JP2005184246A - Imaging unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging unit whereby even a camera beginner like a young mother can simply and surely photograph her child. <P>SOLUTION: When a photographer selects a child photographing mode, photographing is carried out at high shutter speed of 1/500 (second) or over with an object luminance of 12.1 Ev or over, and the shutter speed varies within a range of 1/60 to 1/500 (second) while keeping an aperture to F2.8 in the case of the object luminance of 9.1 Ev or more and 12 Ev or below. In the case of the object luminance of 9 Ev or below, no strobe unit is used, and the amplification factor of an imaging signal outputted from a CCD is increased while keeping the aperture to F2.8 and the shutter speed to 1/60 (second). Although a camera-shake limit shutter speed Tvs is ordinarily 1/60 (second), and the focal distance of a zoom lens is set to a telescopic side, the shutter speed Tvs is shifted to a higher speed, and when the zoom lens is set to a wide angle side, the shutter speed Tvs is shifted to a lower speed. A searching range of auto focus is set to 10cm to ∞, and even a child inclinable to come near its mother can be well focused. Contour emphasis processing weaker than that in an ordinary photographing mode is executed to obtain an image with a soft impression appropriate to the child. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus suitable for photographing a child.

  2. Description of the Related Art Image pickup devices such as a digital camera and a camera-equipped mobile phone (specifically, a camera portion thereof) that convert an image signal output from a solid-state image pickup device such as a CCD into a digital image and store it in a memory card are known. On the other hand, among cameras using a silver salt film, for example, as described in Patent Document 1, there is known a camera that can be adapted to photographing moving children. With this camera, the shutter speed is controlled at high speeds in continuous shooting, and the auto zoom is controlled to the wide-angle side. This makes it possible to shoot without any trouble.

JP-A-5-164955

  In the camera described in Patent Document 1, since the shutter speed is fixed when reaching the limit of the shutter speed at which camera shake is difficult, the automatic exposure interlocking range is narrowed. In addition, there are cases where children are too close to the camera because they are interested in the camera itself. However, in the camera described in Patent Document 1, there are many cases where the child is too close to the camera and is out of focus.

  On the other hand, many imaging devices have sharpness processing (outline emphasis processing) applied by default, but if a child is photographed with the same settings, the child's skin, which should have been soft, should feel softer. There is a disadvantage that it appears unnatural and feels unnatural. Of course, there are many image pickup apparatuses that can adjust the level of the contour enhancement process, but it is difficult for beginners to understand, and the current situation is that shooting is performed as purchased.

  An object of the present invention is to provide an imaging apparatus that allows a camera beginner such as a young mother to easily and reliably photograph a child.

  An imaging apparatus according to the present invention is a mode selection apparatus capable of selecting a child shooting mode in addition to a normal shooting mode in an imaging apparatus that converts an image signal output from a solid-state imaging device into digital data and records the data in a memory card; A strobe device that is permitted during normal shooting mode and prohibited during child shooting mode, a normal automatic exposure control program that is used during normal shooting mode, and a high-speed shutter that is used preferentially during child shooting mode. A memory that selectively stores an anti-shake automatic exposure control program in which an anti-shake shutter speed is determined according to the focal length of the photographing lens, and a shutter speed that corresponds to the brightness of the subject measured by the photometry device. When the shutter speed is lower than the anti-shake shutter speed of the anti-shake automatic exposure control program, Characterized in that it consists of an amplifier for amplifying the image signal output from the device.

  In the child photographing mode, an autofocus device for automatically focusing to a closer distance than in the normal photographing mode is provided. In the child photographing mode, an image signal processing device is provided that lowers the enhancement level of the contour enhancement processing compared to that in the normal photographing mode.

  The imaging apparatus of the present invention is provided so that a child shooting mode can be selected in addition to the normal shooting mode. When the child shooting mode is selected, the use of the strobe device is prohibited, the high-speed shutter is used preferentially, and the shooting lens An anti-shake shutter speed is determined according to the focal length, and when the shutter speed corresponding to the subject brightness is lower than the anti-shake shutter speed, the image signal output from the solid-state image sensor is amplified. Even new camera beginners can easily and reliably shoot children.

  In the child shooting mode, an autofocus device that automatically focuses to a closer distance than in the normal shooting mode is provided, so that even a child who tends to approach the mother can take a photograph in focus. In the child photographing mode, an image signal processing device is provided that lowers the emphasis level of the contour emphasizing process than in the normal photographing mode, so that the child's skin and the like can be photographed with a soft natural tone.

  In FIG. 1 showing an electrical configuration of a digital camera according to an embodiment of the present invention, a CPU 11 is connected to the digital camera 10 via an I / O bus 13 in accordance with various operation signals input from the operation unit 12. Control each part of the main body. The operation unit 12 includes a power button 14, a mode selection dial 15, a zoom button 16, a shutter button 17, and the like. The mode selection dial 15 includes a normal photographing mode suitable for general photographing, a child photographing mode suitable for child photographing, a reproduction mode for reproducing a photographed image and displaying it on a liquid crystal display (LCD) 18. It can be selected alternatively.

  The zoom lens 21 as a photographing lens includes a lens 22 and a diaphragm 23. The lens 22 includes a front group lens that is a variator lens and a rear group lens that is a compensator lens having a focusing function. The lens 22 is driven by a lens driving mechanism 25 including a stepping motor to change the optical zoom magnification and adjust the focus. The aperture 23 is driven by an aperture drive mechanism 26 including a motor, and the aperture diameter is switched. The lens driving mechanism 25 and the aperture driving mechanism 26 are driven by motor drivers 27 and 28 controlled by the CPU 11.

  Behind the zoom lens 21, a CCD 30 is disposed as a solid-state imaging device. The CCD 30 is driven by a CCD drive unit 31. An optical image formed by the zoom lens 11 is formed on the light receiving surface of the CCD 30 and is photoelectrically converted to output an analog imaging signal. This imaging signal is input to an auto gain control amplifier (hereinafter referred to as AGC) 32 and amplified. The amplification factor of the image signal in the AGC 32 is normally a predetermined standard amplification factor. However, as will be described in detail later, the strobe device 33 is not used in the child photographing mode, so that the subject is low in luminance. Is changed by a command signal from the CPU 11.

  The imaging signal amplified by the AGC 32 is converted into digital image data by the A / D converter 35 and then sent to the digital signal processing circuit 37, where edge enhancement processing, median filter, coring processing, automatic white balance, etc. Is given. This image data is subjected to compression processing by the compression processing circuit 38 and then displayed on the LCD 18 as a through image via the video encoder 39. When the shutter button 17 is depressed deeply, the compression processing circuit After being subjected to compression processing at 38, it is stored in the memory card 46 via the media controller 45.

  In addition to the digital signal processing circuit 37 and the media controller 45, the I / O bus 13 is connected to an AE detection circuit 41, an AF detection circuit 42, a main memory 43, and a flash memory 44. The AE detection circuit 41 integrates the luminance signal of the imaging signal and sends the luminance integrated value (subject luminance value (Ev)) as the obtained photometric data to the CPU 11.

  As will be described in detail later, the CPU 11 obtains an aperture value (Av) corresponding to the subject brightness value (Ev) according to the program line of the shooting mode selected by the mode selection dial 15, and sets the aperture value in the aperture 23. As described above, the aperture control signal is output to the aperture drive mechanism 26 via the motor driver 28. The aperture drive mechanism 26 opens and closes the aperture 23 according to the aperture control signal.

  The AF detection circuit 42 decomposes the image pickup signal into a spatial frequency component, and sends the contrast data of the high frequency component to the CPU 11. The CPU 11 controls the lens driving mechanism 25 via the motor driver 27 to move the focusing lens forward and backward in the optical axis direction and stop it at a position where the contrast of the high frequency component of the subject image is highest. At this time, the range in which the focus position is searched is set to 80 cm to ∞ in the normal shooting mode and 10 cm to ∞ in the child shooting mode so that the contrast becomes the highest.

  The main memory 43 is an SDRAM (Synchronous Dynamic Random Access Memory) that performs data transfer in synchronization with a bus clock signal having a fixed period, and is used as a frame memory for temporarily storing image data, as well as various operations. It is used as a work memory when performing etc.

  The flash memory 44 is a known non-volatile memory, and includes a program line of a normal program AE used in the normal shooting mode (see FIG. 2) and a program line of a child shooting program AE used in the child shooting mode (FIG. 3). Reference) and other various programs and data, various control parameters, and the like are also stored. The values of the aperture and shutter speed shown in FIGS. 2 and 3 are values when the sensitivity of the CCD 30 is the same level as ISO 100, which is the standard sensitivity of the silver salt film.

  As shown in FIG. 2, the program line of the normal program AE is such that the aperture diameter of the aperture 23 gradually decreases by about 1/3 aperture (the aperture value increases) as the subject brightness increases. The shutter speed is displaced by about 1/2 Tv to 1 Tv for each aperture value, and as a whole, both the aperture value and the shutter speed increase sequentially as the subject brightness increases. Note that there is a displacement of 1 stop (1 Av) between F2.8 and F4.0. When the subject brightness falls below 9.1 Ev, the aperture F2.8 and shutter speed 1/60 (seconds) remain unchanged, and the flash photography is switched.

  As shown in FIG. 3, the program line of the child photographing program AE has a shutter speed within a range of 9.0 to 9.3 Tv in a luminance range of 12.1 to 15.1 Ev, and F2. Within the range of 8 to F8, the stop changes by about 1/3 stop. In other words, the shutter speed of 9.0 Tv is as fast as 1/500 (seconds), and it is set so that camera shake and subject blur are unlikely to occur even when shooting while chasing a fast-moving child.

  Further, in the luminance range of the subject luminance of 9.1 to 12.3 Ev, the shutter speed is 6.0 to 9.3 Tv (1/60 to 1/500 (with approximately F2.8 of the wide open aperture)). Second)), and the shutter speed is 1/60 (second) or more, so that camera shake is hardly caused. The 6.0 Tv is a shutter speed determined as a camera shake limit, and the camera shake limit shutter speed Tvs varies depending on the focal length of the zoom lens 21. As the focal length of the zoom lens 21 becomes longer, the camera shake limit shutter speed Tvs shifts to the higher speed side.

  When the subject brightness is lower than 9.1 Ev, the shutter speed remains 1/60 (second), the strobe device 33 is not used, the gain of the AGC 32 is increased, and the image output from the CCD 30 is output. Amplify the signal. The exposure control by the gain of the AGC 32 is performed in the range of 5.1 to 9.1 Ev as indicated by the dotted line.

Gain correction will be briefly described with actual numerical values. In the program line shown in FIG. 3, when the subject brightness is 8.0 Ev, the shutter speed necessary for achieving proper exposure can be obtained by the following formula (1).
8.0Ev-3.1Av = 4.9Tv (1)

Since 4.9 Tv <6.0 Tv, it cannot be interlocked with the program line of the child shooting program AE, but the gain of the AGC 32 may be increased by that amount. When the shutter speed is Tv, the camera shake limit shutter speed is Tvs, and the gain correction amount is Sv, the gain correction amount Sv is calculated by the following equation (2).
When Tvs> Tv, Sv = Tvs−Tv, Sv> 0 (2)

Assuming that the subject brightness is 8.0 Ev, the gain correction amount Sv can be obtained from Equation (1) as follows.
8.0Ev-3.1Av = 4.9Tv
Ｖ Sv = Tvs−Tv = 6.0 Tv−4.9 Tv = 1.1 Tv
Therefore, the gain correction amount Sv may be set to 1.1.

  The operation of the digital camera 10 configured in this way will be described. To use the digital camera 10, first, the power button 14 is operated to turn on the digital camera 10. When the user takes a picture of a child, the mode selection dial 15 is turned to match the child photography mode.

  The image data output from the digital signal processing circuit 37 is displayed on the LCD 18 as a through image via the video encoder 39 after passing through the compression processing circuit 38. Using the LCD 18 as an electronic viewfinder, the display image on the LCD 18 is observed to perform framing. As shown in FIG. 4, when the user wants to take a picture, first, when the shutter button 17 is half-pressed (lightly touching the shutter button), the AE process and the AF process are started.

  As shown in FIG. 5, the AE detection circuit 41 takes in the luminance signal of the imaging signal and performs an integration calculation, and sends the luminance integrated value (subject luminance value (Ev)) that is the obtained photometric data to the CPU 11. The CPU 11 obtains an aperture value (Av) and a shutter speed (Tv) corresponding to the subject luminance value (Ev) according to the program line of the child shooting mode, and sets the aperture 23 to the aperture value.

  Under sufficiently bright shooting conditions with subject brightness of 12.1 Ev or higher, such as parks in fine weather, shooting is performed at a high shutter speed of 1/500 (seconds) or more, so there is no camera shake or subject blurring. , You can reliably copy the moving children. Further, when the subject brightness is 9.1 Ev or more and 12 Ev or less, the shutter speed changes in the range of 1/60 to 1/500 (seconds) while the aperture is F2.8, so even when shooting while chasing a moving child. Blur is hard to occur. The camera shake limit shutter speed Tvs is normally 1/60 (second), but when the focal length of the zoom lens 21 is changed to the telephoto side, it is shifted to the high speed side (for example, 1/125 (second). )), When it changes to the wide angle side, it shifts to the low speed side (for example, 1/30 (second)).

  When the subject brightness is 9 Ev or less, the aperture F2.8 and shutter speed 1/60 (seconds) remain unchanged, the strobe device 33 is not used, and the CPU 11 increases the gain of the AGC 32 and outputs it from the CCD 30. Increase the gain of the imaging signal. In this way, since the strobe device 33 is not used, it is possible to photograph a child's natural facial expression without being surprised.

  Further, the AF detection circuit 42 decomposes the imaging signal into spatial frequency components, and sends the contrast data of the high frequency components to the CPU 11. As shown in FIG. 6, the CPU 11 sets the range from 10 cm to infinity (∞), which is the child shooting search range stored in the flash memory 44, as the autofocus search range via the motor driver 27. The drive mechanism 25 is controlled to move the rear group lens of the lens 22 back and forth in the optical axis direction to find and stop the position where the contrast of the high frequency component of the subject image is highest.

  In this child shooting mode, the subject is in focus up to 10 cm at a close distance, so even when shooting a small child who wants to approach the mother, it is possible to reliably shoot without being out of focus. If the image displayed on the LCD 18 is acceptable, the user presses the shutter button 17 deeper as it is. At the next moment, the imaging signal is read out from the CCD 30 during the charge accumulation time corresponding to the shutter speed. The imaging signal output from the CCD 30 is input to the digital signal processing circuit 37 through the AGC 32 and the A / D converter 35.

  As shown in FIG. 7, the digital signal processing circuit 37 reads different parameters from the flash memory 44 depending on whether the shooting mode is the normal shooting mode or the child shooting mode. The contour enhancement processing for child photographing that is weaker than the contour enhancement processing for normal photographing that is used is performed. In the median filter and coring processing, the removal of the noise component is made larger than the sharpness of the image. As a result, the sharpness of the image is reduced, but since the high-speed shutter is preferentially used in the program line of the child shooting mode, camera shake and subject blur hardly occur, rather than a blurred image. The image looks soft and childish.

  The image data output from the digital signal processing circuit 37 is compressed by the compression processing circuit 38 to reduce the data capacity, and then stored in the memory card 46 via the media controller 45.

  When the user selects the normal shooting mode, the autofocus search range is 80 cm to ∞, which is narrower than the child shooting mode, so that the focus is fast. The combination of the shutter speed and the aperture is determined by the program line in the normal shooting mode shown in FIG. When the subject brightness is 9.1 Ev or less, the strobe device 33 is driven to automatically switch to strobe shooting. In addition, since the digital signal processing circuit 37 performs contour enhancement processing or the like on the image data at a normal level, a sufficiently sharp image can be obtained.

  In the embodiment described above, the program line as shown in FIG. 3 is adopted as the program line in the child photographing mode. However, the present invention is not limited to this and is a program line that preferentially uses a high-speed shutter. Of course, the present invention is not limited to that shown in FIG.

  Of course, the present invention is not limited to the numerical values described in the above embodiments. For example, the autofocus search range is set to 80 cm to ∞ in the normal shooting mode and 10 cm to ∞ in the child shooting mode. In the shooting mode, considering that there are few cases where focusing is performed to infinity, the distance may be, for example, 10 cm to 5 m.

  In the above embodiment, a digital camera has been described as an example of the image pickup apparatus of the present invention. However, the present invention is not limited to this, and may be applied to a camera-equipped mobile phone (strictly, its camera unit). Applicable.

It is a block diagram which shows an example of a structure of a digital camera. It is a graph which shows the program line of general imaging | photography mode. It is a graph which shows the program line of child photography mode. It is a flowchart which shows the sequence of imaging | photography mode. It is a flowchart which shows the sequence of AE processing. It is a flowchart which shows the sequence of AF process. It is a flowchart which shows the sequence of an image signal process.

Explanation of symbols

10 Digital camera 11 CPU
15 Mode selection dial 21 Zoom lens 30 CCD
32 AGC
33 Strobe device 37 Digital signal processing circuit 41 AE detection circuit 42 AF detection circuit

Claims (3)

In an imaging device that converts an image signal output from a solid-state imaging device into digital data and records it in a memory card,
A mode selection device capable of selecting a child shooting mode in addition to the normal shooting mode;
A strobe device that is permitted in normal shooting mode and prohibited in child shooting mode,
A normal automatic exposure control program used in the normal shooting mode and a camera shake used in the child shooting mode, which uses the high-speed shutter preferentially and determines the anti-shake shutter speed according to the focal length of the shooting lens. A memory for selectively storing a preventive automatic exposure control program;
An amplifier that amplifies the image signal output from the solid-state imaging device when the shutter speed corresponding to the brightness of the subject measured by the photometry device is lower than the camera shake prevention shutter speed of the camera shake automatic exposure control program;
An imaging device comprising:   2. The image pickup apparatus according to claim 1, further comprising an autofocus device that automatically focuses to a closer distance in the child photographing mode than in the normal photographing mode.   The image pickup apparatus according to claim 1 or 2, further comprising an image signal processing device that lowers an enhancement level of contour enhancement processing in the child photographing mode than in the normal photographing mode.

Images