JPH1139463A - Image reader and image checking device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader and an image reading method which perform accurate shading compensation and an image checking device which performs accurate image checking. SOLUTION: A color CCD camera is moved so that its field angle range can be located at field angle positions AV1 to AV4 like (b) and margin parts of a reference article and an object are repeatedly read as a margin read area RA. And image signals of a full white reference image WW are acquired by collecting image signals of partial white reference images PW1 to PW4 which eliminate edge excesses of images of respectively acquired margin read areas RA. After shading compensation of each CCD of the color CCD camera is performed by using image signals of the full white reference image WW that is acquired in this way, the reference article and the objects are read and image check is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus which reads an image of an object to be read and generates an image signal, and an image inspection apparatus using the same.

[0002]

2. Description of the Related Art In a conventional image reading apparatus, a document placed at a reading position is illuminated by an illumination lamp, and light reflected by the document is passed through an image forming lens to form a charge imaging device (CC).
D) is guided to a line sensor having a plurality of linear (one-dimensional) arrangements to read an image of a document, and the line sensor outputs a value corresponding to the image as an electric signal.

By the way, considering a plurality of CCDs constituting a line sensor in the above configuration, each CCD generally has different characteristics such as sensitivity for each CCD. Therefore, when an image is read by a line sensor having a plurality of CCDs having different characteristics, an accurate image cannot be read in the main scanning direction (CCD array direction). And so on.

Therefore, in order to accurately read an image in the main scanning direction, processing for correcting characteristics such as sensitivity of each CCD (shading correction) has been conventionally performed.

Here, conventional shading correction will be described.

[0006] In the most widespread method for shading correction, a white reference plate is arranged at the end of a document table and read by an image pickup means. In order to perform more accurate shading correction, instead of a single fixed white reference plate, a plurality of plain papers of various whiteness and materials are prepared in advance, and the original paper It has been practiced to select something close to whiteness or material and place it at the reading position. These are not `` plates '' in a strict sense because they are paper used for printing, etc., but using the usual term in shading correction, the following "white reference plate"
I will call it.

After selecting and arranging such a white reference plate, the white reference plate is read while the illumination lamp is turned on, and the obtained data is stored in a memory. Next, reading is performed with the illumination lamp turned off, and the obtained data is stored in the memory. Reading in a state in which the illumination lamp is turned off means reading a state in which no light is guided to the CCD, and therefore, a value corresponding to a dark current (offset) for each CCD is detected.

[0008] The setting for normalizing the output value to make the output difference (dynamic range for each CCD) common between the dark current for each CCD and the current read from the white reference plate is performed. Then, when actually reading the image of the original, the offset levels which are different for each CCD to be output signals from each CCD of the image pickup means are corrected using the shading correction information obtained in advance in this way. You.

[0009]

By the way, the original paper is often not originally white, such as yellow, or a color other than white, or is not completely white due to the occurrence of yellowing, deterioration, and the like. Even if the shading correction is performed on the basis of the white reference plate, the shading correction is strictly different from that of the original document, so that accurate shading correction cannot be performed.

Further, for example, it is conceivable to use a blank portion of a document as a white reference as a white reference. It was difficult.

The present invention intends to overcome the above-mentioned problems in the prior art, and provides an image reading apparatus capable of performing accurate shading correction and an image inspection apparatus capable of performing accurate image inspection by using the same. The purpose is to do.

[0012]

According to a first aspect of the present invention, there is provided an image reading apparatus for reading an image of an object to be read and generating an image signal. Object holding means for holding the object, image pickup means for reading an image of the object to read, and generating an image signal; moving means for relatively moving the object holding means and the image pickup means; Read area specifying means for specifying an area to be read including a blank portion, and control means for controlling the moving means and the image pickup means to read the read area while relatively moving the object to be read and the image pickup means; and Storage means for storing an image signal obtained by reading, and white reference image signal generation for generating a white reference image signal for the imaging means based on an image signal corresponding to a margin portion of the image signal Comprises a stage, on the basis of the white reference image signal and a shading correction unit that performs shading correction, a.

According to a second aspect of the present invention, there is provided the image reading apparatus according to the first aspect, wherein the control means moves the object to be read and the imaging means relative to each other to image the area to be read. The moving means and the imaging means are controlled so as to be repeatedly read in the storage means, and the storage means stores a plurality of image signals obtained by the repeated reading. An image signal corresponding to the portion is collected to generate a white reference image signal corresponding to the entire angle of view of the imaging means.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, a margin portion of each of the plurality of sections obtained by dividing the entire angle of view is repeatedly set to a margin of the full angle of view. It is characterized in that a plurality of image signals are obtained by imaging in different sections.

According to a fourth aspect of the present invention, in the image reading apparatus of the third aspect, a division number operation designating means for designating the number of divisions for dividing the entire angle of view into a plurality of sections is further provided. Prepare.

According to a fifth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to fourth aspects, wherein the imaging means includes an imaging element in which the imaging means is arranged in a dimension. There is a feature.

According to a sixth aspect of the present invention, in the image reading apparatus of any one of the first to fifth aspects, the moving means moves the imaging means and the object holding means to each other. The moving means is two-dimensionally moved while being kept constant, and is further provided with an illuminating means which is arranged at a position fixed with respect to the imaging means and illuminates the object to be read.

According to a seventh aspect of the present invention, in the image reading apparatus of the sixth aspect, the illuminating means is an annular illuminating means provided so as to surround a periphery of an angle of view of the imaging means. And

Furthermore, the apparatus according to claim 8 of the present invention is an image inspection apparatus for reading images of a plurality of objects to be read and inspecting the images by comparing the images with each other. Any one of the image reading apparatus, a signal conversion unit that performs signal conversion according to shading correction on a plurality of inspection image signals obtained by reading a plurality of objects to be read by an imaging unit, and a signal conversion unit. The image processing apparatus includes: a difference detection unit configured to detect a mismatched portion of an image on a plurality of reading objects by comparing a plurality of inspection image signals after the application; and a display unit configured to display a detection result by the difference detection unit.

The term "white" in the present invention is a term that includes not only white in an optically strict sense, but also the color of the fabric of the object to be read and the background color.

The "margin portion" includes not only a portion on the outer periphery of the image area, but also an area in the image area where the material or background color of the object to be read appears.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

[1. Mechanical Configuration and Apparatus Arrangement of Embodiment] First, an outline of an image inspection apparatus according to an embodiment of the present invention will be described.

FIG. 1 is an external perspective view of an image reading apparatus 1a of an image inspection apparatus 1 according to one embodiment of the present invention. 3 and 4, a three-dimensional coordinate system XYZ is defined in which a horizontal plane is an XY plane and a vertical direction is a Z-axis direction.

The image inspection apparatus 1 is configured as a plate inspection apparatus for plate making, and includes proof printing (first school PS1, second school PS).
2)), original films F1, F2 ... and printing plates P1, P2
… Etc. can be compared with each other.
This is used for performing a comparison inspection between S1 and the re-establishment PS2 and determining whether corrections from the first school have been correctly performed at the re-entry stage. Therefore, the object S to be read in this embodiment will be described with these proofs as inspection targets.

In the image inspection apparatus 1, a transparent glass plate 3 is mounted on the upper surface of the main body 2, and proof printing (first school PS1, second school PS2...) And original films F1, F2 are provided on the transparent glass plate 3. , And printing plates P1, P2,... On the upper surface of the main body 2, the Y-side end of the cover member 4 having a plane size slightly larger than the transparent glass plate 3 is set to (+ Y) of the transparent glass plate 3.
The operator oscillates on the side, and an operator places the object S to be read out of the proof printing, the original film and the printing plate on the transparent glass plate 3, and attaches the cover member 4 to the transparent glass plate 3. When folded up, the sheet-like object S is sandwiched between the transparent glass plate 3 and the cover member 4 and held.
As described above, in this embodiment, the transparent glass plate 3 and the cover member 4 constitute a reading object holding unit that holds the reading object S such as a proof print.

FIG. 2 is a diagram showing an electrical configuration of the image inspection apparatus 1 together with a control system having an optical configuration and a mechanical configuration.

This apparatus comprises a control arithmetic unit 61 serving as a control unit, a white reference image signal generation unit, a shading correction unit, a signal conversion unit and a difference detection unit.
A computer unit having a PU and a memory is provided. As an input / output device of the control operation device 61,
A color CRT 62, a keyboard 63, a mouse 64, a monochrome plotter 65, and a color printer 66 are provided.
3. A read area designation unit is formed by the mouse 64, and the color CRT 62, the monochrome plotter 65, and the color printer 66 each function as a display unit.
In addition, the control arithmetic unit 61 is a voice unit controller 6
A voice message is transmitted to the operator by controlling the voice unit 68 via. Further, the control arithmetic unit 61 can control the turning on and off of the round fluorescent lamp 22 via the illumination controller 69. Further, the image signals of the three RGB components obtained by the color CCD camera 40 as the image pickup means are given to the image input circuit 70, subjected to appropriate image processing, and then sent to the control arithmetic unit 61. In addition, the control operation device 61
Motor 8 for driving the lens via the motor controller 71
1 (described later in detail), and the X-drive and Y-drive pulse motors 14a and 14b can be controlled via the motor controller 72, respectively. Further, a magnetic disk 73 is electrically connected to the control arithmetic unit 61 as an external recording medium functioning as a storage unit.

Next, the main part of this apparatus will be described.

FIG. 3 is a sectional view of the image reading apparatus 1a of FIG. 1 in a state where the cover member 4 is laid on the transparent glass plate 3. Inside the main body 2, a base frame 5 is arranged on the bottom surface side, and an XY drive mechanism 10 as a moving means is provided on the base frame 5. This XY
As shown in FIG. 3, the drive mechanism 10 has an X extending in the X direction.
It is composed of a drive unit 11a and a Y drive unit 11b extending in the Y direction, and these units are provided in parallel with the transparent glass plate 3.

In the X drive unit 11a, the ball screw 1
One end of 2a is rotatably supported by a bearing (not shown) and the other end is connected to an X drive pulse motor (not shown). A coupling block 13a is screwed into an intermediate portion of the ball screw 12a. Further, a Y drive unit 11b is fixed on the coupling block 13a. The basic configuration of the Y drive unit 11b is the same as that of the X drive unit 11a, and a description thereof will be omitted.

In the XY drive mechanism 10 constructed as described above, the X drive and Y drive pulse motors 14a and 14
By controlling b, the coupling block 13b screwed to the ball screw (not shown) of the Y drive unit 11b can be moved two-dimensionally in the X and Y directions and in parallel with the transparent glass plate 3, Therefore, the color CCD camera 40 can be moved two-dimensionally while keeping the distance from the transparent glass plate 3 constant.

FIG. 4 is a perspective view showing the structure of the structure 50. As shown in the drawing, the illumination unit 20 and the optical system 30 are provided in the two-dimensionally movable coupling block 13b.
And a structure 50 formed by integrating the color CCD camera 40.

In the illumination unit 20, a circular fluorescent lamp 22 as an annular illumination means is accommodated in a cylindrical main body cover 21, and the lighting controller 69 controls the turning on and off. When the round fluorescent lamp 22 is turned on, the illumination light IL from the round fluorescent lamp 22 passes through the opening 23 provided on the upper part of the main body cover 21 and further passes through the transparent glass plate 3 to read the object S to be read. Incident on a part of. As described above, in this embodiment, the illumination light IL locally illuminates a part of the object S to be read by the round fluorescent lamp 22, so that the illuminance distribution in the illumination area can be made uniform. .

The light reflected from the illumination area of the object S is guided to the color CCD camera 40 by the optical system 30. The optical system 30 includes a plurality of lens groups including a movable lens group, and a lens driving motor 81 drives the movable lens group to move the movable lens group in the direction of the optical axis OA, thereby changing the magnification of the optical system 30. Is possible.

The color CCD camera 40 has two
It has a CCD which is an image pickup device arranged in a dimension, and can generate an image signal of a two-dimensional image.

In the structure 50 configured as described above, the reading unit S placed on the transparent glass plate 3 is locally and uniformly illuminated by the illumination unit 20, and the optical system 30 is illuminated.
, The image of the illumination range is appropriately scaled, and the image is captured by the color CCD camera 40. Moreover, this structure 5
0 is attached to the coupling block 13b, so that the X- and Y-drive pulse motors are controlled by the motor controller while capturing the local image of the object S to be read in the two-dimensional manner as described above. The whole image on the reading target S can be read by moving the structure 50.

Further, since the lighting unit 20 is also provided in the structure 50, the lighting unit 20 is always at a fixed position by the color CCD camera 40, and the image is always taken under uniform illumination regardless of the image taking position. And the X and Y drive units 11a and 11b of the XY drive mechanism 10 and the transparent glass plate 3 as described above.
Are provided in parallel, so that the color CCD camera 40
Since the distance between the object and the object to be read S is always constant irrespective of the imaging position, the imaging condition can always be kept constant.
Therefore, even if the color CCD camera 40 is moved and the margin reading area RA (corresponding to the “read area”) is repeatedly read while moving the color CCD camera 40, a partial white reference image signal can always be generated under the same conditions, and an accurate white reference image signal can be generated. Shading correction can be performed.

In this embodiment, the image inspection is performed by taking images of the first school and the second school and comparing them with the above-mentioned apparatus configuration. In this apparatus, shading correction is performed before this. . In order to obtain an entire white reference image signal which is a read output signal (maximum output signal) corresponding to white at the time of the shading correction, a blank portion such as a first school or a re-school is read.

FIG. 5 is a diagram showing a designation screen for designating the margin reading area RA. In the figure, a margin reading area RA described later is represented as a rectangle. Such a blank reading area RA is read by the color CCD camera 40 to obtain an entire white reference image signal.

In this apparatus, however, the operator can specify the number of divisions of the full angle of view of the color CCD camera 40 according to the size of the margin of the document. That is, in the division number designation box DB in the figure, the operator uses the mouse 64 to select one of the horizontal (X direction) and vertical (Y direction) division number designation keys KX1 to KX5 and KY1 to KY5 of the angle of view. Click to highlight and specify the number of divisions. Then, a rectangle corresponding to the margin reading area RA having a size corresponding to the designated number of divisions is displayed on the color CRT 62 screen, and the operator can move it to a desired position by dragging it with the mouse 64. The display area DA moves when a rectangle corresponding to the margin reading area RA reaches the periphery of the display screen, or when an operator operates a cursor key on the keyboard 63. When the margin reading area RA is determined, the determination key D
Click K, and then click the cancel key CK if you want to change the position.

When the margin reading area RA is determined in this way, the operator clicks the reading execution key RK.
Then, when the number of divisions in the horizontal and vertical directions is “1”, the color CCD camera 40 reads the area indicated by the margin reading area RA only once as the entire margin reading area, and conversely, reads the horizontal and vertical directions. If one or both of the number of divisions in the direction is “2” or more, the margin reading area R
Read repeatedly as A.

That is, when there is a margin large enough to be read as a whole white reference image in the original, the image signal read by the color CCD camera 40 is used as the whole white reference image signal. When there is no large margin, by repeatedly reading a blank portion in the reading object S having a size of approximately one section, which is obtained by equally dividing the entire angle of view of the color CCD camera 40 into a plurality of sections. , Color C
A partial white reference image signal for each of the sections of the CCD array of the CD camera 40 is obtained, and these signals are processed by the control arithmetic unit 6
1 collects the whole white reference image signal by software.

FIG. 6 is a view showing the concept of repeatedly reading the margin reading area RA by the image inspection apparatus 1. Hereinafter, FIG.
Will be described as an example, and a process of generating a partial white reference image signal by divisional reading will be described.

In FIG. 6A, the color CCD camera 4
The partial white reference images PW1 to PW4 are １ ／ of the size of the entire white reference image WW having a size corresponding to the full angle of view of 0. That is, this example shows a case where the number of divisions in the horizontal and vertical directions is “2” (2 × 2 division).

FIG. 6B shows the angle-of-view positions AV1 to AV4 of the color CCD camera 40 with respect to the blank reading area RA during repeated reading. As shown in the figure, a margin reading area R is provided for each of the angle-of-view positions AV1 to AV4.
A is located in the four corner sections of the full angle of view. FIG. 7 is a diagram showing this state. As shown in FIG. 7, the margin reading area RA is slightly larger than the areas of the respective partial white reference images PW1 to PW4. This is because the reading position does not always match the rectangle displayed on the screen, and when the margin reading area RA is designated, the area displayed on the screen of the color CRT 62 and the corresponding margin reading area RA are required. This is because the area of the white reference image PW1 to PW4 is set slightly larger than the size of the area to prevent a necessary partial white reference image signal from becoming insufficient. Therefore, when an actual whole white reference image signal is generated, an extra blank reading area RA and partial white reference images PW1 to PW4 are used.
And the image signals of the partial white reference images PW1 to PW4 are collected by deleting the image signals of the deletion areas DA1 to DA4 between these areas.

As described above, in this apparatus, the number of divisions of the color CCD camera 40 by a plurality of sections of the entire angle of view can be designated as different on a selection screen as shown in FIG. FIG. 8 is a diagram illustrating another example of the number of divisions. That is, in this apparatus, the number of divisions in the horizontal and vertical directions is equally specified in the range of "1" to "5", such as dividing the entire white reference image WW shown in FIG. Alternatively, the number of divisions in the vertical and horizontal directions may be different in the range of “1” to “5”, such as dividing the entire white reference image WW shown in FIG. 8B into six (2 × 3). It can also be specified as a number.

The shading correction is performed by software using the control arithmetic unit 61 using the whole white reference image signal obtained as described above.

[2. Processing Procedure of Embodiment] Next, the procedure of the shading correction processing, that is, the generation of the white reference image signal and the shading correction in this embodiment will be described with reference to the flowchart of FIG.

First, a pre-scan of the object S is performed (step S1), and thereafter, an image of the display area is displayed on the screen of the color CRT 62 (step S2).

Then, as described above, while moving the margin reading area RA, it is determined whether or not there is a sufficient margin in the read object S for obtaining the entire white reference image signal by one reading. A judgment is made (step S3).

If there is a sufficient margin, the operator determines the above-mentioned margin reading area RA in the margin, and the area is read by the color CCD camera 40 (step S4), and the entire white is read. A reference image signal is generated (Step S5).

Conversely, if there is not enough blank space,
The operator designates the number of divisions of the entire white reference image WW and the margin reading area RA as described above, and instructs to execute reading (step S6). Then, the blank reading area RA is repeatedly read (step S7). Then, the margin reading area RA obtained in step S6
The whole white reference image signal is generated by collecting the partial white reference image signals in the image signal (step S8).

As described above, the whole white reference image signal is prepared. Next, the whole white reference image WW is displayed on the color CRT 62 (step S9), and the whole white reference image WW is displayed.
There is no image other than margins such as characters and pictures in it,
Then, the operator determines whether the entire white reference image WW may be determined (step S10). Then, if the entire white reference image WW cannot be determined due to the inclusion of characters, pictures, and the like, the process returns to step S2 to regenerate the entire white reference image signal, and steps S2 to S2 are performed again.
Step 10 is repeated. Conversely, if the entire white reference image WW can be determined without including characters or pictures, shading correction is performed using the entire white reference image signal (step S11). Step S
For the eleventh shading correction itself, a conventionally used method can be used.

The above is the procedure of the shading correction processing.

Further, in this apparatus, the above-described shading correction processing is performed when reading the read object S such as the first school and the second school, and the images are compared to perform the plate inspection processing. FIG. 10 is a flowchart of the plate inspection process according to this embodiment. Hereinafter, the procedure of the plate inspection process will be described with reference to FIG.

First, the operator sets a reference object such as the first school PS1 on the transparent glass plate 3 (step S21) and instructs execution. Then, the first shading correction process is performed on the reference object according to the procedure described with reference to FIG. 9 (step S22).

Next, when the operator instructs to read the reference object, the reference object is read (step S2).
3). Here, signal conversion corresponding to the first shading correction process is performed on the image signal read by the color CCD camera 40. The image signal of the reference object thus obtained is stored on the magnetic disk 73.

Similarly, the operator sets an object such as the re-establishment PS2 on the transparent glass plate 3 (step S24).
When the execution is instructed, the second shading correction processing is performed according to the procedure of FIG. 9 (step S25), and then the reading of the object is executed (step S26), and the image signal is stored in the magnetic disk 73. Then, signal conversion corresponding to the second shading correction processing is performed. If the color or material of the target object is the same or almost the same, the second
Can be omitted, and the result of the first shading correction process for the reference object can be used.

When the process of reading the reference object and the target object is completed, an alignment process is performed (step S27). This process is performed by the operator using the color CR.
The user operates the mouse 64 while looking at the image displayed on T62 to set the alignment reference coordinates, which are the coordinates for superimposing the reference object and the target object, so that the two images overlap each other so that they overlap each other. The entire image is superimposed so that the comparison between the coincidence and the non-coincidence of the two images can be performed.

When the alignment process is completed as described above, a plate inspection process (step S28) is performed. In the plate inspection process, the worker sets the “threshold”, “garbage removal size”,
When plate inspection conditions such as “display format”,... Are set, a difference detection process for detecting a difference between the reference object (first school) and the target object (re-school) is executed. That is, the image data of the reference object and the object is divided into a plurality of sections, and the image of the reference object and the image of the object are locally matched for each of the divided areas, and the difference between the two images is calculated. The value is compared with the set “threshold value”. If the difference is larger than the threshold value, it is determined that there is a difference in the divided area. As a result, a matching part that matches between the reference object and the target object and a mismatching part that does not match are detected. Then, a difference display image is created according to the set “display format”. further,
A contour extraction process, which is a process of extracting a block in which image data having a difference between the reference object and the target object equal to or larger than a threshold value, is extracted. Then, the number of pixels constituting the outline of the obtained block is counted and compared with the set dust removal size. For a block larger than the dust removal size,
The X and Y coordinates of the four corners of the frame surrounding the block are obtained and stored on the magnetic disk 73.

When the plate inspection process is completed, the plate inspection result on which the above-mentioned difference display image, frame, and the like are displayed is displayed on the screen of the color CRT 62, or is output to output paper by the monochrome plotter 65 or the color printer 66 ( Step S2
9) to end the plate inspection process.

As described above, according to the embodiment of the present invention, the color CCD camera 40 reads the white reference area including the blank portion of the reading object S, and generates a white reference image signal. , The shading correction can be performed more accurately than using a white reference image signal generated by reading a white reference plate or the like different from the read object S prepared in advance. .

Further, while moving the color CCD camera 40, the margin reading area RA is repeatedly read, and a partial white reference image signal corresponding to a margin portion among a plurality of image signals obtained by the reading is gathered to obtain the color CCD camera 40. Since the entire white reference image signal corresponding to the entire angle of view is generated and the shading correction is performed using the signal, even when the read object S does not have a sufficient blank space, the blank space is repeatedly read as the blank space reading area RA to obtain an accurate image. Shading correction can be performed.

Further, since the image inspection is performed by performing the shading correction, an accurate image inspection can be performed since there is no nonuniform output value for each CCD.

Further, the output range of the CCD, which has been narrowed because the color of the paper or the like of the object S is not completely white, can be expanded by the above-described shading correction. Can be detected with higher accuracy.

Further, even when the reference object and the object are different in paper and the output value ranges by the CCD are different from each other, the same output range can be converted by the shading correction as described above, so that more accurate image inspection can be performed. It can be performed.

[3. Modified Example] In this embodiment, the color CCD camera 40 is provided with a two-dimensional CCD array and two-dimensionally reads an image. However, the present invention is not limited to this. In a scanner that reads an image while moving the sensor vertically in the linear array direction, a blank portion of the object S
Line sensor CCD even when only a part of the array width of D
By moving the object to be read in the array direction and reading it, etc., the blank portion is repeatedly read, and the partial white reference image signal resulting therefrom is collected, and shading correction is performed based on the linear whole white reference image signal. Is also good.

In this embodiment, the color CCD camera 40 is moved to repeatedly read the margin reading area RA.
May be moved integrally, or the object S to be read itself may be moved.

Further, in this embodiment, the read area is set to be larger than the area of the partial white reference image, and the image signals of the delete areas are deleted. However, the present invention is not limited to this, and the present invention is not limited to this. One of the overlapping portions of the white reference image signal may be deleted, or the margin reading area may have the same size as the area of the partial white reference image.

Further, in this embodiment, the image inspection apparatus 1 includes the image reading apparatus 1a, but the image reading apparatus alone is also included in the scope of the present invention.

[0071]

As described above, according to the first to eighth aspects of the present invention, a reading area including a blank portion of an object to be read is read by the imaging means to generate a white reference image signal. Since the shading correction is performed based thereon, it is possible to perform more accurate shading correction than using a white reference image signal generated by reading a white reference plate or the like different from a prepared object to be read in advance. .

According to the second to fourth aspects of the present invention, the area to be read is repeatedly read by the image pickup means while the object to be read and the image pickup means are relatively moved, and a plurality of images obtained thereby are obtained. An image signal corresponding to a blank portion of the signal is collected to generate a white reference image signal corresponding to the entire angle of view of the imaging unit, and shading correction is performed using the signal, so that there is not enough blank space in the object to be read. Even in this case, accurate shading correction can be performed.

According to an eighth aspect of the present invention, a plurality of inspection images obtained by reading a plurality of objects by an imaging means using any one of the first to seventh aspects of the invention. Performs signal conversion in accordance with shading correction on the signal, and then detects a mismatched portion of an image on a plurality of reading objects by comparing a plurality of image signals to be inspected thereafter. Image inspection can be performed.

[Brief description of the drawings]

FIG. 1 is a partial external perspective view of an image inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an electrical configuration of the image inspection apparatus together with a control system of an optical configuration and a mechanical configuration.

FIG. 3 is a partial cross-sectional view of the image inspection apparatus.

FIG. 4 is a perspective view showing a configuration of a structure.

FIG. 5 is a diagram showing a designation screen for designating a margin reading area.

FIG. 6 is a diagram showing a concept of repeatedly reading a margin reading area.

FIG. 7 is a diagram illustrating a positional relationship of a margin reading area with respect to a position of each angle of view.

FIG. 8 is a diagram showing an example of the number of divisions of the angle of view.

FIG. 9 is a flowchart of shading correction and white reference image signal generation processing.

FIG. 10 is a flowchart of an image inspection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image inspection apparatus 1a Image reading apparatus 3 Transparent glass plate 4 Cover member 10 XY drive mechanism 22 Round fluorescent lamp 40 Color CCD camera 61 Control arithmetic unit 73 Magnetic disk PW1-PW4 Partial white reference image RA Margin reading area S Object to be read WW Whole white reference image

Claims (8)

[Claims] 1. An image reading apparatus for reading an image of an object to be read to generate an image signal, comprising: an object holding means for holding an object to be read; an image of the object to be read; Imaging means for generating; moving means for relatively moving the object-to-be-readed object holding means and the image-taking means; area-to-be-reading specifying means for specifying an area to be read including a blank portion of the object to be read; Control means for controlling the moving means and the image pickup means so as to read the area to be read while relatively moving the object to be read and the image pickup means; and storage means for storing an image signal obtained by the reading. A white reference image signal generation unit configured to generate a white reference image signal for the imaging unit based on an image signal corresponding to the margin portion of the image signal; Image reading apparatus characterized by comprising: a shading correction means for performing shading correction based on the signal. 2. The image reading apparatus according to claim 1, wherein the control unit moves the object to be read and the imaging unit relatively, and reads the area to be read repeatedly by the imaging unit. Controlling the moving means and the imaging means, the storage means stores a plurality of image signals obtained by the repeated reading, the white reference image signal generating means, the An image reading apparatus for collecting an image signal corresponding to a margin portion and generating a white reference image signal corresponding to a full angle of view of the image pickup means. 3. The image reading apparatus according to claim 2, wherein, for a plurality of sections obtained by dividing the full angle of view, in each of the repeated readings, the blank portion is imaged in a section having a different full angle of view. An image reading apparatus for obtaining the plurality of image signals. 4. The image reading apparatus according to claim 3, further comprising: a division number operation designating means for designating a division number for dividing the full angle of view into the plurality of sections. apparatus. 5. An image reading apparatus according to claim 1, wherein said image pickup means includes an image pickup device arranged two-dimensionally. apparatus. 6. The image reading apparatus according to claim 1, wherein the moving unit is configured to two-dimensionally maintain the distance between the imaging unit and the object holding unit at a constant distance. An image reading apparatus further comprising: an illuminating unit that is arranged at a position fixed to the imaging unit and illuminates the object to be read. 7. The image reading apparatus according to claim 6, wherein said illumination means is an annular illumination means provided so as to surround the angle of view of said imaging means. 8. An image inspection apparatus for reading images of a plurality of objects to be read and comparing the images with each other for inspection, wherein the image reading apparatus according to any one of claims 1 to 7 is provided. A signal conversion unit that performs signal conversion according to the shading correction on a plurality of inspection image signals obtained by reading a plurality of objects to be read by the imaging unit; and the plurality of the plurality of image signals after performing the signal conversion. A difference detection unit that detects a mismatched portion of the images on the plurality of reading objects by comparing the image signals to be inspected; and a display unit that displays a detection result by the difference detection unit. Image inspection equipment.