JP2017092734A - Imaging apparatus and control method of the same - Google Patents

Abstract

An imaging apparatus capable of reducing display delay during electronic zooming and enabling stable display is provided. An imaging unit that outputs image data of a captured image, a memory that stores image data output from the imaging unit, a scaling unit that performs an enlargement process on the image data stored in the memory, and a scaling unit In the imaging apparatus having the display unit that displays the image data that has been subjected to the enlargement process, the writing of the image data of the area to be scaled by the scaling unit is overtaken by the reading of the image data of the area from the memory. In order to avoid this, a synchronization signal for outputting image data from the imaging unit is generated. [Selection] Figure 1

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus that performs electronic zoom and a control method thereof.

  Conventionally, when a captured image or an image transmitted from the outside is displayed in real time, if the display timing is late with respect to the imaging timing, it is difficult to record quickly following the movement of the subject. There was a problem. In order to solve the above problem, a technique for reducing a delay in display timing (display delay) with respect to image input is disclosed.

  For example, Patent Document 1 discloses a technique for displaying a transmitted image with low delay. In Patent Document 1, the first calculation unit calculates an allowable delay time that represents a delay time that is allowed when writing cannot be completed within a predetermined required time from a writing start time at which image writing is started. The second calculation unit calculates at least a necessary time from the writing start time of the image written with a delay time equal to or shorter than the allowable delay time to the display timing for starting the image display, and the comparison unit calculates the allowable delay The display adjustment unit adjusts the display timing based on the comparison result of the comparison unit, and the display control unit displays the image in synchronization with the adjusted display timing. The delay is reduced.

  Further, a technique related to overtaking control is disclosed regarding a memory access method for reducing display delay. In the overtaking control, it is possible to reduce the amount of delay due to memory access by performing memory access control with a predetermined delay amount so that reading of data does not overtake writing in the same memory area.

  For example, in Patent Document 2, a predetermined delay amount is provided so that reading of data does not overtake writing to the same memory area, and when the delay amount is not within a predetermined range, an access alarm is output and reading is temporarily performed. Thus, the control is performed so that the reading does not overtake the writing.

JP 2012-222463 A JP 2003-323333 A

  When performing imaging and display in an imaging apparatus, it is necessary to keep the display frame rate constant. For example, if you are shooting an object whose size, position, etc. change over time, if the display frame rate changes, smooth changes in the subject in the captured image will be hindered, and the display image will look You may feel uncomfortable. Also, there are cases where the display frame rate cannot be changed, such as when connected to a display device based on a standard. Although Patent Document 1 attempts to reduce display delay by adjusting display timing, it is difficult to apply the disclosed prior art to an imaging apparatus for the above reasons.

  At the time of electronic zoom, when a part of an image is enlarged and displayed, a read area is a part of a write area. Therefore, when data is written to and read from the same memory area at the time of electronic zoom, the timing at which data can be read may be delayed as compared with the case without electronic zoom. When this slow amount exceeds a predetermined delay amount between writing and reading set by the normal overtaking control technique, the display delay amount may become unstable. As a result, a part of the image cannot be updated in time, and the image read in the previous frame is displayed, which may cause the display image to fail with a predetermined delay amount when the electronic zoom is not used. It was. On the other hand, there is a problem in that display delay increases because it is necessary to provide an amount of delay more than necessary in order to prevent the display image from failing during electronic zoom.

  An object of the present invention is to provide an imaging apparatus capable of reducing display delay during electronic zooming and enabling stable display and a control method thereof.

In order to achieve the above object, the present invention has the following configuration.
Imaging means for outputting image data of the captured image;
Storage means for storing the image data output from the imaging means;
A scaling unit for performing an enlargement process on the image data stored in the storage unit;
Display means for displaying the image data enlarged by the scaling means;
Image data is output from the imaging unit so that writing of the image data of the region to be scaled by the scaling unit to the storage unit is not overtaken by reading the image data of the region from the storage unit. An image pickup apparatus comprising: synchronization signal generating means for generating a synchronization signal for generating the synchronization signal.

  According to the present invention, display delay during electronic zooming can be reduced and stable display can be achieved.

The figure showing the timing of the reading / writing of the image of 1st Embodiment Functional block diagram of the first embodiment FIG. 6 is a diagram for explaining a normal image read / write area and a display area according to the first embodiment. The figure explaining the reading / writing area | region and display area of the image at the time of expansion of 1st Embodiment The figure showing the read-write timing of the image at the normal time of 2nd Embodiment The figure showing the timing of the reading / writing of the image of the normal time of 3rd Embodiment The figure showing the read-write timing of the image of the normal time of 4th Embodiment

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing the read / write timing of an image according to the embodiment of the present invention.

[Embodiment 1]
<Configuration of imaging device>
The imaging apparatus according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a functional block diagram of the first embodiment. In FIG. 2, the image sensor 200 converts an optical image that has passed through an optical lens (not shown), a diaphragm, and the like into an electrical signal to generate an image. The image processing unit 201 inputs an image from the image sensor 200 and performs various image processing such as noise removal, gamma processing, interpolation processing, matrix conversion, and composition processing. The memory writing unit 202 writes the data processed by the image processing unit 201 into the memory. VRAMs 203A and 203B are image memories into which image data is written by the memory writing unit 202, respectively. The memory writing unit 202 can generate VRAMs for a plurality of frames in the memory. In the present embodiment, for simplicity of description, the memory writing unit 202 alternately writes image data for one frame in the VRAMs 203A and 203B. In this embodiment, the memory is a storage unit that temporarily stores an image signal and uses a dynamic random access memory (DRAM) that is a volatile memory, but uses other temporary storage means such as a nonvolatile memory. It doesn't matter. The memory reading unit 204 alternately reads the image data written by the memory writing unit 202 to the VRAMs 203A and 203B. The image scaling unit 205 performs an enlargement process on a specific area of the image data read by the memory reading unit 204. The display unit 206 displays the image scaled by the image scaling unit 205 on a display device (not shown). A display device such as a liquid crystal display or a TV monitor is used. In the present embodiment, scaling by the scaling unit 205 is performed so that the size of the area to be enlarged is enlarged to the screen size of the display device.

  A synchronization signal generation unit 207 generates a synchronization signal that defines a frame rate for imaging, live view display, and playback display, and sends the synchronization signal to the imaging sensor 200, the display unit 206, and a scaling control unit 208 described later. In this embodiment, the synchronization signal generation unit 207 controls the image reading speed of the image sensor 200 and the reading speed of the image data input to the image scaling unit 205. The memory writing timing (memory writing speed) is synchronized with the reading speed of the image data from the imaging sensor 200, and the memory reading timing (memory reading speed) is synchronized with the output of the image data for display. Therefore, the image reading speed and the memory writing speed of the image sensor 200 can be achieved by increasing the rate of a synchronization signal (for example, a pixel-by-pixel synchronization signal) generated by the synchronization signal generation unit 207 for image reading of the image sensor 200. Is done. The same applies to other embodiments. The readout timing of the image signal sent from the image sensor 200 to the image processing unit 201 is controlled by the synchronization signal generation unit 207. Specifically, the image readout start timing, the readout period of one image frame, and the like can be controlled. The display frame rate is a constant rate defined by standards such as 30 fps and 60 fps. When the user designates electronic zoom, the zooming control unit 208 receives the synchronization signal sent from the synchronization signal generation unit 207 and determines the enlargement ratio and the enlargement area in units of frame rates. In this embodiment, it is assumed that the scanning order of the imaging unit 200 and the scanning order of the display unit 206 are the same, and for example, both are raster scanning orders.

  With reference to FIG. 3, memory read / write and rate control when the electronic zoom is not used will be described. An image area 300 represents an image area input from the image sensor 200 and written out by the memory writing unit 202. A writing scan 301 represents scanning of writing by the memory writing unit 202, and writing is performed from the upper end to the lower end by raster processing. An image area 310 represents an image area read by the memory reading unit 204. A read scan 311 represents a scan of reading by the memory reading unit 204, and is a raster scan as with the write scan 311. A display 320 represents a display by the display unit 206. In this embodiment, the size of the display 320 is the same as that of the read image area 310. A display scan 321 represents scanning of display by the display unit 206, and performs display processing by raster scanning in the same manner as the scanning 311 for writing.

  In FIG. 3, the display scan 321 needs to be processed at an image size and rate defined by the display device. In the writing scan 301, each processing is performed in accordance with the timing so as to satisfy the rate processing of the display scanning 321. When the electronic zoom is not performed and the display 320 and the readout image size 310 are the same, the readout scanning 301 and the display scanning 321 can be processed at the same rate. On the other hand, with respect to the writing rate, writing is performed at a rate in accordance with the imaging sensor synchronization signal as described later with reference to FIG. When writing and reading are processed at a constant rate as described above, the write scan 301 and the read scan 311 are slightly shifted in timing with a predetermined delay time, and read and write access to the same memory area is performed. Control performed simultaneously is possible.

<Image data read / write timing>
The timing of image reading / writing by the memory writing unit 202 and the memory reading unit 204 in this embodiment will be described with reference to FIG. In FIG. 1, (a) shows the read / write timing when the electronic zoom is not used, and (b) shows the read / write timing when the electronic zoom is used. In each case, the horizontal axis represents time, the vertical axis represents the vertical position of the horizontal line of the image, and represents the line from the lower end to the upper end in the direction of the arrow. In FIG. 1A, the imaging sensor synchronization signal 100 represents a synchronization signal of the imaging sensor 200 generated at regular intervals, and is generated by the synchronization signal generation unit 207. Memory write timing 101 represents the memory write timing by the memory writing unit 202. The memory writing unit 202 writes to the memory line by line from the upper end to the lower end of the image according to the timing of the image sensor synchronization signal 100. The display synchronization signal 102 existing at a constant interval represents the synchronization signal of the display unit 206 generated by the synchronization signal generation unit 207. The memory read timing 103 represents the memory read timing by the memory read unit 204. The memory reading unit 204 reads out from the memory line by line from the upper end to the lower end of the image according to the display synchronization signal 202. An area 104 represents a vertical image area read by the memory reading unit 204. In FIG. 1A, both reading and writing are accessed from the upper end to the lower end of the image.

  A period 105 indicates the period of the image sensor synchronization signal 100. A period 106 indicates the period of the display synchronization signal 102. In FIG. 1A, the cycle 105 of the imaging sensor synchronization signal 100 and the cycle 106 of the display synchronization signal 102 are the same, but they may be different by an integer ratio. For example, when the imaging sensor synchronization signal 100 has a frame rate twice that of the display synchronization signal 102, the display synchronization signal 102 is generated with a synchronization signal at an interval twice that of the imaging sensor synchronization signal 100. . In the above case, the memory reading unit 204 may read out the frames written by the memory writing unit 202 by thinning out one frame at a time.

  A phase difference 107 is a phase difference between the imaging sensor synchronization signal 100 and the display synchronization signal 102 and indicates a predetermined delay amount in the synchronization signal generation unit 207. In FIG. 1A, by providing the delay amount 107, it is possible to prevent the image reading timing 103 from overtaking the writing timing 101. The predetermined delay amount 107 is controlled by the synchronization signal generator 207.

  FIG. 1B shows a case where an image is enlarged using electronic zoom. A part of the image is read instead of the entire image by the enlargement process caused by the electronic zoom. An area 118 represents an area of an image in the vertical direction read by the memory reading unit 204. The center 119 is the center of enlargement. In FIG. 1B, the enlargement center 119 indicates the same position as the center of the image. At this time, since the image displayed on the display unit 206 is an enlarged image, the area to be read is not the entire image but a part. The memory reading unit 204 reads the image area 118 centering on the image area 104 in FIG. 1A when the electronic zoom is not used, and 119 in FIG. The read timing 113 is a case where the electronic zoom is not used at a ratio of (partial region to be enlarged of image) / (whole image) in order to display the partial region to be enlarged at the same size and frame rate as the whole image. The read timing 103 is reduced. The timing shown in FIG. 1 is shown in the sub-scanning direction of the screen. However, since the electronic zoom is usually enlarged in the main scanning direction, the reading rate in the main scanning direction is the same as the reading rate in the sub-scanning direction. Has been lowered.

  An imaging sensor for ensuring that the image reading timing 113 in FIG. 1B does not overtake the writing timing 111 when the maximum zoomed-in state by the electronic zoom is the state shown in FIG. The delay amount of the display synchronization signal 112 with respect to the synchronization signal 110 is defined as a phase difference 117. In order to ensure this phase difference 117, the synchronization signal generation unit 207 sets the timing of the imaging sensor synchronization signal 100 ahead by the advance time 120 to timing 110. The advance time 120 is a value obtained by subtracting the phase difference 107 of the display synchronization signal 102 with respect to the imaging sensor synchronization signal 100 from the phase difference 117 to be secured when the electronic zoom is not used. In other words, when the electronic zoom is used, the image signal corresponding to the position on the image to be read first for display is written a certain time (for example, phase difference 117) before the reading timing. The advance time 120 is determined. Thereby, it can be ensured that the read timing 113 does not pass the write timing 111.

  When the magnification of the electronic zoom is not maximum, the image reading area 118 in FIG. 1B is widened, and the inclination is larger than the memory reading timing 103. Therefore, the advance time 120 in that case may be smaller than the advance time 120 when the magnification of the electronic zoom is maximum. However, this is limited to the case where the center of enlargement 119 coincides with the center of the image. In the normal electronic zoom, the center of the image coincides with the center of enlargement 119 as in the optical zoom. However, when the image is expanded more generally, for example, when the center of enlargement can be selected, the advance time 120 is determined according to the start position of the display range using the electronic zoom. For example, the advance time 120 is determined so that the start position of the display range is written at a timing earlier than the memory read timing at that position by a predetermined time (for example, the phase difference 107). In this case, for example, if the timing for writing the start position of the display range using the electronic zoom is delayed by the time tr from the timing for writing the start of the frame, the advance time 120 may be set to the time tr. it can. The time tr can be determined from, for example, the slope of the write timing 111 (that is, the write speed) and the position of the first line in the display range.

  As described above, since the timing of the display synchronization signals 102 and 112 is a constant period, the display frame rate is constant, and the delay time can be reduced to the minimum.

<Rate control of memory read / write>
With reference to FIG. 4, memory read / write and rate control when the electronic zoom is used will be described. An image area 400 represents an image area input from the image sensor 200 and written out by the memory writing unit 202. A writing scan 401 represents scanning of writing by the memory writing unit 202, and writing is performed from the upper end to the lower end by raster processing. An image area 410 represents a read image area in the same memory as the memory write. A reading area 410 represents a reading area when electronic zooming is performed, and a reading scan 411 represents reading scanning. A display 440 represents a display by the display unit 206. A display scan 441 represents scanning of display by the display unit 206, and performs display processing by raster scanning. The image scaling unit 205 enlarges the image size of the image area 410 to the image size of the display image area 440.

  As described above, the display scan 441 needs to be processed in the area and rate specified by the display device (or predetermined for the display device). As shown in FIG. 4, since the size of the readout image area 410 and the size of the display image area 440 are different, the readout scanning rate and the display scanning rate are different. As shown in FIG. 1B, the start timing of the readout scan is the same as that of the display scan, but the readout scan is slower. Here, the speed is represented by, for example, the number of pixels or lines of original image data read or displayed per time. On the other hand, since the readout timing is almost the same as the start of the scanning timing, a phase difference 117 is required in the readout image area 410 of FIG. 4 so that the readout timing does not pass the writing scan 401.

  As described above, the phase difference 107 between the imaging sensor synchronization signal 100 and the display synchronization signal 102 that should be ensured by the magnification of the electronic zoom is advanced, and the timing of the imaging sensor synchronization signal 100 is advanced to the timing of the synchronization signal 110 to obtain the imaging sensor synchronization signal. 100, the display synchronization signal 102, and the phase difference are defined as a phase difference 117. In this way, it can be ensured that the image reading timings 103 and 113 do not pass the writing timings 101 and 111 even when the electronic zoom magnification changes, and the timing of the display synchronization signals 102 and 112 depends on the electronic zoom magnification. Therefore, the display frame rate can be kept constant and the delay time can be shortened.

  In the present embodiment, the imaging sensor synchronization signal 100 is described as being advanced with respect to the display synchronization signal 102, but the timing between the two is relative, and the display synchronization signal 102 is the timing of the imaging sensor synchronization signal 100. It can also be delayed.

  With respect to the main scanning direction, the timing control in the sub-scanning direction in FIG. 3 is similarly applied to the main scanning direction, so that the writing of the image data to the enlargement target area is overtaken by the reading of the image data in that area. Can be prevented. In this case, “line” is read as, for example, “pixel”, the synchronizing signal in the sub-scanning direction is changed to the corresponding synchronizing signal in the main scanning direction, and the read / write timing is changed from the timing in the sub-scanning direction to the main scanning direction. Should be read as timing. Alternatively, for the main scanning direction, for example, a line buffer for one line is prepared without performing control as in the sub-scanning direction, and the image data written in the VRAM is displayed once from the VRAM. The target line may be read out and stored in the line buffer, and the enlargement target area may be read out from the line buffer in synchronization with the synchronization signal in the main scanning direction and displayed. With such a configuration, it is possible to prevent the read timing from being overtaken by the write timing. This can be applied to other embodiments in addition to the first embodiment. Of course, this is only an example, and other methods may be applied to adjust the timing of writing image data in the memory in the main scanning direction and the display timing. The same applies to other embodiments.

[Embodiment 2]
Hereinafter, an imaging apparatus according to the second embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is that, in the first embodiment, the timing of the imaging sensor synchronization signal is advanced according to the electronic zoom magnification. However, in the second embodiment, the timing according to the electronic zoom magnification is used. Thus, the timing of the imaging sensor synchronization signal is fixed, and the imaging readout speed is increased. In the second embodiment, control is performed from the viewpoint that the readout start timing of the image sensor is a constant period even in the case of electronic zoom enlargement.

  The timing of image reading / writing by the memory writing unit 202 and the memory reading unit 204 in this embodiment will be described with reference to FIG. In FIG. 5, (a) shows the read / write timing when electronic zoom is not used, and (b) shows the read / write timing when electronic zoom is used. In each, the horizontal axis represents time, and the vertical axis represents the vertical position of the horizontal line of the image. The vertical axis represents the line from the lower end to the upper end in the direction of the arrow. In FIG. 5A, the imaging sensor synchronization signal 500 that exists at regular intervals represents the synchronization signal of the imaging sensor 200 that is generated by the synchronization signal generation unit 207. A memory write timing 501 represents a memory write timing by the memory writing unit 202. The memory writing unit 202 writes to the memory line by line from the upper end to the lower end of the image according to the timing of the imaging sensor synchronization signal 500. A display synchronization signal 502 existing at a constant interval represents a synchronization signal of the display unit 206 generated by the synchronization signal generation unit 207. The memory reading unit 204 starts reading image data from the memory according to the display synchronization signal 202 and reads from the memory line by line from the upper end to the lower end of the image according to the memory read timing 503. An area 504 represents a vertical image area read by the memory reading unit 204. In FIG. 5A, both reading and writing are accessed from the upper end to the lower end of the image. The writing period 507 is a writing period from when the writing timing 501 started from the imaging sensor synchronization signal 500 reaches the lower end line of the image and writing of one frame is completed. The writing period 507 is also a period for reading image data from the image sensor 200. That is, the inclination of the writing timing 501 represents the memory writing speed and the image reading speed from the image sensor 200. When the speed is high, the inclination is steep and the period 507 is short. Conversely, when the memory writing speed and the image reading speed from the image sensor 200 are slow, the slope becomes gentle and the period 507 becomes long.

  In FIG. 5A, a predetermined delay amount is provided so that the image reading 503 does not overtake the writing 501. The predetermined delay amount is controlled by the synchronization signal generator 207. The embodiment without the electronic zoom in FIG. 5A is the same as FIG. 1A of the first embodiment.

  Next, FIG. 5B will be described. FIG. 5B shows a case where the image is enlarged by electronic zoom. A part of the image is read out by the enlargement process caused by the electronic zoom. An area 518 represents an area of an image in the vertical direction read by the memory reading unit 204. The center 519 is the center of enlargement. FIG. 5B shows a case where the position is the same as the center of the image. At this time, since the image displayed on the display unit 206 is an enlarged image, the area to be read is not the entire image but a part. The memory reading unit 204 reads the image area 504 in FIG. 5A when the electronic zoom is not used, and the image area 518 around the center 519 in FIG. 5B when the electronic zoom is enlarged.

  5B when the image is magnified by the electronic zoom, the synchronization signal generation unit 207 can capture the image sensor 200 as much as it can be ensured that the image read timing 513 in FIG. 5B does not pass the write timing 511. The image reading period 517 is shortened by increasing the image reading speed. The memory write timing 511 is also advanced in synchronization with the image reading speed of the image sensor 200. Accordingly, the writing period 507 of the image writing process 501 is shortened to 517 in the writing process 511, and it can be ensured that the read timing 513 does not pass the write timing 511.

  When the magnification of the electronic zoom is not the maximum, the image reading area 518 in FIG. 5B becomes wide and the inclination of the memory reading timing 503 becomes larger (steep), so the writing period becomes shorter than the writing period 507, It becomes longer than the writing period 517.

  As described above, according to the electronic zoom magnification, the image reading period from the image sensor and the writing to the memory are increased by increasing the image reading speed from the imaging sensor 200 and the writing timing (that is, the writing rate) of the image data to the memory by the synchronization signal generation unit 207. The periods 501 and 511 are shortened. By doing so, it is possible to ensure that the image reading timings 503 and 513 do not overtake the writing timings 501 and 511, and therefore the timings of the imaging sensor synchronization signal 100 and the display synchronization signal 102 should be constant regardless of the electronic zoom magnification. It is possible to stabilize the delay time from imaging to display and to reduce the delay time to a minimum.

  However, the method of this embodiment has limitations. For example, the timing for reading the uppermost line of the area 518 in FIG. 5B (that is, the timing of the display synchronization signal) needs to be later than the timing for writing the image data of the display target portion of that line. The image reading speed from the image sensor 200 and the writing speed of image data to the memory are naturally limited, and the electronic zoom magnification, that is, the enlargement target area is determined so that the above condition is satisfied even if the speed is increased to the limit. Or the phase difference 707 needs to be determined.

  With respect to the main scanning direction, the timing control in the sub-scanning direction of FIG. 5 is similarly applied to the main scanning direction, so that the writing of the image data to the enlargement target area is overtaken by the reading of the image data in that area. Can be prevented. In this case, “line” is read as, for example, “pixel”, the synchronizing signal in the sub-scanning direction is changed to the corresponding synchronizing signal in the main scanning direction, and the read / write timing is changed from the timing in the sub-scanning direction to the main scanning direction. Should be read as timing.

[Embodiment 3]
Hereinafter, the imaging apparatus according to the third embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is that in the first embodiment, the center of the electronic zoom is the center of the image, but in the third embodiment, the center of the electronic zoom is other than the center of the image. There is also a good thing. In the first embodiment, the time for advancing the timing of the image sensor synchronization signal 100 is determined according to the magnification of the electronic zoom, but in the third embodiment, not only the magnification of the electronic zoom but also the center position of the electronic zoom is considered. It is characterized in that the timing of the image sensor synchronization signal is determined according to the amount. 6A, 6B, and 6C are diagrams illustrating the timing of image reading and writing by the memory writing unit 202 and the memory reading unit 204 when the center position of the electronic zoom is different. 6A shows a case where the center of the electronic zoom is the center of the image, FIG. 6B shows a case where the center of the electronic zoom is above the center of the image, and FIG. 6C shows a case where the center of the electronic zoom is the image center. An example is shown below the center.

  In FIG. 6A, the image sensor synchronization signal 600 exists at regular intervals. A write timing 601 represents a write timing by the memory writing unit 202. The display synchronization signal 602 exists at regular intervals. A memory read timing 603 represents the memory read timing by the memory read unit 204. A region 604 represents a vertical image region written by the writing unit 202. The image is written in the memory from the upper end to the lower end of the image at the write timing 601.

  An image area 608 in FIG. 6A represents a vertical image area read by the memory reading unit 204. A center 609 is the center of the electronic zoom, and coincides with the center of the written image area 604 in FIG. In this case, the synchronization signal generation unit 202 performs control to advance the imaging sensor synchronization signal 600 by the advance time 605 to ensure that the memory read timing 603 does not pass the memory write timing 601. At this time, the phase difference of the display synchronization signal 602 with respect to the imaging sensor synchronization signal 600 is a delay amount 607.

  An image area 618 in FIG. 6B represents a vertical image area read by the memory reading unit 204. A center 619 is the center of the electronic zoom. The readout area 618 is closer to the upper end side of the image area 604 than the readout area 608 in FIG. The center 619 of the electronic zoom is also located above the center of the image area 604 and the center 609 of the electronic zoom in FIG. That is, the center and the area of the electronic zoom are close to the upper end side of the image. In this case, the synchronization signal generation unit 202 performs control to advance the imaging sensor synchronization signal 610 by the advance time 615 to ensure that the memory read timing 613 does not pass the memory write timing 611. At this time, the phase difference of the display synchronization signal 612 with respect to the imaging sensor synchronization signal 610 is a delay amount 617.

  An image region 628 in FIG. 6C represents a vertical image region read by the memory reading unit 204. A center 629 is the center of the electronic zoom. The readout area 628 is closer to the lower end side of the image area 604 than the readout area 608 in FIG. The center 629 of the electronic zoom is also located below the center of the image area 604 and the center 609 of the electronic zoom in FIG. That is, the center and area of the electronic zoom are close to the lower end side of the image. In this case, the synchronization signal generation unit 202 performs control to advance the imaging sensor synchronization signal 620 by the advance time 625 to ensure that the memory read timing 623 does not pass the memory write timing 621. At this time, the phase difference of the display synchronization signal 622 with respect to the imaging sensor synchronization signal 620 is a delay amount 627.

  As described above, the synchronization signal generation unit 202 appropriately advances the timing of the image sensor synchronization signal 600 by a necessary time according to the electronic zoom area, that is, the magnification of the electronic zoom and the electronic zoom center position, so that the image reading 603 is written 601. The delay amount of the display synchronization signal 602 with respect to the imaging sensor synchronization signal 600 can be controlled to the minimum.

  As described above, whatever part of the original image the image area to be enlarged by the electronic zoom is, the part that is read out earliestly among the image areas to be electronic zoomed is written at a timing earlier than the readout timing. As shown, the image sensor synchronization signal is advanced and the image signal is written to the memory. As for the advance time of the imaging sensor synchronization signal, for example, the time until writing of the first line of the display target region is completed from the timing of the original imaging sensor synchronization signal, and the advance time may be used. If the writing rate of image data is W (line / unit time) and the first line to be displayed is the nth line from the first line of the original image, n / W is the advance time. On the contrary, regardless of the part of the original image that is enlarged by electronic zoom, the part that is read out the earliest of the electronic zoom target image area is written at a timing earlier than the readout timing. Thus, the display synchronization signal is delayed and the image signal is read from the memory. In this case, the read time delay time is also n / W.

  Regarding the main scanning direction, the timing control in the sub-scanning direction in FIG. 6 is similarly applied to the main scanning direction, so that the writing of the image data to the enlargement target area is overtaken by the reading of the image data in that area. Can be prevented. In this case, “line” is read as, for example, “pixel”, the synchronizing signal in the sub-scanning direction is changed to the corresponding synchronizing signal in the main scanning direction, and the read / write timing is changed from the timing in the sub-scanning direction to the main scanning direction. Should be read as timing.

  In the third embodiment, scanning is performed from the upper end to the lower end of the image. When scanning from the lower end to the upper end, the reverse is true, but the timing of the image sensor synchronization signal 600 can be determined similarly.

[Embodiment 4]
Hereinafter, an imaging apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. The difference from the second embodiment is that the center of the electronic zoom is the center of the image in the second embodiment, but the center of the electronic zoom is other than the center of the image in the fourth embodiment. There is also a point. In the second embodiment, it is determined how much the image reading speed from the image sensor 200 is increased and the image reading period is shortened according to the magnification of the electronic zoom. The feature is that the image reading speed and image reading period of the image sensor are determined in consideration of the center position of the image sensor. FIGS. 7A, 7B, and 7C are diagrams illustrating the timing of image reading and writing by the memory writing unit 202 and the memory reading unit 204 when the center position of the electronic zoom is different. FIG. 7A shows the case where the center of the electronic zoom is the center of the image, FIG. 7B shows the case where the center of the electronic zoom is above the center of the image, and FIG. 7C shows the center of the electronic zoom. An example is shown below the center.

  The imaging sensor synchronization signal 700 in FIG. 7A exists at regular intervals. A write timing 701 represents a write timing by the memory writing unit 202. The display synchronization signal 702 exists at regular intervals. Memory read timing 703 represents the memory read timing by the memory read unit 204. An area 704 represents a vertical image area written by the writing unit 202. Access is made from the upper end to the lower end of the image at the write timing 701.

  An image area 708 in FIG. 7A represents a vertical image area read by the memory reading unit 204. The center 709 is the center of the electronic zoom, and is the center of the written image area 704 in FIG. In this case, the synchronization signal generation unit 202 controls the image reading speed from the imaging sensor 200, sets the image reading period from the imaging sensor 200, that is, the memory writing period of the read image data as the period 705, and the memory reading 703 is the memory writing 701. Guarantee that you will not overtake. At this time, the phase difference of the display synchronization signal 702 with respect to the imaging sensor synchronization signal 700 is the phase difference 707 and can be made constant regardless of the electronic zoom magnification and the electronic zoom center position.

  An image area 718 in FIG. 7B represents a vertical image area read by the memory reading unit 204. A center 719 is the center of the electronic zoom. The readout area 718 is closer to the upper end side of the image area 704 than the readout area 708 in FIG. The center 719 of the electronic zoom is also located above the center of the image area 704 and the center 709 of the electronic zoom in FIG. That is, the center and the area of the electronic zoom are close to the upper end side of the image. In this case, the synchronization signal generation unit 202 controls the image reading speed from the imaging sensor 200, sets the image reading period, that is, the memory writing period to the period 715, and ensures that the memory reading timing 713 does not pass the memory writing timing 711. At this time, the phase difference of the display synchronization signal 712 with respect to the imaging sensor synchronization signal 710 is the phase difference 717, and can be made constant regardless of the electronic zoom magnification and the electronic zoom center position.

  An image area 728 in FIG. 7C represents a vertical image area read by the memory reading unit 204. A center 729 is the center of the electronic zoom. The readout area 728 is closer to the lower end side of the image area 704 than the readout area 708 in FIG. The center 729 of the electronic zoom is also located below the center of the image area 704 and the center 709 of the electronic zoom shown in FIG. That is, the center and area of the electronic zoom are close to the lower end side of the image. In this case, the synchronization signal generation unit 202 controls the image reading speed from the image sensor 200, sets the image reading period, that is, the memory writing period to the period 725, and ensures that the memory reading 723 does not overtake the memory writing 721. At this time, the phase difference of the display synchronization signal 722 with respect to the imaging sensor synchronization signal 720 is the phase difference 727, and can be made constant regardless of the electronic zoom magnification and the electronic zoom center position.

  As described above, whatever part of the original image the image area to be enlarged by the electronic zoom is, the part that is read out earliestly among the image areas to be electronic zoomed is written at a timing earlier than the readout timing. As described above, the reading rate of the image signal from the image sensor 200 and the memory writing rate are increased to write the image signal into the memory. These rates are assumed to be the same value, and will be referred to as a memory write rate in the following description. The degree to which the memory writing rate is increased is, for example, estimated from the timing of the original imaging sensor synchronization signal and the original memory writing rate, to the writing completion timing until the writing of the first line of the display target area is completed. If the write completion timing is delayed with respect to the display synchronization signal, the memory write rate may be increased so that the write completion timing is advanced at least by the delay time. For example, the writing rate of the original image data is W (line / unit time), and the first line to be displayed is the nth line from the first line of the original image. In this case, n / W is the time required to write the nth line from the imaging sensor synchronization signal. If the initial phase difference 707 between the imaging sensor synchronization signal and the display synchronization signal is Tp, W may be determined so that n / W ≦ Tp. That is, W ≧ n / Tp. Since there is an upper limit to the memory write rate, Wmax ≧ n / Tp when the enlargement rate is maximized and the region to be enlarged is at the lowest position (that is, when n is maximized) is the memory write rate. It is necessary to determine Tp so as not to exceed the upper limit.

  Regarding the main scanning direction, the timing control in the sub-scanning direction of FIG. 7 is similarly applied to the main scanning direction, so that the writing of the image data to the enlargement target area is overtaken by the reading of the image data in that area. Can be prevented. In this case, “line” is read as, for example, “pixel”, the synchronizing signal in the sub-scanning direction is changed to the corresponding synchronizing signal in the main scanning direction, and the read / write timing is changed from the timing in the sub-scanning direction to the main scanning direction. Should be read as timing.

  As described above, the synchronization signal generation unit 202 controls the image reading speed from the image sensor 200 (and the writing speed of the image data to the memory) according to the electronic zoom area, that is, the electronic zoom magnification and the electronic zoom center position. The image reading timing 703 can be controlled so as not to pass the writing timing 701, and the delay amount of the display synchronization signal 702 with respect to the imaging sensor synchronization signal 700 can be reduced to a constant and minimum.

  In the fourth embodiment, scanning is performed in the direction from the upper end to the lower end of the image. When scanning from the lower end to the upper end, the reverse is true, but the image reading speed from the image sensor 200 can be similarly controlled. As a result, the image reading 703 is controlled so as not to overtake the writing 701, and the delay amount of the display synchronization signal 702 with respect to the imaging sensor synchronization signal 700 can be reduced to a constant and minimum.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 Image sensor synchronization signal, 101 Memory write timing, 102 Display synchronization signal, 103 Memory read timing, 104 Image vertical readout area (normal time), 105 Image sensor synchronization signal period, 106 Display synchronization signal period, 107 Phase difference (delay amount) between imaging sensor synchronization signal and display synchronization signal, 118 Image vertical readout area (when enlarged), 119 Center of magnification

Claims (11)

Imaging means for outputting image data of the captured image;
Storage means for storing the image data output from the imaging means;
A scaling unit for performing an enlargement process on the image data stored in the storage unit;
Display means for displaying the image data enlarged by the scaling means;
Image data is output from the imaging unit so that writing of the image data of the region to be scaled by the scaling unit to the storage unit is not overtaken by reading the image data of the region from the storage unit. An image pickup apparatus comprising: synchronization signal generating means for generating a synchronization signal for generating the synchronization signal. The synchronization signal generating unit changes a reading speed of image data read from the storage unit for display according to a screen size of the display unit, and starts writing image data from the imaging unit. The phase difference between the synchronization signal and the synchronization signal for starting the reading of the image data to the scaling unit is written to the storage unit in the image data of the region where the phase difference is scaled by the scaling unit. 2. The imaging apparatus according to claim 1, wherein the synchronization signal is generated so as to have a phase difference that is not overtaken by reading out image data of a region from the storage unit. The imaging apparatus according to claim 2, wherein the synchronization signal generation unit accelerates a synchronization signal for starting writing of image data from the imaging unit due to the phase difference. The imaging apparatus according to claim 2, wherein the synchronization signal generation unit delays a synchronization signal for starting reading of image data to the scaling unit due to the phase difference. The synchronization signal generating unit changes a reading speed of image data read from the storage unit for display according to a screen size of the display unit, and starts writing image data from the imaging unit. The phase difference between the synchronizing signal and the synchronizing signal for starting the reading of the image data to the scaling unit is kept constant, and the image data of the area to be scaled by the scaling unit is written to the storage unit The imaging apparatus according to claim 1, wherein the image data writing speed from the imaging unit to the storage unit is increased so as not to be overtaken by reading the image data of the area from the storage unit. . The imaging means outputs the image data in units of frames,
The imaging apparatus according to claim 1, wherein a center of the region coincides with a center of the frame. The imaging means outputs the image data in units of frames,
The imaging apparatus according to claim 1, wherein the center of the region does not always coincide with the center of the frame. The image data is output from the imaging unit in the order of raster scanning and displayed by the display unit, and the synchronization signal generation unit changes at least the synchronization signal of the image data in the sub-scanning direction by the scaling unit. The imaging device according to claim 1, wherein the imaging device is generated according to a region to be multiplied. 9. The imaging apparatus according to claim 8, wherein the synchronization signal generation unit generates at least a synchronization signal in the main scanning direction of the image data according to a region to be scaled by the scaling unit. Imaging means for outputting image data of the captured image;
Storage means for storing the image data output from the imaging means;
A scaling unit for performing an enlargement process on the image data stored in the storage unit;
In an imaging apparatus having display means for displaying image data enlarged by the scaling means,
Image data is output from the imaging unit so that writing of the image data of the region to be scaled by the scaling unit to the storage unit is not overtaken by reading the image data of the region from the storage unit. A method for controlling an imaging apparatus, characterized by generating a synchronization signal for the purpose. A computer having an imaging means for outputting image data of the captured image;
Storage means for storing the image data output from the imaging means;
A scaling unit for performing an enlargement process on the image data stored in the storage unit;
Display means for displaying the image data enlarged by the scaling means;
Image data is output from the imaging unit so that writing of the image data of the region to be scaled by the scaling unit to the storage unit is not overtaken by reading the image data of the region from the storage unit. A program for functioning as a synchronization signal generating means for generating a synchronization signal.

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