JP4987800B2 - Imaging device - Google Patents

Description

  The present invention relates to an image pickup apparatus that uses a margin of a bus bandwidth that is provided by means for compressing / decompressing a bus through which an image passes in order to temporarily store an image obtained by an image pickup device.

  In recent digital still cameras, the number of pixels and the continuous shooting speed are remarkably improved, and HD (High Definition) is also progressing in digital video cameras, and the amount of data processed per unit time is increasing year by year.

  When processing images with such a large amount of data, the bus bandwidth that can be handled by the storage unit, which is indispensable for processing images during continuous shooting, is not only speeding up the circuit, but also the rules of processing performance. It is often a condition.

In order to cope with this, connecting a large number of storage units or increasing the processing frequency directly leads to an increase in cost and power.
In particular, in a digital camera, it is possible to simultaneously capture still images of over 10 million pixels while always displaying HD video, while handling a large amount of data compared to conventional SD (Standard Definition) video display, and Since it is necessary to perform multi-pixel still image processing in parallel, more powerful processing performance is required. Also, when recording an image with a digital camera, JPEG compression is usually performed. However, in order to perform recording within a predetermined amount of data on a recording medium, the recording can be performed by repeating the JPEG compression process several times. It is necessary to determine a quantization table suitable for the target image, which increases the processing time per image and hinders continuous shooting speed improvement.

  Therefore, for example, by referring to the quantization table created at the time of image display at the time of image recording, the entire processing time is shortened by the creation time of the quantization table for image recording, and the processing time with the margin is used for continuous processing. The creation time of the quantization table for image recording is shortened by improving the shooting speed (see, for example, Patent Document 1) and by predicting the quantization table prior to shooting, and the processing time in which the margin is generated is used. Therefore, it is conceivable to improve the continuous shooting speed (for example, see Patent Document 2).

In addition, as an example of performing high-quality image display while suppressing an increase in power consumption and heat generation, for example, by compressing a display image sent from the image processing device to the display device, between the image processing device and the display device There are some which reduce the data amount of the display image sent by (see, for example, Patent Document 3).
JP 2002-112086 A JP 2002-247517 A JP 2004-104222 A

  However, as described above, when referring to the quantization table created at the time of image display at the time of image recording, or when predicting the quantization table prior to shooting, as shown in FIG. If the angle of view of the image displayed on the screen is the same, the quantization table at the time of image display can be referred to at the time of image recording or the quantization table can be predicted. When the angle of view is different from the image displayed on the screen, that is, as shown in FIG. 10, an image obtained by the image sensor is recorded in a state where a part of the image displayed on the display is enlarged by electronic zoom or the like. In this case, there is a problem that the display image and the recorded image do not match and the quantization table cannot be referred to or predicted.

  As described above, when a display image sent from the image processing device to the display device is compressed, it is effective for reducing the data amount of the display image sent between the image processing device and the display device. In recent years, it is not effective in reducing the bus bandwidth of the storage unit for temporarily storing images, and the bus bandwidth of the storage unit is often a rule condition of the processing speed.

  Therefore, the present invention can use a quantization table generated at the time of image display as a quantization table used at the time of image recording even when the angle of view differs between the image obtained by the image sensor and the display image. An object is to provide an imaging device.

In order to solve the above problems, the present invention adopts the following configuration.
That is, the image pickup apparatus of the present invention has an image pickup device, a photographing shutter that starts recording preparation or recording processing of an image obtained by the image pickup device when pressed by a photographer, and a memory that stores an input image. A display unit that displays an input image, a resizing unit that changes the size of the input image, and image processing that performs image processing on the input image and sends the processed image to the storage unit via a bus A display compression unit that compresses an image after image processing sent from the storage unit via the bus and sends the image to the storage unit via the bus, and is sent from the storage unit via the bus A display decompression unit that decompresses the compressed image, and an image that is sent to the resizing unit is switched to either an image obtained by the imaging device or an image sent from the display decompression unit. A second bus switching unit for switching an image to be sent to the image processing unit to either an image sent from the resizing unit or an image obtained by the imaging device, and to the display unit A third bus switching unit that switches the image to be sent to either the image sent from the display expansion unit or the image sent from the resize unit, a recording unit for recording the input image, and the bus And a recording compression unit that compresses an image after image processing sent from the storage unit and sends it to the recording unit, and the display compression unit is used for display compression used when compressing an input image A quantization table for recording compression used in the recording compression unit is generated with reference to the quantization table, and each of the first to third bus switching units does not press the photographing shutter. An image obtained by the imaging device is input to the resizing unit, an image sent from the resizing unit is input to the image processing unit, and an image sent from the display decompression unit is input to the display unit. When the image capturing shutter is pressed, an image obtained by the image sensor is input to the image processing unit, and an image sent from the display expansion unit is input to the resizing unit. The image is switched so that the image sent from the resizing unit is input to the display unit.

  Further, the display compression unit displays the display compression rate during the recording period of the image after the image processing, the display compression rate when the photographing shutter is not pressed, or the display compression during the recording preparation period of the image after the image processing. You may comprise so that it may become higher than a rate.

  According to the present invention, even when the angle of view differs between the image captured by the image sensor and the display image, the quantization table created at the time of image display can be referred to at the time of image recording, and the processing time when there is a margin can be reduced. This can improve the continuous shooting speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an imaging apparatus according to an embodiment of the present invention.
An image pickup apparatus 1 shown in FIG. 1 includes an image pickup device 2, a photographing shutter 3, a storage unit 4, a display unit 5, a resize unit 6, an image processing unit 7, a display compression unit 8, and a display expansion unit 9. The bus switching units 10 to 12, the recording unit 13, the recording compression / expansion unit 14, the display enlargement / reduction control unit 15, the bus 16, and the CPU 17.

  The imaging element 2 is configured by, for example, a CCD (Charged Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like, and sends out an image obtained by imaging a subject.

When the photographing shutter 3 is pressed by the photographer, it outputs a signal indicating that to the CPU 17.
The storage unit 4 is configured by, for example, a DRAM (Dynamic Random Access Memory), an SDRAM (Synchronous DRAM), or a DDR SDRAM (Double Data Rate SDRAM), and is sent from the image sensor 2 and the image processing unit 7. An image sent from the display compression unit 8, an image sent from the display decompression unit 9, or an image sent from the recording compression / decompression unit 14.

The display unit 5 is composed of, for example, an LCD (Liquid Crystal Display) or the like, and displays an input image.
The resizing unit 6 changes the size of the input image.

The image processing unit 7 performs predetermined image processing such as Bayer interpolation processing, color matrix conversion processing, and edge enhancement processing on the input image.
The display compression unit 8 performs JPEG compression on the image after image processing sent from the storage unit 4 via the bus 16.

The display decompression unit 9 decompresses the compressed image sent from the storage unit 4 via the bus 16.
The bus switching unit 10 selects an image to be sent to the resizing unit 6 as either an image obtained by the imaging device 2 (an image sent from the imaging device 2 to the storage unit 4) or an image sent from the display expansion unit 9. Switch to.

The bus switching unit 11 switches the image sent to the image processing unit 7 to either the image sent from the resizing unit 6 or the image obtained by the imaging device 2.
The bus switching unit 12 switches the image sent to the display unit 5 to either the image sent from the display decompression unit 9 or the image sent from the resizing unit 6.

The recording unit 13 is configured by, for example, a flash memory or the like, and records an input image.
The recording / compression / decompression unit 14 JPEG-compresses the image after image processing sent from the storage unit 4 via the bus 16 and stores the image via the bus 16 (temporarily stores it in the storage unit 4 and then again via the bus 16). The image is sent to the recording unit 13 or an image recorded on the recording unit 13 is expanded and sent to the display unit 5.

  The display enlargement / reduction control unit 15 outputs an instruction to enlarge or reduce the image displayed on the display unit 5 to the CPU 17 based on the operation of an operation button (not shown) by the photographer, and is displayed on the display unit 5. Change the size of the image.

  The CPU 17 controls various operations of the imaging apparatus 1 based on a signal indicating the state of the photographing shutter 3 output from the photographing shutter 3 and a display enlargement / reduction instruction output from the display enlargement / reduction controller 15.

  For example, the CPU 17 outputs a switching signal to each of the bus switching units 10 to 12 and outputs an image to be sent to the resizing unit 6 when the photographing shutter 3 is not pressed and there is no instruction for image enlargement / reduction. The image obtained by the image sensor 2 is switched, the image sent to the image processing unit 7 is switched to the image sent from the resizing unit 6, and the image sent to the display unit 5 is changed to an image sent from the display expansion unit 9. Only the image obtained by the image sensor 2 is displayed on the display unit 5 (setting state (1)). The operation period of the imaging apparatus 1 at this time is hereinafter referred to as “display only period”.

  Further, the CPU 17 presses the photographing shutter 3 halfway (a state where the photographing shutter 3 is pushed to a depth of about half of the state where the photographing shutter 3 is not pushed down to the bottom) and enlarges the display of the image. When there is an instruction to reduce / reduce, a switching signal is output to each of the bus switching units 10 to 12, the image to be sent to the image processing unit 7 is switched to the image obtained by the image sensor 2, and the image to be sent to the resizing unit 6 is displayed. The image sent from the decompression unit 9 is switched to the image sent to the display unit 5 and the image sent from the resizing unit 6 is switched to prepare for recording an image obtained by the image sensor 2 (AF (Auto Focus) or AE). (Shooting assisting action such as (Auto Exposure)) is performed (setting state (2)). The operation period of the imaging apparatus 1 at this time is hereinafter referred to as “recording preparation period”.

  Further, the CPU 17 switches to the bus switching units 10 to 12 when the photographing shutter 3 is fully pressed (the photographing shutter 3 is pushed down to the lowest position) and there is an image display enlargement / reduction instruction. A signal is output, the image sent to the image processing unit 7 is switched to the image obtained by the imaging device 2, the image sent to the resizing unit 6 is switched to the image sent from the display decompression unit 9, and the display unit 5 The image to be sent is switched to the image sent from the resizing unit 6 so that the image obtained by the image sensor 2 is recorded (setting state (3)). The operation period of the imaging apparatus 1 at this time is hereinafter referred to as “recording period”.

Note that the CPU 17 executes the setting state (1) even when the photographing shutter 3 is half-pressed or fully pressed when there is no instruction to enlarge or reduce the display of the image.
FIG. 2 is a diagram illustrating the display compression unit 8.

The display compression unit 8 illustrated in FIG. 2 includes a compression unit 18, quantization table generation units 19 and 20, and a compression amount detection unit 21.
The quantization table generating unit 19 includes a display table 19-1, a scaling factor (hereinafter referred to as SF) 19-2 for multiplying the quantization table by an arbitrary magnification and changing the magnification, a magnification determining unit 19-3, and a display. A compression quantization table 19-4 and a multiplier 19-5 are provided.

The quantization table generation unit 20 includes a recording table 20-1, an SF 20-2, a recording / compression quantization table 20-3, and a multiplier 20-4.
Note that the display table 19-1, the display compression quantization table 19-4, the recording table 20-1, and the recording compression quantization table 20-3 are tables each having an 8 × 8 array, for example. It is assumed that initialization is performed by the CPU 17 when the imaging apparatus 1 is turned on.

FIG. 3 is a diagram illustrating the compression unit 18.
The compression unit 18 illustrated in FIG. 3 includes a DCT conversion unit 18-1, a quantization unit 18-2, and a Huffman coding unit 18-3.

  The compression unit 18 performs a DCT operation on the “image before display compression” output from the image processing unit 7 and converts it from the time domain to the frequency domain by the DCT conversion unit 18-1. 2, quantization processing is performed using the display compression quantization table 19-4 generated by the quantization table generation unit 19, and Huffman coding based on the occurrence frequency is performed in the Huffman coding unit 18-3. Do.

In FIG. 2, the compression amount detection unit 21 detects a compression amount for each image compressed by the compression unit 18, and outputs the detected compression amount to the magnification determination unit 19-3.
The magnification determining unit 19-3 determines whether or not the compression amount output from the compression amount detection unit 21 is within the appropriate range, and when determining that the compression amount is within the appropriate range, SF19-2 An instruction signal for instructing selection of a magnification for compression is output.

In addition, the SF 19-2 selects a magnification corresponding to the instruction signal output from the SF 19-2 from among a plurality of preset magnifications, and outputs the selected magnification to the multiplier 19-5.
The multiplier 19-5 multiplies each parameter of the display table 19-1 by the magnification output from the SF 19-2 to generate a display compression quantization table 19-4. This display compression quantization table 19-4 is updated as a display table 19-1 used when the next display compression quantization table 19-4 is generated.

  Further, the multiplier 20-4 of the quantization table generation unit 20 uses each parameter of the display compression quantization table 19-4 output from the quantization table generation unit 19 at a predetermined magnification output from the SF 20-2. , The recording compression quantization table 20-3 is generated and output to the recording compression / decompression unit 14. Note that the magnification output from the SF 20-2 may be the same as or different from the magnification output from the SF 19-2.

FIG. 4 is a diagram showing the recording compression / decompression unit 14. In addition, the same code | symbol is attached | subjected to the same structure as the structure shown in FIG.
The recording compression / expansion unit 14 shown in FIG. 4 includes a DCT conversion unit 18-1, a quantization unit 18-2, a Huffman encoding unit 18-3, and an expansion unit 14-1.

  The recording compression / decompression unit 14 performs JPEG compression processing on the “image before recording compression” sent from the image processing unit 7 in the same manner as the display compression unit 8, and then performs storage unit 4 via the bus 16. To send. In this compression processing, the recording compression quantization table 20-3 generated by the display compression unit 8 is used. The recording compression / decompression unit 14 performs an expansion process on the image read from the recording unit 13 via the bus 16 in the expansion unit 14-1, and then sends the image to the display unit 5. This decompression process is the reverse of the JPEG compression process, that is, Huffman decoding, inverse quantization, and inverse DCT transform are sequentially performed on the image read from the recording unit 13.

FIG. 5 is a diagram for explaining the operation of each of the bus switching units 10 to 12.
As illustrated in FIG. 5, the bus switching unit 10 causes the resizing unit 6 to transmit an image obtained by the imaging device 2 by connecting the terminal A and the terminal C in the “display only period”. Further, the bus switching unit 10 causes the resizing unit 6 to send the image sent from the display expansion unit 9 by connecting the terminal B and the terminal C in the “recording preparation period” or “recording period”.

  Further, the bus switching unit 11 causes the image processing unit 7 to send an image sent from the resizing unit 6 by connecting the terminal E and the terminal F in the “display only period”. Further, the bus switching unit 11 causes the image processing unit 7 to transmit an image obtained by the imaging device 2 by connecting the terminal D and the terminal F in the “recording preparation period” or the “recording period”.

  Further, the bus switching unit 12 causes the display unit 5 to transmit an image transmitted from the display expansion unit 9 by connecting the terminal G and the terminal I in the “display only period”. Further, the bus switching unit 12 causes the display unit 5 to send an image sent from the resizing unit 6 by connecting the terminal H and the terminal I in the “recording preparation period” or “recording period”.

  As a result, the image compressed by the display compression unit 8 in the “display only period” is an image whose size has been changed by the resize unit 6 (“image after resizing”). Therefore, the bandwidth of the bus 16 in the “display only period” is reduced, and the continuous shooting speed can be improved using the reduced bandwidth of the bus 16.

  In addition, the image compressed by the display compression unit 8 in the “recording preparation period” or “recording period” is an image before the size is changed by the resizing unit 6 (“image before resizing”). Therefore, the recording compression quantization table 20-3 can be generated with reference to the display compression quantization table 19-4 in the “recording preparation period” or the “recording period”, thereby reducing the recording processing time. The continuous shooting speed can be improved by using the shortened processing time.

FIG. 6A is a diagram for explaining an operation flow of the imaging apparatus 1 in the “display only period”.
First, the image sensor 2 sends an image obtained by imaging a subject to the storage unit 4 via the bus 16.

  Next, the resizing unit 6 reads out an image stored in the storage unit 4 via the bus 16 and changes the size of the image based on an instruction sent from the display enlargement / reduction control unit 15. In the present embodiment, the image size is changed by the resizing unit 6 so that the data amount of the image after the size change is 1/16 of the data amount of the image before the size change. Shall be.

Next, the image processing unit 7 performs image processing such as Bayer interpolation processing, color matrix conversion processing, and edge enhancement processing on the image whose size has been changed by the resizing unit 6.
Next, the display compression unit 8 performs JPEG compression on the image processed by the image processing unit 7 and then sends the image to the storage unit 4 via the bus 16. In the present embodiment, the display compression of the display compression unit 8 is performed so that the data amount of the image after the display compression process is １ ／ of the data amount of the image before the display compression process is performed. Assume that the rate is set.

Next, the display decompression unit 9 reads the image compressed by the display compression unit 8 from the storage unit 4 via the bus 16, performs decompression processing on the image, and sends the image to the display unit 5.
The display unit 5 displays the image expanded by the display expansion unit 9.

  In the “display only period” in the imaging apparatus 1 of the present embodiment, the image obtained by the imaging device 2 is immediately resized, and then image processing, display compression, and display expansion are performed. When the image data amount is A [MB / s], the image data amount sent from the image sensor 2 to the storage unit 4 is A [MB / s], and the image data sent from the storage unit 4 to the resize unit 6 Data amount is A [MB / s], the image data amount sent from the display compression unit 8 to the storage unit 4 is A / 80 [MB / s], and the image amount sent from the storage unit 4 to the display decompression unit 9 The data amount is A / 80 [MB / s], and the bandwidth of the bus 16 is A + A + A / 80 + A / 80 = 81 A / 40 [MB / s].

  On the other hand, in the “display only period” in the conventional imaging device (an imaging device having a configuration other than the display compression unit 8, the display expansion unit 9, and the bus switching units 10 to 12 shown in FIG. 1), as shown in FIG. 7A. After the image obtained by the image sensor 2 is sent to the storage unit 4 via the bus 16, the image processing unit 7 performs image processing on the image read from the storage unit 4 via the bus 16. The image is sent to the storage unit 4 via the bus 16 and is resized on the image read from the storage unit 4 via the bus 16 by the resizing unit 6 and displayed on the display unit 5. Therefore, the data amount of the image sent from the image sensor 2 to the storage unit 4 is A [MB / s], the data amount of the image sent from the storage unit 4 to the image processing unit 7 is A [MB / s], and the image The data amount of the image sent from the processing unit 7 to the storage unit 4 is A [MB / s], the data amount of the image sent from the storage unit 4 to the resizing unit 6 is A [MB / s], and the bus 16 Is A + A + A + A = 4A = 160 A / 40 [MB / s].

  Therefore, as shown in FIG. 8, in the “display only period”, the bandwidth (81A / 40) of the bus 16 in the imaging device 1 of the present embodiment is greater than the bandwidth (160A / 40) of the bus 16 in the conventional imaging device. Can also be reduced.

FIG. 6B is a diagram for explaining an operation flow of the imaging apparatus 1 in the “recording preparation period”.
First, the image sensor 2 sends an image obtained by imaging a subject to the storage unit 4 via the bus 16.

  Next, the image processing unit 7 reads the image stored in the storage unit 4 via the bus 16 and performs image processing such as Bayer interpolation processing, color matrix conversion processing, and edge enhancement processing on the image.

  Next, the display compression unit 8 performs JPEG compression on the image processed by the image processing unit 7 and sends the image to the storage unit 4 via the bus 16. In the present embodiment, the display compression rate of the display compression unit 8 is set so that the data amount of the image after the display compression process is 1/5 of the data amount of the image before the display compression process. Shall.

Next, the display decompression unit 9 reads an image stored in the storage unit 4 via the bus 16 and performs decompression processing on the image.
Next, the resizing unit 6 changes the size of the image expanded by the display expansion unit 9 and sends it to the display unit 5.

Then, the display unit 5 displays the image whose size has been changed by the resizing unit 6.
In the “recording preparation period” in the image pickup apparatus 1 of the present embodiment, image processing, display compression, and display expansion are performed on the image obtained by the image pickup element 2 and then the image is resized. The image data amount sent to the unit 4 is A [MB / s], the data amount of the image sent from the storage unit 4 to the image processing unit 7 is A [MB / s], and the display compression unit 8 to the storage unit 4 The data amount of the image sent to the display unit is A / 5 [MB / s], the data amount of the image sent from the storage unit 4 to the display expansion unit 9 is A / 5 [MB / s], and the bandwidth of the bus 16 Becomes A + A + A / 5 + A / 5 = 12 A / 5 = 96 A / 40 [MB / s].

  On the other hand, in the “recording preparation period” in the conventional imaging apparatus, image processing is performed on the image obtained by the imaging element 2 as in the “display only period” in the conventional imaging apparatus described above (see FIG. 7A). After that, to resize and display, the data amount of the image sent from the image sensor 2 to the storage unit 4 is A [MB / s], and the data amount of the image sent from the storage unit 4 to the image processing unit 7 is A. [MB / s], the data amount of the image sent from the image processing unit 7 to the storage unit 4 is A [MB / s], and the data amount of the image sent from the storage unit 4 to the resize unit 6 is A [MB / s s], and the bandwidth of the bus 16 is A + A + A + A = 4A = 160 A / 40 [MB / s].

  Therefore, as shown in FIG. 8, in the “recording preparation period”, the bandwidth (96A / 40) of the bus 16 in the imaging device 1 of the present embodiment is also larger than the bandwidth (160A / 40) of the bus 16 in the conventional imaging device. Can also be reduced.

  FIG. 6C is a diagram for describing the flow of the operation of the imaging apparatus 1 in the “recording period”. The display operation from when the image is sent from the image sensor 2 to when the image is displayed on the display unit 5 is the same as the display operation of the image pickup apparatus 1 during the “recording preparation period” shown in FIG. Here, only the recording operation from when the image is sent from the image sensor 2 to when the image is recorded in the recording unit 13 will be described.

First, the image sensor 2 sends an image obtained by imaging a subject to the storage unit 4 via the bus 16.
Next, the image processing unit 7 reads the image stored in the storage unit 4 via the bus 16 and performs image processing such as Bayer interpolation processing, color matrix conversion processing, and edge enhancement processing on the image.

  Next, the recording compression / decompression unit 14 performs JPEG compression on the image processed by the image processing unit 7 and stores it in the storage unit 4 via the bus 16. In the present embodiment, the recording compression rate of the recording compression / expansion unit 14 is set so that the data amount of the image after the recording compression process is 1/5 of the data amount of the image before the recording compression process. It shall be.

Then, an image stored in the storage unit 4 is read out via the bus 16 and then recorded in the recording unit 13.
Also in the “recording period” of the imaging device 1 of the present embodiment, the image obtained by the imaging device 2 is subjected to image processing, display compression, and display expansion, and then resized. Therefore, the image data amount sent from the image sensor 2 to the storage unit 4 is A [MB / s], and the data amount of the image sent from the storage unit 4 to the image processing unit 7 is A [MB / s]. The data amount of the image sent from the compression unit 8 to the storage unit 4 is A / 5 [MB / s], and the data amount of the image sent from the storage unit 4 to the display decompression unit 9 is A / 5 [MB / s]. The data amount of the image sent from the recording compression / decompression unit 14 to the storage unit 4 is A / 5 [MB / s], and the data amount of the image sent from the storage unit 4 to the recording unit 13 is A / 5 [MB / s]. s], and the bandwidth of the bus 16 is A + A + A / 5 + A / 5 + A / 5 + A / 5 = 14A / 5 = 112A / 40 [MB / s].

  On the other hand, in the “recording period” in the conventional imaging apparatus, as shown in FIG. 7B, the image obtained by the imaging device 2 is subjected to image processing and then resized and displayed. Further, the image obtained by the image sensor 2 is subjected to image processing and then compressed and recorded. Therefore, when the data amount of the image after the recording / compression process is 1/5 of the data amount of the image before the recording / compression process, the data amount of the image sent from the image sensor 2 to the storage unit 4 is A [MB / s. The data amount of the image sent from the storage unit 4 to the image processing unit 7 is A [MB / s], the data amount of the image sent from the image processing unit 7 to the storage unit 4 is A [MB / s], The data amount of the image sent from the storage unit 4 to the resizing unit 6 is A [MB / s], the data amount of the image sent from the recording compression / decompression unit 14 to the storage unit 4 is A / 5 [MB / s], The data amount of the image sent from the storage unit 4 to the recording unit 13 is A / 5 [MB / s], and the bandwidth of the bus 16 is A + A + A + A + A / 5 + A / 5 = 22A / 5 = 176 A / 40 [MB / s]. become.

  Therefore, as shown in FIG. 8, in the “recording period”, the bandwidth (112A / 40) of the bus 16 in the imaging device 1 of the present embodiment is larger than the bandwidth (176A / 40) of the bus 16 in the conventional imaging device. Can be small.

  In the imaging apparatus 1 according to the present embodiment, display compression is performed on an image after image processing, the image is stored in the storage unit 4, and the image stored in the storage unit 4 is expanded. Therefore, the bandwidth of the bus 16 can be reduced, and the continuous shooting speed can be improved using the reduced bandwidth of the bus 16.

  In the imaging apparatus 1 of the present embodiment, the recording compression quantization table 20-3 generated based on the display compression quantization table 19-4 that is updated in units of frames is used to generate a recording image. On the other hand, since JPEG compression is performed, two steps are usually required: a step for generating a recording compression quantization table and a step for performing JPEG compression using the recording compression quantization table. However, since only one step of performing JPEG compression using the recording compression quantization table 20-3 can be performed, the time required to record one frame of image can be reduced, and the reduced time can be reduced. This can improve the continuous shooting speed.

  In the imaging apparatus 1 of the present embodiment, image processing, display compression, and display expansion are performed after resizing the image in the “display only period”, so image processing, display compression, and display expansion are performed. After that, the number of pixels to be processed in each of image processing, display compression, and display expansion can be reduced, and the bandwidth of the bus 16 can be reduced accordingly. it can. Thereby, the continuous shooting speed can be further improved by utilizing the reduced bandwidth of the bus 16. The reduced bandwidth of the bus 16 is used to improve the display image quality by using the image processing by repeating the transfer of the image data a plurality of times from the storage unit 4 when processing one image. Also good.

  In the imaging apparatus 1 of the present embodiment, the image is resized after performing image processing, display compression, and display expansion in the “recording preparation period” or “recording period”, so that the image is displayed on the display unit 5. Recording compression quantization table 20-3 generated based on display compression quantization table 19-4, even if the angle of view is different between the captured image and the image actually obtained by image sensor 2. Can be used to perform display compression.

  In addition, the image displayed on the display unit 5 in the “recording period” is used to check whether the subject is accurately captured, for example, whether the angle of view is not deviated at the moment when the photographing shutter 3 is pressed. Therefore, the information value is lower than the image displayed on the display unit 5 in the “display only period” or “recording preparation period”. That is, since there is often no problem even if the display compression rate of the display compression unit 8 is increased in the “recording period”, the display of the display compression unit 8 in the “recording period” as shown in FIGS. You may comprise so that a compression rate may become higher than the display compression rate of the display compression part 8 in a "display only period" or a "recording preparation period." In the example shown in FIG. 9, the display compression rate of the display compression unit 8 in the “recording period” is 1/10.

  As a result, since the display compression ratio of the display compression unit 8 in the “recording period” is increased, the bandwidth of the bus 16 can be afforded, so that the surplus can be used for continuous shooting processing and high image quality. In addition, continuous shooting speed and high image quality can be improved.

  Further, in the “display only period” or “recording preparation period”, it is not necessary to record an image in the recording unit 13, so that there is a margin in the bandwidth of the bus 16 compared to the “recording period”. Therefore, as shown in FIG. 5, even if the display compression rate of the display compression unit 8 is lowered in the “display only period” or “recording preparation period”, the bandwidth of the bus 16 does not become a rule condition of the processing performance. A high-quality image can be displayed on the display unit 5. Therefore, the photographer can fully confirm the state of the subject while viewing the image displayed on the display unit 5, or can accurately prepare for photographing.

  In the above embodiment, the bus switching units 10 to 12 are based on the signal indicating the state of the photographing shutter 3 output from the photographing shutter 3 by the CPU 17 and the display enlargement / reduction instruction output from the display enlargement / reduction control unit 15. The switching operation is controlled and the display compression rate of the display compression unit 8 is changed. The signal indicating the state of the photographing shutter 3 output from the photographing shutter 3 and the output from the display enlargement / reduction control unit 15 are output. The displayed enlargement / reduction instruction is directly input to the bus switching units 10-12 and the display compression unit 8 without going through the CPU 17, and the bus switching units 10-12 perform a switching operation or display compression based on those signals and instructions. The unit 8 may change the display compression rate.

It is a figure which shows the imaging device of embodiment of this invention. It is a figure which shows a display compression part. It is a figure which shows a compression part. It is a figure which shows a recording compression expansion part. It is a figure for demonstrating operation | movement of a bus switching part. It is a figure for demonstrating the flow of operation | movement of the imaging device of this embodiment in a "display only period." It is a figure for demonstrating the flow of operation | movement of the imaging device of this embodiment in a "recording preparation period." It is a figure for demonstrating the flow of operation | movement of the imaging device of this embodiment in a "recording period." It is a figure for demonstrating the flow of operation | movement of the conventional imaging device in a "display only period" or a "recording preparation period". It is a figure for demonstrating the flow of operation | movement of the conventional imaging device in a "recording period." It is a figure which shows the bus band of the memory | storage part in the conventional imaging device, and the bus band of the memory | storage part in the imaging device of this embodiment. It is a figure which shows the bus band of the memory | storage part in the conventional imaging device, and the bus band of the memory | storage part in the imaging device of other embodiment. It is a figure which shows the image when not enlarging display, the image when enlarging display, and a recording image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Imaging element 3 Shooting shutter 4 Memory | storage part 5 Display part 6 Resizing part 7 Image processing part 8 Display compression part 9 Display expansion | extension part 10-12 Bus switching part 13 Recording part 14 Recording compression expansion part 15 Display expansion / reduction control Part 16 Bus 17 CPU
18 Compression unit 19, 20 Quantization table generation unit 21 Compression amount detection unit 14-1 Decompression unit 18-1 DCT conversion unit 18-2 Quantization unit 18-3 Huffman encoding unit 19-1 Display table 19-2 SF
19-3 Magnification Determination Unit 19-4 Display Compression Quantization Table 19-5 Multiplier 20-1 Display Table 20-2 SF
20-4 Quantization table for recording compression 20-5 Multiplier

Claims (2)

An image sensor;
A shooting shutter that starts recording preparation processing or recording processing of an image obtained by the imaging device when pressed by a photographer;
A storage unit for storing input images;
A display for displaying the input image;
Resize part to change the size of the input image,
An image processing unit that performs image processing on an input image and sends the image to the storage unit via a bus;
A display compression unit that compresses an image after image processing sent from the storage unit via the bus and sends the compressed image to the storage unit via the bus;
A display decompression unit for decompressing the compressed image sent from the storage unit via the bus;
A first bus switching unit that switches an image to be sent to the resize unit to one of an image obtained by the imaging device or an image sent from the display decompression unit;
A second bus switching unit that switches an image to be sent to the image processing unit to either an image sent from the resizing unit or an image obtained by the imaging device;
A third bus switching unit for switching an image to be sent to the display unit to one of an image sent from the display decompression unit or an image sent from the resizing unit;
A recording unit for recording an input image;
A recording compression unit that compresses an image after image processing sent from the storage unit via the bus and sends the image to the recording unit;
With
The display compression unit generates a recording compression quantization table used in the recording compression unit with reference to a display compression quantization table used when compressing an input image,
In each of the first to third bus switching units, when the photographing shutter is not pressed, an image obtained by the imaging element is input to the resizing unit, and an image sent from the resizing unit is the image The image is switched so that an image input to the processing unit and sent from the display expansion unit is input to the display unit. When the photographing shutter is pressed, an image obtained by the imaging device is the image processing. An image pickup apparatus that switches an image so that an image input from the display and sent from the display decompression unit is input to the resizing unit, and an image sent from the resizing unit is input to the display unit . The imaging apparatus according to claim 1,
The display compression unit displays a display compression rate in the recording period of the image after the image processing from a display compression rate when the photographing shutter is not pressed or a display compression rate in the recording preparation period of the image after the image processing. An imaging device characterized by a higher height.