JP3359180B2 - Image reading apparatus and image reading method - 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 reading apparatus capable of reading both sides and an image reading method .

[0002]

2. Description of the Related Art FIG. 9 is a schematic diagram showing the configuration of a document reading section of a conventional image reading apparatus. In FIG. 9, 19 and 20 are CCs.
A sensor such as D, 21 is a fluorescent lamp as a light source, 22 is a document, and 23 is a reading guide. The document 22 is irradiated with light from the fluorescent lamp 21 through a slit provided in the reading guide 23, and the reflected light is converted into an electric signal by the sensors 19 and 20, and is read.

In such an image reading apparatus, the position of the slit of the reading guide 23 is shifted between the front and back sides so as not to be affected by the incident light on the opposite surface. Further, when performing frame processing or the like, a reading guide 2 is provided so that a portion with the document 22 and a portion without the document 22 can be clearly distinguished.
3, the portion of the original 22 that is under the background is blackened, or the mirror is made to be mirror-reflected so that the incident light is totally reflected.
The portion without 2 has a method of reading black data.

FIG. 10 is a block diagram showing the configuration of an image processing section in a conventional image reading apparatus. In FIG. 10, reference numeral 19 denotes a CCD for reading the front surface, reference numeral 20 denotes a CCD for reading the back surface, reference numeral 26 denotes an A / D conversion circuit for converting front and back image data read by the CCDs 19 and 20 into multi-valued data, and reference numeral 27.
Denotes an image processing circuit for performing shading correction, etc., 28 denotes a binarization processing circuit for binarizing data, and 29 denotes an image processing circuit for removing isolated points. The front and back analog image data read by the CCDs 19 and 20 are converted into digital multi-values by the A / D conversion circuit 26 and subjected to image processing such as shading correction by the image processing circuit 27. Subsequently, through a binarization processing circuit 28, image processing such as removal of isolated points is performed by an image processing circuit 29, and finally image data to be displayed / recorded is created.

When an original is read by such an image reading apparatus, there are descriptions on both sides of the original 22. Especially when the paper quality is low, when the sensors 19 and 20 receive light, transmitted light is mixed with reflected light. In some cases, even image data of a surface is read. This phenomenon will be referred to as show-through in the future. The undercoating of the original 22 applied to the reading guide 23 has some effect in suppressing show-through in that light transmitted from the reflective surface is reduced at the same time, but it is in fact completely prevented. It is impossible.

[0006] As a countermeasure, it is necessary to adjust the reading density or the like, and the sharpness of the entire image is sacrificed. In particular, when the background is blackened, the entire image data is darkened, so this tendency becomes remarkable.

[0007]

However, in the above-mentioned prior art, since a measure is taken to minimize show-through, a translucent original such as a second original drawing in which the original format is printed on the back side is used. When reading a corrected article or the like from the back side, the data written from the back side is lost because show-through is suppressed, and the read image is rather unclear.

Further, although show-through is conventionally suppressed, it is necessary to make adjustments such as lowering the reading density when the original is thin paper, etc., and to show-through while maintaining the clarity of the surface image. It was not possible to eliminate them completely.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, an image according to claim 1
In the reading device, front side image data and back side image data
Sensor that reads the data and mirror image inversion of the back side image data
Mirror image reversing means, and the density of the surface image data and
The back side image data mirror-inverted by mirror image inversion means
Show-through included in the surface image data by comparing the density of
Discriminating means for discriminating image data.
It is assumed that.

Further , according to the image reading method of the present invention,
Scans the front side image data and back side image data of the original
Mirror image of the back side image data, and
Before the mirror image is inverted by the mirror image inverting means.
By comparing the density of the back side image data,
Distinguishing show-through image data included in the
Things.

[0011]

Embodiment 1 FIG. 1 is a block diagram showing the configuration of an image reading apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a CCD for reading a front surface as a first sensor, 2 denotes a CCD for reading a back surface which is a second sensor, and 3 denotes a multi-value digital image data read by the CCDs 1 and 2. A / D conversion circuit for converting, 4 is an image processing circuit for performing shading correction and the like, 5 is a binarization processing circuit for converting multi-values to binary, 6 is a back side image mirroring processing circuit as mirror image inverting means, 7 Denotes a front and back image synthesizing circuit as an adding means. Reference numeral 8 denotes an image processing circuit for removing isolated points and the like.

The front and back analog image data read by the CCDs 1 and 2 are converted into digital multi-values by an A / D conversion circuit 3, passed through an image processing circuit 4 for shading correction and the like, and converted into binary data by a binarization processing circuit 5. Be transformed into Note that the surface of the document to be finally obtained as image data is called the front surface, and the opposite surface is called the back surface.

Next, FIG. 2 is a diagram showing a state of image combining by the image reading apparatus of the present embodiment. The combining operation of the front and back images will be described below with reference to FIG. 2 and FIG. Both sides of the original image 9 are read by the CCDs 1 and 2, respectively, and are binarized by the binarization processing circuit 5. Then, of the front and back image data 10 and 11 which have been binarized, only the back image data 11 is mirror-inverted by the mirroring processing circuit 6, and the mirror-inverted back image 12 is combined with the front image data 10 and the front and back image data. The combined image 13 is obtained in the circuit 7.
Here, when the image data of the front and back sides is combined, if the image of the opposite side is show-through on each side, it is not combined. The determination of the show-through image may be performed by a method as in a third embodiment described later.

Next, the necessity of mirror image inversion will be described with reference to FIG. In FIG. 3, reference numeral 14 denotes a front side image read by the CCD 1, 15 denotes a back side image read by the CCD 2, and 16 denotes a mirror-reversed back side image. When the translucent document is read from both sides, the entire image of the back side image 15 is a mirror image obtained by inverting the front side image 14 from side to side, and in this state, the positional shift of the front and back images is complicated. Therefore, if the back side image 16 in which the image data of the back side is mirror-inverted and the positional relationship in the horizontal direction of the image matches the front side image is used, the alignment of the front and back images can be performed more easily. Further, since both sides of the document are read at the same time, even if the document is read slightly obliquely, if the mirror image is inverted, there is no effect on the image synthesis. As a special example, when the image on the back surface is completely equal to the left and right, it is not necessary to perform such mirror image inversion processing.

As described above, in this embodiment, since the two-sided image of the document is read at the same time, the positional deviation of the front and back images is mechanically constant. Furthermore, by inverting the backside image to a mirror image, if the frame of the recorded image is used, it is possible to accurately combine the front and back images. Then, the unclear image on each of the front and back sides compensates for the lack of each other, and finally a clear recorded / displayed image is obtained. In the present embodiment, two CCDs are provided for reading the images on the front and back sides. However, for example, both CCDs may be read by one CCD.

As described above, in this embodiment, even when reading a translucent original, it is possible to easily and reliably read the front and back images of the original without losing necessary data.

Embodiment 2 Since the combination of the front and back images as in Embodiment 1 described above is effective only when the original is translucent, it is impossible to read a normal opaque original. Therefore, in the second embodiment, the flow of image signal processing is switched between the case of reading a normal document and the case of reading a translucent document,
A normal opaque document can be clearly read.

FIG. 4 is a block diagram showing the configuration of such an image reading apparatus. Since the basic configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted. In the image reading apparatus shown in FIG. 4, the transparency of the document is measured by the document transparency measuring circuit 9 as the detecting means, and the control circuit 30 as the control means switches the switch 10 according to the measurement result. When the document is a translucent document, the switch 10 is switched to the a side, and the combining process of the front and back images as described above is performed. When the document is an opaque document, the switch 10 is switched to the b side. No synthesis processing is performed.

Next, FIG. 5 shows the configuration of the document transparency measuring section 9, and the configuration for automatically determining the transparency of the document will be described. A light source 12 and a light receiving element 13 are provided to measure the transparency of the original above and below the passage of the original 11 in the transport path, and the light from the light source 12 is incident on the light receiving element 13 so that the light transmitted through the original enters. Has become. The transparency of the document can be measured based on the output level of the light receiving element 13 when the document passes. The switching of the processing according to the document can be performed manually.

As described above, in this embodiment, normal opaque documents can be read without combining processing, and in the case of translucent documents, combining processing can be performed. It is possible to read high-quality images.

Third Embodiment FIG. 6 is a block diagram showing the configuration of an image reading apparatus according to a third embodiment of the present invention. Here, the same components as those in FIG. 1 or FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. In FIG.
14 is a back side image mirroring processing circuit, 15 is a front and back side image comparison circuit, 16 is a show-through data erasing circuit, and 17 is a binarization processing circuit for converting a multi-value into a binary value.

First, as in the first and second embodiments, the CCD 1
The A / D conversion circuit 3 converts the analog original image data of the front and back read by the A / D conversion circuit 3 into digital multi-values, and the image processing circuit 4 performs image processing such as shading correction.

In order to facilitate the positioning of the front and back images of the digital multi-valued data at this stage, the back surface data is mirror-inverted by a mirror image reversing circuit 14 and the mirror-reversed back surface data is compared by a front surface data and a front and back image comparison circuit 15. I do.

FIG. 7 shows a specific example of image data according to the third embodiment. In the figure, A is the data of the front surface image to be recorded, and B is the image data of the back surface to show through. The image data A has a front surface density equal to or higher than that of the back surface, and the image data B has a back surface density sufficiently higher than that of the front surface due to the transmission of the document paper. In the front and back image comparison circuit 15 as the discriminating means, when the density of the front side image data is equal to or higher than that of the back side (image data A), it is stored as it is, and the density of the back side image data is sufficiently higher than that of the front side. In this case (image data B), the data is erased from the front surface image by the show-through data erasing circuit 16. By repeating this process, it is possible to obtain image data in which only show-through image data is selectively deleted without damaging the image data on the front surface. Here, the level of the show-through image signal and the level of the image signal to be erased are adjusted so as to be the same level in the data erasing circuit 16.

As described above, in this embodiment, by comparing the image data on the front and back sides of the read original at the multi-value stage, only the show-through data is reliably erased from the read image data, and there is no show-through. A high quality read image can be obtained.

Fourth Embodiment In the third embodiment described above, an example is shown in which the show-through of the back image is erased when the front image of the document is read. FIG. 8 shows a block diagram of the configuration. Since the configuration in FIG. 8 is basically the same as the configuration in FIG. 6, the same components are denoted by the same reference numerals and description thereof will be omitted. In FIG. 8, reference numeral 18 denotes a surface image mirroring circuit. In the fourth embodiment, the image data on both the front and back sides is converted into multi-valued digital data, and mirror images of each of the front and back sides are created. In the same way as comparing the front side image data and the mirror image of the back side with multiple values and obtaining the front side image with show-through removed,
By comparing the back side image data and the mirror image of the front side with multi-values, it is possible to obtain the back side image data from which show-through is eliminated.
In this way, it is possible to obtain a double-sided read image in which only show-through of each other is selectively erased.

[0027]

As described above , according to the present invention,
Can easily show-through image data contained in surface image data.
In addition, it has become possible to reliably determine.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image reading apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of a combining operation of front and back images of the image reading apparatus according to the embodiment.

FIG. 3 is an explanatory diagram of mirror image inversion of the image reading apparatus according to the embodiment.

FIG. 4 is a block diagram illustrating a configuration of an image reading apparatus according to an embodiment.

FIG. 5 is a schematic diagram of a document transparency measuring unit according to the embodiment.

FIG. 6 is a block diagram illustrating a configuration of an image reading apparatus according to an embodiment.

FIG. 7 is an explanatory diagram of show-through of a document.

FIG. 8 is a block diagram illustrating a configuration of an image reading apparatus according to an embodiment.

FIG. 9 is a schematic diagram of a document reading unit of a conventional image reading apparatus.

FIG. 10 is a configuration block diagram of a conventional image reading apparatus.

[Explanation of symbols]

 1, 2 CCD 6, 14 Backside image mirroring circuit 7 Front / backside image synthesizing circuit 9 Original transparency measurement unit 15 Front / backside image comparison circuit 16 Show-through data erasing circuit 18 Frontside image mirroring circuit 30 Control circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-62216 (JP, A) JP-A-5-22572 (JP, A) JP-A-6-217123 (JP, A) JP-A-6-217123 319035 (JP, A) JP-A-6-125453 (JP, A) JP-A-6-86055 (JP, A) JP-A-5-347701 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (14)

(57) [Claims] 1. An original image data and a back image data of a document.
A mirror for reversing the back side image data , a mirror for reversing the mirror image by the mirror image reversing unit,
Compare the density of the image data of the reverse side image that has been inverted, and
Determine the show-through image data included in the surface image data
An image reading apparatus comprising: a determination unit . 2. The sensor according to claim 1, wherein the sensor comprises:
A first sensor for reading front side image data ,
An image reading apparatus, comprising: a second sensor for reading image data . 3. The method of claim 1, wherein the sensor, the
An image reading apparatus wherein reading of front side image data and back side image data is performed by one sensor. (4) 2. The surface image data according to claim 1,
Erasing the show-through image data from the show-through data eraser
An image reading apparatus comprising: (5) 2. The surface image data according to claim 1,
And the back side image mirror-inverted by the mirror image inversion means
Image combining means for combining data.
Image reading device. 6. 6. The method according to claim 5, wherein
When performing synthesis, the back side included in the surface image data
The feature is that the image data is not synthesized.
Image reading device. 7. 6. The transparency according to claim 5, wherein
Detecting means for detecting the original, and
When it is detected that the original is a transparent original,
And the detecting means detects that the original is
A synthesizing means for detecting an opaque document;
To prevent the synthesis process from being performed. Control means to control
An image reading apparatus comprising: Claim 8. Original image data and back image data
Data, and the reverse side image data is mirror-inverted.
The density of the surface image data and the mirror image reversal
The density of the inverted back side image data is compared and the front side is compared.
Determining show-through image data included in image data
An image reading method comprising: 9. 9. The surface image data according to claim 8, wherein
Is read by the first sensor, and the back side image data is
Reading by a second sensor different from the first sensor
An image reading method, comprising: 10. 9. The surface image data according to claim 8, wherein
And the back side image data are read by one sensor.
An image reading method. 11. 9. The surface image data according to claim 8, wherein
Deleting the show-through image data from the data
Image reading method. 12. 9. The surface image data according to claim 8, wherein
Synthesizing the backside image data with the mirror image inverted
An image reading apparatus characterized by the above-mentioned. Claim 13 13. The method according to claim 12, wherein the combining is performed.
At this time, the show-through image data included in the surface image data
Image reading characterized by not combining data
Method. 14. 13. The method according to claim 12, wherein the original is transparent.
The original is a translucent original.
The original is opaque.
If it is detected that the document is a draft,
An image reading method characterized by performing control so as not to occur.