apparatus having the blank document detection system in FIG.
A document set by the user (a document to be determined to be an image at least here) is read by the scanner 1 (step 901).

The number of black pixels in the image data read from the document is detected by a normal blank document detection operation to determine whether the document is blank (step 902), and the number of black pixels is determined on the LCD 5a of the operation display unit 5. The number is displayed on the number detection screen 5c (step 903).
Based on a user's instruction to change the threshold value (number of black pixels) with reference to the display contents of the pixel number detection screen 5c, the processing shown in FIG. Is changed (step 904).

Next, a fourth example of the blank document detection system according to the present invention will be described with reference to FIGS.
FIG. 10 is a block diagram showing a fourth system configuration example of the portion of the facsimile apparatus shown in FIG. 1 that performs blank document detection according to the present invention.

  The blank document detection system of this example includes a scanner 1, an operation display unit 5, a RAM 9, and a threshold value update / setting unit 24 configured by the CPU 7, ROM 8, RAM 9 and the like in FIG. 1.

  The threshold updating / setting unit 24 includes a line density specifying unit 25, a black pixel number counting unit 26, a pixel number calculating unit 27, and a threshold updating unit 28. With this configuration, The blank page original detection system of this example can automatically change the threshold value for each line density by the user in the blank page original detection system in FIG.

  That is, first, when the threshold update / setting unit 24 determines that the user has selected the threshold automatic change mode of the present example via the operation display unit 5, the blank page detection is performed on the LCD 5a of the operation display unit 5. The threshold automatic change screen 5d is displayed. In the display state of this blank page detection threshold automatic change screen 5d, the user presses the scanner 1 to perform a normal key operation. A desired original is read by selecting a desired reading line density. The line density selected here is read by the line density specifying unit 25 and temporarily stored in the RAM 9.

Further, the black pixel count of the image data read in this way is counted by the black pixel count counting unit 26, and the count value is multiplied by, for example, “0.7” by the pixel number calculating unit 27, and this black data is counted. Give a margin to the number of pixels.
Then, the threshold value updating unit 28 registers the value in the RAM 9 as a new blank sheet detection threshold value in association with the line density temporarily stored in the RAM 9 by the line density specifying unit 25.

  As a result, when the number of counted black pixels is “100”, “70” becomes a new threshold value. After the threshold value has been set, the detected black density is detected by reading at the set linear density. When the number of pixels is “70” or less, it is determined as a blank original. Therefore, the original (black pixel number “100”) read to determine the threshold value (“70”) is not determined to be blank.

Such a threshold value changing process operation will be described with reference to FIG.
FIG. 11 is a flowchart showing an example of processing operation according to the present invention of the facsimile apparatus having the blank document detection system in FIG.
First, a screen such as a blank paper detection threshold automatic change screen is displayed on the LCD of the operation display unit 5 (step 1101).

  Then, on this screen, the user sets a document having the lowest density (a document with many blank pages) to be determined as a document on the scanner 1 (step 1102), selects a reading line density (step 1103), and a start key. When is pressed, the scanner 1 starts reading a document (step 1104).

  During this reading operation, the number of black pixels is detected (steps 1105 and 1106). If the number of black pixels for one page of the document is detected (step 1107), the number of black pixels is multiplied by “0.7” (step 1108), and the value corresponds to the line density selected in step 1103. The registered content in the RAM 9 is updated as the blank sheet detection threshold value (step 1109).

  Further, whether or not to change the threshold value for blank sheet detection at other scanning line densities is displayed on the LCD, and when the user changes the threshold value for blank sheet detection at other scanning line densities. When instructed, the processing from step 1102 is repeated (step 1110), and when it is selected not to change, the screen is returned to the normal standby screen (step 1111) and the processing is terminated.

  As described above, the facsimile apparatus as the image reading apparatus described with reference to FIGS. 1 to 11 stores a threshold value previously associated with each line density in the RAM 9 and sets the line set when the document is read. The density is discriminated by the line density discriminating unit 14, and the site selection unit 15 and the setting unit 16 switch to a threshold value corresponding to the line density to detect a blank original.

  Further, the threshold value associated with each line density stored in the RAM 9 is displayed on the operation display unit 5 by the threshold value display unit 21 according to line density, and the user for the displayed threshold value for each line density is displayed. Based on the change instruction, the threshold value changing unit 22 changes the stored contents in the RAM 9.

  At this time, the pixel number display unit 23 displays the number of black pixels of the document counted by the pixel number counting unit 18 on the operation display unit 5, so that the user can easily change the threshold value. Alternatively, the user reads a document with many white parts that the user wants to use as a normal document, and the threshold updating unit 28 sets the line to the value calculated by the pixel number calculating unit 27 based on the number of black pixels (multiplied by 0.7). The threshold value in the RAM 9 corresponding to the density is automatically changed.

  Further, in the black pixel search method, one main scanning line is divided into four blocks, one block is set as a reading target range of each line, and the next line is set as the reading target range of the next block of the previous line. In the block, the black pixel is searched every other byte, and the search start address of each block is alternately performed odd and even every four lines.

  As a result, black pixels are detected for about 1/8 of the area in front of the document, and the amount of processing is reduced, enabling high-speed black pixel search processing. It should be noted that isolated dots of 1 dot and 2 dots in one byte to be searched are regarded as erroneous detection due to dust of the image sensor and are not counted as black pixels.

Next, a fifth example of the blank document detection blank document detection system according to the present invention will be described with reference to FIGS.
In this example, the selection of the threshold value is controlled in accordance with the setting of the reading mode (whether the original to be read is a halftone original or a normal line drawing original).

  That is, when only one blank sheet detection threshold is associated with a mode for reading a document (line drawing, halftone), the characteristics of the read image output (for example, halftone output is a set of fine points). Depending on the output of the body, it may not be possible to determine that the original is actually recognized as blank, as in the following example.

  For example, when a paper having a dark background is read as a document in the halftone reading mode, the dark portion is read as an image even if there is a slight difference in shading. In this case, there is actually no image on the original, but there is a high possibility that the background of the original is read and output as a large number of small black pixel points. As a result, even when there is no image on the document, the number of scanned black pixels is larger than when scanned in the line drawing mode. There is a possibility that it cannot be judged.

In order to cope with such a problem, a blank document detection system having the configuration shown in FIG. 12 is used.
FIG. 12 is a block diagram showing a fifth system configuration example of the portion of the facsimile apparatus in FIG. 1 that performs blank document detection according to the present invention.

  The blank document detection system of the fifth example includes a scanner 1, an operation display unit 5, a RAM 9, and a threshold value control processing unit 13a and a document determination unit 17a including the CPU 7, ROM 8, RAM 9 and the like of FIG. Become.

  In this example, the RAM 9 stores in advance a list of threshold values of the number of black pixels for each line density for each reading mode that is distinguished depending on whether the document to be read is a halftone document or a normal line drawing document. In addition, the black pixel counting procedure by the pixel number counting unit 18a of the document discrimination unit 17a is stored in advance for each reading mode and each line density.

  The threshold value control processing unit 13a includes a reading mode / line density determination unit 14a, a threshold value selection unit 15a, and a setting unit 16a. In the reading mode / line density determination unit 14a, the user operates the operation display unit 5. The instructed reading mode and line density are determined and notified to the threshold selection unit 15b and the document determination unit 17a.

  The threshold selection unit 15a refers to the list of black pixel count threshold values for each reading mode and each line density stored in advance in the RAM 9, and the reading notified from the reading mode / line density determination unit 14a. The threshold value of the number of black pixels corresponding to the mode and the line density is specified and notified to the setting unit 16a. The setting unit 16 a stores the threshold value of the number of black pixels notified from the threshold value selection unit 15 a using the RAM 9.

  The document discriminating unit 17a includes a pixel number counting unit 18a and a comparing / determining unit 19a. The pixel number counting unit 18a counts the number of black pixels of image data read by the scanner 1, and compares the result with the comparing / determining unit 19. Notify When performing this counting, the pixel number counting unit 18a reads out the counting procedure corresponding to the reading mode and the line density determined by the reading mode / line density determining unit 14a from the RAM 9, and based on this procedure, the black pixel counting (counting) is performed. I do. For example, if the halftone original reading mode or fine line density is selected, the isolated points shown in FIG. 5 are also counted.

  The comparison / determination unit 19a compares the number of black pixels notified from the pixel number counting unit 18a with the threshold value of the number of black pixels stored in the RAM 9 by the setting unit 16a, and the image data read by the scanner 1 is It is determined whether the document is a blank document.

A processing operation according to the present invention of a facsimile apparatus equipped with such a blank sheet original detection system will be described with reference to FIG.
FIG. 13 is a flowchart showing an example of the blank document detection processing operation according to the present invention of the facsimile apparatus provided with the blank document detection system in FIG.

When starting to read a document, the user selects a reading mode and a line density from several types of reading modes and reading line densities (step 1301).
A black pixel counting procedure corresponding to the selected reading mode and linear density is selected from the RAM 9 of FIG. 12 (step 1302).

  Further, from the selected reading mode and line density, a blank sheet detection threshold value corresponding to each reading mode and line density registered in advance in the RAM 9 in FIG. 12 is selected (step 1303), and the original is read. (Step 1304), the number of black pixels is detected (Step 1305).

  When reading is completed (step 1306), the number of black pixels in the document is determined based on the counting procedure selected in step 1302 (step 1307).

  When the number of black pixels thus determined is compared with the threshold value read from the RAM 9 in step 1303 (step 1308), and the number of black pixels of the read original is smaller than the threshold value read from the RAM 9 Then, a blank sheet detection flag is set in the RAM 9 (step 1309), and it is determined that a blank sheet document has been read (step 1310).

  If the read document black pixel count is larger than the threshold value read from the RAM 9, the blank sheet detection flag in the RAM 9 is reset (step 1311), and it is determined that a normal document is read (step 1312).

  As described above, when the number of black pixels on the read document surface is compared with a predetermined threshold value of the number of black pixels to determine whether or not it is blank, a threshold value for detecting a blank document is detected. Can be changed depending on the reading mode, for example, more accurate blank sheet detection can be performed even for a halftone original.

  When the flag in the RAM 9 is set, the facsimile apparatus shown in FIG. 1 notifies the user that the blank document has been read via the display unit or buzzer of the operation display unit 5, and from the document. Storage of the image data in the image memory 3 and communication via the modem 10 and the network control unit 11 are interrupted. Alternatively, such interruption is not performed, and it is only necessary to warn the user that a blank original has been read via the display unit or buzzer of the operation display unit 5.

Next, a black pixel search technique according to the invention by the blank document detection system in FIG. 12 will be described with reference to FIGS.
14 and 15 are explanatory diagrams illustrating an example of black pixel search processing by the blank paper detection system in FIG.

  In this example, if the data read from the image sensor contains dust-like data due to the performance of the image sensor, it is not possible to determine that the document is blank even though it was actually a blank document. On the other hand, the black pixels as the image are extracted with high accuracy without determining the dust data as an image due to the difference in the reading mode.

  In this example, as a plurality of procedures, a plurality of conversion tables (black pixel count conversion tables) used when counting black pixels are provided, and the black pixel count conversion table is selected according to the reading mode and the line density to select black. Assume that the pixel counting procedure is switched.

  Here, the black pixel count conversion table means that when the image data read by the CIS or the like is transferred to the line buffer (RAM 9) in units of one line and the number of black pixels of this image data is calculated in units of one byte, It is a table for converting the number of black pixels from the appearance pattern of black pixels in a byte.

  For example, as shown in FIG. 14, if 1-byte data transferred is “FF (HEX)” data, the number of black pixels is 8, and if the data is “77 (HEX)”, the number of black pixels Is converted to 6 pieces. By adding all the converted numbers, the number of black pixels for one page of the document is calculated.

In this example, the number of black pixels converted from the image data is set as follows depending on the reading mode and the line density.
For example, when the original is read in the halftone mode or when the original is read with a fine line density, an isolated point of about 1 pixel or 2 pixels in 1-byte image data as shown in FIG. Since there is a high possibility that the 1-byte data is also an image, a table that accurately converts this 1-byte data into 1 pixel and 2 pixels is selected and counted.

  Further, when the original is read in the line drawing mode or when the original is read with a rough line density, the image data as shown in FIG. 15 is highly likely to be dirt or other dust data on the original. A table to be converted to “0” pixels is selected so that each is not counted.

  Note that how many isolated points are determined as dust data by the conversion table depends on the performance of the reading element such as CIS and CCD and the original to be determined as blank paper. Is measured and evaluated.

  That is, when starting to read a document, the user selects a line drawing or halftone mode depending on the read image. From the mode thus selected, a black pixel count conversion table prepared in advance in a RAM, a ROM or the like is selected. For example, if the reading mode is halftone, the number of black pixels is counted with reference to a black pixel count conversion table prepared for halftone in advance.

  As described above, a plurality of procedures (counting black pixels) for counting the number of black pixels (black pixel count table) are provided, and scanning is performed by selecting an optimal procedure according to a mode (line drawing, halftone) for reading a document and a line density. It is possible to accurately determine whether a black pixel is dust data or image data, and the counting accuracy of the number of black pixels as image data is improved. Further, by improving the counting accuracy of the number of black pixels in the image data, the threshold of the number of black pixels for determining whether or not the document is a blank sheet becomes more accurate, and the accuracy of blank sheet detection is improved.

Next, a sixth example of the blank document detection system according to the present invention will be described with reference to FIGS. 16 and 17.
In this example, the threshold value for discriminating a blank document set / changed by each technique described with reference to FIGS. 1 to 15 is further changed in accordance with the user's operation.

That is, when the user uses a document whose threshold value for blank document detection is lower than the threshold value for detecting a blank document after changing / setting the threshold value for determining a blank document using the techniques described in FIGS. In some cases, it is erroneously detected as a blank document.
In order to cope with such a problem, a blank document detection system having the configuration shown in FIG. 16 is used.

FIG. 16 is a block diagram showing a sixth system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG.
The blank document detection system of the sixth example includes an operation display unit 5, a RAM 9, a document determination unit 17 including the CPU 7, ROM 8, and RAM 9 of FIG. A threshold value changing unit 33 is provided.

  If the number of black pixels detected from the read original is equal to or less than the threshold value of the number of black pixels for detecting a blank sheet, the document determination unit 17 determines that the document is a blank document. Based on the determination result, the blank document notification unit 31 warns the user of the possibility of reading a blank document via the operation display unit 5 using a sound unit such as a buzzer or a display unit such as an LCD or LED. To do.

  When the user cancels the warning with a blank page detection cancel key or a switch provided on the operation display unit 5 and instructs to continue the transmission of the document in response to this warning, the forced transmission unit 32 displays the blank document. The image data read from the document determined as is transmitted via the modem 10 and the network control unit 11 in FIG.

  As described above, when image data read from a document determined as a blank document is transmitted by the forced transmission unit 32, the threshold value changing unit 33 uses the number of black pixels of the document to store the image data in the RAM 9. Change the threshold.

  For example, the threshold value changing unit 33 writes a value obtained by multiplying the number of black pixels of the transmitted document by 0.7 to give a margin to a predetermined address in the RAM 9 as a new threshold value. When the number of read black pixels is “100”, “70” becomes a new threshold value. Thereafter, when the detected number of black pixels is “70” or less, it is determined as a blank document. The transmitted original with the number of black pixels of “100” is not determined as a blank original.

Note that if the warning is not canceled from the user even after a certain time, for example, 1 minute, even if the warning is issued, the transmission is continued as it is. In this case, the threshold value of the number of black pixels used for detecting blank paper is not changed.
In this way, by changing the threshold value of the number of black pixels used for detecting a blank page, it is possible to perform blank page detection that matches the document used by the user.

The threshold value changing unit 33 can also write a new threshold value in the RAM 9 as follows.
That is, when image data is transmitted by the forced transmission unit 32, the threshold value changing unit 33 stores the number of black pixels of the image data as a log data at a predetermined address in the RAM 9. Note that the area for storing log data is divided according to the reading conditions such as the reading mode and the linear density.

  Then, for each of a plurality of (for example, five) storage operations under the same reading conditions, an average value is obtained, and a value obtained by multiplying the average value by “0.7” to provide a margin is newly set. A value is written to a predetermined address in the RAM 9. The number of operations for calculating the average value from the log data can be arbitrarily set by the user via the operation display unit 5.

  By performing the threshold value changing process in this way, it is possible to set a threshold value corresponding to a change in the document used by the user, and to detect a blank document that matches the user's document used. . Even if only a special document that is not normally used is read and detected as blank, it can be forcibly transmitted without changing the threshold value.

  In addition, when the forced transmission unit 32 transmits image data, the threshold value changing unit 33 sets a new threshold value based on the number of black pixels read this time on a display device such as an LCD on the operation display unit 5. A display is made to allow the user to select whether or not to write to the RAM 9, and when the user instructs writing (registering) based on the display, the threshold value of the RAM 9 is changed to a new value. If there is no registration instruction, the log data is stored in a predetermined area of the RAM 9 and the process is terminated.

A processing operation according to the present invention of a facsimile apparatus equipped with such a blank sheet original detection system will be described with reference to FIG.
FIG. 17 is a flowchart showing an example of the blank document detection processing operation according to the present invention of the facsimile apparatus provided with the blank document detection system in FIG.

  The original is read under the set reading conditions (reading mode, linear density) (step 1701). As a result, when the original is determined to be a blank original (step 1702), a buzzer, LCD, or the like is displayed via the operation display unit 5 in FIG. The user is warned to that effect (step 1703).

  When the user cancels this warning and instructs to continue the transmission of the document (step 1704), the number of black pixels of the document is associated with the reading condition and stored in the RAM 9 of FIG. 1 as log data (step 1705). .

  When the number of log data reaches a value (MAX) arbitrarily set in advance by the user (step 1706), a new threshold value is calculated using the log data (step 1707) and stored in the RAM 9. The threshold value is changed to the calculated threshold value (step 1708). The change to the new threshold value may be performed based on an instruction from the user.

  In this way, by changing the threshold value of the number of black pixels used for detecting blank paper, it is possible to set a threshold value corresponding to the change of the document used by the user, and to match the user's document used. It is possible to detect a blank white document.

Next, another example of the image reading apparatus according to the present invention will be described with reference to FIGS.
FIG. 18 is a block diagram showing another configuration example of the image reading apparatus according to the present invention.

  The image reading apparatus of this example is a facsimile apparatus, and includes a scanner 51, a display unit 52, an operation unit 53, a communication unit (indicated as “NCU” in the figure) 54, a controller 55, a ROM 56, a RAM 57, and a plotter 58 on an internal bus. 59 to be connected.

The scanner 51 is particularly a part related to the image reading apparatus of the present invention, and reads a transmission image and a copy image.
The display unit 52 is composed of an LCD or the like, and notifies the user (user, operator) of the operation state of the facsimile apparatus such as “communication” and “error state”.

The operation unit 53 includes a numeric keypad and a one-touch key, and is operated when the user uses the facsimile apparatus.
The communication unit 54 is composed of a modem, a network control device, etc., and transmits dial pulses, detects incoming signals, switches between telephones and facsimiles, etc., and controls connection with a destination device via a public line or a dedicated line. Do.

The controller 55 includes a CPU and the like, and controls the overall operation of the facsimile apparatus including the blank document detection process according to the present invention.
The ROM 56 stores a program and data for operating the CPU of the controller 55.

The RAM 57 stores CPU control data, for example, data when an error occurs and received data.
The plotter 58 has a laser printer mechanism, and prints out a copy image read by the scanner 51 or image data received by the communication unit 54.

The operation of the facsimile apparatus of this example having such a configuration will be described.
When the operator sets an original on the scanner 51, designates the other party with a one-touch key of the operation unit 52, and presses the start key, the controller 55 activates the scanner 51 and carries the original into the scanner 51. Start scanning the document.

The read image data is encoded by an encoding / decoding unit (not shown) and temporarily stored in the RAM 57.
Then, a connection is made with the other party specified by the operation unit 52 via the communication unit 54. When the connection is completed, the image data stored in the RAM 57 is transmitted.

  In such a process, if the operator sets the original on the scanner 51 upside down, blank image data is transmitted. Therefore, in order to cope with such a problem, the facsimile apparatus of this example A blank sheet original detection mechanism having the configuration shown in FIG. 19 is provided to detect a blank sheet according to the present invention.

FIG. 19 is a block diagram illustrating a configuration example of a portion related to blank document detection of the facsimile apparatus in FIG.
In FIG. 19, 60 is a document, 61 is a CIS, 62 is an A / D (analog / digital) conversion unit, 63 is a blank page determination unit, 64 is a first detection unit, 65 is a second detection unit, and 66 is a third detection unit. The detection unit, 67 is a selection unit, and 68 is a notification unit. Each of the blank sheet determination unit 63, the first to third detection units 64-66, the selection unit 67, and the notification unit 68 is configured in the controller 65.

The CIS 61 is provided in the scanner 51 of FIG. 18 and receives reflected light from the original 60 sent one by one from a plurality of originals set by the operator and converts it into an electrical signal (analog).
The A / D converter 62 converts the analog signal from the CIS 61 into a digital signal. The digital signal converted by the A / D converter 62, that is, image data is stored in the RAM 57 and transmitted or copied by the processing of the controller 55.

The blank sheet determination unit 63, the first to third detection units 64 to 66, the selection unit 67, and the notification unit 68 constitute a part particularly related to blank document detection according to the present invention.
That is, the blank sheet determination unit 63 determines whether or not the document 60 is a blank document based on the image data output from the A / D conversion unit 62 for each document 60.

In the first detection unit 64, when the blank sheet determination unit 63 determines that the document 60 is a blank document, the detection result is immediately output.
The second detection unit 65 outputs a detection result when the total number of documents 60 determined as a blank document by the blank sheet determination unit 63 reaches a predetermined number.

The third detection unit 66 outputs a detection result when the blank sheet determination unit 63 determines that all the documents set by the operator are blank documents.
The selection unit 67 selects and activates one of the first to third detection units 64 to 66 based on an instruction from the operator via the operation unit 53.

Thus, the detection result output from any of the first to third detection units 64 to 66 activated by the selection unit 67 is passed to the notification unit 68.
If there is a detection result output from any of the first to third detection units 64 to 66, the notification unit 68 outputs a notification prompting the operator to check the set document through the display unit 52.

  In response to the notification by the notification unit 68, the operator confirms the print density of the document, decides whether to reset the document, transmit it as it is, or stop the operation. Give instructions.

  If there is a continuation instruction from the operator, the controller 55 continues reading the document or transmits the read image information. If there is a stop instruction, the controller 55 reads the document or transmits the read image information. To stop.

Hereinafter, such a blank document detection operation will be described with reference to FIGS.
FIG. 20 is a flowchart showing a processing operation example of the blank original detection method of the present invention by the facsimile apparatus in FIG.

When the start key on the operation unit 53 is pressed (step 2001), it is determined whether or not a document is set (step 2002).
If no document is set, an error is displayed on the display unit 52 (step 2003). If a document is set, the first document is carried in (step 2004), and image data is read (step 2005).

Here, it is determined whether or not an instruction to detect a blank document is issued via the operation unit 53 (step 2006).
If there is no instruction to detect a blank document, the presence or absence of the next document is confirmed (step 2010). If there is a next document, the process from the next document carry-in in step 2004 is repeated. .

If an instruction for detecting a blank document is issued in step 2006, it is first determined whether one of the first and second detection units 64 and 65 is selected (step 2007).
If one of the first and second detection units 64 and 65 is selected, the selected detection unit is activated to perform a blank document detection operation (step 2008).

  If no blank document detection result is output from the detection unit selected from the first and second detection units 64 and 65 (step 2009), the presence or absence of the next document is confirmed (step 2010). Exit. In step 2009, if a detection result of a blank document is output, the notification unit 67 notifies the operator via the display unit 2 (step 2011).

  In step 2007, if the third detection unit 66 is selected except for the first and second detection units 64 and 65, the third detection unit 66 is activated to perform a blank document detection operation. (Step 2012).

  The detection of the blank document by the third detection unit 66 determines whether or not all the set documents are blank. First, from the step 2004 until the next document disappears (step 2013). Repeat the process.

  If no blank document detection result is output from the third detection unit 66 (step 2014), the blank document detection process is terminated. If the blank document detection result is output, the notification unit 67 displays the blank document detection result. The operator is notified via the unit 52 (step 2011).

FIG. 21 is a flowchart showing an example of the processing operation according to the present invention of the first detection unit in FIG.
The determination result of the blank sheet determination unit 63 in FIG. 19 is input (step 2101). If the determination result is not “blank document” (step 2102), the determination result of the blank sheet determination unit 63 for the next document (step 2103) is displayed. Input (step 2101). If there is no next document, the process is terminated.

  If the determination result of the blank sheet determination unit 63 is “blank document”, information (blank document detection result) that a blank document has been detected is output to the notification unit 68 of FIG. 19 (step 2104). As described above, the first detection unit 64 controls the output of the blank document detection result every time the blank sheet determination unit 63 determines that the document is blank.

FIG. 22 is a flowchart showing an example of the processing operation of the second detection unit in FIG. 19 according to the present invention.
The determination result of the blank sheet determination unit 63 in FIG. 19 is input (step 2201). If the determination result is not “blank document” (step 2202), the determination result of the blank sheet determination unit 63 for the next document (step 2203) is displayed. Input (step 2201). If there is no next document, the process is terminated.

  If the determination result of the blank sheet determination unit 63 is “blank document”, one count value t is added (step 2204), and it is determined whether the count value t has reached a predetermined value T as a result of the addition (step 2204). Step 2205). If not reached, the determination result of the blank sheet determination unit 63 for the next original (step 2203) is input (step 2201).

When the count value t reaches the predetermined value T, information indicating that a blank document is detected (blank document detection result) is output to the notification unit 68 of FIG. 19 (step 2206).
As described above, the second detection unit 65 controls the output of the blank document detection result when the blank page determination result (the number of blank pages) for the document of the blank page determination unit 63 reaches the predetermined value T.

FIG. 23 is a flowchart showing an example of the processing operation according to the present invention of the third detection unit in FIG.
The determination result of the blank sheet determination unit 63 in FIG. 19 is input (step 2301). If the determination result is “blank document” (step 2302), a predetermined flag is turned on (step 2303).

  Then, the determination result of the blank page determination unit 63 for the next document (step 2304) is input, and the processing from step 2301 is repeated. If there is no next document, that is, for all the documents, the blank page determination unit 63 performs. If the determination result is “blank document”, information indicating that a blank document is detected (blank document detection result) is output to the notification unit 68 of FIG. 16 (step 2305).

In step 2302, if the determination result of the blank sheet determination unit 63 is not “blank document”, the flag turned on in step 2303 is turned off (step 2306), and the process ends.
As described above, the third detection unit 66 outputs the blank document detection result only when the blank sheet determination unit 63 determines that all the documents are blank.

  In the facsimile apparatus as the image reading apparatus described above with reference to FIGS. 18 to 23 and the blank sheet original detection method, the detection result is output in advance if the first detection unit 64 (even one sheet is determined to be a blank sheet original). ), Second detection unit 65 (waits for output of detection results until a predetermined number of blank originals are determined), and third detection unit 66 (if all originals are not determined as blank originals, detection results are not output). Is provided so that the user can select one of them.

  For example, when the first detection unit 64 is selected, if the blank sheet determination unit 63 determines that the document 60 is a blank sheet, the first detection unit 64 immediately detects that a blank document has been detected (blank document detection result). ) Is output. Based on the output from the first detection unit 64, the facsimile apparatus stops reading image information for subsequent documents and notifies the operator. As a result, the operator can recognize an erroneous set or the like in which the front and back sides of the originals are reversed without waiting until the reading operation for all of the many originals 60 is completed.

  Further, in the second detection unit 65 and the third detection unit 66, the final result is not output until the blank sheet determination unit 63 determines that a certain number of sheets or all the originals are blank. Although it takes a long time, by allowing the operator to select such a mode arbitrarily, the operator can select the optimum blank document detection function according to the document, and the performance and convenience of the facsimile apparatus. Will improve.

Next, still another example according to the image reading apparatus of the present invention will be described with reference to FIGS.
FIG. 24 is a block diagram showing still another configuration example according to the present invention of the image reading apparatus of the present invention.

  The image reading apparatus of this example is a facsimile apparatus, and in particular, the facsimile apparatus shown in FIG. 1 except that the scanner 1a is provided with an automatic double-sided document feeder (described as “ARDF” in the figure) 1b. In almost the same manner, the encoding / decoding unit 2a, the image memory 3a, the plotter 4a, the operation display unit 5e, the switch (indicated as “SW” in the figure) 6a, the CPU 7a, the ROM 8a, the RAM 9a, the modem 10a, and the network control unit 11a The connection is made via the bus 12a.

  By providing the automatic double-sided document feeder 1b, the scanner 1a of this example not only automatically feeds a normal single-sided document, but also sequentially feeds a set of documents based on an instruction from the operation display unit 5e. In addition, the image data can be read, and the image data on both sides of the document can be read by automatically inverting the front and back of each document.

  For example, when a blank document is detected by the above-described various detection functions when a plurality of originals are continuously read on a single side and image data is compressed and stored in the image memory 3a, for example, In the facsimile machine, the automatic duplex document feeder 1b is used to invert a document detected as a blank page and read image data on the opposite side.

As a result, even when originals that are stacked upside down are mixed, correct image data can be automatically captured, and useless output can be avoided.
Hereinafter, such processing operation will be described with reference to FIGS.

FIG. 25 is a flowchart showing an example of the reading processing operation according to the present invention of the facsimile apparatus in FIG.
The document set on the automatic duplex document feeder 1b is conveyed, the image data is read, and compressed and stored in the image memory 3a (step 2501).

  It is determined whether or not the accumulated image data is a blank original based on the black pixel search technique, the blank original detection technique (threshold setting technique) described with reference to FIGS. 1 to 23 (step 2502). . When a document is detected as a blank page, a blank page detection flag is set in association with the document in the read document page management RAM, that is, the RAM 9a in FIG. 24 (step 2503).

  Then, it is determined with reference to the document reversal flag set in the RAM 9a whether the blank document detection has occurred during normal document conveyance or when it has been reversed and conveyed (step 2505).

  If the document reversal flag is not set (ON), it is normal document conveyance, the document reversal flag is set (ON), and the document is reversed via the automatic duplex document feeder 1b of FIG. Step 2507), returning to the processing of step 2501, step 2508) of repeating the reading operation of the image data for the inverted document.

  If the document reversal flag is set (ON), the document is already reversed, the document reversal flag is reset (step 2506), and the process returns to step 2501 to repeat the operation of reading image data from the next document. (Steps 2508, 2509). In this case, both the image data on both sides of the document are not output in the output process shown in FIG.

  If it is determined in step 2502 that the document is not a blank document, the blank sheet detection flag in the RAM 9a is reset (step 2504), and the image data reading operation for the document on the next page is performed (step 2509).

FIG. 26 is a flowchart showing an output processing operation example according to the present invention of the facsimile apparatus in FIG.
When outputting the image data read by the operation shown in FIG. 25, first, it is referred to whether or not the blank sheet detection flag of the RAM 9a of FIG. 24 corresponding to the original is set (ON) (step 2601).

  If the blank paper detection flag is not set (ON), the image data stored in the image memory is transmitted and output through the output device, here, the modem 10a and the network control unit 11a in FIG. 24 as usual. (Step 2602), the image is deleted from the image memory (Step 2603), and the process for the document of the next page is repeated (Step 2604).

If the blank sheet detection flag is not set (ON) in step 2601, it means that the document is blank, and the image data stored in the image memory is not output from the image memory. It is deleted (step 2603).
In this way, the original of the page determined to be blank is not transmitted and output, but only normal original pages are continuously transmitted.

FIG. 27 is a flowchart showing another example of reading processing operation of the facsimile apparatus in FIG. 24 according to the present invention.
In this example, in the operation shown in FIG. 25, the determination of validity / invalidity for a document detected as a blank sheet is left to the judgment of the user (operator). After the processing of step 2502 in FIG. 25, step 2703 is performed. 2704 is provided.

  That is, if it is detected in step 2502 that the document from which the image data has been read is a blank sheet, first, that fact is notified to the user through a buzzer or display via the operation display unit 5a of FIG. Step 2703).

  Then, when the user determines that the page is blank and inputs a determination to that effect using a specific key or the like provided on the operation display unit 5a (step 2704), after the blank page detection flag is set in the RAM 9a in step 2503 If it is determined that the document is a thin document and not a blank sheet, the normal document processing in step 2504 is performed. With this process, even when both sides of the document are detected as white paper, any valid image data can be output based on the user's confirmation.

  As described above with reference to FIGS. 1 to 27, the image reading apparatus of the present example and its black pixel search method and blank page document detection method can detect a blank page document with high accuracy and efficiency. It is possible to improve the performance and reliability of a facsimile apparatus, a scanner apparatus, etc., and to improve convenience.

  For example, a facsimile apparatus as an image reading apparatus of this example stores a threshold value previously associated with each line density, determines a document reading line density, and sets the threshold value corresponding to this line density. Switch to detect blank documents. As a result, it is possible to detect a blank original with high accuracy.

  Further, in this facsimile apparatus, a threshold value associated with each line density stored in the storage unit is displayed, and the displayed threshold value for each line density is changed based on an instruction from the user. As a result, the detection of a blank original can be further improved.

Further, by displaying the counted number of black pixels of the document at that time, the user can easily change the threshold value.
Alternatively, the user can read a document with many white parts to be used as a normal document and automatically change the threshold corresponding to the line density by the number of black pixels. Can be easily.

  In addition, the threshold value is stored in association with not only the line density but also the reading mode selected when the document is composed of line drawings and halftones, and based on the optimum threshold value for the selected reading mode, Perform detection. As a result, it is possible to detect a blank document with high accuracy corresponding to the type of document.

  Further, in the black pixel search method of the facsimile apparatus as the image reading apparatus of this example, one main scanning line is divided into four blocks, and one block is set as a reading target range of each line, and the next line is the previous line. The next block is set as a reading target range. In each block, black pixels are searched every other byte, and the search start address of each block is alternately odd and even every four lines. Black pixels are detected for about 1/8. This makes it possible to efficiently search for black pixels.

  Further, in this black pixel search, the 1-dot and 2-dot isolated points in one byte to be searched are regarded as erroneous detection due to dust or the like of the image sensor and are not counted as black pixels. This makes it possible to search for black pixels more efficiently.

  In addition, there are a plurality of procedures for counting (counting) the number of black pixels for each line density and each document reading mode, and the number of black pixels is counted by switching the procedure according to the selected line density and reading mode. As a result, the optimum number of black pixels corresponding to the document type can be counted.

  Further, even when it is determined that the document is a blank document, if the user supports forced transmission, the threshold value is changed to a new threshold value based on the number of black pixels at that time. For example, after a predetermined number of forced transmissions, the average value is changed. Thereby, the user can easily change and set the threshold value.

  In addition, the facsimile apparatus as the image reading apparatus of this example and the blank document detection method thereof have a first detection function (a detection result is output if even one sheet is determined as a blank document), and a second detection function. (Waiting for output of detection results until a predetermined number of blank originals are determined), and a third detection function (if all originals are not determined as blank originals, detection results are not output) One of them can be selected, and the user can select the optimum blank document detection function according to the document, thereby improving the performance and convenience of the apparatus.

  Further, the operation is stopped at the time of notification to the user, and the user is made to select whether to repeat the operation or continue the process, and perform a process according to the selection. This further improves the convenience of the apparatus.

  In addition, this invention is not limited to each example demonstrated using FIGS. 1-27, In the range which does not deviate from the summary, various changes are possible. For example, in this example, the facsimile apparatus is described as an image reading apparatus. However, a copying machine with an automatic document feeding function or a scanner apparatus connected to a computer may be used. Further, although the description has been made with respect to the facsimile apparatus that scans by moving the original, the facsimile apparatus has a structure in which the original is fixed and the optical system is moved and scanned, and also in a copying machine that does not have an automatic original feeding function. Applicable.

  Further, the blank document detection unit described with reference to FIGS. 19 to 23 can also be applied to the facsimile apparatus in FIG. 1 described in detail with reference to FIGS. In this case, the threshold value stored in the RAM 9 by the threshold changing unit 33 and the transmission to the original determined as a blank original by the forced transmission unit 32 in FIG. 16 based on the notification result in the notification unit 68 in FIG. Change the value.

  As described above, according to this example, the detection of a blank document can be performed with high accuracy according to the use environment, and the user can select the optimum blank document detection function according to the document. Therefore, it is possible to improve the reliability, operability, convenience, and performance of an image reading apparatus such as a facsimile apparatus, a scanner apparatus, or a copying machine with an automatic document feeding function.

  For example, by automatically changing the threshold value according to the line density, it is possible to detect a highly accurate blank document according to the use environment of the apparatus.

  Also, in an image reading apparatus equipped with an automatic double-sided document feeder, it is possible to detect a blank document with high accuracy according to the usage environment of the apparatus by automatically changing the threshold value according to the line density. Therefore, it is possible to avoid re-reading the image data by erroneously detecting a blank original and inverting the original.

  Further, it is possible to avoid useless output of a blank original in the image reading apparatus provided with the automatic duplex original feeder.

  In addition, since the user can change the threshold value for each line density, it is possible to detect a blank document with an optimum threshold value according to the type of document used by the user.

  Further, since the threshold value for each set linear density is displayed, the user can make the change more accurately and easily.

  Further, it is possible to automatically change the threshold value for each type of document and for each linear density.

  Further, not only the line density but also the threshold value for each reading mode such as halftone can be changed and set, so that a more accurate blank document can be detected.

  In addition, by making it possible for the user to perform a judgment operation, it is possible to avoid useless output of a blank document and useless rereading operation in the image reading apparatus, and to read and Output is possible.

  In addition, the threshold value can be automatically changed to the number of black pixels when the user forcibly outputs, and subsequent reading and output of a similar document is facilitated.

  Further, by obtaining the change of the threshold value based on the forced output by an average over a plurality of times, accurate detection of a blank original can be stabilized.

  In addition, by allowing the user to select and instruct execution of the threshold value change based on the forced output, it is possible to avoid a bad influence on the detection of a blank document with respect to a normal document by a special document.

  In addition, by allowing the user to select a blank document detection decision timing from a plurality of options, the user can select the optimal blank document detection function according to the document, improving the performance and convenience of the device. To do.

  Further, when the user detects a blank document, the operation of the apparatus can be stopped and the user can select whether to repeat the operation or continue, further improving the convenience of the apparatus.

  Further, the processing time can be shortened, and the black pixel search in the image reading apparatus can be made efficient.

  Further, the calculation of dust-like black pixels can be avoided, and the black pixel search in the image reading apparatus can be further improved in accuracy and efficiency.

  Further, the black pixel search in the image reading apparatus can be performed with high accuracy by performing the black pixel search according to the procedure for each reading mode.

  Further, the black pixel search in the image reading apparatus can be performed with high accuracy by performing the black pixel search according to the procedure for each line density.

  Further, by allowing the user to select a blank document in the image reading apparatus from a plurality of procedures, it is possible to detect a blank document with high accuracy for each document.

  In addition, when detecting a blank document in the image reading apparatus and notifying the user, it is possible to stop the operation of the apparatus so that the user can select whether to repeat the operation or continue the processing, thereby improving the convenience of the apparatus. It becomes.

1 is a block diagram showing an embodiment of a configuration according to the present invention of an image reading apparatus of the present invention. FIG. 2 is a block diagram showing a first system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG. 1. 3 is a flowchart showing an example of blank document detection processing operation of the facsimile apparatus in FIG. 1 according to the present invention. It is explanatory drawing which shows the 1/2 part of the search process example of the black pixel concerning invention. It is explanatory drawing which shows 2/2 part of the search process example of the black pixel concerning invention. FIG. 3 is a block diagram showing a second system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG. 1. 7 is a flowchart showing an example of processing operation according to the present invention of a facsimile apparatus having the blank document detection system in FIG. 6. FIG. 6 is a block diagram showing a third system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG. 1. FIG. 9 is a flowchart showing an example of a processing operation according to the present invention of a facsimile apparatus having the blank document detection system in FIG. 8. FIG. 7 is a block diagram showing a fourth system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG. 1. FIG. 11 is a flowchart showing an example of processing operation according to the present invention of a facsimile apparatus having the blank document detection system in FIG. 10. FIG. FIG. 9 is a block diagram showing a fifth system configuration example of a portion for detecting a blank original according to the present invention of the facsimile apparatus in FIG. 1. 13 is a flowchart showing an example of processing operation according to the present invention of a facsimile apparatus having the blank document detection system in FIG. It is explanatory drawing which shows the 1/2 part of the search process example of the black pixel by the blank paper detection system in FIG. It is explanatory drawing which shows 2/2 part of the search process example of the black pixel by the blank paper detection system in FIG. FIG. 10 is a block diagram illustrating a sixth system configuration example of a portion that performs blank document detection according to the present invention of the facsimile apparatus in FIG. 1; FIG. 17 is a flowchart showing an example of a blank document detection processing operation according to the present invention of the facsimile apparatus provided with the blank document detection system in FIG. 16. It is a block diagram which shows the other structural example which concerns on this invention of the image reading apparatus of this invention. FIG. 19 is a block diagram illustrating a configuration example of a portion related to blank document detection of the facsimile apparatus in FIG. 18. FIG. 19 is a flowchart showing an example of processing operation of the blank original detection method of the present invention by the facsimile apparatus in FIG. 18. FIG. It is a flowchart which shows the process operation example concerning this invention of the 1st detection part in FIG. It is a flowchart which shows the process operation example concerning this invention of the 2nd detection part in FIG. It is a flowchart which shows the process operation example concerning this invention of the 3rd detection part in FIG. It is a block diagram which shows the further another structural example which concerns on this invention of the image reading apparatus of this invention. FIG. 25 is a flowchart showing an example of a reading processing operation according to the present invention of the facsimile apparatus in FIG. 24. FIG. 25 is a flowchart showing an output processing operation example according to the present invention of the facsimile apparatus in FIG. FIG. 25 is a flowchart showing another example of the reading processing operation according to the present invention of the facsimile apparatus in FIG. 24. FIG.

Explanation of symbols

  1, 1a: scanner, 1b: automatic duplex document feeder (“ARDF”), 2, 2a: encoding / decoding unit, 3, 3a: image memory, 4, 4a: plotter, 5, 5e: operation display unit, 5a: LCD, 5b: threshold change screen, 5c: pixel number detection screen, 5d: blank paper detection threshold automatic change screen, 6, 6a: switch (SW), 7, 7a: CPU, 8, 8a: ROM 9, 9a: RAM, 10, 10a: Modem, 11, 11a: Network control unit, 12, 12a: Bus, 13, 13a: Threshold control processing unit, 14: Line density determination unit, 14a: Reading mode Line density discrimination unit, 15, 15a: threshold selection unit, 16, 16a: setting unit, 17, 17a: document discrimination unit, 18, 18a: pixel count unit, 19, 19a: comparison / discrimination unit, 20: Threshold update unit, 21: Threshold display by line density Unit: 22: threshold value changing unit, 23: pixel number display unit, 24: threshold value updating / setting unit, 25: line density specifying unit, 26: black pixel number counting unit, 27: pixel number calculating unit, 28 : Threshold update unit, 31: blank document notification unit, 32: forced transmission unit, 33: threshold change unit, 51: scanner, 52: display unit, 53: operation unit, 54: communication unit (NCU), 55: controller, 56: ROM, 57: RAM, 58: plotter, 59: internal bus, 60: document, 61: CIS (contact image sensor), 62: A / D (analog / digital) converter, 63: Blank sheet determination unit, 64: first detection unit, 65: second detection unit, 66: third detection unit, 67: selection unit, 68: notification unit.

Claims (30)

Reading means for scanning the document and reading the image data, counting means for counting the number of black pixels of the image data read by the reading means, the number of black pixels counted by the counting means and the number of black pixels stored in advance An image reading apparatus having means for determining whether the original is a blank original based on a comparison with a threshold),
A line density discriminating unit for discriminating the linear density of the original reading; a storage unit for storing the threshold value previously associated with each of a plurality of line densities; And a selection means for selecting a threshold value associated with the image reading apparatus, wherein a blank page original is detected by switching the threshold value in accordance with a linear density for reading the original. Reading means for scanning the document and reading the image data, counting means for counting the number of black pixels of the image data read by the reading means, the number of black pixels counted by the counting means and the number of black pixels stored in advance An image reading apparatus having means for determining whether the original is a blank original based on a comparison with a threshold),
A line density discriminating means for discriminating the linear density of document reading;
Storage means for storing the threshold value previously associated with a plurality of linear densities;
Selecting means for selecting a threshold value associated with the linear density determined by the linear density determining means from the storage means;
Means for comparing the number of black pixels of the read document surface with the threshold value selected by the selection means to determine whether the document is a blank document;
An image reading apparatus comprising: a document reversing reading unit configured to reverse a document when the document is determined to be a blank document and scan the reversed surface to read image information. The image reading apparatus according to claim 2,
Holding means for holding image information read from the original, output means for reading out and outputting the image information from the holding means, and means for suppressing output of the image information of the original determined to be a blank original by the output means An image reading apparatus comprising: The image reading apparatus according to any one of claims 1 to 3,
Based on an instruction from the user, a means for displaying a threshold value associated with each linear density stored in the storage means and a threshold value for each linear density stored in the storage means displayed by the means. And an image reading apparatus.   5. The image reading apparatus according to claim 1, further comprising means for displaying the number of black pixels of the document counted by the counting means. An image reading apparatus according to any one of claims 1 to 5,
Corresponding to the means for determining the reading of the specific document by the reading means based on the instruction from the user, and the line density at the time of reading the specific document determined by the linear density determining means at the time of reading the specific document by the means And a means for changing the threshold value stored in the storage means to the number of black pixels of the specific document counted by the counting means. The image reading apparatus according to any one of claims 1 to 6,
Storage means for storing the threshold value associated with each line density for each reading mode including line drawing mode and halftone mode, mode determining means for determining the reading mode selected by the user, and mode determination A reading mode determined by the means and a means for selecting a threshold value corresponding to the line density determined by the line density determining means, and the threshold value corresponding to the reading mode and the line density for reading a document. An image reading apparatus that detects a blank original by switching between the two. Reading means for scanning the document and reading the image data, counting means for counting the number of black pixels of the image data read by the reading means, the number of black pixels counted by the counting means and the number of black pixels stored in advance An image reading apparatus having means for determining whether the original is a blank original based on a comparison with a threshold),
Mode discrimination means for discriminating a reading mode including a line drawing mode and a halftone mode selected by the user;
Storage means for storing the threshold value previously associated with each reading mode;
Means for selecting a threshold value associated with the reading mode determined by the mode determining means from the storage means;
An image reading apparatus for detecting a blank original by switching the threshold value corresponding to the reading mode. The image reading apparatus according to claim 1, wherein:
A means for notifying a user of a determination result that the original is a blank original; and a means for determining whether to output image information of an original determined to be a blank original based on an instruction from the user. An image reading apparatus. The image reading apparatus according to claim 1, wherein:
Means for notifying a user of a determination result that the original is a blank original;
Forced output means for outputting a document determined as a blank document based on an output instruction from the user even if the determination result is a blank document;
An image reading apparatus comprising: means for changing a threshold value used for determining whether the document is a blank document based on the number of black pixels of the document output by the forcible output unit. An image reading apparatus that scans a document and reads image information from the document,
Means for comparing the number of black pixels of the read document surface with a predetermined threshold value of the number of black pixels to determine whether the document is a blank document;
Means for notifying a user of a determination result that the original is a blank original;
Forced output means for outputting a document determined as a blank document based on an output instruction from the user even if the determination result is a blank document;
An image reading apparatus comprising: means for changing a threshold value used for determining whether the document is a blank document based on the number of black pixels of the document output by the forcible output unit. The image reading apparatus according to claim 10 or 11, wherein:
Means for storing the number of black pixels of the document for each output from the forced output means;
Means for counting the number of outputs in the forcible output means and obtaining an average value of the number of stored black pixels when the number of times reaches a predetermined number,
An image reading apparatus, wherein a threshold value used for determining whether the document is a blank document is changed based on the average value. An image reading apparatus according to any one of claims 10 to 12,
Means for allowing the user to select whether or not to change the threshold value used for the determination of the blank document based on the number of black pixels of the document output by the forced output means;
An image reading apparatus that changes the threshold value when there is a change selection instruction from a user. An image reading apparatus according to any one of claims 1 to 13,
Either of a plurality of detection means for outputting a detection result that the document is a blank document in a different procedure based on a determination result that the document is a blank document, and a plurality of detection means based on an instruction from a user And a selection means for selecting one of them, and if there is an output of a detection result from the detection means selected by the selection means, a notification for urging the user to check the document is output. apparatus. An image reading apparatus that scans a document and reads image information from the document,
A determination unit that determines whether or not a document is a blank document, and a plurality of detection units that output detection results that the document is a blank document in different procedures based on the determination result of the blank document by the determination unit If the selection means for selecting one of the plurality of detection means based on an instruction from the user and the output of the detection result from the detection means selected by the selection means, the user checks the document. An image reading apparatus comprising: notification means for outputting a notification for prompting the user. An image capturing device according to claim 14 or claim 15,
An image reading apparatus comprising: a first detection unit that, as the plurality of detection units, immediately outputs a detection result that a document is a blank document when the document is determined to be a blank document; The image reading device according to any one of claims 14 to 16,
An image reading apparatus comprising: a second detection unit that outputs a detection result indicating that the document is a blank document when a predetermined number of documents are determined as a blank document as the plurality of detection units. The image reading apparatus according to any one of claims 14 to 17,
An image reading apparatus comprising: a third detection unit that outputs a detection result indicating that the document is a blank document when all the documents are determined to be blank documents. The image reading apparatus according to any one of claims 14 to 18,
When the notification prompting the check is output, a stop unit that stops reading the image information with respect to the document, and if there is a continuation instruction from the user after the reading unit stops reading the image information, An image reading apparatus comprising: means for continuing reading. A method for searching for a black pixel by the image reading device according to any one of claims 1 to 19,
The main scanning line for document reading is divided into four blocks, and one block is set as the reading target range for each line, and the next line is set as the reading target range for the next line of the previous line. A black pixel search method for an image reading apparatus, wherein black pixel search is performed, and search start addresses of each block are alternately performed at odd and even intervals every four lines. A method of searching for black pixels in an image reading device for searching for the number of black pixels in image data scanned and read from an original,
The main scanning line for document reading is divided into four blocks, and one block is set as the reading target range for each line, and the next line is set as the reading target range for the next line of the previous line. A black pixel search method for an image reading apparatus, wherein black pixel search is performed, and search start addresses of each block are alternately performed at odd and even intervals every four lines.   22. The black pixel search method for an image reading apparatus according to claim 20, wherein the 1 dot and 2 dot isolated points in 1 byte to be searched are not counted as black pixels. A black pixel search method for an image reading apparatus. A black pixel search method for an image reading apparatus according to any one of claims 20 to 22,
The black pixel counting procedure is recorded in advance for each reading mode including a line drawing mode and a halftone mode, and black pixels are counted based on the counting procedure corresponding to the reading mode selected by the user. A black pixel search method for a reading apparatus. A black pixel search method for an image reading device according to any one of claims 20 to 23,
A black pixel searching method for an image reading apparatus, wherein black pixel counting procedures are recorded in advance for each line density, and black pixels are counted based on the counting procedure corresponding to the line density. A blank sheet original detection method for an image reading apparatus according to any one of claims 1 to 13,
One corresponding to the user's instruction is selected from a plurality of detection procedures for outputting the detection result that the set document is a blank document in different procedures based on the determination result that the document is a blank document. And a blank document detection method for an image reading apparatus, comprising: a step of outputting a notification prompting a user to check a document if a detection result output from the detection procedure selected in the step is output. .   A blank document detection method of an image reading apparatus that scans a document and reads image information from the document, the step of determining whether or not the document is a blank document, and a determination result of the blank document in the step A step of selecting one corresponding to the user's instruction from a plurality of detection procedures for outputting a detection result that the set original is a blank original in different procedures; and from the detection procedure selected in the step And a step of outputting a notification prompting a user to check a document if a detection result is output.   27. The blank document detection method of the image reading apparatus according to claim 25, wherein, as the plurality of detection procedures, when the document is determined as a blank document, the document is immediately detected. A blank document detection method for an image reading apparatus, comprising: a first detection procedure for outputting a detection result indicating that the document is a blank document.   28. The blank document detection method of the image reading apparatus according to claim 25, wherein the document is detected when a predetermined number of documents are determined as the blank document as the plurality of detection procedures. A method for detecting a blank document in an image reading apparatus, comprising: a second detection procedure for outputting a detection result indicating that the document is a blank document.   29. The blank document detection method of the image reading apparatus according to claim 25, wherein the document is a blank document when all the documents are determined to be blank documents as the plurality of detection procedures. A blank sheet original detection method for an image reading apparatus, comprising a third detection procedure for outputting a detection result of   30. The blank document detection method of the image reading apparatus according to claim 25, wherein reading of image information on the document is stopped when a notification prompting the user to check the document is output. And a step of continuing to read the original if there is a continuation instruction from the user after the reading of the image information is stopped by the step.

Images