JPH06233178A - Image scanner - Google Patents

Abstract

PURPOSE:To obtain a high quality image even at the time of picking up an object to be photographed, having a deviation in a luminance by changing an exposure value of a photoelectric converting means at every one line of sub-scanning. CONSTITUTION:A preliminary scanning electric signal of the whole image pickup picture based on main scanning and sub-scanning by a CCD 6 of a photoelectric converting means is stored is a memory 16 of a control unit 1. A main CPU 11 of a camera box 2 corresponding to the storage calculates both a correct exposure value of the whole image pickup picture and an exposure correct value at avery one line of sub-scanning, and in accordance with these calculated values, a storage time of the CCD 6, and the light quantity of an iris 3 are adjusted at every one line of sub-scanning through a CCD driving device 13 and an iris motor 5 which are controlled by the CPU 11, and by the adjustment at every one line, an image having a high quality is obtained even in the case of phtographing an object to be photographed having a deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-lens reflex camera type image scanner.

[0002]

2. Description of the Related Art In a conventional image scanner, a line (one-dimensional) type photoelectric conversion element, for example, a CCD is used, and main scanning is electrically performed mechanically and sub-scanning is mechanically performed to capture two-dimensional image data. There is something. Since image scanning using this line-type CCD takes a long time for sub-scanning, many of them mainly input a transmission original or a reflection original, which is a stationary subject. If the subject is limited to these originals, apply uniform illumination to the originals and
The original is quickly and accurately read while keeping the CD accumulation time constant.

On the other hand, there is also one in which a landscape or the like is input even with a stationary subject by an image scanner using a line type CCD. In this case, since the brightness of the subject greatly varies, the accumulation time of the CCD or the aperture value of the lens is changed according to the brightness of the subject. There are two general methods for this. In one method, one exposure value is determined based on the luminance information of the photographing screen obtained by the preliminary scanning so that the CCD is not saturated, and the entire photographing screen is main-scanned with a constant aperture value and a constant CCD integration time. It is an image scanner. The other method is an image scanner that scans the entire photographic screen with a constant aperture value and a constant CCD integration time by obtaining brightness information of the photographic screen by a photometric photoelectric conversion element other than the CCD for photographing. Is.

[0004]

However, using an image scanner using a line type CCD, it has a bright blue sky (bright portion) and a bottom (dark portion) as shown in FIG. When a subject is photographed, the brightness is deviated within the photographing screen. In this case, according to the exposure control in which the entire photographic screen has a constant aperture value and a constant CCD integration time, if the CCD is saturated in a high-brightness portion, or on the contrary, the exposure is corrected so as not to be saturated,
There is a problem that the low brightness part is dark and it is difficult to obtain contrast.

Therefore, in an image scanner using a line-type CCD, a system capable of performing exposure correction for each sub-scanning line is added to the system for controlling the exposure of the entire photographic screen to obtain a higher quality image. The purpose is to secure.

[0006]

In order to achieve the above object, the image scanner of the present invention is provided in the vicinity of the conjugate plane of the imaging optical system (3) and performs the main scanning of the photographing screen by electronic scanning. A storage type photoelectric conversion means (6) for converting the brightness of the photographic screen into an electric signal; a diaphragm means (4) for adjusting the amount of light passing through the imaging optical system (3); and a direction perpendicular to the main scanning direction. In an image scanner equipped with sub-scanning means (7-9, 14) for moving the photoelectric conversion means in the direction of forming to perform sub-scanning of the photographic screen, a predetermined storage time of the photoelectric conversion means and a predetermined light amount of the diaphragm means are set. Under the state, a storage unit (1 that stores the electric signal of the entire photographic screen obtained by the main scanning by the photoelectric conversion unit and the sub-scanning by the sub-scanning unit
6), first calculating means (S108) for calculating the proper exposure value of the entire photographing screen based on the electric signal stored in the storing means (16), and the photographing screen based on the electric signal stored in the storing means. Second for calculating the exposure correction value for each sub-scan of
Calculation means (S110), and change means (S114, S115) for changing at least one of the accumulation time of the photoelectric conversion means and the light amount of the diaphragm means based on the results of the first calculation means and the second calculation means. Characterized in that the main scanning of the photoelectric conversion means is performed under the condition of the accumulation time of the photoelectric conversion means and the light amount of the diaphragm means changed by the changing means, and then the photoelectric conversion means is moved by the sub-scanning means. .

[0007]

According to a first aspect of the present invention, under the condition of a predetermined storage time of the photoelectric conversion means and a predetermined light amount of the diaphragm means, the entire photographic screen obtained by the main scanning by the photoelectric conversion means and the sub-scanning by the sub-scanning means. Having a storage unit for storing an electric signal (so-called preliminary scanning), the first calculation unit calculates an appropriate exposure value of the entire photographic screen based on the electric signal stored in the storage unit, and then for each sub-scanning line. Second exposure compensation amount
It is calculated by the calculation means. Since the changing unit changes the accumulation time of the photoelectric conversion unit and the light amount of the diaphragm unit for each sub-scanning line, even when a subject having an uneven luminance is photographed during the main scanning, It is possible to obtain high-quality images.

According to the second aspect of the present invention, the second photoelectric conversion means is provided even if the second photoelectric conversion means for photometrically measuring the brightness of the entire photographing screen is different from the first photoelectric conversion means for finally capturing the image. After the first exposure means calculates the proper exposure value of the entire photographic screen based on the result of (1), the second exposure means further calculates the exposure correction amount for each sub-scanning line. Since the changing unit changes the accumulation time of the photoelectric conversion unit and the light amount of the diaphragm unit for each sub-scanning line, even when a subject having an uneven luminance is photographed during the main scanning, It is possible to obtain high-quality images.

[0009]

1 is a diagram showing the basic construction of a single-lens reflex camera type image scanner according to a first embodiment of the present invention. The single-lens reflex camera type image scanner comprises a control unit 1, a camera body 2 and an interchangeable lens 3. The control unit 1 and the camera body 2 are connected by a signal / power cable. The camera body 2 and the interchangeable lens 3 are connected by a bayonet mount, and signals are connected by contact pins.

Main CPU in control unit 1
Reference numeral 11 controls the clock of the CCD 6 via the CCD drive circuit 13 in the camera body 2 to perform main scanning of the CCD 6. The CCD 6 is composed of one line for a black-and-white image, and is composed of three lines having RGB filters for a color image. Also the main CPU 11
Is an analog (A) image analog signal from the CCD 6.
/ A / D converted by the digital (D) converter 15 and stored in the memory 16. The digital signal stored in the memory 16 is output to the I / F 17 and transmitted from the I / F 17 to a computer (not shown) or the like. The digital signal stored in the memory 16 is stored as data of brightness BV (1,1) to brightness BV (64,100), for example, if the CCD 6 has 64 pixels per line and the sub-scanning step is 100. To be done.

The main CPU 11 also controls the sub CPU 10 in the camera body 2. The sub CPU 10 drives the stage motor 9 via the stage motor drive circuit 14 in the camera body 2. When the stage motor 9 rotates, the feed screw 8 rotates and the stage 7 moves.
The CCD 6 on the stage 7 is a CCD as shown in FIG.
Sub-scanning is performed by moving from the position 6 '(start position) to the position of CCD 6 "(end position). When the end position is reached, the sub-scan returns to the start position. The iris motor 5 is driven via the iris motor drive circuit 12 to open and close the iris 4.

When photometry of the entire photographic screen is performed without performing preliminary scanning, a photometric CCD is provided inside the camera body 2.
(Not shown) or a photometric device 20 that can be externally connected is used. For example, this photometric device 20 includes a lens 2
1, SPD (silicon photodiode) 22 and A /
It is composed of a D converter 23. The operation of this embodiment will be described with reference to the flowchart shown in FIG. Note that C
Description will be made assuming that the CD 6 has 64 pixels per line and the sub-scanning step is 100.

In step S101, FRG = 0 is set. In step S102, it is determined whether or not a preliminary scan button (not shown) has been pressed. If the preliminary scan button is pressed, the process proceeds to step S103, and if the preliminary scan button is not pressed, the process proceeds to step S105. When the pre-scan button is pressed, that is, in step S103, the initialized FRG = 0 is changed to FRG = 1, and then the CCD 6
Then, main scanning and sub-scanning are performed to perform preliminary scanning (step S104). This prescan is a constant iris aperture,
In addition, the CCD accumulation time is fixed. By this preliminary scanning, the brightness BV (1,1) to the brightness BV (6
4, 100) is accumulated (step S105), and when all the sub-scanning is completed, it returns to the start position (step S10).
6).

If the pre-scan button is not pressed, that is, in step S107, photometry is performed by a photometry element in the camera body 2 different from the CCD 6 or the external photometry device 20. This element does not have to be a line sensor in particular, and may be any element as long as it is capable of photometrically measuring the entire photographing screen. In step S108, the proper exposure value B for the entire shooting screen
Calculate Vav. When preliminary scanning is performed by the CCD 6 (step S104), for example, brightness BV (1,1) to brightness B
The overall average luminance of V (64,100) may be used as the proper exposure value BVav. Even when photometry is performed by an element different from the CCD 6 (step S107), the average brightness of the entire photographic screen may be obtained. The reason for obtaining the average brightness of the entire photographing screen in this way is to use it as a reference for main scanning.

In step S109, it is determined whether FRG = 1. If FRG = 1, it means that the CCD 6 has performed the preliminary scanning, and therefore the process proceeds to step S110.
If FRG = 1 is not satisfied, the process proceeds to step S111. In step S110, the brightness BV obtained by the preliminary scanning
The exposure correction value Ym for each sub-scanning line is calculated based on (1, 1) to the brightness BV (64, 100). That is, the brightness BV (1,1) to the brightness BV (64,1), ...
(1, m) to brightness BV (64, m), ... Brightness BV
The exposure correction value Ym for (100) to luminance BV (64,100) and 100 lines is calculated. In the calculation of the exposure correction value Ym, for example, when the proper exposure value X and the average brightness for one line of the m-th line are BVm, the exposure correction value Ym of the m-th line is expressed by Formula 1.

[0016]

## EQU1 ## Ym = X / BVm In step S111, it is determined whether FRG = 1. If FRG = 1, the process proceeds to step S114, and if FRG = 1, the CCD 6 has not performed the preliminary scanning, so the process proceeds to step S112. Step S1
In 12, the CCD 6 performs the main scanning, and the brightness BV (1,
1) to data of brightness BV (64,1) are obtained. However, since the CCD 6 performs main scanning while the CCD 6 is moving in the sub-scanning direction after the second line of sub-scanning, strictly speaking, it is different from the luminance data obtained by the preliminary scanning of the CCD 6 performed in step S104.

In step S113, the brightness BV (1,
The exposure correction value Ym of the m-th line is calculated from the data of m) to luminance BV (64, m). In step S114, the proper exposure value B of the entire photographing screen obtained in step S108
Exposure correction value Y of the m-th line obtained by Vav and CCD6
The accumulation time of the CCD 6 is changed based on m (correction value obtained in step S110 and step S113), and also in step S115, the iris opening / closing drive is performed based on the exposure correction value Ym of the m-th line. The relationship between the proper exposure value and the exposure correction value Ym is that the proper exposure value X, the exposure correction value Ym on the m-th line, and the average brightness for one line on the m-th line are BV
If an appropriate exposure value for the mth and mth lines is Qm, it is expressed as in Equation 2.

[0018]

## EQU2 ## Qm = BVm.Ym. Then, substituting equation 1 into equation 2, Qm =
It becomes X. In step S116, step S120
It is determined whether or not the sub-scanning one-line drive instructed in step 1 has been completed. The first line of the sub-scan is step S120.
Since there is no command for this step, skip this step.

In step S117, step S115
It is determined whether or not the iris opening / closing drive instructed in step 3 has been completed. If the sub scanning drive is completed and the iris opening / closing drive is completed, the main scan is read in step S118. Since the main scanning is performed with the exposure value changed for each line of the shooting screen, it is possible to obtain a high-quality image even when shooting a subject having a luminance deviation.

In step S118, it is determined whether the sub-scan has read the final line. If the final line has not been read, the process proceeds to step S120, and the main CPU 1
1 to the stage drive circuit 14 via the sub CPU 10
A command for driving one line of the sub-scan is issued to, and if the last line is read, the main scan ends. In addition,
In the present embodiment, the case where the CCD 6 is composed of one line has been described, but in the case where the CCD 6 is composed of three lines each having an RGB filter, steps S110 and S1.
The correction values for the three RGB lines may be calculated in step S118, S118, or the like, or main scanning may be performed. Alternatively, so-called frame sequential scanning may be performed. In the case of frame sequential, steps S109 to S120 are performed only on the R line, and then steps S109 to S1 are performed only on the G line.
20 and then step S109 to step S120 for the B line may be performed. In such a case, step S11
0, it is also possible to characterize the exposure correction value obtained in S113 for each RGB.

[0021]

As described above, according to the present invention, since the exposure value of the photoelectric conversion means can be changed for each sub-scanning line,
Even when a subject having an uneven brightness is photographed, it is possible to obtain an effect that a high quality image can be obtained. In the case of scanning in the frame sequential manner, it is possible to intentionally change the B-G-R ratio partially.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an image scanner of a single-lens reflex camera type that is an embodiment.

FIG. 2 is a flowchart showing exposure control of a single-lens reflex camera type image scanner that is an embodiment.

FIG. 3 is an example of a subject on a shooting screen.

[Explanation of symbols]

 1 Control Unit 2 Camera Body 3 Focusing Optical System Lens Barrel 4 Iris 5 Iris Motor 6 CCD 7 Stage 8 Feed Screw 9 Stage Motor 10 Sub CPU 11 Main CPU 12 Iris Motor Drive Circuit 13 CCD Drive Circuit 14 Stage Motor Drive circuit 15 A / D converter 16 Memory 17 I / F 20 External photometric device 21 Lens 22 SPD 23 A / D converter

Claims (3)

[Claims] 1. A storage-type photoelectric conversion means which is provided in the vicinity of a conjugate plane of an image forming optical system and converts the brightness of the photographing screen into an electric signal by performing main scanning of the photographing screen by electronic scanning; Diaphragm means for adjusting the amount of light passing through the imaging optical system; sub-scanning means for sub-scanning the photographing screen by moving the photoelectric conversion means in a direction perpendicular to the main scanning direction. In the image scanner, under the condition of a predetermined storage time of the photoelectric conversion means and a predetermined light amount of the diaphragm means, an electric power of the entire photographing screen obtained by the main scanning by the linear image sensor and the sub-scanning by the sub-scanning means. Storage means for storing a signal; first calculating means for calculating an appropriate exposure value of the entire photographing screen based on the electric signal stored in the storage means; and an electric signal stored in the storage means Based on the results of the second calculation means for calculating the exposure correction value for each sub-scan of the photographic screen based on the signal, and the accumulation time of the photoelectric conversion means or Change means for changing at least one of the light quantities of the diaphragm means, and main scanning of the photoelectric conversion means under the condition of the accumulation time of the photoelectric conversion means and the light quantity of the diaphragm means changed by the change means. And then moving the photoelectric conversion means by the sub-scanning means. 2. A storage-type first photoelectric conversion means which is provided in the vicinity of the conjugate plane of the imaging optical system and which converts the luminance of the photographing screen into an electric signal by performing main scanning of the photographing screen by electronic scanning. Diaphragm means for adjusting the amount of light passing through the imaging optical system; and sub-scanning means for sub-scanning the photographing screen by moving the photoelectric conversion means in a direction perpendicular to the main scanning direction. In an image scanner provided, a second photoelectric conversion unit that converts the brightness of the entire photographic screen into an electric signal, a storage unit that stores the electric signal of the entire photographic screen obtained by the second photoelectric conversion unit, First calculating means for calculating an appropriate exposure value of the entire photographic screen based on the electric signal stored in the storing means; and a predetermined storage time of the photoelectric conversion means and a predetermined light amount of the diaphragm means under the condition of the first calculating means. 1 Second calculation means for calculating an exposure correction value for each sub-scan of the photographing screen based on an electric signal obtained by the main scanning of the electric conversion means; and a result of the first calculation means and the second calculation means. And a change means for changing at least one of the accumulation time of the photoelectric conversion means and the light quantity of the diaphragm means, based on the accumulation time of the photoelectric conversion means and the light quantity of the diaphragm means changed by the change means. Under the above condition, the photoelectric conversion means is main-scanned, and then the sub-scanning means is used to move the photoelectric conversion means. 3. The second calculation means calculates the exposure correction value based on an electric signal obtained while the first photoelectric conversion means is being moved by the sub-scanning means. The image scanner described in 2.