JP3027663B2 - Image input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input technique and an input medium used for the same, and more particularly to a facsimile, an optical character reader (OCR), a scanner, etc. for inputting characters or image information on a form using the form as a medium. The present invention relates to a technology effective when applied to the image input technology.

[0002]

2. Description of the Related Art For example, in an information processing system or the like, image data such as characters and images are automatically read from a medium such as a form using a well-known optical character recognition (OCR) technique as a means for data input. That is being done.

Conventionally, as a method of collecting characters and images as binary data by an image input device, a photoelectric conversion element (C
A binarized image is obtained as a photoelectric conversion signal by a binarizing circuit using a CD sensor or the like.

In the binarization circuit, not only characters and images to be processed, but also backgrounds behind them (input media, generally, papers and forms) are faithfully photoelectrically converted.

A method for obtaining a binary image is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 8-200666, it is known to perform background pixel tracking individually and independently for each pixel in the main scanning direction. That is, in order to eliminate the influence of the fluctuation of the background color, for example, the fluctuation of the photoelectric conversion element due to the fluctuation of the photoelectric conversion element, the fluctuation of the sensitivity between the pixels, the change of the paper illuminance due to the influence of the lens and the light source, the output fluctuation is reduced. The white level on the paper is tracked perpendicular to the scanning direction of the photoelectric converter so as to absorb light.

In this case, as described in Japanese Patent Application Laid-Open No. Sho 62-154185, when there is a factor such as a black line or a binding hole in which the white level of the paper suddenly changes, black spouting occurs thereafter. Alternatively, a character image is blurred, and a solution is disclosed. It disturbs the background tracking on the paper in order to accurately binarize the image signal, track the background accurately, find the difference between it and the input signal, and suppress the error of the signal component to the required accuracy. When a factor, for example, a binding hole or the like exists, a certain restriction is imposed on the tracking control for the background change, so that the background tracking is performed faithfully. That is, in the reading range excluding the leading edge and the trailing edge on the sheet, the background tracking is restricted, thereby preventing a problem caused by a black line, a binding hole, or the like.

[0007]

However, even if the above-described countermeasure according to the prior art is taken, different types of paper may be stuck in the reading range except the leading and trailing edges of the paper, or a correction liquid may be used. If the white level is higher than the background color of the paper due to correction or writing with a highlighter, the background tracking is restricted, and the normalized signal (the signal generated from the background signal and the input signal) becomes small. . In other words, the normalized signal (the black component of the character or image data) at the sticking point has a value smaller than the actual value and is blurred.

When the value stored in the white level background memory is updated in order to prevent the occurrence of the above-mentioned blurring, the normalized signal becomes large, and the background level of the paper exceeds the binarization threshold. Black source data that does not exist on the paper.

Hereinafter, the problems of the above-described prior art will be described with reference to the drawings.

FIG. 3 shows marks 29a to 29e written on the sheet 25. The marks 29a to 29c are portions of a white level larger than the background of the sheet.
Is written on the address label 30 attached to the address label. The mark 29c and the mark 29e have a print density of about 50%, which is lighter than other marks.

FIGS. 6A and 6B show examples of an analog system 38 obtained by scanning such marks by an optical system (lamp and photoelectric converter) (not shown) and a paper feed mechanism.
And (b) (a).

The reading scan is performed by a combination of a main scanning direction 26 by a photoelectric conversion element (not shown) and a sub-scanning direction 27 by sheet feeding. Numeral 28 indicates one bit (one pixel) of the image sensor 1, and scans the marks 29a to 29e.

FIGS. 6 (a) and (b) 36a and (b)
Reference numeral 36b in (a) denotes a read slice for obtaining binarized data, and indicates two values that differ depending on the background tracking control method.

For example, FIG.
As disclosed in Japanese Patent No. 54185, the background tracking control within the reading range excluding the leading and trailing ends of the form is restricted, and even if the background white level increases due to the address label 30, the reading is performed. The slice 36a shows no change. Among the marks 29a to 29e, the mark 29c on the address label 30 falls below the read slice 36a due to an increase in the background white level. As shown by a broken line, data is missing. For the marks 29a and 29b, binary black data is obtained, but there is a problem that the marks 29a and 29b are output in a smaller size than the actual entry pattern. The limit of background tracking in this case is, as shown in FIG. 5A, a function F that sets the tracking amount to “0” regardless of the input x for tracking within the reading range.
_{This is because 1} (x) was used.

On the other hand, if the function F ₂ (x) shown in FIG.
The mark 29c can be captured as binary black data without dropping. However, in the portion where the background returns to the original sheet from the address label section, the background white level remains at a large value and does not change, and the read slice 36b has a value higher than the background white level of the actual sheet. In other words, there is a problem that the black data is output in spite of the white background of the paper, and the black data is continuously output until the end of the paper.

FIGS. 4 (a) and 4 (b) show FIG.
An example of taking image data in the cases (a) and (b) will be described. In the figure, the dashed line indicates the area of the address label 30.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image input apparatus capable of accurately and high-quality capturing not only characters and images described in an input medium but also characters and images described in a unique background area existing in the input medium. To provide technology.

[0018]

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0020]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

According to the present invention, an image input device is provided in which characters and images on an input medium are two-dimensionally scanned by a photoelectric converter in a main scanning direction and a sub-scanning direction which are orthogonal to each other and are converted into electric signals to obtain image data. In the apparatus, a first memory for holding a white level of a leading end of an input medium for each pixel in a main scanning direction, and a second memory for tracking and holding a white level of an input medium for each pixel in a main scanning direction in a sub scanning direction. A second memory, a first control unit for updating the second memory by tracking the background white level, and detecting the presence of a unique background area different from the white level at the leading end of the input medium within the reading range of the input medium. In order to detect, a white level of the leading end of the input medium held in the first memory is compared with an input signal level, and a first logic signal indicating a determination result of presence / absence of a unique background area by a predetermined threshold value; 1 A second logic for detecting the end position of the peculiar background area in the sub-scanning direction by taking a logical product of the logic signal and the second logic signal obtained by inverting the first logic signal by one line in the sub-scanning direction, and taking a logical product; And writing the white level of the second memory tracked by the first control means at the end position of the peculiar background area detected by the second control means with the contents of the first memory. By changing, the background white level is returned to the white level at the leading end of the input medium.

[0022]

[0023]

[0024]

According to the image input device of the present invention described above,
The second control means detects a peculiar background area existing in the input medium and controls the background tracking operation by the first control means. The value of the background white level changed by the control means can be accurately returned to the white level in the background of the input medium itself when switching from the singular background area to the original input medium. While avoiding loss of image data such as characters and images in the middle, failures such as black data sprouting after the end of the unique background area can be reliably prevented, and image data existing in both the input medium and the unique background area Can be captured accurately and with high quality.

[0025]

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image input device according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a binarization processing circuit in the image input device of this embodiment.

In FIG. 1, reference numeral 1 denotes an image sensor comprising a photoelectric converter such as a CCD sensor, 2 denotes an amplifier for amplifying an input signal from the image sensor 1, and 3 denotes an A / D converter for converting an analog signal to a digital signal. Reference numeral 4 denotes a logarithmic converter for performing a multiplication / division operation by an adder, and reference numerals 16 and 18 are stored in a background tracking white level memory 11 which holds logarithmic or function F (x) values and a background white level tracking value. Adder 17 for adding the respective values to each other, 17 is a ROM in which the function F (x) is stored, 5, 12, 14, and 19 are latch circuits, 20
Is a comparator for comparing an input level with a designated read slice 23 to obtain a binarized output 21.

Reference numeral 13 denotes a paper leading edge white level memory comprising a line memory for storing the background white level of the leading edge of the paper, and reference numeral 6 compares an input signal with the leading white level of the paper leading edge white level memory 13. A ROM for detecting that the level has become larger than the background white level and outputting it as a logical signal; 7, a line memory for delaying the output of the ROM 6 by one bit; 8, an inverter for inverting the output of the ROM 6; Is an AND circuit for generating an edge signal by the delay line memory 7 and the inverter 8, and 10 is a background tracking white level memory 11 by the edge detection signal 9a.
Is a selector for switching the input to the output between the output (B input) of the background tracking white level memory 11 itself, which is sequentially updated, and the output (A input) of the paper leading edge white level memory 13.

Hereinafter, an example of the operation of the present embodiment having the above configuration will be described.

A scanning signal of a character or an image document output from the image sensor 1 is amplified by an amplifier 2 and input to an A / D converter 3 of n bits, and further output from the A / D converter 3. Is input to the logarithmic converter 4. Where n
Usually uses 6 to 8 bits. The output of the logarithmic converter 4 is input to one of the adders 16 through the latch circuit 5, and the other input of the adder 16 is from the background tracking white level memory 11 in which the tracking value of the background white level is stored. The output is input, and the difference between the two inputs is output from the adder 16. It is conventionally known that the adder 16 functions as a subtractor by setting one input to be negative and the other input to be positive.

Since the output of the adder 16 is the difference between the background tracking value and the input signal, that is, the difference after logarithmic conversion, it is an output obtained by normalizing the input signal component. Therefore,
By comparing with the designated read slice 23 by the comparator 20, the binarized output 21 can be easily obtained.

FIG. 2 is an explanatory diagram showing an example of control in this embodiment. FIG. 2A shows an address label 30 attached to a sheet 25 as an input medium.
Has a value larger than the white level of the background of the paper 25.

The paper 25 is scanned in the main scanning direction 26 by the image sensor 1 and in the sub-scanning direction 27 by a paper feed mechanism (not shown). 28 is an image sensor 1
Is one bit (one pixel) and passes over the address label 30 and is read.

FIG. 2 (b) shows a case where an image sensor 1 is provided.
The state of the analog signal output 32 at the bit 28 is shown. The portion before the leading edge of the paper 25 is black, and the leading edge of the paper 25 is at the background white level of the paper 25. Also, the address label 30
In the portion, the background level becomes higher than the background level of the sheet 25, becomes the background level of the sheet 25 again, and further becomes black after the end of the sheet 25.

Reference numeral 33 denotes the value of the background white level of the leading end of the sheet 25 stored in the sheet leading edge white level memory 13 and is held until the next sheet 25 is updated. 36 is a level (background white level tracking value) of the input signal level in background white level tracking, and 35 is a read slice for binarization determined by the background white level tracking value 36.

When the reading of the sheet 25 is started, the sheet 2
5, the background white level tracking value (WL) also changes, for example, as shown in FIG.
It follows with the function F ₂ (x) of (b).

The tip signal 22 in FIG.
, That is, the white level at the leading end of the sheet 25 is stored and held in the leading edge white level memory 13 (WLH). The leading edge white level (WLH) of the sheet 25 and the white level (LOG) of the sheet 25 as an input signal are stored in a ROM.
6 and a difference between the two is detected as a unique background area such as an address label 30 having a white level higher than the background white level of the paper 25. The detected unique background area detection signal 6a (first logic signal) is shown in (b) of FIG. The method of detecting the unique background area detection signal 6a based on the difference between the two is not limited to using the ROM 6, but may use a comparator or the like. That is,
It can detect a point where the threshold value theta ₁ or there is a difference between the inputs.

The detection of the unique background area detection signal 6a ends at the rear end of the address label 30 (returns to the "L" level). Further, the singular background area detection signal 6a is delayed by one bit by the delay line memory 7 ((c) in FIG. 2C) and the singular background area detection signal 6a is inverted by the inverter 8. The inversion detection signal 8a ((d) in FIG. 2 (c)) (the second logic signal) obtained by the AND operation is ANDed by the AND circuit 9 to obtain (e) in FIG. 2 (c). Edge detection signal 9a shown
Get. The edge detection signal 9a indicates that the unique background area whose white level is higher than the background white level of the paper 25, such as the address label 30, has ended. At this timing, the background white level tracking value 36 is changed to the current address label. Switching from 30 to the background white level 34 of the paper 25. This switching is realized by the selector 10.

The edge detection signal 9a is normally at "L" level. In this state, the selector 10 outputs the B input, that is, the background tracking level (WL). It is updated with the value of the signal level (LOG). That is, it follows the background level of the paper 25. Here, when the edge detection signal 9a becomes "H" level, that is, at the timing when the address label 30 returns to the background of the paper 25, the selector 10 previously stores it in the paper leading edge white level memory 13 as described above. The output is switched to a white level output (A input) at the leading end of the paper 25 being output.

As a result, the background tracking white level 31
From the background white level 32 of the address label 30 to the paper 25
It switches to its own background white level 34. The read slice 23 follows this, and transitions from 37 to 35.

As described above, according to the present embodiment, the paper 25
If there is a unique background area such as an address label 30 having a background white level different from that of the paper 25 in the reading range of the paper 25, the background tracking white level 31 and the reading slice 23
During the reading of the address label 30 as well as after the end of the reading direction, it is possible to reliably prevent problems such as the above-described occurrence of data blurring, missing data, and black sprouting, and to improve the reading accuracy. Improvement can be achieved.

In this embodiment, the case where the address label 30 is attached has been described as an example of the unique background area larger than the background white level of the paper 25. However, the present invention is not limited to this. The same effect can be obtained when the paper 25 on which the correction ink application area or the writing area by the highlighter pen exists is read.

In the above description, the threshold value θ ₁ for detecting a white level abnormality (a phenomenon that becomes larger than the background white level of the paper 25 like the address label 30) is determined by the degree of the white level abnormality. It can be appropriately selected according to the degree of character / image data blurring, and can be switched and used depending on the type of paper 25 (the thinner the paper, the higher the abnormal level).

[0045]

FIG. 7 is an explanatory diagram showing an input medium according to a reference example of the present invention.

The input medium 50 of this embodiment has a background white level higher than the background white level of the input medium 50 at a position after the end of the data area 51 in which characters, graphics, and the like are written in the reading direction. For example, a label 52 or the like is attached.

Thus, for example, image input can be performed normally in both the data area 51 and the label 52 without adding a special function to the conventional character / image input device. That is, even if a defect such as black spring occurs after the end of the label 52 due to the presence of the label 52, the image capturing operation of the data area 51 and the label 52 has already been completed. The reading of the area 51 and the label 52 can be performed without any inconvenience.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof. Needless to say.

[0049]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

That is, according to the image input apparatus of the present invention, not only the characters and images described on the input medium but also the characters and images described on the unique background area existing on the input medium are accurately and accurately captured. Can be obtained.

[0051]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a binarization processing circuit in an image input device according to an embodiment of the present invention.

FIGS. 2A to 2C are explanatory diagrams illustrating an example of control of an image input device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a state of an input medium.

FIGS. 4A and 4B are explanatory diagrams showing an example of the operation of the related art.

FIGS. 5A and 5B are explanatory diagrams showing an example of the operation of the related art.

FIGS. 6A and 6B are explanatory diagrams showing an example of the operation of the related art.

FIG. 7 is an explanatory diagram showing an input medium that is a reference example of the present invention.

Continuing from the front page (72) Inventor Motonobu Fukushi 2880 Kozu, Odawara-shi, Kanagawa Prefecture Hitachi, Ltd. Storage Systems Division (72) Inventor Masahisa Watanabe 2-6-1 Otemachi, Chiyoda-ku, Tokyo Hitachi Electronics Engineering Inside (72) Inventor Tsuneo Meguro 2-6-2 Otemachi, Chiyoda-ku, Tokyo Hitachi Electronics Engineering Co., Ltd. (56) References JP-A-64-42783 (JP, A) JP-A-59-189784 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60 G06K 9/38 G06T 1/00

Claims (1)

(57) [Claims] 1. An image input device for two-dimensionally scanning characters and images on an input medium by a photoelectric converter in a main scanning direction and a sub-scanning direction which are orthogonal to each other and converting them into electric signals to obtain image data. The white level at the leading end of the input medium is defined as a pixel in the main scanning direction.
A first memory for holding each, before the white level of the input medium for each pixel of the main scanning direction
A second memory for tracking and holding in the sub-scanning direction; first control means for tracking the background white level and updating the second memory; and an input medium within a reading range of the input medium. Destination
Detects the presence of a unique background area different from the white level at the edge
For this purpose, the input signal level is compared with the white level of the leading end of the input medium held in the first memory,
A first threshold value indicating a determination result of the singular background region by a threshold value
A logic signal, the first logic signal, and a first logic signal obtained by inverting the first logic signal.
2 in the sub-scanning direction by one line.
And taking the logical product of the
Second control means for detecting an end position in the scanning direction;
Wherein the said tracked by the first control means second note
The white level of the light is detected by the second control means.
At the end position of the singular background area,
The white background can be changed by rewriting the contents of the memory.
An image input apparatus , wherein a level is returned to a white level at the leading end of the input medium .