JP4648595B2 - Electronic camera and electronic zoom control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic camera and an electronic zoom control method for taking a subject image by an image sensor such as a CCD (Charge-Coupled Devices), and more particularly to an electronic camera for appropriately controlling an electronic zoom of a subject image displayed on a monitor. And an electronic zoom control method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a so-called electronic camera that forms a subject image on an image sensor, such as a CCD, by an imaging optical system, converts the image into an electrical signal, and records the image data of the obtained subject image on a recording medium such as a semiconductor memory. Is becoming widespread.
[0003]
In addition, this type of electronic camera has a through image display function that instantly displays image data obtained from the image sensor on a color liquid crystal display (LCD), so the user does not look into the viewfinder. In both cases, the subject image can be confirmed using the LCD as a monitor.
[0004]
Furthermore, recently, there are many devices equipped with a so-called electronic zoom function that electronically changes the display magnification of a subject image displayed as a through image on the LCD.
[0005]
[Problems to be solved by the invention]
By the way, with regard to this through image display function, for example, in Japanese Patent Laid-Open No. 2000-156833, by adjusting the charge accumulation period in the image sensor in accordance with the subject luminance, even with a dark subject, the appropriate brightness can be obtained. A technique for displaying a through image is disclosed. Regarding the electronic zoom function, for example, Japanese Patent Application Laid-Open No. 2000-069370 discloses a technique for performing enlarged display by reading a part of the image data and performing resizing when reading the image data from the image sensor. Has been.
[0006]
However, the technique disclosed in Japanese Patent Laid-Open No. 2000-156833 has a disadvantage that the darker the subject, the more delayed the charge readout timing from the image sensor, and the longer the live view display. Therefore, the technique disclosed in Japanese Patent Laid-Open No. 2000-069370 also has a drawback that when the operator performs an electronic zoom operation, the response speed of a dark subject is slower than that of a bright subject. Will be included.
[0007]
The present invention has been made in consideration of such circumstances, and when an operator performs an electronic zoom operation, even if it is a dark subject, it provides an operational feeling equivalent to that of a bright subject. It is an object of the present invention to provide an electronic camera and an electronic zoom control method that enable this.
[0008]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides an image sensor capable of reading out information related to a subject image at a plurality of different readout cycles, and a subject image generated based on the read-out information , Display means for displaying in synchronization with the vertical synchronizing signal of the image sensor, and reading of information relating to the subject image from the image sensor has not been completed and an electronic zoom instruction has been issued, Image processing means for performing image processing for display at a magnification at which a step width for changing display magnification is fixed with respect to information relating to used image information, and causing the display means to display the display image that has been subjected to image processing Provided is an electronic camera comprising display update means .
[0009]
In this electronic camera, taking into consideration that the readout cycle of the subject image from the image sensor varies depending on the brightness of the subject, the step width during electronic zooming is controlled according to the readout cycle. More specifically, when the subject is dark and the reading cycle becomes long, the step width at the time of electronic zoom is increased.
[0010]
Thus, regardless of the readout cycle at that time, the electronic zoom can be performed so that the rate of change per unit time is constant, and when the operator performs the electronic zoom operation, even if it is a dark subject, a bright subject It is possible to provide an operational feeling equivalent to that of
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 is a block diagram showing a configuration of an electronic camera according to an embodiment of the present invention.
[0013]
In the figure, 1 is an imaging lens system composed of various lenses, 2 is a lens control unit for driving the lens system 1, and 3 is a CCD color imaging device for photoelectrically converting a subject image to obtain image information, 4 is an image sensor control unit for driving the image sensor 3, 5 is an A / D converter that preprocesses an analog signal output from the image sensor 3, and converts the analog signal into a digital signal, and 6 is a digital code A memory that stores the converted image data, a memory control unit that controls access to the memory 6, a YC generation unit that separates the image data into luminance components and color components, and an arbitrary portion of the image data An image processing unit 9 including a resizing unit for converting to an arbitrary size, a data compression unit for encoding image data, and a data decompression unit for returning the encoded data to the image data, 9 is supplied from the memory control unit 7 D / A converter for converting the image data to be converted into an analog form suitable for monitor display, 10 for displaying the display data obtained by the D / A converter 9, and 11 for image data as external storage A detachable memory card 12 for storing “” indicates a card interface for controlling access to the memory card 11. In the figure, reference numeral 13 denotes a system controller for comprehensively controlling each part, and reference numeral 14 denotes an operation switch system including various SWs.
[0014]
In the electronic camera of this embodiment, the system controller 13 performs overall control, and in particular, controls driving of the image sensor 3 by the image sensor control unit 4 to perform exposure (charge accumulation) and signal readout, This is taken into the image processing unit 8 via the memory control unit 7 to generate image data for recording, and then recorded on the memory card 11 via the card interface 12. The electronic zoom control that is a feature of the present embodiment is executed by the electronic zoom control unit 131 of the system controller 13.
[0015]
FIG. 2 is a timing chart relating to the through image display in the conventional and the present embodiment. In the figure, (A) is a through image time chart of a conventional high brightness subject, (B) is a conventional through image time chart of a low brightness subject, and (C) is a through image of a low brightness subject in the present embodiment. Each time chart is shown.
[0016]
In FIG. 2, VD is a vertical synchronization signal indicating a frame period in the image sensor control unit 4. The charge accumulation period indicates an exposure period in which the image sensor 3 accumulates charges. On the other hand, the charge reading period indicates a period during which the charge (image data) stored in the charge accumulation period is taken into the memory 6. The image processing period indicates a period during which the image processing unit 8 performs image processing such as YC conversion and resizing processing.
[0017]
FIG. 3 is a diagram illustrating a configuration example of data processing in the through image display of the electronic camera.
[0018]
As shown in FIG. 3, the memory 6 should display two frames (x4, x5) of read data storage memory for storing the read image data on the display unit 10 as a memory necessary for the through image display. A display memory for storing image data is provided for two frames (x12, x13). In order to switch the input / output of these memories, the memory control unit 7 has switches (x17 to x20).
[0019]
Here, first, a conventional procedure for displaying a through image will be described with reference to FIGS.
[0020]
First, as shown in FIG. 2A, for a high-luminance subject, charges are accumulated in the image sensor 3 in a cycle T1 (1). Next, in the cycle T2, the charge accumulated in the cycle T1 is stored in the read data storage memory x4 (2). At the same time, in the period T2, the charge of the next frame is accumulated (3).
[0021]
In the cycle T3, the image data stored in the read data storage memory x4 in the cycle T2 is YC converted and resized by the image processing of the image processing unit 8 and stored in the display memory x12 (4). The image data stored in the display memory x12 is displayed on the monitor by the display unit 10 via the memory control unit 7 and the DA conversion unit 9. At the same time, in the cycle T3, the charges accumulated in the cycle T2 are stored in the read data storage memory x5 (5), and the charges in the next frame are accumulated (6).
[0022]
In the cycle T4, the image data stored in the read data storage memory x5 in the cycle T3 is YC converted and resized by the image processing of the image processing unit 8 and stored in the display memory x13 (7). At the same time, the charges accumulated in the cycle T3 are stored in the read data storage memory x4 (8), and the charges in the next frame are accumulated (9). Thereafter, the processes of the cycle T3 and the cycle T4 are alternately repeated until the through image display is completed.
[0023]
Secondly, as shown in FIG. 2B, the low-brightness object spans a plurality of periods such as a period T1 to a period T2, a period T3 to a period T4, a period T5 to a period T7, and a period T8 to a period T10. In this way, charge is accumulated. In this case, the charge readout period is a cycle T3, a cycle T5, and a cycle T8, and the image processing period is a cycle T4, a cycle T6, and a cycle T9.
[0024]
That is, the display update timing is 1/2 or 1/3 in the through image display for the low-brightness object shown in the second, compared to the through image display for the high-brightness object shown in the first. However, it is inversely proportional to the charge accumulation period. Therefore, when the step width for changing the display magnification is fixed, the operational feeling of the electronic zoom for a low-luminance subject is ½ or less compared to that for a high-luminance subject.
[0025]
Based on this point, a procedure for displaying a through image of a low-luminance subject in the present embodiment will be described next with reference to FIGS. 2 and 3.
[0026]
In the present embodiment, as shown in FIG. 2C, the display is updated at the period T5, the period T7, the period T8, and the period T10 even for a low-luminance subject. In this case, the image data subjected to the image processing in the period T4 and the period T5 is the charge accumulated in the period T1 to the period T2, read out in the period T3, and stored in the read data storage memory x4. Further, the image data subjected to the image processing in the period T6, the period T7, and the period T8 is the one in which charges are accumulated in the periods T3 to T4, the charges are read out in the period T5, and stored in the read data storage memory x5.
[0027]
In the present embodiment, first, after image processing is performed on the image data read at the cycle T3 at the cycle T4, the image data read at the cycle T5 is subjected to image processing at the cycle T6. By controlling the step width so that the rate of change per unit time becomes a predetermined value, it is possible to provide an operational feeling equivalent to that of a high-luminance subject. That is, by controlling the step width of the display magnification change according to the brightness of the subject, the electronic zoom of the subject image displayed on the monitor can be appropriately performed regardless of the readout cycle of the image data from the image sensor 3. Realize control.
[0028]
Second, the image processing unit 8 performs image processing to interpolate the display update using the image data read in the cycle T3 in the interval between the image processing in the cycles T4 and T6, that is, in the cycle T5. By performing the above, it is possible to keep the display cycle constant.
[0029]
Note that, in the period T5, the period 7, the period T8, and the period T10, this image processing and display update are performed only when the operator is performing an electronic zoom operation. Thereby, the power consumption of image processing and the load of camera control can be minimized.
[0030]
FIG. 4 is a flowchart showing an image processing procedure in each cycle during live view display in the present embodiment.
[0031]
The electronic zoom control unit 131 first determines whether or not reading of image data in the previous cycle has been completed (step S1). If completed (YES in step S1), the electronic zoom control unit 131 updates the memory location for the next read data storage (step S2). This means switching between x2 and x3 by the switch x17 in FIG.
[0032]
Next, the electronic zoom control unit 131 checks whether or not an electronic zoom instruction is given by the operator (step S3), and if so (YES in step S3), calculates an electronic zoom magnification (step S4). Based on the calculated electronic zoom magnification, the image processing unit 8 is caused to perform image processing (step S5). At this time, the image data used for image processing is image data that has been read immediately before.
[0033]
Then, the electronic zoom control unit 131 displays the image data obtained by this image processing on the display unit 10 and updates the subject image displayed on the monitor (step S6).
[0034]
On the other hand, when the reading of the image data in the previous cycle is not completed (NO in step S1), the electronic zoom control unit 131 issues an electronic zoom instruction from the operator without updating the read data storage memory location. (Step S7), and if so (YES in step S7), the electronic zoom magnification is calculated (step S8) as described above. Based on the calculated electronic zoom magnification, the image processing unit 8 is caused to perform image processing (step S9). At this time, the image data used for the image processing is the image data used in the previous period.
[0035]
Then, the electronic zoom control unit 131 displays the image data obtained by this image processing on the display unit 10 and updates the subject image displayed on the monitor (step S10).
[0036]
Note that the switch x18 in FIG. 3 indicates a storage source of image data to be subjected to image processing, that is, image data that has been read immediately before. The switch x18 is switched at the timing of step S2 when the next read data storage memory location is updated.
[0037]
On the other hand, the switch x19 indicates the storage location of the image data after image processing. The switching of the switch x19 is performed at the timing of step S6 or step S10 when the display is updated. By performing image processing on an area different from the image data being displayed from the display unit 10, image processing can be performed without damaging the currently displayed image.
[0038]
As described above, the electronic camera of this embodiment appropriately controls the electronic zoom of the subject image displayed on the monitor.
[0039]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, the electronic zoom can be performed so that the rate of change per unit time is constant regardless of the readout cycle at that time, and the operator performs the electronic zoom operation. Even if it is a dark subject, it is possible to provide an operational feeling equivalent to that of a bright subject.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electronic camera according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a timing chart relating to a through image display according to the related art and the present embodiment.
FIG. 3 is a diagram illustrating a configuration example of data processing in a through image display of an electronic camera.
FIG. 4 is an exemplary flowchart illustrating an image processing procedure in each cycle when a through image is displayed in the electronic camera of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Lens system 2 ... Lens control part 3 ... Image sensor 4 ... Image sensor control part 5 ... A / D converter 6 ... Memory 7 ... Memory control part 8 ... Image processing part 9 ... D / A converter 10 ... Display part DESCRIPTION OF SYMBOLS 11 ... Memory card 12 ... Card interface 13 ... System controller 14 ... Operation switch system 131 ... Electronic zoom control part

Claims (3)

An image sensor capable of reading out information related to a subject image at a plurality of different readout cycles;
Display means for displaying a subject image generated based on the read information in synchronization with a vertical synchronization signal of the image sensor ;
When reading of information related to the subject image from the image sensor has not been completed and an electronic zoom instruction has been issued, the step width for changing the display magnification with respect to the information related to the image information used in the previous cycle is Image processing means for performing image processing for display at a fixed magnification;
An electronic camera comprising: a display updating unit that causes the display unit to display the display image that has been subjected to the image processing . The image processing means performs image processing for interpolating an image to be displayed by the display means in synchronization with a vertical synchronization signal of the image sensor using a subject image read immediately before. The electronic camera according to claim 1. An electronic camera having an imaging device capable of reading a subject image at a plurality of different readout cycles and a display means for displaying a subject image read from the imaging device in synchronization with a vertical synchronization signal of the imaging device. A zoom control method,
When reading of information related to the subject image from the image sensor has not been completed and an electronic zoom instruction has been issued, the step width for changing the display magnification with respect to the information related to the image information used in the previous cycle is Perform image processing for display at a fixed magnification,
An electronic zoom control method , comprising: displaying the image subjected to image processing on the display means .

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