JP2979828B2 - Image reading method and apparatus - 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 method and apparatus, and more particularly, to an image reading method and apparatus which can be applied to image input of an apparatus for capturing and extracting printed symbols and characters on electronic parts and performing automatic recognition. About.

[0002]

2. Description of the Related Art A conventional image reading method and apparatus will be described in detail with reference to the drawings.

[0003] As a conventional technique, for example, Japanese Patent Application Laid-Open
There is an image reading apparatus disclosed in JP-A-63884. FIG. 11 is a configuration diagram showing a conventional image reading apparatus. The image reading apparatus shown in FIG. 11 captures a print symbol on the IC 1 as an object to be captured and outputs a video signal aa by a TV camera 3a, and an A / D converter that converts the video signal aa from analog to digital and outputs image information ba. D conversion unit 4a, image information ba
Is compared with a threshold value to convert it into binary image information c and output it, and receives image information ba in the first imaging, obtains a density distribution of dots on a diagonal line of the image, A background density value determination unit 10 that outputs the most frequent density value as a background density value i, and a reference threshold value generation that generates a first threshold value j when the background color is white (density value 0). A unit 11 and an adder 9 for adding a background density value i and a first threshold value j to generate a second threshold value k.

A video signal a output from the TV camera 3a
A is A / D converted by the A / D conversion unit 4 a and input to the binarization unit 5. The binarizing unit 5 stores image information ba of the first imaging.
Is binarized by the first threshold value j from the reference threshold value generation unit 11, and the binary image information c
Is cut off by a switch or the like (not shown) and is not output.
At this time, at the same time, the background density value determination unit 10
A background density value i is obtained based on “a” and output to the adder 9. The adder 9 adds the first threshold value j and the background density value i to generate a second threshold value k, which is again input to the binarization unit 5 as the optimum threshold value of the image information ba. . Here, the binarization unit 5
Binarizes the image information ba according to the optimal threshold value,
The binary image information c is output.

[0005]

In the above-described conventional image reading method and apparatus, since the binarization is performed using the value obtained by adding the background density value to the reference threshold value as the optimum threshold value, the background density value becomes large. If the contrast with the density value of the portion to be extracted by binarization is small, the threshold value exceeds the density value of the portion to be extracted, so that the binarization cannot be performed correctly.

[0006]

According to a first image reading method of the present invention, a half mirror for bisecting an image of an object is provided.
And focusing on one optical axis bisected by the half mirror
Outputting the focused first image information at the point position
A first TV camera and an out-of-focus position on the other optical axis
Output the second image information that is out of focus.
An image reading apparatus comprising: a second TV camera, and comparing the image information captured by the first and second TV cameras with a threshold to generate a binary image. obtain the first image information and the second image information, and performing binarization of the first image information and the second image data as a threshold.

Further, the first image reading apparatus according to the present invention is an image reading apparatus which generates a binary image compared with a threshold to the image information captured by the TV camera, the image
The half mirror, and the half mirror
At the focal point on one of the optical axes
A first TV camera that outputs first image information;
At the out-of-focus position on one of the optical axes and in front of the object to be imaged.
The point where the first image information is imaged is out of focus.
The image processing apparatus includes a second TV camera that outputs second image information, and a binarizing unit that binarizes the first image information using the second image information as a threshold.

[0008] A second image reading method according to the present invention comprises:
Beam splitter that divides the image of the object into a specific light intensity ratio
And the first light amount ratio divided by the beam splitter.
A first optical information output unit that outputs first image information having a large light amount on the optical axis.
1 TV camera and the beam splitter
A second image information having a small light amount on the optical axis of the second light amount ratio;
And a second TV camera for outputting information.
An image reading device that generates a binary image by comparing image information captured by the second TV camera with a threshold value,
For the same portion of the object, the first image information ,
Obtain a second image information, the difference between the average density value of the said the average density value of the first image information second image information to calculate, in the concentration average value to the second image information The first image information is binarized using a value obtained by adding the difference as a threshold value.

[0009] The second image reading apparatus according to the present invention is an image reading apparatus which generates a binary image compared with a threshold to the image information captured by the TV camera, the
Beam splitter that divides the image of the object into a specific light intensity ratio
And the first light amount ratio divided by the beam splitter.
A first optical information output unit that outputs first image information having a large light amount on the optical axis.
1 on the optical axis of the TV camera and the second light amount ratio,
Light intensity at a location where the first image information of the object is imaged
A second TV camera that outputs small second image information; a first average value calculating unit that calculates an average density value of the first image information; and a second average camera that calculates a density average value of the second image information. Second average value calculating means for calculating, and subtracting means for calculating the difference between the density average values of the first and second image information,
Adding means for adding the difference between the density average values to the second image information and outputting the difference as a threshold value; and binarizing means for binarizing the first image information based on the threshold value It is comprised including.

[0010]

Next, a first image reading method and apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a first image reading method and apparatus according to the present invention. An image reading apparatus shown in FIG. 1 includes a half mirror 2 for bisecting a printed symbol image on an IC 1 as an object to be imaged, and a half mirror 2
A TV camera 3a which outputs aa a focused video signal at an in-focus position on one of the optical axes divided by
A TV camera 3b which outputs an out-of-focus video signal ab at an out-of-focus position on the other optical axis, and A / D conversion of the video signal aa and the video signal ab to obtain in-focus image information ba An A / D conversion unit 4a and an A / D conversion unit 4b for outputting the defocused image information bb, and binarizing the image information ba using the image information bb as a threshold and outputting it as binary image information c. And a binarizing unit 5.

FIGS. 2 to 7 are views for explaining an image reading method performed in the embodiment of FIG. FIG.
Is a schematic diagram showing the symbol “0” on the IC 1 to be imaged and extracted, where the density value of the symbol portion 13 is higher than that of the background portion 12. FIG. 3 is a density value graph of the image information ba, and FIG.
5 is a density value graph of the image information bb, FIG. 5 is a density value graph showing the image information ba and the image information bb superimposed (that is, FIG. 3 and FIG. 4 are superimposed), and FIG.
6 is a graph showing the binary data of FIG. Here, FIGS.
Here, for the sake of simplicity, only the primary value at the line of interest 14 shown in FIG. 2 is shown.

The TV camera 3a and the TV camera 3b are
The same part on the IC 1 is imaged through the half mirror 2 to output a video signal aa and a video signal ab.
The A / D converter 4a and the A / D converter 4b output the image information ba and the image information bb. here,
Since the TV camera 3a is located at the in-focus position, the image information ba obtained therefrom has a density value with sharp edges as shown in FIG. On the other hand, in the case of the TV camera 3b, since it is at the out-of-focus position, the image information bb obtained therefrom
As shown in FIG. 4, the density peak value is lower than that of the image information ba and the edge portion is wider. This relationship is the same regardless of the magnitude of the image contrast. Next, the binarizing unit 5 binarizes the image information ba using the image information bb as a threshold value and outputs it as binary image information c.
At this time, as shown in FIG. 5, the image information ba and the image information bb have the following relationship: background part: (image information ba) <(image information bb) symbol part: (image information ba)> (image information bb) . Therefore, the binarization unit 5 calculates the difference between the image information ba and the image information bb, and performs binarization based on the sign of the difference.
The binary image information c shown in FIG. 6 is output.

Next, a second image reading method and apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 7 is a block diagram showing one embodiment of the second image reading method and apparatus according to the present invention. The image reading device shown in FIG. 7 includes a beam splitter 6 that divides a printed symbol image on the IC 1 as an object to be captured into a light amount ratio of 1: 2, for example, and an optical axis having a light amount ratio of 2 divided by the beam splitter 6. A TV camera 3a that outputs a video signal da with a large light amount, another TV camera 3b that is on the optical axis with a light amount ratio of 1 and outputs a video signal db with a small light amount, a video signal da and a video signal db A / D which converts A / D and outputs image information ea of large light amount and image information eb of small light amount
A conversion unit 4a and an A / D conversion unit 4b; an average value calculation unit 7a and an average value calculation unit 7b for calculating a density average value fa of the image information ea and a density average value fb of the image information eb; A subtractor 8 for calculating the difference between the image data and the density average value fb and outputting a density average value difference g;
And a density average value difference g, and outputs the result as a threshold value h. The adder 9 binarizes the image information ea based on the threshold value h and outputs the result as binary image information c. And

FIGS. 2, 6 and 8 to 10 are views for explaining an image reading method performed in the embodiment of FIG. FIG. 2 is a schematic diagram showing a symbol “0” on the IC 1 to be imaged and extracted, where the density value of the symbol portion 13 is higher than that of the background portion 12. FIG. 6 shows the binary image information c.
8 is a density value graph of image information ea, FIG. 9 is a density value graph of image information eb, FIG.
Is a density value graph in which the threshold value h of the image information ea is superimposed. Here, FIGS. 6 and 8 to 10 show only one-dimensional values at the line of interest 14 shown in FIG. 2 for simplicity.

The TV camera 3a and the TV camera 3b are
The same location on the IC 1 is imaged via the beam splitter 6 to output a video signal da and a video signal db, which are converted by the A / D converter 4a and the A / D converter 4b into image information ea and image information eb. Is output as Here, the TV camera 3a is on the optical axis with the light amount ratio of 2, while
In the case of the V camera 3b, since it is on the optical axis with the light amount ratio of 1, the relationship between the image information ea and the image information eb obtained therefrom is
As shown in FIGS. 8 and 9, the image information eb is data in which the density peak value and the density difference between the background portion and the symbol portion are smaller than the image information ea. This relationship is the same regardless of the magnitude of the image contrast. Next, the average value calculation unit 7a and the average value calculation unit 7b respectively use the density average value fa and the density average value fb of the image information ea and the image information eb.
Is calculated. Next, the subtractor 8 calculates (average density value fa)-(average density value fb) and outputs the result as a density average value difference g. Further, the adder 9 adds the image information eb to the density average value difference g and outputs the result as a threshold value h.
As shown in FIG. 10, the relationship is as follows: background portion: (image information ea) <(threshold value h) symbol portion: (image information ea)> (threshold value h). Therefore, the binarization unit 5 calculates the difference between the image information ea and the threshold value h, binarizes the difference based on the sign, and outputs the binary image information c shown in FIG.

[0018]

According to the present invention, instead of performing binarization by using a value obtained by adding a background density value to a reference threshold value as an optimum threshold value, the first image reading method and apparatus according to the first embodiment employs a focus shift. The in-focus image information is binarized by using the obtained image information as a threshold value. In the second image reading method and the second image reading apparatus, the first image information captured with the first light amount is
The second image information obtained with a second light amount lower than the first light amount is obtained, the difference between the respective average density values is calculated, and the difference is added to the second image information to obtain a value. Since the first image information is binarized as a threshold value, even when the background density value is large and the contrast with the density value of the portion to be extracted by the binarization is small, the portion where the threshold value should be extracted There is an effect that the binarization can be correctly performed without exceeding the density value of.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a first image reading apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a symbol “0” on IC1 in FIG. 1;

FIG. 3 is a diagram showing a density value graph of image information ba in FIG. 1;

FIG. 4 is a diagram showing a density value graph of image information bb in FIG. 1;

FIG. 5 is a diagram illustrating a density value graph in which image information ba and image information bb in FIG. 1 are superimposed.

FIG. 6 is a graph showing binary data of binary image information c in FIG. 1;

FIG. 7 is a configuration diagram illustrating an embodiment of a second image reading apparatus according to the present invention.

8 is a diagram showing a density value graph of image information ea in FIG. 7;

FIG. 9 is a diagram illustrating a density value graph of image information eb in FIG. 7;

FIG. 10 is a diagram illustrating a density value graph in which image information ea and a threshold value h in FIG. 7 are superimposed.

FIG. 11 is a configuration diagram showing a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 IC 2 Half mirror 3a, 3b TV camera 4a, 4b A / D conversion part 5 Binarization part 6 Beam splitter 7a, 7b Average value calculation part 8 Subtractor 9 Adder 10 Background density value judgment part 11 Reference threshold Generator aa In-focus video signal ab Out-of-focus video signal ba Out-of-focus image information bb Out-of-focus image information c Binary image information da High light intensity video signal db Low light intensity video signal ea High light intensity Image information eb light amount image information fa density average value of image information ea fb density average value of image information eb g density average value difference h threshold value i background density value j first threshold value k second threshold Threshold

Claims (4)

(57) [Claims] A half mirror for bisecting an image of an object to be imaged
And focusing on one optical axis bisected by the half mirror
Outputting the focused first image information at the point position
A first TV camera and an out-of-focus position on the other optical axis
Output the second image information that is out of focus.
An image reading apparatus comprising: a first TV camera and a second TV camera; and comparing the image information captured by the first and second TV cameras with a threshold to generate a binary image. before said first image information
And obtaining the second image information, and performing binarization of the first image information using the second image information as a threshold value. 2. An image reading apparatus for generating a binary image by comparing image information picked up by a TV camera with a threshold, and a half mirror for bisecting the image, and one optical axis bisected by the half mirror. Top Focus Position
Output the focused first image information.
The TV camera is located at a non-focusing position on the other optical axis, and
Focus on a location where the first image information of the object is captured.
A second TV camera that outputs shifted second image information; and a binarizing unit that binarizes the first image information using the second image information as a threshold value. Image reading device. 3. A video camera for dividing an image of an object to be photographed into a specific light amount ratio.
Beam splitter and the beam splitter
A first image information having a large light amount on the optical axis having the first light amount ratio;
A first TV camera for outputting a report, and the beam splitter.
On the optical axis of the second light intensity ratio divided by
A second TV camera that outputs the second image information of
An image reading apparatus that generates a binary image by comparing image information captured by the first and second TV cameras with a threshold value , wherein the first image information and the ,
Obtain a second image information, the difference between the average density value of the said the average density value of the first image information second image information to calculate, in the concentration average value to the second image information An image reading method, wherein the first image information is binarized using a value obtained by adding the difference as a threshold value. 4. A beam splitter that divides an image of an object to be imaged into a specific light amount ratio in an image reading apparatus that generates a binary image by comparing image information captured by a TV camera with a threshold value.
And an optical axis having a first light intensity ratio divided by the beam splitter
A first image information for outputting first image information with a large light quantity
A TV camera and second image information with a small light amount at a position where the first image information of the object to be imaged is located on the optical axis of the second light amount ratio.
A second TV camera for outputting the average, a first average value calculating means for calculating the average density value of the first image information, and a second average value for calculating the average density value of the second image information Calculation means; subtraction means for calculating the difference between the average density values of the first and second image information; and addition for adding the difference between the density average values to the second image information and outputting it as a threshold value And a binarizing unit for binarizing the first image information based on the threshold value.