JP2000350081A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deviation in timing of a photographing period and a display period during focus adjustment. SOLUTION: A camera system comprises a camera and a personal computer. The camera transmits a photographed image as a full screen YUV signal to the personal computer via a universal serial bus USB interface (S11). Receiving a mode switching signal for denoting the changeover of a focus adjustment mode from the personal computer (YES in S12), the camera transmits a luminance signal of a segmented image which is a part area of the full image pattern (S13). The camera transmits only the luminance signal of the segmented image pattern until receiving an end signal, and the camera transmits the full image pattern YUV signal to the personal computer (S11), when the end signal (YES in S14) is received.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly, to a camera that converts a captured image into a digital signal and transmits the digital signal.

[0002]

2. Description of the Related Art A camera system used in a TV conference system and the like, which is now widely used, includes a camera and a personal computer (hereinafter, referred to as a PC), and transmits an image photographed by the camera to the PC. To display the received image on the display device. The video captured by the camera is input as an analog video signal to an interface board called a video capture board of the PC. In the PC, the analog video signal input to the interface board is converted into a digital signal and displayed on a display device.
However, since the digitalization of the signal processing circuit inside the camera has recently been advanced, the development of a technique for transmitting an image captured by the camera to a PC using a digital signal has been advanced. Japanese Patent Application Laid-Open No. Hei 10-232924 describes a technique using a USB (Universal Serial Bus) interface as a method of transmitting a video signal captured by a camera to a PC as a digital signal.

[0003]

The USB interface is a serial interface having a low transfer rate. Since the video signal of the camera has a large amount of data, it takes time to transmit the video signal using the USB interface. When displaying a video signal received on the PC side on a display, image processing takes a long time because the data amount of the video signal is large. Therefore, there is a problem that it takes time from when the image is taken by the camera to when it is displayed on the display of the PC.

In order to reduce the time required to transmit a video signal from the camera to the PC, a method of transmitting the video signal after compressing the image is considered. However, although the transmission time is shortened, it takes time to expand the video signal that has been image-compressed on the PC side, and it takes time from when the image is captured by the camera to when it is displayed on the display on the PC side.

[0005] Incidentally, the focus adjustment of the camera is performed by the operator adjusting the focus of the camera lens while watching the image projected on the display of the PC. If it takes a long time from when the image is taken by the camera to when it is displayed on the display on the PC side, it becomes very difficult to smoothly adjust the focus of the camera.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a camera in which the difference between the timing of image pickup and the time of display during focus adjustment of the camera is reduced.

[0007]

According to one aspect of the present invention, there is provided a camera comprising: a lens having a focus adjustable; and an image sensor for receiving an image transmitted through the lens and reading an image. A conversion unit for converting an image read by the image sensor into a digital signal, a selection unit for selecting at least a part of the converted digital signal, and a signal selected by the selection unit among the digital signals. Transmitting means for transmitting, wherein the selecting means selects at least a part of the digital signals during the focus adjustment of the lens.

[0008] Preferably, the selection means of the camera selects a signal related to at least a part of an area of the image read by the image sensor from the digital signal.

[0009] More preferably, the converted digital signal includes a luminance signal and a color difference signal, and the selecting means selects only the luminance signal from the converted digital signals.

[0010] More preferably, the camera further comprises designation means for designating a partial area of the image read by the image pickup device, and the selection means selects a signal related to the area designated by the designation means from the digital signal. It is characterized by the following.

According to these inventions, during the focus adjustment, at least a part of the digital signal obtained by converting the captured image is selected and transmitted, so that the transmission speed of the digital signal can be increased. And a camera that can reduce the deviation of the display timing.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding members.

[First Embodiment] FIG. 1 is a block diagram showing a schematic configuration of a camera system according to a first embodiment of the present invention. Referring to FIG. 1, the camera system includes a camera 100 and a personal computer 200. The camera 100 includes a lens 101 capable of focus adjustment, an image sensor 102 for receiving light captured by the lens 101 and converting the light into an electric signal, and an image sensor 1
02 for performing predetermined processing on the signal output by
It includes an AGC 103, an A / D converter 104 for converting an analog signal into a digital signal, a signal processing circuit 105 for performing predetermined signal processing on the digital signal, a memory 106, and a USB interface circuit 107.

The focus of the lens 101 is adjusted by changing the focal length. The focal length of the lens 101 changes when the operator moves the adjustment knob.

The image pickup device 102 is a photoelectric conversion device such as a CCD, and receives light transmitted through the lens 101 and converts the light into an electric signal. The CDS / AGC 103 is used for the imaging device 10.
Sampling processing and automatic gain adjustment processing are performed on the electric signal output from the signal generator 2, and the signal is amplified to a required signal amplitude. A
The / D converter 104 converts a signal output from the CDS / AGC 103 from an analog signal to a digital signal.

The signal processing circuit 105 includes the A / D converter 10
Image processing such as white balance adjustment, gamma correction, and contour correction is performed on the digital video signal converted into a digital signal in step 4.

The video digital signal subjected to the image processing by the signal processing circuit 105 is stored in the memory 106.

The USB interface circuit 107 is a circuit for outputting all or a part of the video digital signals stored in the memory 106 to the personal computer 200, and is connected to the personal computer 200 by a serial interface.

The personal computer 200 is provided with a U for receiving a digital video signal transmitted by the camera 100.
An SB interface circuit 201, an image processing unit 202 for performing image processing on the received video digital signal,
And a display device 203 for displaying a video digital signal on which image processing has been performed.

Here, transmission of moving image data from the camera 100 to the personal computer 200 will be described. YUV data is used as moving image data to be transmitted. The YUV data includes a luminance signal Y and a color difference signal U (R-
Y) and a color difference signal V (BY), and Y, U,
Y and V are arranged in this order. It is 2 with 4 data of YUYV
Shows the value for the pixel. For example, if the image size is 640 × 4
In the case of 80, if the luminance signal Y is 8 bits, the color difference signal U is 8 bits, and the color difference signal V is 8 bits, the data amount of one screen is 652,800 bytes (640 × 480 × 2). Since moving image data usually needs to be transmitted from several screens to several tens of screens per second, it takes time to transmit moving image data when a USB interface having a low transmission speed is used. This means that it takes time from when the image is captured by the camera 100 to when the image is displayed on the display device 203 of the personal computer 200.
There is a timing difference between the time when the image is captured by the camera and the time when the image is displayed on the display 203 of the personal computer 200.

The focus can be adjusted by the operator using the display device 20.
Since it is determined whether or not the lens 101 is in focus while watching the image projected on the image No. 3, it is difficult to adjust the focus if the above timing shift occurs.

In the camera system according to the present embodiment, the camera 1 is controlled only during the focus adjustment of the lens 101.
From 00, the amount of data transmitted to the personal computer 200 is reduced. For example, image size 6
Out of 40 × 480, each of the vertical and horizontal sizes is 1
An image having an image size of 160 × 120 at / 4 is transmitted. At this time, the amount of data to be transmitted is 38,400 bytes, which is 1/1 of that in the case of transmitting one screen.
It becomes 16.

If only focus adjustment is performed, there is no need to display in color on the display device 203, and monochrome display is sufficient. Therefore, only the luminance signal is transmitted from the camera 100 to the personal computer 200. As a result, the amount of data to be transmitted is 19200 bytes,
1/3 compared to transmitting one screen data in color
It becomes 2.

If the amount of data to be transmitted is reduced to such an amount, the image pickup device 102 and the display 203
The difference in timing from when the image is displayed is reduced, and the focus adjustment of the lens 101 can be easily performed.

Further, since the amount of data to be transmitted is reduced, there is no need to perform image compression on the camera 100 side. Even when the image is compressed by the camera 100, the amount of data is small, so that the time required for the image compression processing by the camera 100 and the processing for decompressing the image compressed data by the personal computer 200 do not take much time. . Accordingly, it is possible to reduce the difference in timing between when the image is captured by the image sensor 102 and when the image is displayed on the display device 203, and the focus of the lens 101 can be easily adjusted.

Next, focus adjustment processing performed by the personal computer 200 and the camera 100 when the focus of the lens 101 is adjusted will be described. FIG. 2 is a flowchart showing the flow of the mode selection process performed by personal computer 200. Referring to FIG. 2, it is determined whether or not focus adjustment mode is selected in personal computer 200 (S01).
The focus adjustment mode is selected by the operator performing a predetermined operation from the mouse or keyboard of the personal computer 200. For example, if a focus adjustment mode selection key is assigned to the function key F1 of the keyboard, the focus adjustment mode is selected by the operator pressing the function key F1.

If the focus adjustment mode has been selected, the process proceeds to step S02, and if not, the mode selection process ends.

In step S02, a mode switching signal is transmitted to the camera 100 via the USB interface circuit 201. The mode switching signal is a signal for instructing the camera 100 to switch to the focus adjustment mode.

In the next step S03, it is determined whether or not the personal computer 200 has selected to end the focus adjustment mode. The end of the focus adjustment mode is selected by the operator performing a predetermined operation using a mouse, a keyboard, or the like. For example, if a key for selecting the end of the focus adjustment mode is assigned to the function key F2 of the keyboard, the operator can select the end of the focus adjustment mode by pressing the function key F2.

When the focus adjustment mode is selected in step S01, the process waits in step S03 until the end of the focus adjustment mode is selected. When the end of the focus adjustment mode is selected (YE in S03)
S), and proceed to step S04.

In step S04, an end signal is transmitted to the camera 100 via the USB interface circuit 201. The end signal is a signal for instructing the camera 100 to end the focus adjustment mode.

FIG. 3 is a flowchart showing the flow of the focus adjustment process performed by the camera 100. FIG.
, The camera 100 transmits a YUV signal of all screens (hereinafter, referred to as all screens) of an image captured by the image sensor 102 from the USB interface circuit 107 to the personal computer 200 (S11). In the present embodiment, the image size of the entire screen is 640 × 480. The YUV signal transmitted in step S11 is 652,800 bytes (640 × 480 × 2) per screen.

Then, the USB interface circuit 10
At 7, it is determined whether or not a mode switching signal has been received from the personal computer 200 (S12). If a mode switching signal has been received, the process proceeds to step S13; otherwise, the process proceeds to step S11.

In step S13, a video digital signal transmitted from the camera 100 to the personal computer 200 is set as a luminance signal Y of a screen (hereinafter referred to as a cut screen) indicating a partial area of the entire screen. In the present embodiment, the image size of the cut screen is set to 160 × 120. Therefore,
The video digital signal transmitted in step S11 is 638,400 bytes (160 × 120) per screen. Note that the image size of the cut screen is not limited to this, and is 1/16, 1/2 of the image size of the entire screen.
An arbitrary image size such as 5, 1/36 or the like can be used.

In the next step S14, it is determined whether or not the USB interface circuit 107 has received from the personal computer 200 an end signal indicating the end of the focus adjustment mode. If an end signal has been received, the process proceeds to step S11; otherwise, the process proceeds to step S13.
Proceed to.

As described above, the camera 100 according to the present embodiment transmits the YUV signal for one screen from the USB interface circuit 107 to the personal computer 200 when not in the focus adjustment mode. In this case, since the amount of data to be transmitted is large, the timing when the image is captured by the image sensor 102 of the camera 100 and the timing when the image is displayed on the display device 203 of the personal computer 200 are shifted.

On the other hand, during the focus adjustment mode, only the luminance signal Y of the cut screen is transmitted in step S13. The image size of the cut screen is smaller than the image size of the full screen,
It is 1/4 in the vertical and horizontal directions. The luminance signal Y is YUV
The data amount is one half that of the signal. Thus, the digital video signal transmitted from the camera 100 to the personal computer 200 during the focus adjustment mode has a data amount of 1/32 of that in the non-focus adjustment mode.

Therefore, during the focus adjustment mode, the timing difference between when the image is captured by the image sensor 102 and when the image is displayed on the display device 203 is small.

FIG. 4 is a diagram showing an example of a cutout screen transmitted by the camera 100 during focus adjustment. Referring to FIG. 4, cut screen 301 transmitted during the focus adjustment mode is 1/1 in the vertical and horizontal directions of full screen 300.
It is four times the size. Then, the cut screen 301
Are located at substantially the center of the entire screen 300. Normally, when performing focus adjustment, the subject to be focused is often located at the center of the entire screen 300.

As described above, in the camera system according to the present embodiment, a video digital signal having a small image size is transmitted from the camera 100 to the personal computer 200 while the focus of the lens 101 of the camera 100 is adjusted.
, The data amount of the video digital signal to be transmitted can be reduced, and the timing difference between when the image is captured by the image sensor 102 and when the image is displayed on the display device 203 can be reduced. it can. As a result, focus adjustment can be easily performed.

A video digital signal transmitted from the camera 100 to the personal computer 200 is converted into a luminance signal Y.
Since only the digital video signal is transmitted, the data amount of the video digital signal to be transmitted can be reduced, and the timing shift between when the image is captured by the image sensor 102 and when the image is displayed on the display device 203 can be further reduced. As a result, the focus adjustment of the lens 101 can be performed more easily.

[First Modification of Cut Screen] The cut screen described above has an image size 1/4 times the vertical and horizontal directions of the entire screen 300, and the position thereof is approximately at the center of the entire screen.
In this case, it is possible to focus on a subject projected only in the central portion of the entire screen, but it is not possible to focus on a subject in a peripheral portion thereof. Therefore, when the entire screen is displayed after the focus adjustment, the image of the peripheral portion may be blurred. In the modified example of the cutout screen, the cutout screen is provided not only in the central portion of the entire screen but also in the peripheral portion thereof, and it is possible to focus on the subject projected in the peripheral portion. .

FIG. 5 is a diagram showing a first modification of the cutout screen. Referring to the figure, the first cutout screen 311 is located substantially at the center of the entire screen 310 with respect to the entire screen 310,
The cut screen 312 is located at the upper left corner of the entire screen 310.
The image size of the first cut screen 311 and the second cut screen 312 is 1/16 of the entire screen 310.

During the focus adjustment mode, the digital video signal transmitted from the camera 100 to the personal computer 200 has a data amount of 1/16 of that in the non-focus adjustment mode.

While the focus of the lens 101 of the camera 100 is being adjusted, a first cutout screen 311 and a second cutout screen 312 are displayed on the display device 203. Therefore, the focus can be adjusted not only for the subject shown on the first cutout screen 311 but also for the subject shown on the second cutout screen 312.

In this modification, the second cut screen has the same image size as the first cut screen. However, the present invention is not limited to this. The data amount of the video digital signal transmitted from the camera 100 to the personal computer 200 is
As long as the data amount does not hinder the focus adjustment, it may be smaller or larger than the first cutout screen.

The second cut screen 312 is displayed on the entire screen 310.
Is arranged at the upper left corner, but is not limited to this, and may be arranged anywhere around the first cutout screen 311 in the entire screen 310.

[Second Modification of Cut Screen] FIG. 6 is a diagram showing a second modification of the cut screen. Referring to the figure, the first cutout screen 321 is located substantially at the center of the entire screen 320,
Four second cutout screens 322, 323, 324, and 325 are located at four corners of the entire screen 320, respectively. And the first
The image size of the cut screen 321 is 1/1 of the entire screen 310.
6, and the image size of the four second cutout screens is 1/32 of the entire screen 310.

During the focus adjustment mode, the digital video signal transmitted from the camera 100 to the personal computer 200 has a data amount 1/16 that of the non-focus adjustment mode.

Also, while the focus of the lens 101 of the camera 100 is being adjusted, the first cutout screen 321 and the four second cutout screens 322, 323, and 32 are displayed on the display device 203.
4,325 will be displayed. This allows
Not only the subject shown on the first cutout screen 311 but also
The focus can also be adjusted for the subject displayed on the second cutout screens 322, 323, 324, and 325.

The second cutout screens 322, 323, 32
4, 425 sets the image size to 1/1 of the first cut screen 321.
However, the image size is not limited thereto, and may be a smaller image size or a larger image size.

Although the second cutout screen is arranged at the four corners of the entire screen 320, the present invention is not limited to this.
For example, they may be arranged on the upper, lower, left, and right sides of the first cutout screen 321, or six or eight pieces may be arranged around the first cutout screen.
You may make it arrange | position individually.

[Second Embodiment] In the camera system according to the first embodiment, the position of the cut screen in the entire screen is fixed. In the camera system according to the second embodiment, the position of the cut screen in the entire screen is designated from the personal computer so that the user can arbitrarily select the cut screen from the entire screen.

The schematic configuration of the camera system according to the second embodiment is the same as the schematic configuration of the camera system according to the first embodiment shown in FIG. In the lens 101, an adjustment knob for focus adjustment provided on the lens 101 is moved by driving a motor. The motor is driven according to an adjustment signal received from the personal computer 200. Therefore, the operator can adjust the focus of the camera 100 from the personal computer 200.

FIG. 7 is a flowchart showing the flow of the switching process performed by personal computer 200 according to the second embodiment. Referring to FIG. 7, it is determined whether or not focus adjustment mode is selected in personal computer 200 (S21). If the focus adjustment mode has been selected, the process proceeds to step S22; otherwise, the mode selection process ends.

In step S22, a coordinate value on the switching screen is input. In this case, when the operator indicates the position of the cut screen in the image displayed on the display device 203 from the keyboard or the mouse of the personal computer 200, the coordinate values in the entire screen are input. Specifically, a pointer that can be moved by a mouse is displayed on the display device 203, and the position of the cutout screen is determined based on the position on the display indicated by the displayed pointer.

Next, in step S23, a mode switching signal is transmitted to the camera 100 via the USB interface circuit 201. In step S24, step S2
The coordinate value of the cut screen input in step 2 is transmitted to the camera 100 via the USB interface circuit 201. Then, in step S25, an adjustment signal is transmitted to the camera 100 via the USB interface circuit 201.
The adjustment signal is input by an operator performing a predetermined operation from a keyboard or a mouse.

In the next step S26, it is determined whether the personal computer 200 has selected the end of the focus adjustment mode. If end is selected,
An end signal is transmitted to the camera 100 via the USB interface circuit 201 (S27).

FIG. 8 is a flowchart showing a flow of focus adjustment processing performed by the camera 100 according to the second embodiment. Referring to FIG. 8, camera 100
Transmits the full-screen YUV signal from the USB interface circuit 107 to the personal computer 200 (S31). In the present embodiment, the image size of the entire screen is 640 × 480. Y transmitted in step S31
The UV signal is 652,800 bytes per screen (640 bytes).
× 480 × 2).

Then, the USB interface circuit 10
At 7, it is determined whether a mode switching signal has been received from the personal computer 200 (S32). If a mode switching signal has been received, the process proceeds to step S33; otherwise, the focus adjustment processing ends.

In step S33, the coordinate values of the switching screen are received from the personal computer 200, and a cut-out screen of the received coordinate values is determined. Then, step S34
The video digital signal transmitted from the camera 100 to the personal computer 200 is defined as a luminance signal Y of the cut-out screen. In the present embodiment, the image size of the cut screen is set to 16
0 × 120. Therefore, the video digital signal transmitted in step S34 is 19200 bytes (160 × 120) per screen. Note that the image size of the cut screen is not limited to this, and may be any image size such as 1/16, 1/25, 1/36 of the image size of the entire screen.

In step S35, the USB interface circuit 107 receives the adjustment signal. Camera 100
Drives the motor in response to the received adjustment signal, and moves the adjustment knob of the lens 101. Thereby, the focus of the lens 101 is adjusted.

In the next step S36, it is determined whether or not the USB interface circuit 107 has received an end signal indicating the end of the focus adjustment mode from the personal computer 200. If an end signal has been received, the process proceeds to step S11; otherwise, the process proceeds to step S31.
Proceed to.

FIG. 9 is a diagram showing an example of a cut-out screen transmitted by the camera 100 according to the second embodiment in the focus adjustment mode. The cut screen 331 can be moved to any part of the entire screen 330.

As described above, in the camera system according to the second embodiment, since the position of the cutout screen 331 can be freely moved by the operator, the entire screen 330 can be moved.
The subject to be focused can be arbitrarily selected.

[Third Embodiment] Next, a camera system according to a third embodiment will be described. In the camera system according to the first or second embodiment, switching of the focus adjustment mode is performed by the personal computer 2.
00, the focus adjustment mode is switched by the camera 100 in the camera system according to the third embodiment.

FIG. 10 is a block diagram showing a schematic configuration of a camera system according to the third embodiment. This is a configuration in which a mode switch 110 is added to the camera 100 of the camera system according to the first embodiment shown in FIG. The configuration excluding the mode changeover switch 110 is the same as that of the camera system according to the first embodiment, and thus the description thereof will not be repeated.

The mode switch 110 is a button switch for instructing the camera 100 to switch the focus adjustment mode. In addition, the camera 10
The switching of the focus adjustment mode may be instructed by detecting that the adjustment knob provided on the 0 lens 101 has been moved. The camera 100 is in a focus adjustment mode while the mode changeover switch is ON, and is in a normal shooting mode other than the focus adjustment mode while it is OFF.

FIG. 11 is a flowchart showing the flow of the focus adjustment process performed by the camera 100 according to the third embodiment. Referring to FIG.
No. 0 transmits the YUV signal of the entire screen from the USB interface circuit 107 to the personal computer 200 (S41). In the present embodiment, the image size of the entire screen is 640 × 480. The YUV signal transmitted in step S41 has 652,800 bytes (64 bytes) per screen.
0 × 480 × 2).

Then, it is determined whether or not the changeover switch has been turned ON (S42). If turned on, step S
Proceed to 43, otherwise proceed to step S41.

In step S43, the video digital signal transmitted from the camera 100 to the personal computer 200 is set as the luminance signal Y of the cut screen. In the present embodiment, the image size of the cut screen is set to 160 × 120. Therefore, the video digital signal transmitted in step S11 is 19200 bytes per screen (160 × 12
0). Note that the image size of the cut screen is not limited to this, and is 1/16 of the image size of the entire screen,
Any image size such as 1/25 or 1/36 can be used.

In the next step S44, it is determined whether or not the changeover switch has been turned off (S44). If the switch is turned off, the process proceeds to step S41; otherwise, the process proceeds to step S44.

As described above, in the camera system according to the third embodiment, the focus adjustment mode is switched by the camera 100.
Even when the PC 0 and the personal computer 200 are set apart from each other, the focus can be adjusted without operating the personal computer at all while staying close to the camera.

In the camera systems according to the first to third embodiments, while adjusting the focus of the camera 100, the image size of the image transmitted from the camera 100 to the personal computer 200 is reduced, and only the luminance signal is output. Although transmission is performed, a color signal having a reduced image size may be transmitted, or only the luminance signal Y may be transmitted without reducing the image size.

The embodiments disclosed this time are illustrative in all respects, and should not be construed as limiting. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a camera system according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of a mode selection process performed by the personal computer 200 according to the first embodiment.

FIG. 3 is a flowchart illustrating a flow of a focus adjustment process performed by the camera 100 according to the first embodiment.

FIG. 4 is a diagram illustrating an example of a cutout screen transmitted by the camera 100 during focus adjustment according to the first embodiment.

FIG. 5 is a diagram showing a first modification of the cutout screen.

FIG. 6 is a diagram showing a second modification of the cutout screen.

FIG. 7 is a flowchart illustrating a flow of a switching process performed by a personal computer 200 according to the second embodiment.

FIG. 8 is a flowchart illustrating a flow of a focus adjustment process performed by the camera 100 according to the second embodiment.

FIG. 9 is a diagram illustrating an example of a cutout screen transmitted by the camera 100 according to the second embodiment in a focus adjustment mode.

FIG. 10 is a block diagram illustrating a schematic configuration of a camera system according to a third embodiment.

FIG. 11 is a flowchart illustrating a flow of a focus adjustment process performed by a camera according to a third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 camera 101 lens 102 image pickup device 104 A / D converter 107, 201 USB interface circuit 200 personal computer 203 display device

Claims (4)

[Claims] A focus-adjustable lens; an image sensor for receiving an image transmitted through the lens and reading an image; a conversion unit for converting an image read by the image sensor into a digital signal; Selecting means for selecting at least a part of the converted digital signal; and transmitting means for transmitting a signal selected by the selecting means among the digital signals, wherein the selecting means includes the lens Wherein at least a part of the digital signal is selected during the focus adjustment. 2. The camera according to claim 1, wherein the selection unit selects a signal related to at least a partial area of an image read by the image sensor from the digital signal. 3. The converted digital signal includes a luminance signal and a chrominance signal, and wherein the selecting means selects only the luminance signal from the converted digital signals. Or the camera according to any of 2. 4. A digital camera according to claim 1, further comprising designating means for designating a partial area of the image read by the image pickup device, wherein the selecting means selects a signal related to the area designated by the designating means from the digital signal. The camera according to claim 1, wherein: