JP3733250B2 - Image reading method and storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention Image reading method and storage medium More specifically, it is suitable for reducing reading density fluctuations and reading color fluctuations during image reading using an image sensor that converts reflected light from an original into an electrical signal. Image reading method and storage medium About.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is an image reading apparatus that includes an image sensor that converts reflected light from a document into an electrical signal, a reference white plate for shading correction, and the like.
[0003]
FIG. 11 is a schematic diagram showing a configuration of an image reading system of an image reading apparatus according to a conventional example. The image reading system of the image reading apparatus includes an original platen glass 1101, a dummy glass 1103, a reference white plate (hereinafter, white plate) 1104 for shading correction, an illumination light source 1105 for original illumination, a first mirror 1106, and a second mirror 1107. , A third mirror 1108, a lens 1109, and an image sensor 1110.
[0004]
In FIG. 11, the reflected light from the document 1102 passes through a first mirror 1106, a second mirror 1107, a third mirror 1108, and a lens 1109, and is imaged on the light receiving surface of an image sensor 1110. Is converted to In this case, the white plate 1104 is disposed on the upper surface of the dummy glass 1103, and the image data read from the white plate 1104 is used as a coefficient for shading correction (correction of color unevenness of the read image) at the time of document reading.
[0005]
FIG. 12 is a perspective view showing a configuration example of a scanning mechanism for two-dimensionally reading a document image by moving the first to third mirrors of the conventional image reading apparatus. The scanning mechanism of the image reading apparatus includes an original scanner motor 1201, a timing belt 1202, a mirror driving shaft 1203, wires 1204 and 1205, a first mirror base 1206 having a first mirror, and a second mirror and a third mirror. 2 mirror base 1207, signal plate 1208, and home position sensor 1209 are provided.
[0006]
In FIG. 4, the rotation of the document scanner motor 1201 rotates the mirror drive shaft 1203 via the timing belt 1202. The rotation of the mirror drive shaft 1203 winds up the wires 1204 and 1205 and moves the first mirror base 1206 and the second mirror base 1207. At this time, the moving amount of the second mirror table 1207 is set to be exactly ½ of the moving amount of the first mirror table 1206. The signal plate 1208 and the home position sensor 1209 are for detecting that the first mirror base 1206 is at a predetermined position (home position). When the signal plate 1208 crosses the home position sensor 1209, the home position sensor An electrical signal is output from 1209.
[0007]
FIG. 13 is an explanatory diagram showing a sequence example when a document image is read using the image reading apparatus shown in FIGS. That is, FIG. 13 shows an example of a sequence in which the following (A) shading sample and (B) scanning (image reading) are alternately repeated and M times of image reading are performed.
[0008]
(A) Shading sample
The white plate 1104 is read, and the read image data is stored in a memory for use as a shading correction coefficient at the time of reading a document.
[0009]
(B) Scan (image reading)
The first mirror table 1206 and the second mirror table 1207 are moved to read the document image two-dimensionally.
[0010]
When the reading of the document image is completed, the first mirror table 1206 and the second mirror table are driven via the timing belt 1202, the mirror drive shaft 1203, and the wires 1204 and 1205 by driving the document scanner motor 1201 for reading the next image. 1207 is moved in the reverse direction (Back).
[0011]
[Problems to be solved by the invention]
However, in the conventional image reading apparatus, when a discharge light-emitting type light source such as a fluorescent lamp or a xenon tube is used as a light source for illuminating a document, problems as shown in FIGS. 14 and 15 show general characteristics of a discharge light emission type light source. FIG. 14 shows a state in which the light amount gradually decreases from (A) the initial lighting amount immediately after starting the lighting of the light source according to the continuous lighting time, and changes to (B) the lighting amount when stable. FIG. 15 shows an example of characteristics of a three-wavelength type discharge light source used for color image reading. In this case, the time for reaching the stable light amount and the amount of change from the initial light amount vary depending on R (red), G (green), and B (blue).
[0012]
As described above, when a discharge-type illumination light source is used as the document illumination light source of the image reading apparatus, the continuous lighting time light amount or the R, G, and B light emission amounts gradually change, so the document reading level is always constant. This makes it difficult to maintain this state, and causes reading density fluctuations, reading color fluctuations, and the like. In particular, when such an image reading apparatus is used in a copying machine or a color copying machine, the density and color of the copy image are not stable, which is a serious problem.
[0013]
The present invention has been made in view of the above-described points, and has made it possible to considerably reduce reading density fluctuation and reading color fluctuation. Image reading method and storage medium The primary purpose is to provide
[0014]
In addition, the present invention has been made in view of the above-described points, and even when the image reading apparatus of the present invention is used in a copying machine, it is less likely to affect the reduction in copy speed. Image reading method and storage medium Is the second purpose.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 provides: An image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein a light amount variable step for changing a light amount for illuminating a document based on a light amount control value, and a light amount adjusted by the light amount variable step A reference white plate reading step for illuminating the reference white plate with a light amount and converting the reflected light from the reference white plate into an electrical signal, and shading correction data based on the data read in the reference white plate reading step is stored. The document is illuminated with a light amount adjusted using the same light amount control value as the light amount control value used in the shading correction data storage step and the reference white plate reading step, and the reflected light from the document is converted into an electrical signal. An original reading step to be converted, and the original image data read in the original reading step to the shading correction data storage step. The shading correction step for performing the shading correction using the shading correction data saved in the step and the data read in the reference white plate reading step are compared with a predetermined value, and based on the comparison result, the next light quantity variable step is compared. It has a series of control procedures with a control step for changing the light quantity control value It is characterized by that.
[0016]
In order to achieve the above object, the present invention according to claim 2 provides: An image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein a gain variable step for changing an amplification factor for amplifying an image read signal based on a gain control value, and illuminating the reference white plate A reference white plate reading step for converting the reflected light from the reference white plate into an electrical signal at an amplification factor set in the gain variable step, and shading correction data based on the data read in the reference white plate reading step Illuminating the document with a light amount adjusted using a light amount control value that is the same as the light amount control value used in the reference white plate reading step, and storing reflected light from the document. A document reading step for converting to an electrical signal at an amplification factor set in the gain variable step, and a document reading step in the document reading step. The shading correction step for performing shading correction using the shading correction data saved in the shading correction data saving step and the data read in the reference white plate reading step are compared with a predetermined value, Based on the comparison result, it has a series of control procedures with a control step for changing the gain control value for the next gain variable step. It is characterized by that.
[0017]
In order to achieve the above object, the present invention according to claim 3 provides: An image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the amount of light for illuminating a document is varied based on a light amount control value, and an amplification factor for amplifying an image read signal is set as a gain control value. A light amount variable and gain variable step that varies based on, and the reference white plate is illuminated with the light amount adjusted in the light amount variable and gain variable step, and the reflected light from the reference white plate is reflected in the light amount variable and gain variable step A reference white plate reading step for converting to an electrical signal at an amplification factor set in step (a), a shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step, and the reference white plate reading Illuminate the document with a light amount adjusted using the same light amount control value as the light amount control value used in the step, An original reading step for converting reflected light from the original document into an electrical signal at an amplification factor used in the reference white plate reading step, and saving the original image data read in the original reading step in the shading correction data saving step The shading correction step for performing shading correction using the shading correction data and the data read in the reference white plate reading step are compared with a predetermined value, and based on the comparison result, the light amount for the next variable light amount and variable gain step A series of control procedures with a control step for changing the control value and the gain control value It is characterized by that.
[0018]
In order to achieve the above object, the present invention according to claim 4 provides: A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the image reading method is configured to measure the amount of light that illuminates a document. A light amount variable step that varies based on a control value, and a reference white plate reading step that illuminates the reference white plate with the light amount adjusted in the light amount variable step and converts the reflected light from the reference white plate into an electrical signal. A light amount adjustment using a shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step, and a light amount control value that is the same as the light amount control value used in the reference white plate reading step. A document reading step is performed to illuminate the document with a predetermined amount of light and convert reflected light from the document into an electrical signal. The shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step and the data read in the reference white plate reading step on the original image data read in the original reading step. , Having a series of control procedures with a control step for comparing with a predetermined value and changing the light amount control value for the next light amount variable step based on the comparison result It is characterized by that.
[0019]
In order to achieve the above object, the present invention according to claim 5 provides: A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, the image reading method amplifying an image reading signal A gain variable step that varies the rate based on a gain control value, and a reference white that illuminates the reference white plate and converts the reflected light from the reference white plate into an electrical signal at an amplification factor set in the gain variable step A plate reading step, a shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step, and a light amount control value that is the same as the light amount control value used in the reference white plate reading step. The original is illuminated with the light quantity adjusted, and the reflected light from the original is converted into the gain variable scan. A document reading step for converting the electrical signal into an electrical signal with the amplification factor set in step 1, and the shading correction data stored in the shading correction data storage step for the document image data read in the document reading step. A series of control procedures including a shading correction step to be performed and a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the gain control value for the next variable gain step based on the comparison result Have It is characterized by that.
[0020]
In order to achieve the above object, the present invention according to claim 6 provides: A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the image reading method is configured to measure the amount of light that illuminates a document. The reference white plate with a light amount variable and a gain variable step that varies based on the control value and varies an amplification factor for amplifying the image reading signal based on the gain control value, and a light amount adjusted by the light amount variable and the gain variable step. A reference white plate reading step for converting reflected light from the reference white plate into an electrical signal at an amplification factor set in the light amount variable and gain variable steps, and data read in the reference white plate reading step A shading correction data storage step for storing shading correction data based on the reference white plate reading Illuminate the original with a light quantity adjusted using the same light quantity control value as the light quantity control value used in the step, and reflect the reflected light from the original with an amplification factor used in the reference white plate reading step. A document reading step for converting to a document, a shading correction step for performing shading correction on the document image data read in the document reading step using the shading correction data stored in the shading correction data storage step, and the reference white plate reading step A series of control procedures including a control step for comparing the data read in step (b) with a predetermined value and changing the light amount control value and gain control value for the next variable light amount and gain variable step based on the comparison result. It is characterized by that.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0033]
FIG. 1 is a block diagram showing a configuration of a main part of an image reading apparatus according to an embodiment of the present invention. An image reading apparatus according to an embodiment of the present invention includes an image sensor 101, variable gain amplifiers 102, 103, and 104, A / D converters 105, 106, and 107, a shading correction circuit 108, a line memory 109, and an illumination light source 110. , A lamp power supply 111, a CPU 112, and an original platen glass on which an original as shown in FIG. 11 is placed, a reference white plate, and a dummy glass (not shown) provided with a reference white plate. ing.
[0034]
The configuration of each part will be described in detail. The image sensor 101 forms an image of the reflected light from the original irradiated with light from the illumination light source 110 on the light receiving surface and converts it into electrical signals (R, G, B). In addition, the image sensor 101 reads the reference white plate and outputs it to the variable gain amplifiers 102, 103, and 104 when obtaining shading correction data. The variable gain amplifiers 102, 103, and 104 amplify the electric signals (R, G, and B) output from the image sensor 101 so as to have appropriate signal amplitudes, and output the amplified signals to the A / D converters 105, 106, and 107. To do. The A / D converters 105, 106, and 107 convert the electric signals (R, G, and B) amplified by the variable gain amplifiers 102, 103, and 104 into digital signals for each light receiving pixel on the light receiving surface of the image sensor 101. The signal is converted into a signal and output to the shading correction circuit 108 and the line memory 109.
[0035]
The shading correction circuit 108 performs a shading correction operation on the electrical signals (R, G, B) digitized by the A / D converters 105, 106, 107, and outputs a document reading signal (R, G, B). To do. The line memory 109 is for storing shading correction data used in the shading correction calculation in the shading correction circuit 108. As the shading correction data, image data obtained by reading a reference white plate (however, before shading correction is performed). ). The illumination light source 110 is a light source for illuminating a document or a reference white plate. When the CPU 112 controls the lamp power source 111, switching between lighting / extinction and the amount of illumination light change. The lamp power supply 111 is a power supply that can supply power to the illumination light source 110 and change the amount of illumination light.
[0036]
The CPU 112 is a central processing unit that controls the variable gain amplifiers 102, 103, 104, the lamp power supply 111, and the line memory 109, and is stored in the image reading apparatus or supplied from the outside of the image reading apparatus. Based on the above, processing shown in flowcharts of FIGS. 3 to 6 described later is executed. As a method for supplying the control program of the present invention from the outside to the image reading apparatus according to the embodiment of the present invention, a storage medium storing the control program of the present invention (a storage medium such as a floppy disk or a CD-ROM) Is inserted into a storage medium drive of a computer, and the control program of the present invention read from the storage medium is supplied to the image reading apparatus.
[0037]
Correspondence between each component in the claims and each unit in the image reading apparatus according to the embodiment of the present invention is as follows. The image reading means in the claims corresponds to the image sensor 101, the gain variable means in the claims corresponds to the variable gain amplifiers 102, 103, and 104, and the shading correction means in the claims corresponds to the shading correction circuit 108. The document illumination means in the claims corresponds to the illumination light source 110, the light quantity variable means in the claims corresponds to the lamp power supply 111, and the control means in the claims corresponds to the CPU 112.
[0038]
Next, an image reading operation and shading correction of the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing shading correction of the image reading apparatus.
[0039]
In the image reading apparatus, the CPU 112 controls the lamp power supply 111 so that the illumination light source 110 is switched between turning on / off and the amount of illumination light. The reflected light from the original irradiated with light from the illumination light source 110 forms an image on the light receiving surface of the image sensor 101, is converted into an electrical signal (R, G, B), and is output from the image sensor 101. Since the R, G, and B signals output from the image sensor 101 are analog signals, they are amplified by the variable gain amplifiers 102, 103, and 104 so as to have appropriate signal amplitudes. The R, G, and B signals amplified by the variable gain amplifiers 102, 103, and 104 are signal units of the light receiving pixels on the light receiving surface of the image sensor 101 by the A / D converters 105, 106, and 107, respectively. Is converted into a digital signal.
[0040]
The R, G, and B signals digitized by the A / D converters 105, 106, and 107 are input to the shading correction circuit 108, and the result of the shading correction calculation is output from the shading correction circuit 108 to read the document. Signal (R, G, B). As described above, the line memory 109 stores shading correction data used in the shading correction calculation in the shading correction circuit 108. As the shading correction data, image data obtained by reading a reference white plate (however, Use before shading correction.
[0041]
Next, the content of the shading correction calculation performed by the shading correction circuit 108 is shown in the following equation (1).
[0042]
SHi = [SH-TAR / Wi] × Si (1) formula
Here, i: Pixel No.
SHi: Image data after shading correction
Si: Image data before shading correction
Wi: Image data when reading the reference white plate
(However, before shading correction)
SH-TAR: Target value for shading correction
By performing the above equation (1) for each of R, G, and B signals and for each pixel, shading correction as shown in FIG. 2 is performed. In FIG. 2, a waveform indicated by a solid line is a read waveform of the reference white plate (but before shading correction) when the horizontal axis is the main scanning direction (pixel arrangement in the image sensor 101). By performing the shading correction calculation of equation (1), image data as indicated by the broken line in FIG. 2 can be obtained.
[0043]
Next, a method for correcting the amount of light of the illumination light source 110 in the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. 1, 3, 4, 7, and 8. 3 and 4 are flowcharts showing the light amount correction control of the image reading apparatus, and FIGS. 7 and 8 are explanatory diagrams showing the relationship between the LAMP-DATA change amount and the ND value of the image reading apparatus.
[0044]
3 and 4, in step S301, R, G, B from the image data (stored in the line memory 109) at the (N-1) th shading sample (reading of the reference white plate). The CPU 112 detects the maximum values Rmax, Gmax, and Bmax of each signal by examining the contents of the line memory 109. In step S302, the CPU 112 calculates the following equation (2) between Rmax, Gmax, Bmax detected in step S301 and a predetermined coefficient, and the CPU 112 obtains the ND value as a result.
[0045]
ND = α · Rmax + β · Gmax + γ · Bmax (2)
(Note that the three coefficients α, β, and γ include “φ”.
(It shall be a free value)
In step S303, the CPU 112 determines whether or not the ND value calculated in step S302 is smaller than a predetermined value K1. If “ND <K1” in step S303, the CPU 112 determines that the amount of light tends to become insufficient. In step S307, the parameter for determining the amount of lamp light (hereinafter, LAMP-DATA) is increased by a predetermined value. Used as the LAMP-DATA for the Nth and subsequent shading samples and image reading. Conversely, if “ND ≧ K1” in step S303, the next determination process is received in step S304.
[0046]
In step S304, the CPU 112 determines whether or not the value of ND is greater than a predetermined value K2. If “ND> K2” in step S304, the CPU 112 determines that the amount of light tends to be excessive, and in step S306, LAMP-DATA is reduced by a predetermined amount, and the Nth and subsequent shading samples and images Used as LAMP-DATA during reading. On the other hand, if “ND ≦ K2” in step S304, the result of the determination in step S303 is K1 ≦ ND ≦ K2. In this case, it is determined that the amount of light is in an almost appropriate state, and LAMP-DATA is not changed (updated).
[0047]
As described above, in the light quantity correction control shown in the flowcharts of FIGS. 3 and 4, as shown in FIG. 7, the value of ND is the following (1) to (3), that is,
(1) ND <K1
(2) K1 ≦ ND ≦ K2
(3) K2 <ND
The update of LAMP-DATA is switched to “constant amount increase”, “constant amount decrease”, or “change pear” depending on which range of the data exists. If this idea is developed, for example, as shown in FIG. 8, a method of arbitrarily setting the change amount of LAMP-DATA according to the obtained ND value can be easily considered.
[0048]
Next, a gain correction method for each of the R, G, and B variable gain amplifiers 102, 103, and 104 in the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. This will be described with reference to FIGS. 5 and 6 are flowcharts showing the amplifier gain correction control of the image reading device, and FIGS. 9 and 10 are explanatory diagrams showing the relationship between the amount of change in the amplifier gain of the image reading device and the value of Smax. 5 and 6 have been described for one channel of R, G, and B, and it is assumed that R, G, and B are independently subjected to gain correction control.
[0049]
5 and 6, in step S501, the CPU 112 detects the signal Smax having the maximum signal level from the reference white plate reading data at the (N-1) th shading sample. In step S502, the CPU 112 compares Smax detected in step S501 with a predetermined value LS1. If “Smax <LS1” in step S502, the CPU 112 determines that the amplifier gain tends to be insufficient, and in step S506, the corresponding amplifier gain is increased by a predetermined amount, and the Nth and subsequent shading samples and Used as an amplifier gain when reading images. Conversely, if “Smax ≧ LS1” in step S502, the next determination process is received in step S503.
[0050]
In step S503, the CPU 112 compares the value of Smax with a predetermined value LS2. When “Smax> LS2” in step S503, the CPU 112 determines that the amplifier gain is too large, and in step S507, the corresponding amplifier gain is decreased by a predetermined amount, and the Nth and subsequent shading samples and images are read. Used as an amplifier gain. On the other hand, in the case of “Smax ≦ LS2” in step S503, when combined with the determination result in step S502, “LS1 ≦ Smax ≦ LS2” is obtained. In this case, it is determined that the amplifier gain is substantially appropriate, and the amplifier gain is not changed (updated).
[0051]
As described above, in the amplifier gain correction control shown in the flowcharts of FIGS. 5 and 6, as shown in FIG. 9, the value of Smax is the following (1) to (3), that is,
(1) Smax <LS1
(2) LS1 ≦ Smax ≦ LS2
(3) LS2 <Smax
The update of the amplifier gain control amount is switched to “increase by a certain amount”, “decrease by a certain amount”, or “not to change” depending on which range of the signal is present. If this idea is developed, for example, as shown in FIG. 10, a method of arbitrarily setting the change amount of the amplifier gain control according to the obtained value of Smax can be easily considered.
[0052]
In the above-described embodiment of the present invention, the image reading apparatus itself has been described. However, the image reading apparatus of the present invention can be applied to an image reading unit of a copying machine (monochrome copying machine, color copying machine). is there.
[0053]
As described above, according to the image reading apparatus according to the embodiment of the present invention, the illumination light source 110 that illuminates the document, the image sensor 101 that converts the reflected light from the document or the reference white plate into an electrical signal, When a lamp power source 111 that changes the amount of light emitted from the illumination light source 110 to an appropriate amount of light, a variable gain amplifier 102 to 104 that amplifies an output signal from the image sensor 101 to an appropriate signal level, and a reference white plate is read The CPU 112 changes the light amount control value for the lamp power supply 111 according to the signal level and changes the gain control value for the variable gain amplifiers 102 to 104, and thus has the following operations and effects.
[0054]
In the above configuration, the CPU 112 of the image reading apparatus has insufficient light amount when the maximum value Rmax, Gmax, Bmax of each signal R, Gmax, Bmax and a predetermined coefficient ND is ND <K1 during light amount correction control. The parameter (LAMP-DATA) for determining the lamp light quantity is increased by a predetermined value and used as the Nth shading sample and LAMP-DATA at the time of image reading. When ND> K2, it is determined that the amount of light tends to be excessive, and LAMP-DATA is reduced by a predetermined amount and used as the Nth and subsequent shading samples and LAMP-DATA at the time of image reading. In the case of K1 ≦ ND ≦ K2, it is determined that the light amount is in an almost appropriate state, and LAMP-DATA is not changed (updated).
[0055]
Further, when the signal Smax of the maximum signal level detected from the reference white plate read data at the (N-1) th shading sample is Smax <LS1 during the amplifier gain correction control, the amplifier gain tends to be insufficient. Therefore, the amplifier gain is increased by a predetermined amount and used as the Nth and subsequent shading samples and the amplifier gain at the time of image reading. In the case of “Smax> LS2”, it is determined that the amplifier gain is too large, the corresponding amplifier gain is reduced by a predetermined amount, and used as the amplifier gain for the Nth and subsequent shading samples and image reading. When LS1 ≦ Smax ≦ LS2, it is determined that the amplifier gain is in an almost appropriate state, and the amplifier gain is not changed (updated).
[0056]
That is, in the embodiment of the present invention, the lighting energy supplied from the lamp power supply 111 to the illumination light source 110 and the signal output from the image sensor 101 with respect to the light amount variation and color variation of the illumination light source 110 in the image reading apparatus. Since the amplifier gain for amplifying the image can be tracked by the sequential control, there is an effect that it is possible to considerably reduce the reading density fluctuation and reading color fluctuation which are the conventional problems.
[0057]
Further, in the embodiment of the present invention, the necessary light amount control amount and each amplifier gain are updated after the next image reading, so that even when the image reading apparatus of the present invention is used in a copying machine, the copying speed is increased. There is an effect that it is possible to make it difficult to affect the reduction of the above.
[0058]
The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. A storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the program code stored in the storage medium. Needless to say, this can also be achieved by executing read.
[0059]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
[0060]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0061]
Further, by executing the program code read out by the computer, not only the functions of the above-described embodiments are realized, but also the OS operating on the computer based on the instruction of the program code performs the actual processing. Needless to say, a case where the function of the above-described embodiment is realized by performing part or all of the processing is also included.
[0062]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.
[0063]
【The invention's effect】
As explained above, according to the present invention, The image reading method and the storage medium of the present invention are applied. Since the lighting energy supplied from the light quantity variable means to the original illumination means can be made to follow the light intensity fluctuation and the color fluctuation of the original illumination means in the image reading apparatus by sequential control, the reading density fluctuation and the reading color, which are the conventional problems. There is an effect that the taste fluctuation can be considerably reduced. In particular, by performing the control according to the present invention, it is possible to control the reading of the reference white plate once per reading of the original, and the reading of the reference white plate and the shading correction of the original are corrected based on the same amount of light. There is an effect that can be.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a main part of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing shading correction of the image reading apparatus according to the embodiment of the present invention.
FIG. 3 is a flowchart showing light amount correction control of the image reading apparatus according to the embodiment of the present invention.
FIG. 4 is a flowchart showing light amount correction control of the image reading apparatus according to the embodiment of the present invention.
FIG. 5 is a flowchart showing amplifier gain correction control of the image reading apparatus according to the embodiment of the present invention.
FIG. 6 is a flowchart showing amplifier gain correction control of the image reading apparatus according to the embodiment of the present invention.
FIG. 7 is an explanatory diagram illustrating a relationship between a change amount of LAMP-DATA and an ND value of the image reading apparatus according to the embodiment of the present invention.
FIG. 8 is an explanatory diagram illustrating a relationship between a change amount of LAMP-DATA and an ND value of the image reading apparatus according to the embodiment of the present invention.
FIG. 9 is an explanatory diagram showing the relationship between the amount of change in amplifier gain and the value of Smax in the image reading apparatus according to the embodiment of the present invention.
FIG. 10 is an explanatory diagram showing the relationship between the amount of change in amplifier gain and the value of Smax in the image reading apparatus according to the embodiment of the present invention.
FIG. 11 is a schematic diagram illustrating a configuration of an image reading system of an image reading apparatus according to a conventional example.
FIG. 12 is a perspective view illustrating a configuration of a scanning mechanism of an image reading apparatus according to a conventional example.
FIG. 13 is an explanatory diagram showing an example of an image reading sequence of an image reading apparatus according to a conventional example.
FIG. 14 is an explanatory diagram showing a characteristic example of a discharge type light source.
FIG. 15 is an explanatory diagram showing a characteristic example of a discharge type light source.
[Explanation of symbols]
101 Image sensor
102, 103, 104 Variable gain amplifier
108 Shading correction circuit
110 Illumination light source
111 Lamp power supply
112 CPU

Claims (6)

An image reading method applied to an image reading apparatus having a reference white plate for shading correction,
A light intensity variable step for varying the light intensity for illuminating the document based on the light intensity control value;
A reference white plate reading step of illuminating the reference white plate with the light amount adjusted in the light amount variable step, and converting reflected light from the reference white plate into an electrical signal;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
A document reading step of illuminating the document with a light amount adjusted using the same light amount control value as the light amount control value used in the reference white plate reading step, and converting reflected light from the document into an electrical signal;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
It has a series of control procedures including a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the light amount control value for the next light amount variable step based on the comparison result. Image reading method. An image reading method applied to an image reading apparatus having a reference white plate for shading correction,
A gain variable step of varying an amplification factor for amplifying the image reading signal based on a gain control value;
A reference white plate reading step of illuminating the reference white plate, and converting reflected light from the reference white plate into an electrical signal at an amplification factor set in the gain variable step;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
An original reading step of illuminating the original with the light amount used in the reference white plate reading step, and converting reflected light from the original into an electrical signal at an amplification factor set in the gain variable step;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
It has a series of control procedures including a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the gain control value for the next gain variable step based on the comparison result. Image reading method. An image reading method applied to an image reading apparatus having a reference white plate for shading correction,
A light amount variable step and a variable gain step for varying the light amount for illuminating the document based on the light amount control value and varying the amplification factor for amplifying the image reading signal based on the gain control value;
The reference white plate is illuminated with the light amount adjusted in the light amount variable and gain variable step, and the reflected light from the reference white plate is converted into an electric signal with the amplification factor set in the light amount variable and gain variable step. A reference white plate reading step to convert;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
The original is illuminated with a light quantity adjusted using the same light quantity control value as that used in the reference white plate reading step, and the reflected light from the original is amplified in the reference white board reading step. A manuscript reading step for converting into an electrical signal at a rate;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
A series of control with a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the light amount control value and the gain control value for the next light amount variable and gain variable step based on the comparison result image reading method characterized by having a step. A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction,
The image reading method includes:
A light intensity variable step for varying the light intensity for illuminating the document based on the light intensity control value;
A reference white plate reading step of illuminating the reference white plate with the light amount adjusted in the light amount variable step, and converting reflected light from the reference white plate into an electrical signal;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
A document reading step of illuminating the document with a light amount adjusted using the same light amount control value as the light amount control value used in the reference white plate reading step, and converting reflected light from the document into an electrical signal;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
It has a series of control procedures including a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the light amount control value for the next light amount variable step based on the comparison result. Storage medium. A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction,
The image reading method includes:
A gain variable step of varying an amplification factor for amplifying the image reading signal based on a gain control value;
A reference white plate reading step of illuminating the reference white plate, and converting reflected light from the reference white plate into an electrical signal at an amplification factor set in the gain variable step;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
An original reading step of illuminating the original with the light amount used in the reference white plate reading step, and converting reflected light from the original into an electrical signal at an amplification factor set in the gain variable step;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
It has a series of control procedures including a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the gain control value for the next gain variable step based on the comparison result. Storage medium. A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction,
The image reading method includes:
A light amount variable step and a variable gain step for varying the light amount for illuminating the document based on the light amount control value and varying the amplification factor for amplifying the image reading signal based on the gain control value;
The reference white plate is illuminated with the light amount adjusted in the light amount variable and gain variable step, and the reflected light from the reference white plate is converted into an electric signal with the amplification factor set in the light amount variable and gain variable step. A reference white plate reading step to convert;
A shading correction data storage step for storing shading correction data based on the data read in the reference white plate reading step;
The original is illuminated with a light quantity adjusted using the same light quantity control value as that used in the reference white plate reading step, and the reflected light from the original is amplified in the reference white board reading step. A manuscript reading step for converting into an electrical signal at a rate;
A shading correction step for performing shading correction using the shading correction data stored in the shading correction data storage step on the original image data read in the original reading step;
A series of control with a control step of comparing the data read in the reference white plate reading step with a predetermined value and changing the light amount control value and the gain control value for the next light amount variable and gain variable step based on the comparison result A storage medium comprising a procedure .

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