JP2002305689A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic camera that can conduct effective smear correction without the need for a particular hardware configuration. SOLUTION: Exposures are carried out for a plurality of number of times at photometry before major photographing under different exposure conditions such as a shutter speed calculates data required smear correction in order to correct smear caused in a vertical transfer path as unnecessary electric charges by a strong incident light onto a photo diode in a CCD image pickup element data required for smear correction are calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera for electronically capturing a subject image, and more particularly, to a solid-state imaging device (CCD).
And smear correction that is generated as unnecessary charges in the transfer path and deteriorates image quality.

[0002]

2. Description of the Related Art Smear is generated as unnecessary charges in a transfer path of a CCD due to strong incident light, and is an error factor for charges due to exposure originally generated in a photodiode. Specifically, the charge generated in the photodiode during the exposure operation by the CCD is output data from the vertical transfer path through the horizontal transfer path, but smear, which is an unnecessary charge, is mixed with the charge generated from the photodiode. That is the problem.

Therefore, the smear charge mixed into the output is
2. Description of the Related Art There is known a conventional technique of correcting a CCD output by reading the output twice. In the first CCD reading, exposure data is read under desired exposure conditions, and the second CCD reading is performed.
In reading, data is read without transferring the photodiode charge to the transfer path. The smear amount is eliminated by subtracting the second read data from the first read data.

Further, for example, an electronic still camera described in Japanese Patent Application Laid-Open No. 5-73335 detects a smear information by performing a pre-metering scan, and removes a smear component based on the smear information detected earlier during the main metering scan. I try to remove it.

[0005] These conventional techniques have the following problems. That is, special hardware (such as a TG (timing generator) for driving the CCD) is used to realize the idle readout of the CCD and the pre-metering scan for smear correction.
And there is a problem that the system is restricted and the cost is increased.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an electronic camera capable of performing effective smear correction without requiring a special hardware configuration. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the object, the present invention is configured as follows.

[0008] An electronic camera according to the present invention includes: an image pickup element for picking up an image of a subject to obtain image information; first exposure data including smear information from the image pickup element; Exposure means for obtaining second exposure data having an exposure time different from that of the first and second exposure data;
Correction means for performing smear correction on image information obtained by the image pickup device based on the exposure data.

According to the present invention, there is provided a smear correction method for an electronic camera which executes a plurality of photometric operations before a photographing operation including a main exposure, wherein photometric data of a first exposure time at a first shutter speed is obtained. Obtaining the photometric data of the second exposure time at the second shutter speed, and removing the amount of smear based on the subtraction between the photometric data of the second exposure time and the photometric data of the first exposure time. And a correction step for obtaining photometric data.

[0010]

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

FIG. 1 is a block diagram showing a circuit configuration of an electronic camera according to one embodiment of the present invention. In the figure,
Reference numeral 101 denotes a lens system including various lenses; 102, a lens driving mechanism for driving the lens system 101; 103, an exposure control mechanism for controlling the diaphragm of the lens system 101;
04 is a mechanical shutter, 105 is a C with a built-in color filter
CD color image sensor, 106 a CCD driver for driving the image sensor 105, 107 a pre-processing circuit including an A / D converter, and 108 a color signal generation process, a matrix conversion process, and various other digital signal processes. Digital process circuit for performing, 109 is a card interface, 110 is a memory card such as CF, and 111 is L
1 shows a CD image display system.

In FIG. 1, reference numeral 112 denotes a system controller (CPU) for integrally controlling each unit,
Reference numeral 13 denotes an operation switch system including various SWs; 114, an operation display system for displaying an operation state, a mode state, and the like;
Reference numeral 15 denotes a lens driver for controlling the lens driving mechanism 102; 116, a strobe as a light emitting unit; 117, an exposure control driver for controlling the strobe 116;
Reference numeral 18 denotes a nonvolatile memory (EEPROM) for storing various setting information and the like.

In the electronic camera according to the present embodiment, the system controller 112 controls the exposure control mechanism 103 and the mechanical shutter 104 and the driving of the CCD image pickup device 105 by the CCD driver 106 to perform exposure (charge accumulation) and signal reading. It is taken into a digital process circuit 108 via a pre-process circuit 107 and subjected to various signal processings.
Through the memory card 110. The CCD image sensor 105 is, for example, an interline type having a vertical overflow drain structure and a progressive (sequential) scanning type.

FIG. 2 is a plan view showing the element structure of the CCD image pickup device 105. Photodiodes 201 are arranged in a matrix as light receiving elements, and a plurality of vertical transfer paths 202 are arranged between the photodiodes 201 in the column direction.
Are arranged, and one horizontal transfer path 203 is arranged at the end of the vertical transfer path 202 in the row direction. The signal charge stored in the photodiode 201 is read out to the vertical transfer path 202 by the charge transfer pulse TG, and is transferred in the transfer path 202 downward in the drawing. The signal charges transferred on the vertical transfer path 202 are then transferred to a horizontal transfer path 203, transferred on the horizontal transfer path 203 leftward on the paper, and finally output via a readout amplifier 204. I have.

Smear, which is generated as unnecessary charge in the vertical transfer path 202 due to strong incident light on the photodiode 201, is an error factor for the charge due to exposure originally generated by the photodiode 201.

The present embodiment is an electronic camera that uses a general-purpose TG (timing generator) that is easily available and is advantageous in cost, and that corrects smear without requiring additional hardware. This embodiment is based on the finding that the amount of smear does not depend on the electronic shutter speed.
Without reading the CD, smear correction data is calculated by a plurality of exposures at the time of photometry before the actual photographing.

FIG. 3 is a diagram showing the relationship between different photometry and the range of brightness (Bv), and the smear detection range. When the range of brightness (Bv) (darkest to brightest) is divided into, for example, three, photometry 1 to photometry 3 correspond to the respective brightness ranges. Each photometry has different shutter speed and sensitivity conditions. The photometry 3 is a photometry corresponding to the smear detection range.

FIG. 4 is a timing chart showing execution of photometry according to the dynamic range of brightness (Bv).

In this embodiment, photometry 2 is first performed.
The shutter speed in photometry 2 is T2, and the ISO sensitivity is S
2. The luminance value is determined based on the data obtained by the photometry 2. That is, when the luminance value is smaller than the photometric lower limit threshold value, photometry 1 is executed (see FIG. 4A). In photometry 1, the shutter speed is T1 (exposure time increase), and the ISO sensitivity is S1. On the other hand, if the luminance value is larger than the photometric lower limit threshold value, it is determined whether the luminance value of the photometry 2 is further larger than the photometric upper limit threshold value.

First, when the luminance value of the photometry 2 does not become larger than the photometry upper limit threshold value, the photometry 2
Is used as it is for calculating the luminance value (see FIG. 4B).

On the other hand, if the luminance value of the photometry 2 is larger than the photometry upper limit threshold value, the photometry 3 is executed. The photometry 3 includes two photometry (photometry 3-1 and photometry 3-2) including photometry for smear detection (FIG. 4C).
reference).

Here, the shutter speed in photometry 3-1 is T3 (exposure time shorter than T2; first exposure time), and the shutter speed in photometry 3-2 is T4 (second exposure time).
Exposure time), and T4 = nT3. n is an arbitrary positive number, and is set to 2 as an example here. The ISO sensitivity of the photometry 3-1 is S3, the ISO sensitivity of the photometry 3-2 is S4, and S4 = S3. In each of the photometry 1 to 3, the aperture (Av) is fixed.

The photometry 3-2 is a photometry for smear detection, and smear correction is performed using exposure data obtained by the photometry 3-2 and exposure data obtained by the photometry 3-1. This will be specifically described with reference to FIG.

FIG. 5A shows the exposure data D1 for the photometry 3-1 and FIG. 5B shows the exposure data D2 for the photometry 3-2 for smear detection.

As described above, the shutter speed in photometry 3-1 is T3 (for example, 1/2500 seconds), and the shutter speed in photometry 3-2 is nT3 (for example, 1/5).
000 seconds; n = 2), and the total exposure amount of the exposure data D1 and D2 differs depending on the shutter speed. However, since the amount of smear does not depend on the electronic shutter speed, the same amount exists in both of the exposure data D1 and D2. Therefore, if the net exposure (output) amount excluding the smear amount is A, this A is (D1-D
2) It is obtained by x2. It is needless to say that n is not limited to 2.

FIGS. 6 and 7 are flowcharts showing the processing operation at the time of photometry in the electronic camera of the present embodiment involving the above-described smear correction.

First, when ON of the first release is detected (step S1), exposure for photometry 2 is set (step S2), and photometry 2 is executed (step S3). The exposure data for the photometry 2 is obtained (step S
4) A luminance determination is performed based on the obtained exposure data (step S5).

That is, in step S5, it is determined whether or not the luminance value calculated from the exposure data for photometry 2 is smaller than a photometry lower limit threshold value.
In the case of YES, the process proceeds to step S6, and in the case of No, the process proceeds to step S10.

If the process proceeds to step S6, the exposure for photometry 1 is set, and then photometry 1 is executed (step S6).
7). After acquiring the exposure data for photometry 1 (step S8), a luminance value is calculated based on the acquired exposure data (step S9), and the entire process of the photometry operation is completed.

As shown in FIG. 7, when the process proceeds from step S5 to step S10, it is further determined whether or not the luminance value calculated from the exposure data for photometry 2 is larger than a photometric upper limit threshold value. . If the determination in step S10 is No, the result of the luminance determination for the photometry 2 falls within the range of the upper limit and the lower limit of the possible threshold value, so the luminance is determined using the exposure data obtained by performing the photometry 2. A value is calculated (step S11).

On the other hand, in the determination of step S10, Ye
In the case of s, photometry 3 needs to be performed. Since the photometry 3 corresponds to the smear detection range, smear detection is also performed.

As described above, the photometry 3 includes the photometry 3-1 and the photometry 3-2. First, in step S12, an exposure setting (Tv3-1 = Tv1) for the photometry 3-1 is performed. The photometry 3-1 is performed under these exposure conditions (step S13),
The exposure data of the photometry 3-1 is obtained (step S1).
4). Next, in step S15, exposure setting for photometry 3-2 (Tv3-1 = Tv1 + 1) is performed. The photometry 3-2 is executed under these exposure conditions (step S16), and the photometry 3-2 is performed.
Is obtained (step S17). And
The amount of smear is detected from the exposure data obtained by each of the photometry 3-1 and 3-2 (step S18), and a luminance value corrected for the amount of smear is calculated based on the amount (step S18).
19).

After the photometric operation as described above is completed, a main exposure (photographing) operation is performed.

The above-described smear correction of the electronic camera according to the present embodiment is based on the knowledge that the amount of smear does not depend on the electronic shutter speed, and is performed by a plurality of exposures (photometry) under different conditions. To obtain the data necessary for smear correction, a CCD with a special driving method as before
Since no reading is required, no additional hardware is required even when a general-purpose TG (timing generator) that is easily available and cost-effective is applied, and a general CCD drive circuit and sensor specifications are used. It is feasible. Moreover, the exposure performance at high luminance can be remarkably improved. Since the calculation of the amount of smear according to the present embodiment is performed based on a preset accumulation time, this can be easily realized. Another advantage is that the smear correction performance is not affected by the brightness (Bv). Further, the smear information obtained in the present embodiment can be effectively used for processing other than photometry, and this will contribute to improving the performance of the entire electronic camera.

It should be noted that the configuration illustrated in the embodiment of the present invention is an example, and is not intended to exclude other configurations, and a part of the illustrated configuration is replaced with another one or illustrated. Another configuration obtained by omitting a part of the configuration, adding another function or element to the illustrated configuration, or combining them is also possible. Also, another configuration that is logically equivalent to the illustrated configuration,
Another configuration including a portion logically equivalent to the illustrated configuration, another configuration logically equivalent to a main part of the illustrated configuration, and the like are also possible. Further, another configuration that achieves the same or similar purpose as the illustrated configuration, another configuration that achieves the same or similar effect as the illustrated configuration, and the like are also possible. Various variations of the various components exemplified in the embodiments of the present invention can be implemented in appropriate combinations. Further, the embodiments of the present invention relate to an invention as an individual device, an invention about two or more related devices, an invention as a whole system, an invention about components inside an individual device, or a method corresponding thereto. It encompasses and includes inventions related to various aspects, stages, concepts or categories, such as inventions. Therefore, the present invention can be extracted from the contents disclosed in the embodiments of the present invention without being limited to the illustrated configuration.

[0036]

As described above, according to the present invention,
An electronic camera capable of performing effective smear correction without requiring a special hardware configuration can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an electronic camera according to an embodiment of the present invention.

FIG. 2 is a plan view showing a structure of a CCD image pickup device of the electronic camera according to the embodiment.

FIG. 3 is a diagram showing different photometry and brightness (B) according to the embodiment.
The figure which shows the relationship with the range of v), and the smear detection range

FIG. 4 is a timing chart showing execution of photometry according to a dynamic range of brightness (Bv) according to the embodiment.

5A and 5B are exposure data D1 related to the photometry 3-1 and FIG. 5B is a photometry 3 for smear detection according to the embodiment.
FIG. 2 shows exposure data D2 according to −2.

FIG. 6 is a flowchart showing a part of an operation example at the time of smear correction of the electronic camera according to the embodiment;

FIG. 7 is a flowchart showing another part of the operation example of the electronic camera according to the embodiment at the time of smear correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Lens system 102 ... Lens drive mechanism 103 ... Exposure control mechanism 104 ... Mechanical shutter 105 ... CCD color image sensor 106 ... CCD driver 107 ... Preprocess circuit 108 ... Digital process circuit 109 ... Card interface 110 ... Memory card 111 ... LCD image display System 112: System controller (CPU) 113: Operation switch system 114: Operation display system 115: Lens driver 116: Strobe 117: Exposure control driver 118: Non-volatile memory

. Of the front page Continued (51) Int.Cl ⁷ identification mark FI theme Court Bu (Reference) G03B 19/02 G03B 19/02 H04N 5/232 H04N 5/232 Z 5/235 5/235 // H04N 101: 00 101 : 00 F term (for reference) 2H002 CC01 DB02 DB19 DB24 DB25 EB00 JA07 2H054 AA01 4C061 LL01 NN01 RR02 RR22 SS22 5C022 AA13 AB02 AB13 AB17 AB37 AC03 AC42 5C024 AX01 BX01 CX13 CX54 CX65 CY14 G11X03 G29 H04 G18X59 DX04

Claims (4)

[Claims] An imaging device that obtains image information by capturing an image of a subject; a first exposure data including smear information from the imaging device; and an exposure device including the smear information. An exposure unit that obtains second exposure data having different times; and a correction unit that performs smear correction on image information obtained by the imaging device based on the first and second exposure data. Electronic camera. 2. The exposure time of the second exposure data is n times (where n ≠) the exposure time of the first exposure data.
The electronic camera according to claim 1, wherein 0). 3. A smear correction method for an electronic camera that performs a plurality of photometric operations before a photographing operation including a main exposure, comprising: obtaining photometric data of a first exposure time at a first shutter speed; Obtaining photometric data of a second exposure time at a shutter speed of; and calculating photometric data excluding a smear amount based on a subtraction between the photometric data of the second exposure time and the photometric data of the first exposure time. A method for correcting smear in an electronic camera. 4. The method according to claim 1, wherein the second shutter speed is equal to the first shutter speed.
4. The smear correction method according to claim 3, wherein the shutter speed is n times (where n ≠ 0).