JPH06334840A - Picture processing method and its device - Google Patents

Abstract

PURPOSE:To provide an output of original information as normal picture information to the utmost by detecting a vertical distance between an original face of a book original and an original placing face to obtain tilt information of the original face and correcting picture information of the book original based on the tilt information. CONSTITUTION:A distance between an original platen glass 2 and an original in the original read scanning direction is read by using a book sensor 100 when an original is copied. Then a tilt obtained by a tilt between the original platen glass 2 and the original face 1a is used to extend a picture of an original projected onto the original platen. Then distortion of a picture due to the tilt of the original face 1a is corrected and a copy picture with fidelity to the original is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus for converting document information read by an image sensor into an electric signal, performing image processing on the converted image data, and sending the image data to an image output apparatus. It is about.

[0002]

2. Description of the Related Art Conventionally, an image processing apparatus of this kind is provided,
For example, a digital copying apparatus reads a document image by exposing and scanning a document placed on a document table, performs various image processing on the read image data, and outputs it to a printer engine (for example, a laser beam printer) as an image signal. By outputting, a desired image can be obtained.

[0003]

By the way, the original placed on the original table is not limited to the sheet original, and a thick original such as a booklet original may be placed.

In this case, if the binding is such that the binding margin portion of the booklet original is flat with respect to the loading surface, this is not a serious problem, but the loading surface and the binding margin portion of the opened document are separated. That is, when a curved mountain-shaped space portion (the vertical distance from the lowest surface to the binding margin portion increases depending on the number of pages) is formed between the document surface and the placement surface, the above image is formed. There is a problem in that the characters and images around the binding margin read by the sensor are distorted and cannot be output as a normal image. It should be noted that this type of problem is not limited to the above digital copying machine, and similarly occurs in a reader device that reads an image with an image reader.

The present invention has been made to solve the above problems, and analyzes the curved surface shape of the document surface in the vicinity of the binding margin in the read booklet document image to automatically correct the distortion of the read image data. It is an object of the present invention to provide an image processing method and an apparatus capable of reading and outputting a booklet document image without distortion by correction.

[0006]

An image processing method according to the present invention detects a vertical distance between a document surface and a document mounting surface of a booklet document placed on a document table, and detects the detected distance data. Inclination information of the document surface is derived based on, and the image information of the read booklet document is corrected based on the derived inclination information.

The image processing apparatus according to the present invention comprises image reading means for reading a booklet original image placed on a document table,
Detecting means for detecting a vertical distance between the original surface of the booklet original placed on the original table and the original placing surface, and derivation for deriving inclination information of the original surface based on the distance data detected by the detecting means. And a correcting means for correcting the image information of the booklet original read by the image reading means based on the tilt information derived by the deriving means.

[0008]

In the image processing method of the present invention, the vertical distance between the original surface of the booklet original placed on the original table and the original placing surface is detected, and the original surface of the original is detected based on the detected distance data. The tilt information is derived, and the image information of the booklet document read based on the derived tilt information is corrected. Therefore, in the read booklet document, the distortion of the curved surface image near the binding margin is corrected, It is possible to output as normal image data as possible.

In the image processing apparatus of the present invention, the derivation means derives the inclination information of the document surface based on the distance data detected by the detection means, and the correction means reads the image based on the derived inclination information. Since the image information of the booklet original read by the means is corrected, even if the document surface near the binding margin of the booklet original is curved with respect to the document placement surface, the read booklet original near the binding margin is read. It is possible to correct the distortion of the image read on the curved surface and output the image data as normal as possible.

[0010]

FIG. 1 is a schematic sectional view for explaining the structure of an image processing apparatus showing an embodiment of the present invention, for example, a case of a digital copying apparatus.

In the figure, reference numeral 1 is a booklet document, which is placed on a document table glass 2. Reference numeral 100 denotes a non-contact displacement sensor (hereinafter, simply referred to as a booklet sensor) such as a laser displacement meter for measuring the distance between the original platen glass 2 and the booklet original 1.
The conveyor belt 101 is configured to be capable of reciprocating scanning movement from a predetermined reference position as shown in the figure. By using the booklet sensor 100, from the inclination information of the original surface 1a having the curved surface facing the binding margin portion, which is a non-contact portion with respect to the original platen glass 2 (original placing surface), and the original surface 1a having the original placing surface, The image data read by the CCD sensor 9 is corrected based on the correction data obtained by the calculation described below, and the distortion of the read image data is automatically corrected.

Reference numeral 4 is a scanner, which is a lamp 3 and a scanning mirror 5.
And the like, and reciprocally scanned in a predetermined direction to form an image of the reflected light of the document on the CCD sensor 9 through the lens 8. In addition, 6,7
Is a scanning mirror.

Reference numeral 10 denotes an exposure control section composed of a laser scanner, which irradiates the photoconductor 11 with a light beam which is modulated based on the image data output from the image signal control section of the controller section CTRL, according to the original. Form an electrostatic latent image. Reference numerals 12 and 13 denote developing devices that visualize the electrostatic latent image formed on the photoconductor 11 with a developer (toner) of a predetermined color. 1
Reference numerals 4 and 15 denote transfer paper stacking units, which store and store standard-size recording media, and are fed to the registration position by the driving of the feeding roller, and the image leading edge alignment timing with the image formed on the photoconductor 11. The paper is fed in the state where it has been removed.

Numeral 16 is a transfer separation charger, which transfers the toner image developed on the photoconductor 11 onto the transfer paper and then the photoconductor 11
It is fixed in the fixing unit 17 via the separated transport belt. Reference numeral 18 denotes a paper discharge roller, which switches the carrying direction of the transferred paper on which the image formation is completed to the paper discharge port and the internal carrying path direction to prepare for the multiplex / double-sided image forming process. 20 is a tray.

At the time of double-sided recording, the paper to be transferred passes through the paper discharge sensor 19 and then the paper discharge roller 18 is rotated in the direction opposite to the paper discharge direction. At the same time, the flapper 21 is raised upward to store the copied transfer paper in the intermediate tray 24 via the transport paths 22 and 23. The transfer paper stored in the intermediate tray 24 is fed during the next back surface recording,
The back side is transferred. Reference numeral 25 is a registration roller, and 26 is a cleaner.

During multiple recording, the flapper 19 is raised to store the copied transfer paper in the intermediate tray 24 via the transport paths 22 and 23. The transfer paper stored in the intermediate tray 24 is fed for the next multiplex recording, and the multiplex transfer is performed.

In the image processing apparatus thus configured, the derivation means derives the inclination information of the document surface based on the distance data detected by the detection means (booklet sensor 100), and based on the derived inclination information. Since the correction means (controller unit CTRL) corrects the image information of the booklet document read by the image reading means (CCD sensor 9), the document surface near the binding margin of the booklet document is curved with respect to the document placement surface. Even if it is,
It is possible to correct the distortion of the read image on the curved surface near the binding margin and output the image data as normal as possible.

FIG. 2 is a sectional view of an essential part for explaining the reading operation of the booklet original 1 by the booklet sensor 100 shown in FIG.

FIG. 3 is a diagram showing the output characteristics of the booklet sensor 100 shown in FIG. 2, in which the horizontal axis represents the scanning direction and the vertical axis represents the distance to the curved surface portion of the document surface 1a of the booklet document 1 (original document). The height h) from the table glass surface to the document surface 1a is shown.

FIG. 4 is a diagram showing the principle of approximate analysis of a curved surface when the distance h shown in FIG. 3 is used as a function, and the same components as those in FIG. 3 are designated by the same reference numerals.

As shown in FIG. 2, when copying an original such as a booklet original 1, the binding margin portion of the booklet is separated from the platen glass 2, so that the image around the binding margin portion is the original image. Causes distortion.

Therefore, in this embodiment, as shown in FIG.
When a document is copied, the distance between the document platen glass 2 and the document in the document reading scanning direction is read using the booklet sensor 100 (reading is performed when the document platen pressure plate is pressed or when the booklet copy mode is designated). And original side 1a
The image of the original document projected on the original platen is expanded using a value derived from the inclination of and, and the image distortion due to the inclination of the original surface 1a is corrected to obtain a copy image more faithful to the original by the following processing. .

First, the document position is read by a document size detection device (sensor) (not shown). Here, based on the read data, the document start position x on the platen glass 2
(0) and x (e) are determined as shown in FIG. Then, for the booklet original 1 shown in FIG. 2, the height h from the original glass 2 to the original surface 1a is measured by using the booklet sensor 100.
Measure (n). Here, n is a number n indicating the document reading position, and the value is “0” at the document starting position x (0). That is, the reading positions x (0), x (1), x
(2), ..., Heights h (0), h with respect to x (n), respectively
(1), h (2), ..., H (n) correspond.

In this embodiment, the reading position increment dx (n) = x (n + 1) -x (n) due to the increase of n is a constant.

Next, each n = 0 by the CCD sensor 9,
Scan the image data of the original for 1 ...
Read in the section from (n) to x (n + 1). At this time, the information read in the section from x (n) to x (n + 1) is referred to as a read pixel P (n) here, and is temporarily stored in the image memory in the controller unit CTRL.

Then, for the read pixel P (n),
The CPU in the controller unit CTRL derives the tilt angle z (n) of the document at that position based on the control calculation program as described below.

In this embodiment, the tilt angle z (n) is
It is derived based on the following formula (1).

Tilt angle z (n) = arctan (dh (n) / dx (n)) where dh (n) = h (n + 1) -h (n) dx (n) = x (n + 1) -x ( n) (1) Then, the read pixel P is obtained from the tilt angle z (n) of this document.
(N) is the width dx (n) projected on the platen glass 2
And the actual pixel width dy (n) on the platen is calculated to extend the width of the read pixel P (n) to this size. That is, the width dx (n) of the read pixel P (n) projected on the platen glass 2 is expressed by the following equation (2): dy (n) = dx (n) / cos (z (n)) ... By expanding the width to dy (n) based on (2), copy image data more faithful to the original can be obtained. In addition,
y (n) is a position on the copy sheet corresponding to the number n indicating the reading position of the document, and y (n + 1) = y (n) + dy (n) (3) according to the following formula (3). It is a position represented by. Manuscript side 1 of these book manuscripts 1
The positional relationship between the image on the a, the platen glass 2, and the copy sheet is as shown in FIG.

FIG. 5 is a characteristic diagram showing the expansion relationship between the original table projection pixels and the pixels on the paper in the image processing method according to the present invention. [Second Embodiment] FIG. 6 is a characteristic diagram showing a pixel expansion processing state in an image processing apparatus according to the second embodiment of the present invention.

As shown in this figure, the pixel width dy (n) on the actual original is processed to be substantially constant, and the inclination dh / dx of the original changes largely, that is, in the vicinity of the binding margin of the original, that is, in FIG. In order to reduce the error of dh / dx even in the vicinity of the position x (c) shown in, the width dx (n) is made variable as follows. With the same configuration as that of the above embodiment, the slope is calculated based on the following formula (4): dx (n) = A · cos (arctan (dh (n-1) / dx (n-1))) (4) ) The same processing as in the above-described embodiment is performed while deciding each position x (n) using the obtained variable dx (n). In this way, the inclination at x (n) is approximated by the inclination of the original surface at the position x (n−1) with respect to the original table, and dx (n) is determined so that dy (n) is almost A at all times. When the change dh (n) in the height of the document surface is large, dx (n) becomes small, and as a result, the read pixel P
It is possible to reduce the magnification error during the expansion of (n). Here, A in the equation (3) is a pixel width that is constant on the document surface 1a. [Third Embodiment] FIG. 7 is a characteristic diagram showing a pixel width expansion processing method in the image processing method according to the present invention.
(B) shows the relationship between the document surface height h (n) read at the reading position x (n) and the differential value (differential coefficient) directly obtained from the value of the height h (n) by numerical differential calculation processing. (C) and (d) show the relationship between the height h (n) approximated by the least square method and the differential value (differential coefficient) derived from the data obtained by differentiating the approximate function.

In this embodiment, the read height data h
(N) is easily differentiated by the least squares method, and is approximated by a simple function (for example, y = αx 2 + βx + c) having a section that is monotonically increasing (or monotonically decreasing), and the differential function is used. The calculation of the value of dh (n) / dx (n) is caused by the reading error of the booklet sensor 100 and the unevenness of the document surface 1a when directly derived from the discrete value data h (n). Differential value dh (n)
The instability of / dx (n) can be removed.

In the application of this embodiment, sections x (0) to x are bounded by the position x (c) where the height h is the maximum value.
It is necessary to use a monotonically increasing function in (c) and a monotonically decreasing function in the sections x (c) to x (e).

As another image processing method, it is also possible to provide the above-mentioned device in both the horizontal and vertical directions of the original and perform the above-mentioned processing regardless of how the original is placed vertically or horizontally.

Further, in the above embodiment, the case where the present invention is applied to the digital copying apparatus has been described. However, in the analog copying apparatus, when the original is placed so that the original height changes in the scanning direction of the exposure lamp. The present invention can be applied if the control for changing the scanning speed of the exposure lamp, which is carried out in the conventional variable magnification analog copying apparatus, is executed during the scanning of one original.

Further, according to the present invention, another image input device for reading an image by bringing an original image into contact with the original platen glass, for example, a digital image scanner used in an input device of an electronic computer or the like, or a platen with an original plate. It can also be applied to a facsimile machine or the like.

Next, the image data correction processing operation in the image processing method according to the present invention will be described with reference to FIG.

FIG. 8 is a flow chart showing an example of the image data correction processing procedure in the image processing method according to the present invention. Note that (1) to (8) indicate each step.

First, the mounting position of the booklet original 1 placed on the original table glass 2 is detected (1). Then, the document start position is determined (2). Next, the height h (n) to the document surface 1a is read at a predetermined interval (3). Next, the original image is read (4) and temporarily stored in an image memory (not shown). Then, the inclination of the curved surface of the original is calculated based on the above-described arithmetic expression (5). Next, it is determined whether or not the slope calculation is completed for all the sections (6), and if NO, the process returns to step (5), and if YES, the pixel width is expanded according to the calculated ratio (7), It is determined whether or not the expansion processing for all the sections has been completed (8). If NO, the procedure returns to step (7), and if YES, another processing is performed.

As described above, according to the image processing method of the present invention, the vertical distance between the document surface of the booklet document placed on the document table and the document placing surface is detected, and the detected distance data is detected. The tilt information of the document surface is derived based on the above, and the image information of the read booklet document is corrected based on the derived tilt information, so that the image of the curved surface near the binding margin of the read booklet document is corrected. It is possible to correct the distortion and output the image data as normal as possible.

[0040]

As described above, in the image processing method of the present invention, the vertical distance between the original surface of the booklet original placed on the original table and the original placing surface is detected, and the detection is performed. The tilt information of the document surface is derived based on the distance data, and the image information of the read booklet document is corrected based on the derived tilt information, so that the curved surface of the read booklet document near the binding margin is corrected. Image distortion can be corrected and output as normal image data as much as possible.

In the image processing apparatus of the present invention, the derivation means derives the inclination information of the document surface based on the distance data detected by the detection means, and the correction means reads the image based on the derived inclination information. Since the image information of the booklet original read by the means is corrected, even if the document surface near the binding margin of the booklet original is curved with respect to the document placement surface, the read booklet original near the binding margin is read. It is possible to correct the distortion of the image read on the curved surface and output the image data as normal as possible.

Therefore, the distortion of the read image peculiar to the booklet original in which the binding margin portion floats above the original document placement surface and the read image information can be corrected according to the distortion of the booklet original. Therefore, it is possible to output the image of the booklet original as a normal image.

[Brief description of drawings]

FIG. 1 is a schematic sectional view illustrating a configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part for explaining a booklet reading operation of the booklet sensor shown in FIG.

FIG. 3 is a diagram showing output characteristics of the booklet sensor shown in FIG.

FIG. 4 is a diagram showing a principle of approximate analysis of inclination of a curved surface when the distance h shown in FIG. 3 is used as a function.

FIG. 5 is a characteristic diagram showing an expansion relationship between original plate projection pixels and paper pixels in the image processing method according to the present invention.

FIG. 6 is a characteristic diagram showing a pixel expansion processing state in the image processing apparatus showing the second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a pixel width expansion processing method in the image processing method according to the present invention.

FIG. 8 is a flowchart showing an example of an image data correction processing procedure in the image processing method according to the present invention.

[Explanation of symbols]

 9 CCD sensor 100 Booklet sensor 101 Conveyor belt CTRL controller section

Claims (2)

[Claims] 1. A vertical distance between a document surface of a booklet document placed on a document table and a document placing surface is detected, and inclination information of the document surface is derived based on the detected distance data. An image processing method characterized by correcting image information of a booklet document read based on derived inclination information. 2. An image reading means for reading a booklet original image placed on the original table, and a detection means for detecting a vertical distance between the original surface of the booklet original placed on the original table and the original placing surface. And a derivation means for deriving inclination information of the document surface based on the distance data detected by the detection means, and an image of the booklet original read by the image reading means based on the inclination information derived by the derivation means An image processing apparatus comprising: a correction unit that corrects information.