JPH09284640A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image pickup device capable of obtaining an image pickup output where favorable image quality if secured by controlling exposure quantity to permit the brightness of a main subject to be the proper one without the influence of a background brightness. SOLUTION: The image pickup device is provided with a diaphragm control part where an image pickup output level within a specified area in an image pickup screen designated by an area generator 63B is integrated by an integrating unit 62B based on an image pickup output signal which is obtained by an image pickup part having a light quantity control means so as to be detected, the image pickup output level in the area within a specified luminance level range in the image pickup screen designated by the area generator 63C is integrated by an integrating equipment 62C so as to be detected and the light quantity control means of the image pickup part is controlled by a diaphragm controller 65, based on the respective detection outputs. The light quantity control means of the image pickup part is controlled so as to permit the image pickup output level obtained by the integrating equipment 62B to be a prescribed level and the specified luminance level range is changed by a setting change means so as to add the image pickup output level.

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 having an automatic light amount control function.

[0002]

2. Description of the Related Art Generally, in an image pickup device, it is necessary to perform image pickup with an appropriate exposure amount in order to obtain an image pickup output that secures a good image quality, and the image pickup output signal level obtained by an image pickup unit is detected, The diaphragm of the image pickup unit is automatically controlled based on the detection output. In the conventional image pickup apparatus, the image pickup signal level is detected for the entire screen including the background, and the automatic aperture control is performed based on the detected signal level. Further, in the automatic aperture control in the conventional imaging apparatus, when the exposure amount is corrected, for example, by changing the internal division ratio between the peak value and the average luminance level in the entire screen, the control target value is changed to the bright side or the dark side. I was trying to shift the characteristics to the side.

[0003]

By the way, in the conventional image pickup apparatus, the image pickup signal level is detected for the entire screen including the background as described above, and the automatic aperture control is performed based on the detected image pickup signal level. For example, the aperture value is affected by the image pickup signal level other than the seed subject, and an appropriate aperture value may not be obtained for the main subject depending on the background image pickup signal level.

For example, the brightness of the main subject becomes improper due to the brightness of the background, such that the main subject is darkly sunk when the subject is backlit, and the main subject is white when the subject is overlit. Further, in the automatic aperture control in the conventional imaging apparatus, when the exposure amount is corrected, for example, by changing the internal division ratio between the peak value and the average luminance level in the entire screen, the control target value is changed to the bright side or the dark side. Since the characteristics are shifted to the side, the aperture value is affected by the area of the high-brightness area regardless of its area, and when the difference between the peak value and the average brightness level is small, the shift amount There was a problem that it was limited. Further, in the conventional image pickup apparatus, since the aperture control is performed on the entire screen, there is a problem that an appropriate aperture value cannot be obtained for a specific area.

Therefore, in view of such conventional problems,
The purpose of the present invention is to be independent of the brightness of the background,
An object of the present invention is to provide an image pickup apparatus capable of obtaining an image pickup output in which a good image quality is ensured by controlling an exposure amount so that the brightness of a main subject becomes an appropriate brightness. Another object of the present invention is to provide an image pickup apparatus capable of obtaining an image pickup output that ensures a good image quality by switching the exposure amount control mode according to the shooting situation.

[0006]

An image pickup apparatus according to the present invention includes an image pickup section having a light amount control means, and an image pickup in a specific area in an image pickup screen based on an image pickup output signal obtained by the image pickup section. The level detection means includes a first level detection means for detecting an output level and a second level detection means for detecting an imaging output level in an area of a specific brightness level range in the imaging screen, and the level detection means. And a control unit that controls the light amount control unit of the imaging unit based on each detection output.

Further, in the image pickup apparatus according to the present invention, the control means performs the image pickup so that the image pickup output level in a specific area in the image pickup screen detected by the first level detection means becomes a predetermined level. It is characterized by further comprising setting changing means for controlling the light amount control means of the unit and changing the setting of the specific brightness level range detected by the second level detecting means so as to include the image pickup output level.

[0008]

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

The image pickup apparatus according to the present invention is constructed, for example, as shown in FIG. The image pickup apparatus shown in FIG. 1 includes an image pickup section 10 and an analog-digital (A / D) conversion section 30 to which the three primary color image pickup signals R, G, B obtained by the image pickup section 10 are supplied via an analog signal processing section 20. , This A / D
The digital signal processing unit 40 and the aperture control unit 60 to which the image pickup data R, G, and B digitized by the conversion unit 30 are supplied, the digital luminance signal Y generated by the digital signal processing unit 40, and two digital color differences. An encoder 50 to which the signals C _R and C _B are supplied, a system controller 70 connected to the diaphragm control unit 60, an operation unit 80 connected to the system controller 70, and the like.

The image pickup section 10 is a color image pickup section provided with a light quantity control means, and for example, image pickup light incident from the image pickup lens 11 through the diaphragm 12 or the like is separated into the color separation prism 1.
3 is decomposed into three primary color light components, and the three primary color images of the subject image are three CCD image sensors 14R, 14G, 14
B is used for imaging. The diaphragm 12 functions as a light amount control means.

Each of the CCD image sensors 14R, 14 described above
The respective color image pickup signals R, G, B obtained by picking up the three primary color images of the subject image with G, 14B are supplied to the A / D conversion unit 30 via the analog signal processing unit 20.

In the analog signal processing section 20, the correlated double sampling (CDS) of the color image pickup signals R, G and B read from the CCD image sensors of the image pickup section 1 is performed. Performs analog signal processing including various level adjustments such as noise removal, gain adjustment, black balance, white balance and shading correction.

Further, the A / D conversion section 30 performs an A / D conversion process in synchronization with a drive clock having a predetermined phase at a clock rate equal to the sampling rate of the analog color image pickup signals R, G, B. Each A / D converter 30
By R, 30G, 30B, the image pickup signals R, G,
Digitize B. Then, the digital color signals R, G, B digitized by the A / D converter 3 are supplied to the digital signal processor 40 and the aperture controller 60.

In the digital signal processing section 40, the above A
Each digital color signal R supplied from the / D conversion unit 30,
Non-linear processing such as image enhancement processing, pedestal addition, gamma, and knee is performed on G and B, and further, matrix calculation processing is performed from the digital color signals R, G, and B to a digital luminance signal Y and two digital color differences. Signals C _R , C
_{Produces B.} Then, the digital luminance signal Y generated by the digital signal processing unit 40 and the two digital color difference signals C _R and C _B are supplied to the encoder 50.

Then, in the encoder 50, from the digital luminance signal Y generated by the digital signal processing section 40 and the two digital color difference signals C _R and C _B , for example, a luminance signal Y conforming to normal NTSC or PAL is obtained. Chroma No. C is produced.

Further, the aperture control unit 60 functions as a control unit for controlling the level detection unit for detecting the image pickup output level of the image pickup unit 10 and the light amount control unit for the image pickup unit, as shown in FIG. It is configured.

That is, the aperture control unit 60 includes a luminance conversion circuit 61 and first to fourth area generators 62A to 62.
D, first to fourth integrators 63A to 63D, first to fourth counters 64A to 64D, and an aperture controller 65, and each digital color signal R digitized by the A / D converter 3. G and B are supplied to the brightness conversion circuit 61 and the fourth area generator 62D.

The brightness conversion circuit 61 includes digital color signals R, G, and G, which are digitized by the A / D conversion section 3.
B is converted into a digital luminance signal Y. The digital luminance signal Y obtained by the luminance conversion circuit 61 is supplied to the third region generator 62C and also to the first to fourth integrators 63A to 63D. .

The first to fourth area generators 62 are also provided.
A to 62D generate a gate pulse in a specific area in the image pickup screen, respectively. The first to fourth integrators 63A to 63D and the first to fourth counters 64A to 64D corresponding to the respective gate pulses are provided. It is designed to be supplied to.

Here, the first area generator 62A is
A gate pulse that makes the entire imaging screen a specific area is supplied to the first integrator 63A and the first counter 64A.

Further, the second area generator 62B supplies a gate pulse having the rectangular area SPOT at the center in the image pickup screen as a specific area to the second integrator 63B and the second integrator 63B.
Is supplied to the counter 64B.

Further, the third area generator 62C supplies the first and second brightness gate pulses, which define an area in a specific brightness level range in the image pickup screen as a specific area, to the third integrator 63C. It is adapted to be supplied to the third counter 64C. The third area generator 62C includes a first and a second area generator 62C.
Of the comparison level generators 66 and 67 and the first and second level comparators 68 and 69. The first level comparator 68 compares the comparison upper limit level IRSHI generated by the first comparison level generator 66 with the digital luminance signal Y obtained by the luminance conversion circuit 61, Digital luminance signal Y is the comparison upper limit level IRSH
When it is I or less, the first luminance gate pulse is output. The second level comparator 69 compares the comparison lower limit level IRSLO generated by the second comparison level generator 67 with the digital brightness signal Y obtained by the brightness conversion circuit 61, Second when the digital luminance signal Y is equal to or higher than the comparison lower limit level IRSLO
The luminance gate pulse of is output. Further, the first and second comparison level generators 66, 67 generate the comparison upper limit level IR generated by the system controller 70.
The SHI and the comparison lower limit level IRSLO can be changed.

Further, the fourth area generator 62D is
A gate pulse having a flesh color area in the image pickup screen as a specific area is supplied to the fourth integrator 63D and the fourth counter 64D. This fourth area generator 62D
Decodes the digital color signals R, G, B supplied from the A / D converter 3 to detect the skin color area and generate a gate pulse.

Further, the first to fourth integrators 63A to 63A to
63D is the first to fourth area generators 62A to 62
The digital brightness signal Y obtained by the brightness conversion circuit 61 in each specific area is integrated based on the gate pulse in the specific area in the imaging screen generated by D, and each integrated value is reduced by the aperture. It is adapted to be supplied to the controller 65. The first integrator 63A integrates the digital brightness signal Y with the entire image pickup screen as a specific area, and supplies the integrated value to the aperture controller 65. The second integrator 63B integrates the digital luminance signal Y with the rectangular area SPOT in the center of the imaging screen as a specific area, and the integrated value thereof is used as the aperture controller 65.
To supply. Further, the third integrator 63C integrates the digital luminance signal Y with a region of a specific luminance level range in the image pickup screen as a specific region, and supplies the integrated value to the aperture controller 65. Further, the fourth integrator 63
D integrates the digital luminance signal Y with the flesh color area in the image pickup screen as a specific area, and supplies the integrated value to the aperture controller 65.

Further, the first to fourth counters 64 described above
A to 64D are the first to fourth area generators 62A to 62D.
The number of pixels in each specific region is counted based on the gate pulse in the specific region in the imaging screen generated by 62D, and each count value is supplied to the aperture controller 65. . The first counter 64A
Counts the number of pixels with the entire imaging screen as a specific area, and supplies the count value to the aperture controller 65. Further, the second counter 64B counts the number of pixels with the rectangular area SPOT in the center of the imaging screen as a specific area, and supplies the count value to the aperture controller 65. Further, the third counter 64C counts the number of pixels with an area in a specific brightness level range in the image pickup screen as a specific area, and supplies the counted value to the aperture controller 65. Further, the fourth counter 64D counts the number of pixels with the flesh color area in the image pickup screen as a specific area, and supplies the count value to the aperture controller 65.

The operation mode of the aperture controller 65 is switched by the system controller 70 based on the operation input of the operation section 80, and each of the first to fourth integrators 63A to 63D obtains the operation mode. Based on the integrated value of the digital luminance signal Y in the specific area and the count value indicating the number of pixels in each specific area obtained by the first to fourth counters 64A to 64D, the following various types Controls the aperture of the mode.

In the full screen mode, the first integrator 63 is used.
From the integrated value of the digital luminance signal Y obtained by A as a specific area and the number of pixels as the counted value obtained by the first counter 64A as a specific area, Average image level (AP
L: Average Picture Level) is obtained, and the diaphragm 12 of the image pickup unit 10 is controlled so that the average image level becomes a predetermined level.

In the spot mode, the integrated value SSACM of the digital luminance signal Y with the central rectangular area SPOT in the image pickup screen obtained by the second integrator 63B as a specific area and the second counter 64B are used. The rectangle area SPOT obtained as a count value
The average image level P _SPT of the rectangular area SPOT is obtained from the number of pixels of, and the diaphragm 12 of the image pickup unit 10 is controlled so that the average image level becomes a predetermined level. As shown in FIG. 6, this spot mode is a mode in which the gate of the rectangular region SPOT is applied to the input signal to obtain a detection signal. In this spot mode, the horizontal start position SPT of the rectangle area SPOT is
HS and end position SPTHE and vertical start position SP
From TVS and the end position SPHTVE, the average image level P _SPT is calculated by P _SPT = SSACM / k (SPTHE-SPTHS) (SPHTVE-SPTVS). Note that k is a coefficient when the digital luminance signal Y is downsampled.

In the luminance gate mode, the digital luminance signal Y in which the region of the specific luminance level range within the image pickup screen obtained by the third integrator 63C is set as the specific region.
The average image level P _MID of the area of the specific brightness level range is obtained from the integrated value MIDACM of MIDCM and the number of pixels MIDPIX of the area of the specific brightness level range obtained as the count value by the third counter 64c. The diaphragm 12 of the imaging unit 10 is controlled so that the average image level becomes a predetermined level. In the luminance gate mode, as shown in FIG. 3, the input signal is gated by luminance to obtain a detection signal. In this brightness gate mode, the system controller 70 controls the brightness upper limit IR by 70.
The SHI and the lower limit IRSLO are designated, and the average image level P _MID is calculated by P _MID = MIDACM / MIDPIX for a specific region in which only pixels having a brightness level within this specific brightness level range are to be detected. In this brightness gate mode, as shown in FIGS. 4A and 4B, the aperture value is not affected by a portion that is too bright or too dark for the set brightness range (near the brightness of the subject). The subject will not be crushed in black or will fly in white even if the subject is backlit, overlit, illuminated by the sun or entering the screen. If the lighting conditions change, such as when the user goes outdoors from indoors, there is no signal between IRSHI and IRSLO, and diaphragm control cannot be performed.
By looking at IPIX / MIDPIX / LOPIX, it can be determined that the lighting conditions have changed. For example H
When IPIX is significantly larger than MIDPIX and LOPIX, the aperture is too wide.

In the skin tone mode, the fourth
Integrated value SSAC of the digital luminance signal Y in which the skin color area in the image pickup screen obtained by the integrator 63D
M and the number of pixels SKPIX in which the flesh color region obtained as a count value by the fourth counter 64D is set as a specific region
From the above, the average image level P _SKN of the skin color area is obtained by P _SKN = SSACM / SKPIX, and the diaphragm 12 of the image pickup unit 10 is controlled so that the average image level P _SKN becomes a predetermined level. As shown in FIG. 5, the skin tone mode is a mode in which an input signal is gated by color to be a detection signal.

Further, in the intelligent mode, the above-mentioned luminance gate mode and skin tone mode are combined, and the average image level P _MID of the area of the specific luminance level range in the luminance gate mode and the average image level P in the skin tone mode are combined. An intermediate value of _SKN is set as an average image level P _INT, and the diaphragm 12 of the image pickup unit 10 is controlled so that the intermediate image level P _INT becomes a predetermined level. In this intelligent mode, the mixing ratio of the luminance gate mode and the skin tone mode is set to the number of pixels S in the skin color area.
It is changed according to KPIX, and as shown in FIG. 7, the luminance gate mode is gradually changed to the skin tone mode as the area of the skin color area is increased. That is, the average image level P _INT in the intelligent mode is f _MID , W _SKN for the luminance gate mode and the skin tone mode, and f is a function for _{obtaining the} weight W _SKN for the skin tone mode from the area of the skin color area.
As (SKPIX), W _SKN = f (SKPIX) W _MID + W _SKN = 1 P _INT = W _MID P _MID + W _SKN P _SKN

In the intelligent mode, the system controller 70 operates the operation unit 80.
The first and second comparison level generators are configured to shift the upper limit IRSHI and the lower limit IRSLO of the luminance in the luminance gate mode at the same time or only one of them when the operation input of the up / down switch provided in 66 and 67 are controlled. As a result, in the intelligent mode, the characteristics of the automatic diaphragm control can be finely adjusted. That is, for example, as shown in FIG. 8, when the range of detected brightness is shifted to the lower side, it is assumed that the screen is dark and the automatic diaphragm control is performed to open the diaphragm 12 and the characteristics of the automatic diaphragm control. Is shifted to "brighter".

Further, in this intelligent mode, the system controller 70 operates the operation unit 8
When the operation input of the one-push button provided in 0 is accepted, the upper limit IRSHI and the lower limit IRSLO of the brightness in the brightness gate mode are reset according to the procedure shown in the flowchart of FIG.

That is, the system controller 70 described above.
When the operation input of the one-push button provided on the operation unit 80 is accepted, the one-field period immediately after that is set to the above-mentioned spot mode, and the average image level P _SPT of the central rectangular area SPOT in the imaging screen is set. After obtaining (step S1), the aperture 12 of the image pickup unit 10 is controlled so that the average image level P _SPT becomes a predetermined level (step S2). Then, for example, an example of the state of the brightness distribution of the imaging screen before and after the operation of the one push button is shown in FIG.
As shown in (A) and (B), the rectangle area S is
The upper limit IRSHI and the lower limit IRSLO of the brightness in the brightness gate mode are reset to IRSHI = P _SPT + Δ IRSLO = P _SPT −Δ so that the average image level P _{SPT of the} POT becomes the center (step S3).

Therefore, by positioning the target object in the rectangular area SPOT in the center of the image pickup screen when the one push button is operated, appropriate automatic aperture control can be performed thereafter for the target object. Will be done.

In this state, the system controller 70 repeatedly determines whether or not the operation input of the one push button is accepted again (step S4), 2
When the operation input for the second time is accepted, the upper limit IRSHI and the lower limit IRSLO of the brightness in the brightness gate mode are returned to the default values, and the normal intelligent mode is returned to.

[0037]

In the image pickup apparatus according to the present invention, the image pickup output level in the specific area in the image pickup screen is made by the first level detecting means on the basis of the image pickup output signal obtained by the image pickup section having the light quantity control means. To detect
The second level detection means detects the image pickup output level in the area of the specific brightness level range in the image pickup screen, and the control means controls the light quantity control means of the image pickup section based on each detected output. By switching the exposure amount control mode in accordance with the above, it is possible to obtain an image pickup output that secures a good image quality.

Further, in the image pickup apparatus according to the present invention, the control means causes the image pickup output level in a specific area in the image pickup screen detected by the second level detection means to be a predetermined level. By controlling the light amount control means of the part and setting change means for changing the setting of the specific brightness level range detected by the first level detection means so as to include the image pickup output level, Therefore, proper automatic aperture control can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image pickup apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a diaphragm control unit in the image pickup apparatus.

FIG. 3 is a diagram schematically showing an example of a brightness distribution of an imaged scene for explaining aperture control in a brightness gate mode in the image pickup apparatus.

FIG. 4 is a diagram schematically showing an example of a brightness distribution of an image capturing scene for explaining aperture control in the brightness gate mode in a backlight condition and an over-forward condition.

FIG. 5 is a diagram schematically showing an image capturing scene for explaining the aperture control of the skin tone mode in the image capturing apparatus.

FIG. 6 is a diagram schematically showing an image capturing scene for explaining spot mode aperture control in the image capturing apparatus.

FIG. 7 is a diagram schematically illustrating an example of a function that determines a weight for a skin tone mode, for explaining aperture control in an intelligent mode in the image pickup apparatus.

FIG. 8 is a diagram schematically showing an example of a luminance distribution of an imaged scene for explaining the iris shift operation in the intelligent mode.

FIG. 9 is a diagram schematically showing an example of a luminance distribution of an imaged scene for explaining the one-push operation in the intelligent mode.

FIG. 10 is a flowchart showing a processing procedure for the one-push operation by the system controller in the imaging apparatus.

[Explanation of symbols]

10 imaging unit, 12 diaphragm, 14R, 14G, 14B
CCD image sensor, 60 aperture control unit, 61 brightness conversion circuit, 62A to 62D first to fourth area generator, 63A to 63D first to fourth integrator, 62A to 62D
62D first to fourth counters, 65 aperture controller,
66, 67 first and second comparison level generators, 68,
69 first and second comparators, 70 system controller, 80 operation unit,

Claims (2)

[Claims] 1. An image pickup unit having a light quantity control unit, a level detection unit for detecting an image pickup output level in a specific region in the image pickup screen based on an image pickup output signal obtained by the image pickup unit, and an image pickup screen. Level detecting means for detecting an image pickup output level in a specific area within the image pickup level, and second level detecting means for detecting an image pickup output level in an area within a specific luminance level range in the image pickup screen An image pickup apparatus comprising: a detection unit; and a control unit that controls a light amount control unit of the image pickup unit based on each detection output of the level detection unit. 2. The control means controls the light quantity control means of the image pickup section so that the image pickup output level in a specific area in the image pickup screen detected by the first level detection means becomes a predetermined level. The image pickup apparatus according to claim 1, further comprising a setting changing unit that changes a setting of a specific luminance level range detected by the second level detecting unit so as to include the image pickup output level.