JP2003346076A - Image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor making detailed analysis of a subject possible without requiring its arrangement to become complex. <P>SOLUTION: An image of a barcode 2 is formed on an image sensor 4 and a sensor output for each pixel is outputted to a computing unit 5. The computing unit 5 restores barcode information based on the sensor outputs. When a distance switch key 8 is switched to a position for long distances, the computing unit 5, using a correction value for each pixel stored in a storage device 7, corrects the sensor outputs coming from the image sensor 4. Thus, while the amount of light which the image sensor 4 receives decreases at long distances with the pixels on edges receiving less light, the barcode information can be read correctly without being affected by the decrease. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus for analyzing image data based on an electric signal output for each pixel from a photoelectric conversion means.

[0002]

For example, in a bar code reader, when the distance to the bar code to be read becomes longer, the amount of received light decreases due to the distance and the angle of view, and it becomes difficult to analyze the object as it is. For this reason, two types of illuminations for short distance and long distance are provided, and the light is received on the image sensor so as to have uniform illuminance. Further, there is also provided one corresponding to a change in the object distance by changing the threshold value itself for analysis.

However, in the case of providing two types of illumination for short distance and long distance, the configuration of the bar code reader becomes complicated, the price increases and the size becomes large.
Further, the method of changing the threshold value for analysis merely changes the threshold value for distinguishing between “0” and “1” with respect to the received signal. However, there is a problem that detailed analysis of the object cannot be performed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image processing apparatus capable of performing a detailed analysis of an object without complicating the configuration.

[0005]

According to the first aspect of the present invention, when an object is imaged, an electric signal for each pixel is output from the photoelectric conversion means. Thereby, the signal processing means
The image data can be analyzed based on the electric signal output for each pixel from the photoelectric conversion means.

Incidentally, the level of the electric signal for each pixel from the photoelectric conversion means varies depending on the object distance to the object. Here, the correction means corrects the electric signal output for each pixel from the photoelectric conversion means with the correction value set for each pixel according to the object distance to the object, so that the object can be reliably detected regardless of the object distance. Can be read.

According to the second aspect of the present invention, the correction means corrects the electric signal output from the photoelectric conversion means for each pixel with a stepwise correction value corresponding to the object distance. It can be prevented from increasing. In this case, since a small change in the object distance does not hinder reading of the object, the object can be reliably read while limiting the number of correction values.

According to the third aspect of the present invention, since the correction means calculates the correction value for each pixel according to the object distance, there is no need to store the correction value and the correction value is set with high accuracy. be able to.

According to the fourth aspect of the present invention, since the object distance to the object is measured by the distance measuring means, the correction value can be automatically set.

According to the fifth aspect of the present invention, the objective distance can be set by the switching operation on the switching means, so that the correction value can be set with a simple configuration.

According to the sixth aspect of the present invention, the correction value for each pixel is set to be ideal data by being multiplied by actual measurement data by the photoelectric conversion means. The correction is performed by multiplying the electric signal output for each pixel from the means by a correction value for each pixel. Since the reliability of such a correction value is high, the accuracy of the correction result can be improved.

According to the seventh aspect of the invention, the correction value for each distance is sequentially changed until the analysis of the image data is established, so that the configuration of the switching means or the distance measuring means can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is applied to a bar code reader will be described below with reference to FIGS. FIG. 1 is a block diagram showing a bar code reader. In FIG. 1, a bar code reading device (corresponding to an image processing device) 1 reads bar code information of a bar code (corresponding to an object) 2. Is converted into an analog electric signal for each pixel and output,
In a digitized state, it is given to an arithmetic unit (corresponding to signal processing means and correction means) 5.

The illumination device 6 irradiates the bar code 2 with light when driven by the arithmetic device 5. Arithmetic unit 5
Is connected to a storage device 7 for storing the output from the image sensor 4. The arithmetic device 5 stores the digitized signal for each pixel received by the image sensor 4 in the storage device 7 and stores the digitized signal. Barcode information is restored based on the digitized signal.

Here, as the optimum object distance from the reading port of the barcode reading device 1 to the object, a long distance that is a predetermined distance from the reading port and a short distance that is close to or close to the reading port are set. The arithmetic unit 5 is provided so that reading can be performed at any distance by operating a distance switching key (corresponding to a switching unit) 8 as described later. In the present embodiment, when reading a barcode label, the sensor output from the image sensor 4 is corrected according to the object distance, and such a sensor output is corrected. It is.

Next, the operation of the above configuration will be described. The user needs to set a long-distance correction value before reading the barcode 2 with the barcode reader 1. The long distance is an object distance to the barcode 2 set in the barcode reader 1.

The user sets an object such as a blank sheet that uniformly and irregularly reflects light at a long distance position. Then, a blank image is picked up by the image sensor 4. When the above settings are completed, the barcode reading device 1
To work. FIG. 2 is a flowchart showing the operation of the arithmetic unit 5. In FIG. 2, when the operation starts, the arithmetic unit 5 drives the illumination device 6 and takes in the sensor output of the long-distance correction value setting image (S101). In this case, the amount of received light corresponding to a blank image picked up by the image sensor 4 is ideally uniform for every pixel of the image sensor 4, but the amount of received light decreases as the objective distance increases. I do. Furthermore, the amount of received light decreases from the pixel at the center to the pixel at the end of the image sensor 4 (FIG. 3).
(B)). That is, even if the state of light reflection by blank paper is uniform over the entire surface, the amount of light received for each pixel of the image sensor 4 varies according to the objective distance.

Then, the arithmetic unit 5 sets a long distance correction value for the sensor output according to the object distance (S10).
2). Specifically, when the actual electric signal output from the image sensor 4 is as shown in FIG. 3B, the ideal sensor output shown in FIG. The correction value for each pixel shown in FIG. That is, the smaller the sensor output value, the larger the correction value.

As described above, when the long distance correction value for each pixel is set in accordance with the object distance, the bar code 2 can be read.
Is driven and the sensor output from the image sensor 4 is taken and stored in the storage device 7 (S103). In this case, when the bar code 2 is located at a long distance, the sensor output from the image sensor 4 has the characteristics shown in FIG. 3B, that is, the received light amount decreases as a whole as compared with the ideal data. At the same time, the pixel located at the end has a tendency to receive less light.

However, the arithmetic unit 5 is provided with the distance switching key 8
Is set to short distance or long distance (S104), and if long distance is set, long distance amplitude correction is executed (S107). That is, the sensor output from the image sensor 4 is amplitude-corrected with the long-distance correction value obtained in step S102. Specifically, FIG.
By multiplying the actual sensor output shown in (b) by the correction value for each pixel shown in (b), a correction signal shown in (c) can be obtained, and this correction signal is affected by the object distance. 3 shows an ideal sensor output from which the is removed.

Then, the corrected sensor output is binarized by a predetermined threshold value, the barcode information is restored based on the binarized data (S105), and the barcode information is output (S106). In this case, if the restoration of the barcode is unsuccessful, the capture of the output from the image sensor 4 and the restoration process are repeated, and if the restoration is successful, the illumination device 6 is turned off and the reading of the barcode is terminated. S104
In the case where the distance switching key 8 is set to the short distance, no correction is performed. In this case, the barcode information is restored by binarizing the actual sensor output with a predetermined threshold value. Will be.

According to such an embodiment, the correction value for each pixel of the image sensor 4 is obtained corresponding to the case where the object distance to the bar code 2 is a long distance, and the image value is read in the case of a long distance reading. Since the sensor output from the sensor 4 is corrected by the correction value for each pixel, the image output is compared with a configuration in which the output from the image sensor is only binarized at a predetermined threshold value regardless of the object distance. A decrease in the amount of light received by the sensor 4 or a variation in the amount of light received for each pixel can be corrected, and the barcode information can be reliably restored.

In addition, since the long distance and the short distance are selected by the distance switching key 8, the correction value can be changed by selecting the object distance up to the bar code 2 with a simple configuration. Furthermore, since the sensor output is corrected instead of changing the threshold value as in the related art, the correction signal is binarized based on the threshold value even when the amplitude of the sensor output is small. This enables detailed analysis of barcode information.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS.
The same reference numerals are given to the same portions as those of the embodiment, and the description is omitted. The second embodiment is characterized in that an object distance to the bar code 2 is measured by a distance measuring means, and the sensor output from the image sensor 4 is corrected according to the measured distance.

FIG. 5 is a diagram schematically showing the configuration of the bar code reader 1. As shown in FIG. In FIG. 5, a distance measuring light source 11 for irradiating a highly directional spotlight is provided near the reading opening of the barcode reading device 1. As the distance measuring light source 11, a laser diode or a light emitting diode having high directivity is used.

FIG. 6 shows a flowchart of the distance measurement by the arithmetic unit (corresponding to the distance measuring means) 5. In FIG. 6, the arithmetic unit 5 turns off the illumination device 6 for barcode illumination (S201), turns on the light source 11 for distance measurement (S202), and captures the sensor output from the image sensor 4 (S202). S203). At this time, the bar code 2 is irradiated with the spot light from the distance measuring light source 11, and the image is captured by the image sensor 4, so that the sensor output from the image sensor 4 indicates the position of the spot light. Become. Next, the distance to the barcode 2, that is, the object distance is obtained based on the principle of triangulation based on the imaging position of the spotlight for distance measurement (S204).

When the object distance up to the barcode 2 is obtained as described above, a correction value is obtained according to the object distance. As means for obtaining a correction value according to such an object distance, a correction value may be obtained from the correspondence between the object distance and the correction value, or a correction value may be obtained from an arithmetic expression for calculating the correction value based on the object distance. it can. Note that a distance sensor of an ultrasonic reflection type, a laser interference type, or the like may be used for distance measurement to the bar code 2.

According to the second embodiment, the object distance to the bar code 2 is determined by the distance measuring means. Therefore, the distance switching key is operated as in the first embodiment. Therefore, the correction value according to the object distance can be automatically set, and the usability is excellent.

The present invention is not limited to the above embodiment. It can be modified or expanded as follows. The correction value may be set stepwise according to the object distance so that a plurality of object distances can be handled by the distance switching key.
In this case, since a small change in the object distance does not hinder reading of the object, the object can be reliably read while limiting the number of correction values. The correction value for each distance may be changed at any time until the analysis is successful. The present invention may be applied to digital still cameras, digital video recorders, and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a barcode reading device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the arithmetic unit;

FIG. 3 is a diagram illustrating a signal output for each pixel when a correction value is obtained.

FIG. 4 is a diagram showing a signal output for each pixel when a correction signal is obtained.

FIG. 5 is a diagram corresponding to FIG. 1 in a second embodiment of the present invention.

FIG. 6 is a flowchart showing a distance measuring operation of the arithmetic unit;

[Explanation of symbols]

1 is a bar code reading device (image processing device), 2 is a bar code, 4 is an image sensor (photoelectric conversion means), 5 is an arithmetic device (signal processing device, correction means, distance measuring means), 6 is a lighting device, 7 Is a storage device, and 8 is a distance switching key (switching means).

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 5B047 BC05 CB18 DA04 DC01 DC13                 5B072 CC24 DD01 FF02 LL07 LL11                       LL18                 5C072 AA01 BA08 FB12 RA16 UA02                       VA07

Claims (7)

[Claims] A photoelectric conversion unit that converts an imaged object into an electric signal for each pixel; and a signal processing unit that analyzes image data based on an electric signal output for each pixel from the photoelectric conversion unit. The image processing apparatus according to claim 1, further comprising: a correction unit configured to correct an electric signal output for each pixel from the photoelectric conversion unit with a correction value set for each pixel according to an object distance to the object. Image processing device. 2. The method according to claim 1, wherein the correction unit has a stepwise correction value corresponding to an object distance, and corrects an electric signal output for each pixel from the photoelectric conversion unit with a correction value corresponding to the object distance. The image processing apparatus according to claim 1. 3. The image processing apparatus according to claim 1, wherein the correction unit calculates a correction value for each pixel according to an object distance. 4. The apparatus according to claim 1, further comprising a distance measuring means for measuring an object distance, wherein said correcting means sets a correction value according to the object distance measured by said distance measuring means.
The image processing device according to any one of the above. 5. The image processing apparatus according to claim 1, further comprising: a switching unit configured to select an object distance in a stepwise manner, wherein the correction unit sets a correction value according to an object distance set by a switching operation on the switching unit. The image processing apparatus according to any one of claims 1 to 3. 6. The correction value for each pixel is set to be ideal data by being multiplied by actual measurement data by the photoelectric conversion means. 3. The image processing apparatus according to claim 2, wherein the correction is performed by multiplying the signal output by a correction value for each pixel. 7. The correction means has a stepwise correction value according to an object distance, and corrects an electric signal output for each pixel from the photoelectric conversion means sequentially with a correction value for each distance. The image processing device according to claim 1.