JPH1188781A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly control image pickup condition to an optimal state without separately providing a photosensor, etc. SOLUTION: An image signal is obtained by performing pre-pickup at specified electronic shutter time T1 at which no image signal from an imaging device is saturated even for the brightest object. And electronic shutter time T2 at which a signal at an optimal level is obtained is calculated from the image signal obtained by the prepickup and main pickup is performed at the calculated electronic shutter time T2 . Consequently, the image signal at the optimal and specified level is promptly obtained without installing the photosensor, etc., with wide dynamic range like a photodiode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus which reads an image of a subject by a two-dimensional solid-state image pickup device and obtains an image signal.

[0002]

2. Description of the Related Art Conventionally, in the field of photographic technology, an image recorded on a photographic film is irradiated with light, and light transmitted through the image is formed on a two-dimensional solid-state image pickup device and read to form an image. 2. Description of the Related Art A technique relating to so-called digital printing, which converts information into a digital image signal and performs printing based on the converted image signal, has been proposed. In addition to the above digital print, an image display device that reads an image recorded on a photographic film to obtain an image signal and displays an image on a monitor such as a CRT based on the obtained image signal is used.

Since a two-dimensional solid-state imaging device for reading an image such as a photographic film generally does not have a sufficient dynamic range, it is necessary to control imaging conditions (imaging conditions) such as sensitivity of the imaging device. There is.
Conventionally, as a method of controlling the imaging conditions, for example, starting the sensitivity of the imaging device from the intermediate sensitivity while performing imaging,
A method is adopted in which adjustment is made stepwise in small units.

However, this method has a problem that the response is slow because it is only possible to gradually adjust the imaging conditions such as the sensitivity of the imaging element, and that it takes time until an image signal of an optimum level is obtained. In particular, when capturing a plurality of images recorded on a photographic film, since it is necessary to position and capture the images one by one, it is necessary to immediately and satisfactorily capture the positioned frame images with optimal sensitivity. This is important because it leads to an improvement in the overall processing capacity.

As a method for enabling quick control of the image pickup conditions, an optical sensor such as a photodiode having a wide dynamic range is provided as in a conventional TV camera, and the amount of light incident on the image pickup device is controlled by the optical sensor. There is a method of detecting and controlling the sensitivity and the like of the image sensor so that the detected light amount becomes constant.

[0006]

However, in the above-described method, an optical sensor having a wide dynamic range must be provided separately from the image pickup device, which causes a problem that the structure is complicated and the cost is increased. .

The present invention has been made in view of the above-described facts, and has as its object to provide an image pickup apparatus capable of quickly controlling an image pickup condition to an optimum state without providing a separate optical sensor.

[0008]

According to a first aspect of the present invention, there is provided an imaging apparatus for obtaining an image signal by reading an image of a subject with a two-dimensional solid-state imaging device, wherein the subject is the brightest. Under a predetermined imaging condition in which the image signal is not saturated even in the case of a subject, a pre-imaging unit that reads the image to obtain an image signal, and a feature amount of the image based on the image signal obtained by the pre-imaging unit. Calculating means for extracting and calculating an imaging condition for obtaining an image signal of a predetermined level set in advance based on the feature amount;
A changing means for changing the imaging condition at the time of the pre-imaging by the pre-imaging means to the calculated imaging condition, and a main imaging means for reading the image and obtaining an image signal under the imaging condition changed by the changing means; , Is provided.

According to the first aspect of the present invention, prior imaging is performed by the pre-imaging means prior to imaging by the main imaging means. This pre-imaging is performed under predetermined imaging conditions under which the image signal is not saturated even when the object to be imaged is the brightest object. For this reason, the image signal obtained by the previous imaging does not saturate irrespective of the actually imaged subject, and it is possible to directly estimate an imaging condition for obtaining an image signal of an optimal level from this image signal. In the arithmetic means,
Based on the image signal obtained by the pre-imaging means,
An imaging condition for obtaining an image signal of a predetermined level is calculated. The changing means changes the imaging conditions at the time of the previous imaging by the previous imaging means to the calculated imaging conditions, and the imaging means reads an image under the changed imaging conditions to obtain an image signal.

In the above, since the imaging conditions for obtaining an image signal of a predetermined level can be calculated from the image signals obtained by the previous imaging, the imaging conditions can be adjusted stepwise in small units as in the prior art. Conditions can be quickly controlled to a desired state. In addition, since the imaging conditions are calculated and controlled based on the image signal obtained from the imaging element at the time of the previous imaging, there is no need to separately provide an optical sensor having a wide dynamic range such as a photodiode, and the structure can be prevented from becoming complicated.

According to a second aspect of the present invention, in the first aspect of the invention, the calculating means calculates an imaging condition in which a maximum value of the image signal obtained by the preceding imaging means is a predetermined value. It is characterized by doing.

According to the second aspect of the present invention, the image pickup condition is calculated such that the maximum value of the image signal obtained at the time of the previous image pickup becomes a predetermined value. By setting the signal level to the predetermined value, the saturation of the image signal at the time of the main imaging can be reliably prevented.

According to a third aspect of the present invention, in the first aspect of the present invention, the two-dimensional solid-state imaging device divides an image signal for one frame into two fields and outputs the signal in a time-series manner. Is characterized in that a calculation is performed based on the image signal of the first field during the image signal acquisition of the second field.

According to the third aspect of the present invention, since the calculation is performed based on the image signal of the first field among the image signals for one frame output from the image sensor, the control of the imaging conditions is further speeded up. Can be. Normally, when displaying an image of a subject read by an image sensor on a monitor such as a CRT, two frames of image signals from the image sensor are transmitted.
The images are divided into fields and output in chronological order, and these image signals are combined (interlaced scanning) to form an image. In this case, if the calculation is performed based on the image signal of the first field during the capture of the image signal of the second field from the image sensor, compared to the case where the calculation is performed based on the image signal of two fields (one frame), Control can be performed quickly.

According to a fourth aspect of the present invention, in the first aspect of the present invention, there is further provided an adjusting means for adjusting a level of an image signal obtained by the main image pickup means in a stepwise manner for each predetermined minute unit. It is characterized by that.

According to the fourth aspect of the present invention, since the level of the image signal obtained by the imaging means is further adjusted by the adjusting means, an image signal of a predetermined level can be obtained reliably. That is, since the pre-imaging means performs pre-imaging under an imaging condition in which the image signal is not saturated regardless of the subject, the image signal obtained by the pre-imaging becomes extremely weak, and the detection accuracy of the image signal and, consequently, the calculation accuracy of the imaging condition are increased. May be inferior. According to the present invention, since the level of the image signal obtained by the main imaging is further adjusted, even if an image signal of a predetermined level cannot be obtained at the time of the main imaging, it can be adjusted so that a signal of a predetermined level can be obtained.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a photographic film system 10 to which the imaging device of the present invention can be applied. The photographic film system 10 includes an image reading unit that reads an image recorded on a negative film by a camera with a two-dimensional solid-state imaging device and converts the image signal into an image signal, and a CRT or the like based on the image signal converted by the image reading unit. And an image processing unit for displaying an image on a monitor, printing on predetermined paper, and the like. As shown in FIG. 1, the image reading section is provided with a negative carrier 14 for transporting the negative film 12 and positioning a predetermined image frame at a reading position. Above the negative carrier 14, a white light source 16 such as a halogen lamp is disposed. Below the negative carrier 14, an imaging lens system 18 and a two-dimensional CCD image sensor (hereinafter, referred to as "image sensor") 22 are arranged in order, and an image emitted from the white light source 16 and positioned at the reading position is read. The transmitted light is
An image is formed on the imaging surface of the imaging element 22 by the imaging lens system 18.

A color filter array 24 and an electronic shutter 26 are integrally formed on the image pickup surface of the image pickup device 22. The color filter array 24 includes R (red), G (green), B
The spectral filter of each color (blue) is two-dimensionally arranged, and the transmitted light of the image positioned at the reading position is divided into R, G, and B color components and is incident on the image sensor 22. The electronic shutter 26 is for changing the sensitivity, which is one of the imaging conditions of the image sensor 22, and controls the opening and closing time of the electronic shutter 26 to control the image sensor 2.
2 can be changed (that is, the signal accumulation time of the image sensor 22).

The image pickup device 22 is connected to a CCD drive circuit 28. The CCD drive circuit 28 includes the crystal oscillator 3
Drive pulses of various waveforms are created in synchronization with the reference pulse from 0, and the created drive pulses are supplied to the image sensor 22 at a predetermined timing. The image pickup device 22 supplies a drive pulse from the CCD drive circuit 28, thereby receiving an NTSC (Nation
al Television System Committee)
The odd-numbered and even-numbered two-field imaging operations (signal accumulation and readout) are alternately and repeatedly performed, and the odd-numbered and even-numbered two-field image signals are output in time series as one frame of image signal. Here, the imaging element 22 performs the reading operation of the other field in which the signal was previously stored while performing the storing operation of either the odd number field or the even number field, and performs one frame in a relatively short imaging time. To get the image.

An amplifier 34, an A / D converter 36, and an image memory 38 are connected in series to the signal output terminal 22A of the image sensor 22 in this order. The image memory 38 is connected to an arithmetic control unit 40 composed of a microcomputer. The arithmetic control unit 40 includes a CPU 40A, a ROM 40B,
A RAM 40C, a VRAM 40D, and an input / output interface (I / F) 40E are provided.
They are interconnected via F.

The input / output I / F 40E of the arithmetic control unit 40 is connected to the negative carrier 14 and the white light source 16 via drivers (not shown), and the electronic shutter 26 via a shutter control unit 32. ing. Arithmetic control unit 40, prior to the start instruction of the normal imaging (main imaging), and transmits the imaging start instruction before including information indicating an electronic shutter time T ₁ to the shutter control unit 32. The shutter control unit 32 is connected to a drive pulse output terminal of the CCD drive circuit 28, and monitors the imaging operation of the image sensor 22 based on the output drive pulse. The shutter control unit 32, opens and closes upon receiving the pre-imaging start instruction from the arithmetic control unit 40, the electronic shutter 26 in a time corresponding to the electronic shutter time T ₁ in synchronization with the imaging operation of the imaging device 22 (storage operation) Control and perform pre-imaging.

Here, the electronic shutter time T ₁ is:
Even when the density of the image recorded on the negative film 12 is very low (for example, in the case of overexposure), a short time corresponding to a predetermined sensitivity at which the signal stored in the image sensor 22 does not saturate is set, ROM 40B in 40
Is stored in For this reason, the image signal obtained by the pre-imaging does not saturate regardless of the density of the negative image. For this reason, taking into account the image signal, the electronic shutter time T at which an image signal of an optimal level can be obtained. _Two
Can be calculated.

[0023] The operation control unit 40 performs calculation of the electronic shutter time T ₂ captures an image color signal obtained before by the imaging from the image memory 38, including after the operation ends, information indicating an electronic shutter time T ₂ The main imaging is performed by transmitting an imaging start command to the shutter drive control unit 32. The calculation of the electronic shutter time T ₂ is started when an image signal for one field is read out from the image sensor 22 after instructing the shutter control unit 32 to start pre-imaging, and the next one field is calculated. Is completed before the reading of data is completed.

The input / output I / F 40E of the arithmetic control unit 40
In addition, an external storage device 42 for storing an image color signal obtained by the main imaging, a keyboard 44 for an operator to input various data and commands, and the like, a CRT 46 as an image display device, And storage device 4
A digital printing unit 50 that prints on a predetermined sheet (for example, photographic paper) based on the image color signal stored in
Is connected.

In the meantime, the digital print section 50 may be a conventional digital printer which scans a laser beam based on the image color signal and prints it on photographic paper. An index printer may be used in which an image is displayed on a liquid crystal panel and the displayed image is printed on photographic paper to create a so-called index print.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS. When reading the image recorded on the negative film 12 for each frame and converting it into digital data, the operator first sets the developed negative film 12 on the negative carrier 14 and then operates the keyboard 44. When a predetermined key of the keyboard 44 is operated, an imaging processing routine shown in FIG. 2 is executed.

In the image pickup processing routine shown in FIG. 2, first, in step 100, the negative film 12 is conveyed, and the image frame on the leading side of the negative film 12 is positioned at the reading position. In the next step 102, a start signal of the operation routine is transmitted. When the start signal is sent in step 102, execution of the calculation routine shown in FIG. 3 is started. The calculation routine in FIG. 3 is executed in a time-sharing manner with the main imaging routine. In step 104, transmit the imaging start instruction before including information indicating an electronic shutter time T ₁ to the shutter control unit 32, an instruction to start before imaging. On this occasion,
The shutter drive unit 32 monitors the operation of the image pickup device 22 by taking in the drive pulse output from the CCD drive circuit 28. When the arithmetic control unit 40 instructs the start of the previous image pickup, the image pickup device 22 At the same time entering the accumulation operation to control the opening time to time T ₁ of the electronic shutter 26. For example, in FIG. 4, the start of the pre-captured at the time t ₀ is indicated, while the electronic shutter 26 from the time t ₁ at which the accumulation operation of the next one field is the start time T ₁ is opened.
Thus, after the signal in the signal storage time T ₁ is stored in the image pickup device 22, the stored signal is read operation (Fig. 4
(B)), the signal is output from the image sensor 22 and the amplifier 3
6 and stored in the image memory 38 via the A / D converter 36. Here, the image signal output from the image sensor 22 (hereinafter referred to as “pre-image signal”) does not saturate regardless of the density of the negative image because the electronic shutter time T ₁ is very short as described above. , The amplitude changes according to the RGB color densities of the image.

In step 106, it is determined whether the calculation of the electronic shutter time T ₂ has been completed.

Here, the calculation processing of the electronic shutter time T ₂ will be described with reference to the calculation routine shown in FIG. In step 200, the pre-imaging signal of the first field output from the imaging device 22 first after the above-described pre-imaging is started is fetched through the image memory 38. Step 2
In 02, the maximum value of the captured previous imaging signal is detected.
Note that the maximum value of the previous imaging signal corresponds to the signal level of the brightest part in the previously captured image. Step 20
In 4, the maximum value of the previous image signal detected in step 202 calculates the electronic shutter time T ₂ which is a predetermined value. Here, by setting the predetermined value to a relatively high level value (e.g., a level of about 80% of full scale), when performing imaging by the electronic shutter time T _2, the optimum level from the image pickup device 22 Is assumed to be obtained.
As a method of calculating the electronic shutter time T ₂ , for example, a method of selecting the electronic shutter time T ₂ by searching a table stored in the ROM 40 </ b> B based on the maximum value of the previous image pickup signal, a method of selecting the image pickup time, Element 2
Level of the image signal output from the 2 is assumed to be proportional to the electronic shutter time, a method of calculating an electronic shutter time T ₂ by performing a simple proportional calculation, among such methods be calculated using other special formulas Either can be adopted.

[0030] stores in the next step 206, the computed electronic shutter time T ₂ in a memory such as RAM40C. In step 208, the electronic shutter time T ₂
(For example, by setting a flag), and the routine ends.

[0031] In the above, prior to detecting the maximum value of the image signal before obtained by the imaging, the maximum value detected is computed the electronic shutter time T ₂ which is a predetermined value (step 202, 204), prior to A specific color area (achromatic color, flesh color, etc.) in the captured image may be extracted, and a signal level corresponding to the brightest part in the extracted color area may be detected. When displaying or printing an image, if a main subject (for example, a human face area) in the image is finished with an appropriate density and color balance, another object (for example, a background) is appropriately finished. Even if they do not, it is often determined that they are good. Therefore, as described above,
Pre extracting an image signal corresponding to, for example, the skin color region in the image, if calculating the electronic shutter time T ₂ on the basis of the maximum value of the extracted previous image signal, the image color signal portion corresponding to a human face area The level can be set to the optimal level.

In the above description, the maximum value of the previous image pickup signal is detected (step 202). However, the previous image pickup signal corresponding to the brightest predetermined area in the previously imaged image is extracted.
The average value of the extracted previous imaging signals may be calculated. In this way, it accurately calculates the electronic shutter time T ₂ even when erroneous detection of event of the previous image signal.

When the end of the calculation is instructed in step 208, the determination in step 106 in FIG. 2 is affirmed, and the process proceeds to step 108. In step 108, it fetches the electronic shutter time T ₂ which is stored in a memory such as as described above RAM40C. In the next step 110, sends the imaging start instruction including information indicating an electronic shutter time T ₂ to the shutter control unit 32, an instruction to start the imaging. At this time, similarly to the above, when the start of the main imaging is instructed by the arithmetic control unit 40, the shutter control unit 32 sets the opening time of the electronic shutter 26 to the time every time the accumulation operation of one field is started. to control the T _2. For example, in FIG. 4, when the start of the main imaging is instructed at the time point t ₄ , the electronic shutter 26 is in the open state for a time period T ₂ from the time points t ₅ and t ₆ when the accumulation operation of one field is started thereafter. Will be kept. Thus, the imaging device 22 signals the signal storage time T ₂ is stored, the stored signal is outputted from the imaging element 22 by the read operation. Here, the electronic shutter time T ₂ are, the most brightest part of the signal level in the image positioned the the reading position as already mentioned (the maximum value of the previous image signal) is defined to be a predetermined level Therefore (step 204), the image color signal output from the image sensor 22 is kept at the optimum level.

In step 108, the above-described actual imaging is performed.
The image color signal for one frame obtained first is
The electronic shutter time T_TwoFine
Determine if adjustment is required. The pre-imaging signal is
Short signal accumulation time T₁Signal obtained by performing pre-imaging with
The electronic shutter time T _Two
May not be calculated accurately. For this reason,
In step 112, the signal of the image color signal obtained by the actual imaging
It is determined whether the level is within a predetermined range. S
If the determination in step 112 is affirmative, step 114
To the electronic shutter time T_TwoAfter adjusting the
Returning to step 106, the main imaging is performed again. In addition,
In step 114, the electronic shutter time T_TwoWho adjust
The method is equivalent to the brightest part in the captured image
Signal level (the maximum value of the image color signal) is above the above range.
If the image color signal is saturated,
Judge electronic shutter time T_TwoIs a predetermined small amount ΔT
Conversely, if the lower limit of the range has not been reached,
It is determined that the signal level is too low and the electronic shutter time T
_TwoIs also described with reference to FIG.
Calculated based on the image color signal obtained in the main imaging.
The electronic shutter time T again_TwoMay be calculated again.
No.

If the image color signal obtained by the actual imaging is at the optimum level, and the determination in step 112 is affirmative, the process proceeds to step 116. In step 116, the obtained image color signal is stored in the external storage device 42. In the next step 118, it is determined whether or not the above-described processing has been completed for all the image frames recorded on the negative film 12. If the determination at step 118 is negative, the process returns to step 100 and returns to steps 100 to 11 described above.
Step 8 is repeated.

Thus, the plurality of images recorded on the negative film 12 are sequentially positioned at the reading position one frame at a time, and the positioned image is imaged twice by the previous imaging and the main imaging. Are read, and the R, G, B image color signals of each image are stored in the external storage device 42 for each frame.
Is accumulated in

The image color signals stored in the external storage device 42 are transmitted to the digital printing unit 5 connected to the arithmetic and control unit 40.
0, etc., as appropriate, and used for creating a photographic print.

As described above, in the present embodiment,
Even when the density of the image recorded on the negative film 12 is very low, pre-imaging is performed at a predetermined electronic shutter time T ₁ (low sensitivity) at which the image sensor 22 does not saturate, and the image is taken in accordance with the density of the image to be imaged. Because I got the imaging signal,
The optimum electronic shutter time T ₂ in the imaging of the image can be calculated directly from the previous image signal. For this reason, it is not necessary to repeat imaging many times as in the case where the electronic shutter time of the image sensor is adjusted step by step in minute units, and the image can be quickly and optimally obtained only in two times of the previous imaging and the main imaging. Can be read. In particular, in the present embodiment, the negative film 1
Immediately after the second image is positioned at the reading position, a state in which a predetermined level of image color signal can be obtained is achieved, so that the processing capability of the photographic film system 10 can be greatly improved.
Moreover, in the present embodiment, since the signal accumulation time (sensitivity of the image sensor 22) at the time of the main imaging is controlled based on the previous imaging signal obtained from the imaging device 22, it is also necessary to separately provide an optical sensor having a wide dynamic range. Without the need for larger equipment,
High cost can be prevented.

In this embodiment, the calculation of the electronic shutter time T ₂ is performed based on the previous image pickup signal for one field which is first read from the image pickup device 22. Can be obtained quickly. That is, since the pre-imaging signal obtained at the time of pre-imaging does not contribute to image formation, it is not necessary to use two fields for the above calculation. As shown in FIG. 4, the calculation of the electronic shutter time T ₂ is started when the previous image pickup signal for one field is read (t _{3 in} FIG. 4), and before the reading of the next one field ends (t ₃ ). ₄ if ask previously) in the calculation is completed, the waiting time T ₃ until the start of the imaging can be shortened.

In the above embodiment, the system 10 for reading an image recorded on the negative film 12 and printing it on a predetermined sheet has been described as an example. However, the present invention is not limited to this. For example, negative film 1
The present invention can also be applied to a photographic printer that directly prints an image formed by light transmitted through 2 on photographic paper or the like. That is, the present invention may be applied to a photometric system of a photographic printer that performs the above-described surface exposure to determine exposure conditions. Further, it is needless to say that the present invention may be applied to a normal TV camera or the like.

In the above embodiment, the image sensor 22
As means for changing the imaging conditions at the time of imaging by
Although the signal accumulation time (sensitivity) of the image sensor 22 is changed based on the electronic shutter time, the present invention is not limited to this. For example, the diaphragm mechanism provided above the image sensor 22 is controlled to control the image sensor. The gain of the variable amplifier that amplifies the output signal from the image sensor 22 may be changed even when the amount of light incident on the image sensor 22 is changed.

In the above embodiment, the image sensor 22
The signal system output from the system conforms to the NTSC system, but the present invention is not limited to this.
Other systems such as AL may be used.

[0043] In the above embodiments, but before using an imaging signal only to the operation of the electronic shutter time T _2, the present invention is not limited thereto and may be used further to other applications. For example, it is determined whether or not an image is recorded on the image frame of the negative film 12 between steps 200 and 202 in FIG. 3, and if the determination is negative, frame advance is performed without performing the subsequent processing (step 118). In the case where there is an image frame on which no image is recorded, frame advance can be performed without taking an image. Further, if the shift amount of the stop position of the image frame is calculated based on the previous imaging signal, and the stop position of the image frame is corrected at the next positioning, the positioning accuracy of the image can be improved. Further, when a DX code is attached to the negative film 12, information recorded in the DX code may be read.

[0044]

As described above, according to the first aspect of the present invention, based on an image signal obtained by pre-imaging,
Since the imaging condition for obtaining an image signal of a predetermined level can be directly calculated, there is an excellent effect that the imaging condition can be quickly controlled to a desired state without providing a separate optical sensor or the like.

According to the second aspect of the present invention, since the imaging condition for calculating the maximum value of the image signal obtained by the previous imaging to a predetermined value is calculated, the saturation of the image signal at the time of the main imaging can be reliably prevented. It has an excellent effect.

According to the third aspect of the present invention, since the imaging condition is calculated based on the image signal of the first field output from the two-dimensional solid-state imaging device, the control of the imaging condition can be performed more quickly. Has the effect.

According to the fourth aspect of the present invention, since the level of the image signal obtained by the main image pickup is further adjusted, there is an excellent effect that an image signal of a predetermined level can be reliably obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a photographic film system to which the present invention is applied.

FIG. 2 is a flowchart illustrating an imaging processing routine.

FIG. 3 is a flowchart showing a calculation routine.

FIG. 4 is a timing chart showing the operation of each unit when reading an image.

[Explanation of symbols]

 Reference Signs List 10 photographic film system (imaging device) 12 negative film (photographic film) 22 two-dimensional CCD image sensor (two-dimensional solid-state image sensor) 26 electronic shutter 28 CCD drive circuit 32 shutter control unit 40 arithmetic control unit

Claims (4)

[Claims] 1. An imaging apparatus for obtaining an image signal by reading an image of a subject by a two-dimensional solid-state imaging device, wherein the image signal is obtained under a predetermined imaging condition in which the image signal is not saturated even when the subject is the brightest subject. A pre-imaging means for reading the image signal to obtain an image signal, based on the image signal obtained by the pre-imaging means,
Calculating means for extracting a feature amount of the image and calculating an imaging condition for obtaining an image signal of a predetermined level based on the feature amount; An imaging apparatus comprising: a changing unit configured to change the imaging condition to the changed imaging condition; and a main imaging unit configured to read the image and obtain an image signal under the imaging condition changed by the changing unit. 2. The imaging apparatus according to claim 1, wherein said calculation means calculates an imaging condition under which a maximum value of the image signal obtained by said pre-imaging means becomes a preset predetermined value. . 3. The two-dimensional solid-state imaging device divides an image signal for one frame into two fields and outputs them in a time-series manner. 2. The imaging apparatus according to claim 1, wherein the calculation is performed based on the image signal. 4. An apparatus according to claim 1, further comprising adjusting means for adjusting a level of an image signal obtained by said main image pickup means in a stepwise manner for each predetermined minute unit.
The imaging method described in the above.