JP2001320559A - Image reader, method for controlling image reader and image read system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an operator reading an image to automatically perform shading correction again without confirming the need for shading correction. SOLUTION: The lighting time of a G-LED at the time when the preceding shading correction is performed is set (S1) and the G-LED is turned on (S2). An image sensor is moved in a horizontal scanning direction only by one line (S3), this time peak value GLVL (n) is detected (S4), when the GLVL (n) surpasses a prescribed white level value WLVL, the GLVL (n) value is compared with a prescribed output level (S5→S6), and when the former is smaller, an acquisition request for new shading data is issued to a host computer (S19). Meanwhile, when the latter is smaller, the G-LED is turned off (S7) and hereafter, the same processing is also applied to an R-LED and a B-LED.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image reading apparatus, a control method for the image reading apparatus, and an image reading system.
More specifically, the present invention relates to an image reading device that performs shading correction of image data and a control method thereof, and an image reading system in which the image reading device and an external device are connected via a predetermined communication network.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus, so-called shading correction is performed on image data because shading (color unevenness) occurs with a change in the light amount of a light source. .

As a method of performing shading correction, for example, an average value of, for example, 16 lines is calculated for each color of RGB to perform shading correction, thereby increasing the accuracy of shading correction. Such a method requires a great deal of time for shading correction. Therefore, recently, a light emitting diode (hereinafter referred to as "LE
D)), a shading data is read only when necessary without always reading the shading data before reading the image data.

[0004]

However, in the above-described conventional image reading apparatus, the user looks at the image data actually read, and determines whether or not the image data is defective in shading. In such a case, the user issues a command for shading correction again before starting image reading, and thus the operation for shading correction is complicated.

The present invention has been made in view of such a problem, and it is possible for an operator who reads an image to automatically perform shading correction again without confirming the necessity of shading correction. It is an object of the present invention to provide a possible image reading device, a control method of the image reading device, and an image reading system.

[0006]

In order to achieve the above object, an image reading apparatus according to the present invention comprises: an original irradiating means for irradiating an original with a variable amount of light; Image reading means for irradiating a document by means to read image data on the document, a standard white plate for shading correction, and shading data acquisition for irradiating the document irradiating means to the standard white plate to obtain shading data And a shading correction unit configured to perform shading correction on the image data read by the image reading unit based on the shading data acquired by the shading data acquisition unit. Light amount checking means for checking the light amount of the original irradiation means before performing Comparing means for comparing the light amount confirmed by the above with a predetermined output level; and when the comparison result of the comparing means determines that the light amount is less than the predetermined output level, an instruction to obtain shading data is issued to the external device. And an acquisition instruction request issuing means for issuing a request.

Further, according to a control method of an image reading apparatus according to the present invention, an image reading step of irradiating a document by document irradiating means based on a command from an external device and reading image data on the document, A shading data obtaining step of irradiating a means on a standard white plate to obtain shading data, and a shading correction step of performing shading correction on the image data based on the shading data. A light amount checking step of checking the light amount of the original irradiation unit before starting the image data reading process; a comparing step of comparing the light amount checked in the light amount checking step with a predetermined output level; When it is determined that the light amount is less than the predetermined output level, the It is characterized in that it contains an acquisition instruction request issued step of issuing an acquisition instruction request shading data.

Further, in the image reading system according to the present invention, an external device and an image reading device are connected via a predetermined communication network, and the image reading device has a variable light amount for irradiating the document. Irradiating means, image reading means for irradiating an original by the original irradiating means based on a command from the external device and reading image data on the original, a standard white plate for shading correction, and the original irradiating means Shading data obtaining means for irradiating a standard white plate to obtain shading data, and shading correction means for performing shading correction on the image data read by the image reading means based on the shading data obtained by the shading data obtaining means. In the image reading system provided with, the image reading device, the image data Light amount checking means for checking the light amount of the original irradiating means before starting the sampling process; comparing means for comparing the light amount confirmed by the light amount checking means with a predetermined value; and the light amount based on the comparison result of the comparing means. Is characterized by having an acquisition instruction request issuing means for issuing a shading data acquisition instruction request to the external device when it is determined that the output level is lower than the predetermined output level.

[0009] Other features of the present invention will be apparent from the following description of embodiments of the invention.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic front view showing an embodiment of a scanner as an image reading apparatus according to the present invention.
FIG. 2 is a bottom view of FIG.

1 and 2, a scanner 1 has a platen glass 2 on which a document is placed, and a black shading correction in the sub-scanning direction (indicated by an arrow A) at the left end of the platen glass 2. And a standard white plate 4 for performing shading correction of three colors of RGB are provided, and a main scanning direction (indicated by an arrow B) is provided in front of the platen glass 2. An index plate 5 is arranged in parallel, and a contact image sensor 7 is arranged inside the scanner body 6.

The contact type image sensor 7 has a light source R
RGB three-color LEDs are integrated, and scanning is performed in the direction of arrow B, which is the main scanning direction, and the LEDs of each color are switched on and off for each line, thereby reading RGB line-sequential color images.

FIG. 3 is a block diagram showing an embodiment of an image reading system according to the present invention. The image reading system is connected to a host computer via a predetermined communication network 8 such as a LAN. .

As described above, the contact type image sensor 7 includes a red LED (hereinafter, referred to as "R-LED") 10, a green LED (hereinafter, referred to as "G-LED") 11, and a blue LED (hereinafter, referred to as "G-LED"). The LED control circuit 13 switches the LED of each color for each line to light up, and reads a color image of RGB lines sequentially.

The analog image signal read by the contact image sensor 7 is amplified by an amplifier 14 and
In the / D conversion circuit 15, for example, it is converted into an 8-bit digital image signal.

The shading RAM 16 stores shading data for reading the data of the standard white plate 4 and the black plate 3 and performing shading correction. The shading correction circuit 17 is stored in the shading RAM 16. The shading correction of the read image signal is performed based on the shading data. The peak detection circuit 18 detects the home position by detecting the peak value of the read image signal line by line.

The gamma conversion circuit 19 performs gamma conversion of an image signal read based on a gamma curve preset by the host computer 9.

The buffer RAM 20 temporarily stores image data in order to match the timing of the actual reading operation with the communication with the host computer 9, and the packing / buffer RAM control circuit 21 is preset by the host computer 9. Image output mode (binary,
After performing packing processing according to 4-bit multi-value, 8-bit multi-value, 24-bit multi-value, etc.), the image data is written to the buffer RAM 21 or the image data is read from the buffer RAM 20 and output to the interface circuit 22.

The interface circuit 22 receives a control signal from the host computer 9 and outputs an image signal.

The CPU 23 has a ROM 23a for storing a control procedure to be described later and a RAM 23b for temporarily storing calculation results and used as a work area. The CPU 23 is connected to the above-mentioned components and controls the entire apparatus. While a document detection signal and a start / stop signal for instructing start / stop of document reading are input to the CPU 23, a motor drive signal for driving a motor (not shown) is output from the CPU 23.

Reference numeral 24 denotes a timing signal generation circuit.
The output of the crystal oscillator 25 is frequency-divided according to the setting of the CPU 23, and various timing signals serving as operation references are generated.

FIG. 4 is a flowchart showing a control procedure at the time of starting reading of the image reading apparatus. The present program is stored in the ROM 23a and executed by the CPU 23.

That is, when a read start command is received from the host computer 9, in step S1, the lighting time of the G-LED 11 at the time of the previous shading correction is set in an LED lighting time setting circuit provided inside the CPU 23, and in step S2. The G-LED 11 is turned on. Next, in step S3, the contact image sensor 7 is moved by one line in the main scanning direction, and in the following step S4, the peak detection circuit 18 uses the current peak value GLVL.
(N) is detected.

In step S5, the current peak value GLVL
It is determined whether or not (n) exceeds a predetermined white level value WLVL (for example, 80H). If the answer is negative (No), the contact image sensor 7 reaches the position facing the standard white plate 4. It is determined that it has not been performed, and the process returns to step S3 to repeat the above-mentioned processing, while the answer to step S5 is affirmative (Ye
In the case of s), it is determined that the contact image sensor 7 has reached the position facing the standard white plate 4, and the process proceeds to step S6.

In step S6, the current peak value GLVL (n) is compared with a predetermined output level obtained by subtracting a predetermined value X (for example, 4) from the previous peak value G (n-1). It is determined whether it is large. And
If the answer is affirmative (Yes), it is determined that the characteristics of the light source have not changed, and the process proceeds to step S7. If the answer is negative (No), it is determined that the characteristics of the light source have changed, and the process proceeds to step S19. Then, a request for shading correction is issued to the host computer 9 again, and the process is terminated.

In this case, in response to a request for shading correction from the image reading device 1, a command for shading correction is returned from the host computer 9, whereby the close contact type image sensor 7 is renewed from the standard white plate 4. Thus, the shading correction of the image data is performed via the shading correction circuit 17.

On the other hand, the answer to step S6 is affirmative (Yes).
When there is no change in the characteristics of the light source, step S
At 7, the G-LED 11 is turned off, and the process proceeds to step S8.

In step S8, the lighting time of the R-LED 10 at the time of the previous shading correction is set in the LED lighting time setting circuit. In step S9, the R-LED 10 is set.
Lights up. Next, in step S10, the peak detection circuit 18 detects the current peak value RGLVL (n), and in the following step S11, a predetermined value X (for example, 4) from the current peak value GLVL (n) and the previous peak value G (n-1) ) Is compared with a predetermined output level to determine whether the former is greater than the latter. And the answer is affirmative (Ye
In the case of s), it is determined that the characteristic of the light source has not changed, and the process proceeds to step S12. On the other hand, when the answer is negative (No), it is determined that the characteristic of the light source has changed, and the process proceeds to step S19. Then, a request for another shading correction is issued to the host computer 9, and the process is terminated.

In the same manner as described above, in response to a request for shading correction from the image reading apparatus 1, a command for shading correction is returned from the host computer 9, so that new shading data is obtained and the shading correction circuit 17 is obtained. , The shading correction of the image data is performed.

On the other hand, if the answer in step S11 is affirmative (Ye
If the characteristic of the light source has not changed in s), the R-LED 10 is turned off in step S12, and the process proceeds to step S13.

In step S13, the lighting time of the B-LED 12 at the time of the previous shading correction is set in the LED lighting time setting circuit.
12 is turned on. Next, in step S15, the current peak value RGLVL (n) is detected by the peak detection circuit 18, and in the following step S16, the current peak value GLVL is detected.
(N) is compared with a predetermined output level obtained by subtracting a predetermined value X (for example, 4) from the previous peak value G (n-1), and it is determined whether the former is larger than the latter. If the answer is affirmative (Yes), it is determined that the characteristics of the light source have not changed, and the process proceeds to step S12, while the answer is negative (N
In the case of o), it is determined that the characteristics of the light source have changed, and the process proceeds to step S19. In the same manner as above, a request for shading correction is issued to the host computer 9 again, and the process ends.

As described above, in response to a request for shading correction from the image reading device 1, a command for shading correction is returned from the host computer 9, so that new shading data is obtained and the shading correction circuit 17 is obtained. , The shading correction of the image data is performed.

On the other hand, if the answer in step S16 is affirmative (Ye
If the characteristic of the light source has not changed in s), the B-LED 12 is turned off in step S17, and the image data reading process is started in step S18.

As described above, in the present embodiment, before performing the image data reading process, the light amount of each of the LEDs 10 to 12 is set to the light amount at the time of the previous shading correction, and the standard white plate 4 is irradiated. The output level of the standard white plate 4 is read by the contact type image sensor 7 for reading, the amount of light is checked based on the output level, it is determined whether or not new shading data should be obtained, and new shading data is obtained. When it is determined that the shading correction should be performed, a series of operations for requesting the shading correction again is automatically performed, so that the reshading correction due to the change in the light amount is automatically performed, and the operator is required to read the image when reading the image. No more bothering.

The present invention is not limited to the above embodiment. In the above embodiment, the contact type image sensor 7 has been described as a sensor for reading an image. However, it is needless to say that a CCD image sensor can be similarly used.

[0037]

As described above, according to the present invention, before reading an image, the light amount of the original irradiating unit is set to the light amount at the time of the previous shading correction, and the standard white plate is irradiated. The output level of the standard white plate is read by the shading data acquisition means that also serves as a controller, and the output level is used to check the amount of light to determine whether to acquire new shading data, and to determine that new shading data should be acquired. In this case, a series of operations for requesting the shading correction again is automatically performed, so that the reshading correction due to the change in the light amount is automatically performed, and the operator is troubled when reading the image. Disappears.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing an embodiment of a scanner as an image reading apparatus according to the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a block diagram showing an embodiment of an image reading system according to the present invention.

FIG. 4 is a flowchart showing a control procedure of a control method of the image reading apparatus according to the present invention.

[Explanation of symbols]

Reference Signs List 1 scanner (image reading device) 4 standard white plate 7 contact image sensor (image reading means, shading data acquisition means) 9 host computer (external device) 10 R-LED (document irradiating means) 11 G-LED (document irradiating means) 12 B-LED (document irradiation means) 17 Shading correction circuit (shading correction means) 18 Peak detection circuit (light quantity confirmation means) 23 CPU (comparison means, acquisition instruction request issuing means)

Claims (15)

[Claims] An original reading unit configured to irradiate an original by the original irradiating unit based on a command from an external device and read image data on the original; A standard white plate for shading correction, a shading data acquisition unit for irradiating the original irradiation unit onto the standard white plate to acquire shading data, and an image data read by the image reading unit by the shading data acquisition unit. An image reading apparatus comprising: a shading correction unit configured to perform shading correction based on the acquired shading data; a light amount confirmation unit configured to confirm a light amount of the original irradiation unit before starting a reading process of the image data; Comparing means for comparing the amount of light confirmed by the means with a predetermined output level; When the light amount is determined to be less than the predetermined output level based on the comparison result of the means, the apparatus has an acquisition instruction request issuing means for issuing a shading data acquisition instruction request to the external device. Image reading device. 2. A light quantity reading means comprising: a light quantity reading means for setting a light quantity of the document irradiating means to a light quantity at the time of a previous shading correction, irradiating the standard white plate and reading a light quantity from the standard white plate. 2. The method according to claim 1, wherein
The image reading device according to claim 1. 3. A shading data acquisition unit, comprising: a receiving unit that receives a shading data acquisition command from the external device in response to a shading data acquisition instruction request to the external device by the acquisition instruction request issuing unit. Acquiring new shading data from the white standard plate when a shading data acquisition command is received by the receiving means, and shading correction means for shading correction of image data based on the newly acquired shading data. 3. The method according to claim 1, wherein
The image reading device according to claim 1. 4. The image reading apparatus according to claim 1, wherein said image reading means also serves as said shading data obtaining means. 5. The image reading apparatus according to claim 1, wherein said document irradiating means is a light emitting diode. 6. The image reading device according to claim 1, wherein the external device is an information processing device. 7. An image reading step of irradiating a document by document irradiating means based on a command from an external device and reading image data on the document, and irradiating the document irradiating means to a standard white plate to generate shading data. A method for controlling an image reading apparatus, comprising: a step of acquiring shading data to be acquired; and a step of performing shading correction for performing shading correction on the image data based on the shading data. A light amount checking step of checking the light amount of the irradiation unit, a comparing step of comparing the light amount confirmed in the light amount checking step with a predetermined output level, and it is determined that the light amount is lower than the predetermined output level based on the comparison result. Requesting the external device to obtain shading data. Control method for an image reading apparatus characterized by comprising the acquisition instruction request issued step of. 8. The light amount checking step further includes a light amount reading step of setting the light amount at the time of the previous shading correction and irradiating the original irradiating means to the standard white plate to read the light amount from the standard white plate. The method for controlling an image reading device according to claim 7, wherein: 9. A receiving step of receiving a shading data acquisition command from the external device in response to a shading data acquisition instruction request to the external device in the acquisition instruction request issuing step; The step, when a shading data acquisition command is received in the receiving step, obtains new shading data from the white standard plate, and the shading correction step performs shading correction of image data based on the newly obtained shading data. 9. The method according to claim 7, wherein the control is performed. 10. An external device and an image reading device are connected via a predetermined communication network, and the image reading device is provided with a document irradiating unit having a variable amount of light for irradiating a document, and An image reading unit that irradiates the original by the original irradiating unit based on a command and reads image data on the original, a standard white plate for shading correction, and a shading data by irradiating the standard white plate with the original irradiating unit. An image reading system comprising: a shading data acquisition unit that acquires the image data; and a shading correction unit that performs shading correction based on the shading data acquired by the shading data acquisition unit. A reading device, wherein the original irradiation means is provided before starting the reading process of the image data; A light amount confirming unit for confirming the light amount, a comparing unit for comparing the light amount confirmed by the light amount confirming unit with a predetermined output level, and the comparison result of the comparing unit determines that the light amount is less than the predetermined output level. And an acquisition instruction request issuing means for issuing a shading data acquisition instruction request to the external device when the image reading is performed. 11. The light amount checking means includes light amount reading means for setting the light amount at the time of the previous shading correction and irradiating the original irradiating means to the standard white plate and reading the light amount from the standard white plate. The image reading system according to claim 10, wherein: 12. When the external device receives a shading data acquisition instruction request from the acquisition instruction request issuing unit, the external device has a response unit that replies a shading data acquisition command to the image reading device. The apparatus has a receiving unit for receiving a shading data acquisition command by the reply unit, and the shading data acquiring unit acquires new shading data from the white standard plate when the shading data acquisition command is received by the receiving unit. The image reading system according to claim 10, wherein the shading correction unit performs shading correction of image data based on the newly acquired shading data. 13. An image reading apparatus according to claim 10, wherein said image reading means also functions as said shading data obtaining means. 14. The image reading system according to claim 10, wherein said document irradiation means is a light emitting diode. 15. The image reading system according to claim 10, wherein the external device is an information processing device.