JPH11298733A - Image reading device, computer-readable storage medium, and storage medium storing data - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable shading correction in a film scanner in response to a change in lamp brightness during scanning. SOLUTION: A CCD 104 is placed at a position 204A of a transmission window 201 of a film holder 102, and a change with time of the brightness of a lamp is read a plurality of times without a film 104, and a plurality of shading correction data are obtained from a plurality of obtained signals. Is created and stored. During the film reading scan, a signal obtained by reading through light from the shading correction window 203 is used as a reference signal, and one of the held shading correction data is selected based on the reference signal. The read film image signal is corrected using the selected shading correction data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus suitable for use in a film scanner for converting an image recorded on a transparent medium such as a film into digital data, a computer-readable storage medium, and a storage medium storing data. It is about.

[0002]

2. Description of the Related Art In a conventional film image reading apparatus, light transmitted through a film illuminated by an illumination optical system is guided to an image sensor such as a CCD, and image information converted into electric signals by the image sensor is obtained. I have. Shading correction is performed on this image information in order to normalize the uneven brightness distribution of the illumination system, the drop in the peripheral light amount of the imaging lens, and the uneven sensitivity of each pixel of the CCD.

[0003] The shading correction currently performed is
Immediately after the power is turned on, the illumination is turned on without any film inserted and the CCD output having distribution is temporarily stored as a reference signal. After that, shading correction data is created so as to normalize the distribution, and a correction operation is performed in pixel units for each scan.A method of performing the correction operation in an analog signal or a method of performing the operation after digitizing the signal is used. At present, however, the method of performing digital correction has become mainstream at the present when the digital operation speed has been improved.

[0004]

However, in such a conventional shading correction of a film reading apparatus, it is not possible to correct a light quantity fluctuation of an illumination system during scanning. Therefore, in order to meet the needs of high image quality, it is necessary to develop a light source with a small fluctuation in light quantity and to add a light quantity stabilizing circuit, which is a factor of increasing costs.

[0005] Further, a sequence in which the light amount is stabilized or a measure in which the lamp is kept attached increases the running cost, and cannot eliminate the cause of the cost increase.

SUMMARY OF THE INVENTION It is an object of the present invention to perform shading correction that can cope with a change in brightness of a light source during scanning.

[0007]

According to the present invention, there is provided an image reading apparatus comprising: light source means for illuminating a transparent medium; and photoelectric conversion means for scanning and reading transmitted light of the transparent medium and converting the light into an electric image signal. Reading means for allowing the photoelectric conversion means to read a transparent portion outside the transparent medium during the scanning to obtain a reference signal; and reading one of the shading correction data from the plurality of shading correction data based on the read reference signal. There is provided a selecting means for selecting, and a correcting means for performing shading correction on the image signal using the selected shading correction data.

In the computer-readable storage medium according to the present invention, an illumination procedure for illuminating the transparent medium with the light source means, and a photoelectric conversion procedure for scanning and reading the transmitted light of the transparent medium and converting the light into an electric image signal. A reading procedure in which the photoelectric conversion procedure reads a transparent portion outside the transparent medium during the scanning so as to obtain reference illumination, and one of the plurality of shading correction data based on the read reference signal. Is stored, and a correction procedure for performing shading correction on the image signal using the selected shading correction data is stored.

In the computer-readable storage medium according to the present invention, a plurality of shading correction data created from a plurality of image signals obtained by reading a plurality of times by a photoelectric conversion unit with respect to a temporal change in brightness after turning on a light source unit. I remember.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a film scanner as an image reading device according to the present invention. First, the configuration will be described. Reference numeral 101 denotes a lamp (fluorescent lamp or the like) serving as an illumination light source, and reference numeral 102 denotes a film holder that holds a film as a transparent medium, and is movable in the Y direction on the paper. Reference numeral 103 denotes an imaging lens system, and reference numeral 104 denotes a CCD linear image sensor (hereinafter, referred to as a linear image sensor). The linear image sensor 104 is arranged such that the Z direction on the paper surface is the longitudinal direction. Due to this positional relationship, the main scanning direction, which is the longitudinal direction of the linear image sensor 104, and the sub-scanning direction, which is the moving direction of the film holder 102, are perpendicular to each other.

Reference numeral 105 denotes an amplifier, which can independently change the gain of RGB signals from a system controller 110 described later. 106 is an A / D converter,
Convert analog signals to digital signals. Reference numeral 107 denotes an image processing unit which performs image processing (to be described later) and processing such as a CCD drive pulse, and is configured by a gate array, and can perform various types of processing at high speed. Reference numeral 108 denotes a line buffer, which temporarily stores image data, and is realized by a general-purpose random access memory. An interface unit 109 is for communicating with an external device 118 such as a personal computer.

Reference numeral 110 denotes a system controller including a CPU, which is connected to a storage medium 119 storing a control program for performing a sequence of the entire film scanner, and in accordance with a command from an external device 118, based on a procedure based on the control program. It controls various operations. Reference numeral 111 denotes a RAM serving as a working area when performing image processing, and is referred to as an offset RAM. Reference numeral 112 denotes a shading RAM that temporarily stores various data such as shading correction, gamma correction, and color data synthesis and image data. 113 is the system controller 11
0, an image processing unit 107, a line buffer 108, an interface unit 109, an offset RAM 111, and a shading RAM 112. The CPU bus comprises an address bus and a data bus.

Reference numeral 114 denotes a sub-scanning motor for moving the film holder 102 in the sub-scanning direction, and here, a stepping motor. Reference numeral 115 denotes a sub-scanning motor driver for driving the sub-scanning motor 114 in accordance with a command from the system controller 110. Reference numeral 116 denotes a sub-scanning position detecting unit for detecting a sub-scanning reference position. A projection (not shown) provided on the holder 102 is detected. Reference numeral 117 denotes a light source lighting circuit for lighting the lamp 101, which is a so-called inverter circuit.

As the storage medium 119, a semiconductor memory, an optical disk, a magneto-optical disk, a magnetic medium, or the like may be used. These may be configured and used in ROM, RAM, CD-ROM, floppy disk, memory card, magnetic card and the like.

FIG. 2 shows the structure of the film holder 102 in detail. In FIG. 2, reference numeral 201 denotes a film transmission window for transmitting optical information of the film.
Reference numeral 202 denotes a main scanning direction (Z
This is a window for obtaining the transparent data in the direction (hereinafter, referred to as “shading window”). Reference numeral 203 denotes a shading correction window that is vacant along the sub-scanning direction (Y direction) of the film, and has a positional relationship such that transparent optical information can be obtained even when a film is inserted.

Reference numeral 204 denotes an original film. 205A,
205B is a position of the linear image sensor 104,
205A indicates that the linear image sensor 104 has obtained information on the position of the shading window 202. Similarly, 205B indicates that the linear image sensor 104 has obtained information on the film passing through the film transmission window 201 and information on the position of the shading window 203.

FIG. 3 shows the output of the linear image sensor 104 at the positions 205A and 205B. A-1,
A-2 and A-3 are outputs of the linear image sensor 104 at the position of 205A. Reference numerals 1, 2, and 3 respectively show how the brightness changes over time after the power is turned on. The lamp 101 has a light emission luminance and a light emission distribution that change with time from when the power is turned on. In particular, a hot cathode tube such as a fluorescent lamp emits a small amount of light because of a small amount of thermoelectrons at the initial stage of power-on (A-1). It has a tendency (A-2, 3). Due to such a light emission mechanism, there is a relationship between the light emission luminance and the light emission distribution, and the power supply shows almost the same change when the power is turned on.

Therefore, A-1, 2, 3 are set at the same power-on timing as in the main scan without the film 204 in advance.
And a plurality of shading data are measured and
To generate shading correction data, and store the data in the shading RAM 112.

FIG. 3B-2 shows the output (image signal) of the linear image sensor 104 at the position 205B with the film 204 inserted. Z1 of FIGS. 2 and 3
The interval between Z2 is a reference signal reading section, and FIG. 2 shows the output of transmitted light. Z3 and Z4 are the results of converting the optical signal transmitted through the film 204 into an electric signal. At this time,
The shading correction data includes Z1 during scanning.
~ Z2, and read the shading RAM 112
, And selects the shading correction data having the closest light amount level. In this case, the shading correction is performed by selecting the shading correction data corresponding to A-2.

FIG. 4 shows a conceptual configuration for performing the above correction. Reference numeral 112 denotes a shading RAM for storing shading correction data.
Plural shading correction data 1 created by PU
6 (Vref1 to 6) are stored. Reference numeral 401 denotes a reference signal portion (Z1 to Z4) from an image signal (Z1 to Z4 in FIG. 2).
Reference signal reading unit for reading 2). In this method, a gate signal through which a reference signal is passed is created by a gate array, and thereafter, a reference signal level Vref is output by, for example, calculating an average value of the reference signal.

Reference numeral 402 denotes a shading data selection unit for selecting shading data in accordance with the amount of Vref, and Vr of the stored shading correction data.
The shading correction data closest to the values of ef1 to efn is selected. For example, | Vrefn-V
A logic circuit is configured to select the one with the smallest value of ref |. Reference numeral 403 denotes a shading correction unit that performs a shading correction operation on an image signal using the selected shading correction data. Basically, data multiplication is performed, and pixel-by-pixel correction is performed. By performing these calculations with a hardware circuit during scanning, image processing is performed in a short time.

Although a plurality of shading correction data are stored in the shading RAM 112 in the above embodiment, the data may be stored in an external storage medium according to the present invention. In that case, connection means such as an interface capable of connecting an external storage medium and communicating with the system controller 110 is provided.

Further, the plurality of shading correction data, the image signal of the film read by the linear image sensor 104, and the reference signal may be output through the connection means and stored in the external storage medium. Good. By doing so, the shading correction of the image signal can be performed by an external device such as a computer performing processing using the external storage medium.

As the external storage medium, a semiconductor memory, an optical disk, a magneto-optical disk, a magnetic medium, or the like is used as in the case of the storage medium 119.
M, CD-ROM, floppy disk, memory card,
The present invention may be applied to a magnetic card.

[0025]

As described above, according to the present invention, a temporal change of a light source such as a lamp is stored as a plurality of shading correction data, a reference signal is obtained during scanning, and shading correction data is selected based on the reference signal. By doing so, it is possible to correct for a temporal change in the light amount. Thereby, higher quality image quality can be provided.

Further, since it is possible to correct even a cheap lamp having a certain degree of aging, the cost can be reduced. Further, since it is not necessary to keep the lighting on in order to stabilize the change in the light amount, the running cost can be reduced.

Further, the image signal is stored in an external storage medium together with the shading correction data and the reference signal, and the shading correction operation is performed by an external device after scanning, thereby eliminating the need for a temporary storage RAM in the film scanner. Thus, further cost reduction is possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a film scan according to the present invention.

FIG. 2 is a configuration diagram of a film holder.

FIG. 3 is a characteristic diagram for explaining shading correction data and an image signal.

FIG. 4 is a block diagram conceptually showing a shading correction process.

[Explanation of symbols]

 Reference Signs List 101 lamp 102 film holder 104 linear image sensor 107 image processing unit 110 system controller 112 shading RAM 119 storage medium 201 film transmission window 202 shading window 203 shading correction window 204 film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/04 103C

Claims (12)

[Claims] 1. A light source means for illuminating a transparent medium, a photoelectric conversion means for scanning and reading the transmitted light of the transparent medium, and converting the light into an electric image signal; Reading means for reading a transparent portion outside the medium so as to obtain a reference signal; selecting means for selecting one of a plurality of shading correction data based on the read reference signal; and the selected shading correction An image reading device comprising: a correction unit configured to perform shading correction on the image signal using data. 2. The plurality of shading correction data are created from a plurality of image signals read by the photoelectric conversion unit a plurality of times with respect to a temporal change in brightness after the light source unit is turned on without the transparent medium. The image reading device according to claim 1, wherein: 3. The image reading apparatus according to claim 1, further comprising a creation unit for creating the plurality of shading correction data. 4. The image reading apparatus according to claim 1, further comprising storage means for storing the plurality of shading correction data. 5. The image reading apparatus according to claim 1, further comprising a connection unit that externally connects a storage unit that stores the plurality of pieces of shading correction data. 6. An output means for outputting the plurality of generated shading correction data, an image signal obtained by reading the transparent medium, and the reference signal to the externally connected storage means via the connection means. The image reading apparatus according to claim 5, wherein the image can be read. 7. An illumination procedure for illuminating a transparent medium with light source means, a photoelectric conversion procedure for scanning and reading the transmitted light of the transparent medium, and converting it into an electric image signal; and a photoelectric conversion procedure during the scanning. Reading a transparent portion outside the transparent medium to obtain a reference signal, a selecting step of selecting one of a plurality of shading correction data based on the read reference signal, And a correction procedure for performing shading correction on the image signal using the shading correction data. 8. The plurality of shading correction data are created from a plurality of image signals read a plurality of times by the photoelectric conversion procedure with respect to a temporal change in brightness after the light source means is turned on without the transparent medium. The computer-readable storage medium according to claim 7, wherein: 9. The computer-readable storage medium according to claim 7, further comprising a creation procedure for creating the plurality of shading correction data. 10. A storage procedure for storing said plurality of shading correction data.
Or a computer-readable storage medium according to item 9. 11. An output procedure for outputting the plurality of shading correction data, an image signal obtained by reading the transparent medium, and the reference signal, and storing the reference signal in the storage means. The computer-readable storage medium according to any one of the preceding claims. 12. A storage medium storing a plurality of shading correction data created from a plurality of image signals obtained by reading a plurality of times by a photoelectric conversion unit with respect to a temporal change in brightness after lighting of a light source unit.