JP4608186B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging apparatus such as a digital still camera.
[0002]
[Prior art]
In a digital still camera, image data compression processing is performed in order to record image data on a recording medium such as an IC card. A compression method generally used is a JPEG (Joint Photographic Coding Experts Group) compression method, and a high compression rate can be realized. However, in the JPEG compression method, the amount of code after compression changes depending on the content of the original image. In a digital still camera, it is necessary to shoot and record a certain number of images regardless of the contents of the subject, so the code amount after compression must be constant. Therefore, pre-compression is performed in advance before actually compressing the image data (main compression), and an optimum compression parameter for obtaining a desired code amount after compression is calculated, and then the main compression is performed using the compression parameter. The system that performs is adopted. Furthermore, in order to reduce the time required for recording image data, the conventional imaging apparatus performs pre-compression only for the first captured image, and then uses the compression parameters calculated at that time. There is an apparatus that compresses all captured images (for example, see Patent Document 1).
[0003]
FIG. 5 is a timing chart showing the operation of such an imaging apparatus. (1) in FIG. 5 shows the timing of system control in the image pickup apparatus, and (2) in FIG. 5 shows the data write and read timings in the memory (eg, SDRAM) of the image pickup apparatus, and the write address and read out of the SDRAM. Indicates a change in address. In (1) of FIG. 5, “CCD” indicates exposure timing and field signal output timing by the CCD, and “CCDW”, “YCP”, and “JPG” are memories of CCD data (described later), respectively. Write timing, YC data (described later) generation timing, and compression processing timing. In (2) of FIG. 5, a solid arrow indicates a change in address of the SDRAM when data is written, and a broken arrow indicates a change in address of the SDRAM when data is read. In general, in a digital still camera, an output signal of an image sensor (CCD) is A / D converted (hereinafter, the converted data is referred to as “CCD data”) and written in a CCD area of the SDRAM. Then, the CCD data is read from the SDRAM, and YC data including a luminance signal (C) and a color difference signal (Y) is generated using the CCD data. The generated YC data is written in the YC area of the SDRAM. Further, the YC data is read from the SDRAM and subjected to compression processing. Code data obtained by compression is written in the code area of the SDRAM. In the case of continuous shooting, this series of operations is repeated.
[0004]
In FIG. 5, when the release button is pressed (start of continuous shooting), the first exposure is started. The CCD sequentially outputs two field signals for the first captured image (in order of A field and B field). These output signals are converted into digital signals, and are sequentially written in the CCD area of the SDRAM (from the top address of the CCD area) (a). Furthermore, reading of the CCD data from the CCD area starts simultaneously with the writing of the CCD data for the B field (b1). Simultaneously with the reading (b1), YC data is generated using the CCD data, and the generated YC data is written into the YC area of the SDRAM (from the start address of the YC area) (b2). The YC data is read from the YC area at the same time as writing (b2), and preliminary compression is performed (c). Then, compression parameters are calculated based on the result of preliminary compression (c).
[0005]
At this point, the second exposure has already been completed, and writing (d) of the second CCD data to the SDRAM has begun. Thereafter, similarly, second YC data is generated using the second CCD data, and written into the YC area of the SDRAM (e2). At the same time as the second YC data is written, the second YC data is read from the YC area (f1), and the main compression (f) of the YC data is performed. The main compression (f) is performed using a compression parameter calculated based on the result of the preliminary compression (c). Code data (first code data) obtained by the main compression (f) is written into the code area of the SDRAM (from the start address of the code area) (f2). For the image obtained by the subsequent exposure, the main compression is similarly performed using the compression parameter calculated as a result of the preliminary compression (c). Thereafter, when code data for three images is written in the code area of the SDRAM, the capacity of the code area of the SDRAM is lost, and the continuous shooting ends.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-328183 (page 3, FIG. 3)
[0007]
[Problems to be solved by the invention]
However, when the above-described processing is performed, there is a problem that it takes time until the image to be actually compressed is exposed after the release button is pressed, and there is a time lag after the release button is pressed. In addition, since the compression parameters suitable for the first captured image are used for compression of all images captured thereafter, an error occurs during compression when continuously shooting a subject with changes, and There has been a problem that the code amount varies. In addition, since the area in which the code data is written in the memory is limited, there is a problem that the number of continuous shots is limited.
[0008]
An object of the present invention is to provide an imaging apparatus capable of maintaining a constant code amount after compression even when continuously shooting a subject with changes.
[0009]
[Means for Solving the Problems]
  The imaging device according to the present invention is an imaging device that compresses continuously captured images in real time. The imaging apparatus continuously captures images, sequentially converts the captured images into digital data and outputs the image data as image data, a memory that stores the image data, and the image data Memory writing means for sequentially writing the imaging data output from the output unit to the memory, and sequentially reading the imaging data from the memory, and using the imaging data, YC data composed of a luminance signal and a color difference signal is generated. The YC processing means for writing the YC data into the memory, the YC data are sequentially read from the memory, the YC data is compressed, and the code data obtained by the compression is stored in the memory. Compression means for writing and calculating a compression parameter based on the compression result. When the first YC data corresponding to the first captured image is read, the compression means compresses the first YC data using a predetermined compression parameter, and based on the compression result A first compression parameter is calculated, and then the first YC data is read again from the memory, and the read first YC data is compressed using the first compression parameter. At the same time, the code data obtained by compression is written into the memory, and a new compression parameter is calculated based on the compression result, and YC data corresponding to the second and subsequent images is read out. In such a case, the YC data is compressed using a compression parameter calculated based on the result of compression of the immediately preceding image, and the code data obtained by the compression is written to the memory. Inclusive, further, calculates a new compression parameter based on the compression resultsThus, when the first YC data corresponding to the first captured image is read, the final compressed data is obtained after performing preliminary compression, which is compression not intended to generate the final compressed data. On the other hand, when the main compression, which is the compression intended to generate the image data, is read out when YC data corresponding to the second and subsequent images is read, the main compression is performed without performing the preliminary compression.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to the present embodiment. In FIG. 1, an image pickup apparatus 2 includes an optical lens 4, an image pickup element 6, an analog circuit 8, an A / D converter 10, a digital signal processing apparatus 12, a memory 14, a timing pulse generator (TG) 16, and a microcomputer (hereinafter referred to as a “computer”). (Referred to as “microcomputer”) 18. In the imaging device (digital still camera) 2, the imaging device 6 is a CCD (charge coupled device), and the memory 14 is an SDRAM (Synchronous Dynamic Random Access Memory). The digital signal processing device 12 includes an SDRAM interface 20, a CCD writing memory controller (hereinafter referred to as “memocon”) 22, a YC processing memocon 24, a YC processing circuit 26, a compression processing memocon 28, and a compression circuit 30. Further, the digital signal processing apparatus 12 includes a controller (card controller) 32 that records image data on an external recording medium (IC card) 34. The microcomputer 18 controls the TG 16, various memory controllers (22, 24, 28), the YC processing circuit 26, the compression circuit 30 and the card controller 32 based on an external input signal (S 1) from the user.
[0015]
  When there is an external input (S1) for instructing the start of continuous shooting in the imaging device 2, the microcomputer 18 causes TG16Is instructed to start continuous shooting mode. TG16In response to the instruction, the CCD 6 is driven in the continuous shooting mode. The subject imaged by the optical lens 4 is converted into an electrical signal by the CCD 6 and output to the analog circuit 8 as an imaging signal. The analog circuit 8 performs predetermined processing on the imaging signal and outputs it to the A / D converter 10. The A / D converter 10 converts an analog signal into a digital signal and outputs it to the digital signal processor 12 as CCD data. The microcomputer 18 causes the CCD write memo controller 22 in the digital signal processing device 12 to write the CCD data output from the A / D converter 10 into the SDRAM 14. When the CCD data is written in the SDRAM 14, the microcomputer 18 causes the YC processing memo controller 24 to read the CCD data and transfer it to the YC processing circuit 26. The microcomputer 18 causes the YC processing circuit 26 to generate YC data composed of the luminance signal (Y) and the color difference signal (C) using the transferred CCD data. The microcomputer 18 causes the YC processing memo control 24 to read the generated YC data from the YC processing circuit 26 and write it to the SDRAM 14. Further, when the YC data is written in the SDRAM 14, the microcomputer 18 causes the compression processing memo control 28 to read the YC data and transfer it to the compression circuit 30. The microcomputer 18 causes the compression circuit 30 to perform JPEG compression processing on the YC data. The microcomputer 18 causes the compression processing memo control 28 to read the code data obtained by the compression processing from the compression circuit 30 and write it into the SDRAM 14. Data exchange between the SDRAM 14 and the various memo controllers (22, 24, 28) (data writing to the SDRAM and data reading from the SDRAM) is all performed via the SDRAM interface 20. During continuous shooting, the above-described series of operations is repeated each time the CCD outputs an image pickup signal.
[0016]
FIG. 2 is a timing chart showing the operation of the imaging apparatus according to this embodiment. (1) in FIG. 2 shows the timing of system control by the microcomputer 18, and (2) in FIG. 2 shows the data write and read timings in the memory (for example, SDRAM) of the imaging apparatus, and the write address and read of the SDRAM. Indicates a change in address. In (1) of FIG. 2, “CCD” indicates the exposure timing and the output timing of the field signal by the CCD, and “CCDW”, “YCP”, and “JPG” respectively write the CCD data to the memory. The timing, YC data generation timing, and compression processing timing are shown. In (2) of FIG. 2, the solid line arrows indicate the SDRAM address change at the time of data writing, and the broken line arrow indicates the SDRAM address change at the time of data reading. In FIG. 2, when the release button is pressed, the first exposure is started, and the CCD 4 outputs two field signals in order (A field and B field in this order) for the first captured image. These signals are converted into digital signals (CCD data) by the A / D converter 10 and output to the digital signal processor 12. The microcomputer 18 causes the CCD write memo control 2 of the digital signal processing device 12 to sequentially write the CCD data for the A field and the B field into the CCD area of the SDRAM 14 (from the start address of the CCD area) (a). Further, the microcomputer 18 causes the YC processing memo controller 24 to read out the CCD data from the CCD area at the same time as the writing of the B field CCD data starts (b1). The microcomputer 18 causes the YC processing memocon 24 to read out the CCD data (b1) and simultaneously transfers it to the YC processing circuit 26. The microcomputer 18 causes the YC processing circuit 26 to generate YC data at the same time as the CCD data is transferred. At the same time as the YC data is generated, the microcomputer 18 causes the YC processing memo controller 24 to read the YC data from the YC processing circuit 26 and simultaneously write it into the YC area of the SDRAM 14 (from the start address of the YC area). (B2). Thereafter, the microcomputer 18 causes the compression processing memo control 28 to read the YC data from the SDRAM 14 (c) and simultaneously transfer it to the compression circuit 30. Then, the microcomputer 18 causes the compression circuit 30 to perform preliminary compression at the same time as the YC data is transferred, and to calculate a compression parameter using the transferred YC data. Specifically, the compression circuit 30 compresses the transferred YC data with a predetermined compression parameter, and calculates, from the compression result, a first compression parameter that is optimal for setting the code amount to a desired value (code Quantity estimate). Further, at the same time as the precompression (c) is completed, the microcomputer 18 causes the compression processing memo control 28 to read the same YC data from the SDRAM 14 again (d1) and simultaneously transfer it to the compression circuit 30. The microcomputer 18 compresses the YC data using the first compression parameter obtained by the preliminary compression (c) at the same time as the YC data is transferred to the compression circuit 30 (first main compression). Thereafter, the microcomputer 18 causes the compression circuit 30 to calculate a second compression parameter that is optimal for setting the code amount to a desired value from the compression result. The microcomputer 18 causes the compression processing memo control 28 to read the code data (first code data) obtained by the first main compression from the compression circuit 30 simultaneously with the compression, and simultaneously with the reading, the first code Data is written into the code area of the SDRAM 14 (from the start address of the code area) via the SDRAM interface 20 (d2).
[0017]
At this time, the second exposure has already been completed, and the second CCD data corresponding to the second captured image is written into the CCD area of the SDRAM 14 (from the start address of the CCD area) by the CCD writing memo controller 22. (E). While the second CCD data is being written, the microcomputer 18 causes the YC processing memo control 24 to read the second CCD data from the SDRAM 14 (f1) and simultaneously transfer it to the YC processing circuit 26. After the second YC data is generated, the microcomputer 18 causes the YC processing memo controller 24 to read the second YC data and write it into the YC area of the SDRAM 14 (from the start address of the YC area) ( f2) (At this time, the main compression (d) is performed for the first image data). After that, the microcomputer 18 causes the compression processing memo control 28 to read the second YC data from the YC area of the SDRAM 12 (g1) and causes the compression circuit 30 to read the same as in the case of the first main compression (d). YC data main compression (g: second main compression) is performed. The compression parameter used for the second main compression (g) is a second compression parameter calculated based on the result of the first main compression (d). Further, the microcomputer 18 causes the compression circuit 30 to calculate a third compression parameter that is optimal for setting the code amount to a desired value from the compression result. The microcomputer 18 stores the code data (second code data) after the second main compression in the compression processing memo control 28 and the code area of the SDRAM 14 (from the next address where the first code data is written in the code area). ) Write (g2).
[0018]
At this time, the third exposure has already been completed, and writing (h) of the third CCD data to the SDRAM 14 has begun. While the third CCD data is being written in the CCD area of the SDRAM 14, the microcomputer 18 causes the YC processing memo control 24 to read the third CCD data from the CCD area (i1) and to read the third CCD data from the YC processing circuit. 26. After the third YC data is generated, the microcomputer 18 causes the YC processing memo control 2 to write the third YC data in the YC area of the SDRAM 14 (i2). At the same time, the compression processing memo control 28 reads the third YC data from the YC area of the SDRAM 12 (j1), and causes the compression circuit 30 to perform the third main compression. The compression parameter used for the main compression (j) is a third compression parameter calculated based on the result of the second main compression (g). The microcomputer 18 causes the compression processing memo control 28 to write the obtained code data (third code data) in the code area of the SDRAM 14 (from the next address where the second code data is written in the code area) ( j2).
[0019]
The microcomputer 18 ends the continuous shooting because there is no free space in the code area of the SDRAM 14 when the third code data is written to the compression processing memo control 28 (j2).
[0020]
In the imaging device according to the present embodiment, as described above, the compression circuit calculates a compression parameter based on the compression result every time compression processing is performed. The compression parameter is a compression parameter that allows the code amount after compression of the image that has been compressed to be a desired value. In the captured image according to the present embodiment, the first captured image is temporarily compressed using YC data using a predetermined compression parameter. Then, a compression parameter is calculated based on the compression result, and the YC data is compressed again using the calculated compression parameter. For the second and subsequent images, the YC data of the image is compressed using a compression parameter calculated based on the compression result of the immediately preceding image. That is, the second and subsequent images are compressed using a compression parameter calculated based on the result of compressing the image captured immediately before.
[0021]
According to the imaging apparatus according to the present embodiment, since the image exposed immediately after pressing the release button is pre-compressed and main-compressed, the image that is actually compressed after the release button is pressed is exposed. The conventional problem that a time lag exists can be solved.
[0022]
In addition, according to the imaging apparatus according to the present embodiment, when the images obtained by the second and third exposures are subjected to main compression, compression parameters suitable for the image obtained by the immediately preceding exposure are used. Even in the case of continuous shooting of a moving subject, it is possible to suppress variations in the amount of code after compression.
[0023]
Note that the image capturing apparatus according to the present embodiment ends the continuous shooting when the code data for three images is acquired, but the number of continuous shooting can be increased or decreased according to the capacity of the memory.
[0024]
(Embodiment 2)
Hereinafter, an imaging apparatus according to the second embodiment will be described. The configuration of the imaging apparatus according to the present embodiment is the same as that of the imaging apparatus according to the first embodiment. Therefore, the operation at the time of continuous shooting of the imaging apparatus according to the present embodiment will be described with reference to FIG. In Embodiment 1, since the capacity of the code area in the memory is limited, only code data for three images can be written in the memory. However, according to the imaging apparatus according to the present embodiment, more data can be written. Code data for an image can be written in the memory. As a result, the number of continuous shots of the imaging apparatus can be increased.
[0025]
FIG. 3 is a timing chart showing the operation of the imaging apparatus according to the present embodiment. (1) in FIG. 3 shows the timing of system control by the microcomputer 18, and (2) in FIG. 3 shows data write and read timings in the SDRAM 14 and changes in the write address and read address of the SDRAM 14. In (2) of FIG. 3, a solid arrow indicates a change in address of the SDRAM when data is written, and a broken arrow indicates a change in address of the SDRAM when data is read. Here, since the operation until the main compression (g: second main compression) of the image obtained by the second exposure is the same as the operation of the imaging apparatus according to the first embodiment, the description thereof is omitted.
[0026]
When the second main compression (g) is finished, the third exposure is already finished, and writing of the third CCD data to the SDRAM 14 is started (h). Here, the microcomputer 18 can cause the CCD writing memo controller 22 to write the CCD data in an arbitrary area of the SDRAM 14. The microcomputer 18 writes the third CCD data in the CCD writing memo control 22 not in the CCD area but in the YC area immediately after the second YC data is read during the second main compression (g) (g1). (H). Referring to FIG. 3, it can be seen that data is not overwritten because the arrow indicating the address change does not overlap in the YC area of the SDRAM 14.
[0027]
The generation and compression itself of the third YC data is the same as the operation described in the first embodiment. Here, the microcomputer 18 writes the generated third YC data in the YC processing memo control 24, the third CCD data has already been read in the YC area of the SDRAM 14, and the fourth CCD data is still written. Write to a free area that has not been written (i2). In the imaging apparatus according to the present embodiment, the address change in the SDRAM 14 when the third YC data is written is the case where the first and second YC data are written, as shown in FIG. This is the same as the address change of the SDRAM 14.
[0028]
In the imaging apparatus according to the present embodiment, the third main compression (j) is performed, and the fourth exposure is already finished at the time (j2) when the third code data is written in the code area of the SDRAM 14. ing. The microcomputer 18 causes the CCD writing memo controller 22 to write the fourth CCD data to the YC area of the SDRAM 14 (k), similarly to the third CCD data. Here, the CCD area of the SDRAM 14 is open. After the fourth main compression (m) is performed in the same manner as the other main compressions described above, the resulting fourth code data is stored in the CCD 14 of the SDRAM 14 by the compression processing memo control 28 in accordance with an instruction from the microcomputer 18. The area is written (m2). In the imaging apparatus according to the present embodiment, the fourth compression parameter based on the result of the third main compression (j) is calculated by the compression circuit 30 according to the instruction from the microcomputer 18. The fourth main compression (m) is performed using these compression parameters. A fifth compression parameter is calculated based on the fourth main compression (m).
[0029]
Here, the data amount of the code data after compression is smaller than the data amount of the CCD data. For example, if the data amount of the code data is about ½ of the data amount of the CCD data, it is already in the CCD area of the SDRAM 14. One code data can be written. Therefore, the fifth exposure is performed, and the microcomputer 18 performs the same processing as the image obtained by the fourth exposure on the obtained fifth image, and then obtains the obtained fifth code data. It is possible to write to the CCD area of the SDRAM 14 (p2).
[0030]
Furthermore, in the imaging apparatus according to the present embodiment, the sixth exposure is completed when the fifth code data is written in the CCD area of the SDRAM 14 (p2). The sixth captured image is also processed in the same way as the third image. Here, the microcomputer 18 causes the compression processing memo control 28 to write the sixth code data obtained as a result of the sixth main compression (s) in the YC area of the SDRAM 14 (s2). The microcomputer 18 writes the sixth code data in the YC area of the SDRAM 14 in the area immediately after the YC data is read during the sixth main compression (s) (s1) (the start address of the YC area). Make it.
[0031]
The microcomputer 18 ends the continuous shooting because the capacity for processing a new captured image in the SDRAM 14 is lost when the sixth code data is written to the YC area of the SDRAM 14 by the YC processing microcomputer 28 (s2). Let
[0032]
According to the imaging apparatus according to the present embodiment, CCD data and code data are sequentially written not only in a predetermined area of the SDRAM but also in an empty area, so that more code data can be stored in the SDRAM. Therefore, it is possible to increase the number of continuous shots of the imaging apparatus.
[0033]
Note that the imaging apparatus according to the present embodiment can provide the same effects as the imaging apparatus according to the first embodiment.
[0034]
Note that the image capturing apparatus according to the present embodiment ends the continuous shooting when the code data for six images is acquired, but the number of continuous shooting can be increased or decreased according to the capacity of the memory. In the imaging apparatus according to the present embodiment, code data for two images is stored in the CCD area of the memory, and code data for three image images is stored in the code area. Depending on the amount of data, the number of code data that can be stored in each region can also be changed.
[0035]
(Embodiment 3)
The operation during continuous shooting of the imaging apparatus according to Embodiment 3 will be described below. The configuration of the imaging apparatus according to the present embodiment is the same as that of the imaging apparatus according to the first embodiment. Therefore, the operation at the time of continuous shooting of the imaging apparatus according to the present embodiment will be described with reference to FIG. In the first embodiment and the second embodiment, all the code data is stored in the SDRAM 14. However, according to the imaging apparatus according to the present embodiment, recording on a recording medium is performed simultaneously with shooting. As a result, new code data can be written in the open SDRAM area, and as a result, the number of continuous shots can be increased.
[0036]
FIG. 4 is a timing chart showing an operation during continuous shooting of the imaging apparatus according to the present embodiment. In the imaging apparatus according to the present embodiment, the microcomputer 18 causes the card controller 32 to send the first code data to the IC card immediately after the compression processing memo control 28 writes the first code data to the SDRAM 14 (d2). 34 (t). Accordingly, the microcomputer 18 sends the code data (sixth code data) of the image obtained by the sixth exposure to the compression processing memo control 28 not in the YC area of the SDRAM 14 but in the code area of the SDRAM 14 and the IC card. The first code data is written in the area where the first code data has been written before being recorded in 34. The other operations up to the sixth main compression (s) are the same as the operations of the image pickup apparatus according to the second embodiment, and a description thereof will be omitted.
[0037]
Here, the microcomputer 18 causes the card controller 32 to monitor the read state of the first code data in the SDRAM 14. Specifically, the microcomputer 18 causes the card controller 32 to acquire the address of the SDRAM 14 from which the first code data is read. At the same time, the microcomputer 18 causes the compression processing memo control 28 to monitor the writing state of the sixth code data in the SDRAM 14. Specifically, the microcomputer 18 causes the compression processing memo control 28 to acquire the address of the SDRAM 14 in which the sixth code data is written.
[0038]
The microcomputer 16 compares the read address of the SDRAM 14 obtained via the card controller 32 with the write address of the SDRAM 14 obtained via the compression processing memocon 28, and the sixth code data is written in the first code data. When it is likely to catch up with reading (when the read address and the write address are likely to match), the operations of the compression processing memo control 28 and the compression circuit 30 are stopped. Thus, before the first code data is written to the IC card 34, the sixth code data is written (overwritten) in the CCD area of the SDRAM 14, and as a result, the first code data is prevented from being destroyed. .
[0039]
Finally, the microcomputer 14 writes the code data (seventh code data) of the image obtained by the seventh exposure in the YC area of the SDRAM 14 in the same manner as the sixth code data according to the second embodiment ( v2). Further, the microcomputer 14 writes the seventh code data in the YC area of the SDRAM 14 in the area immediately after the YC data is read during the seventh main compression (v) (the start address of the YC area). .
[0040]
By the operation as described above, the number of continuous shots, which was 6 in the second embodiment, can be reduced to 7.
[0041]
According to the imaging apparatus according to the present embodiment, simultaneously with shooting, image data stored in the memory is output and recorded on a recording medium. As a result, an empty area is created in the memory, and new code data can be written in that area. As a result, the number of continuous shots of the imaging device can be increased.
[0042]
Note that the imaging apparatus according to the present embodiment can provide the same effects as the imaging apparatus according to the first embodiment.
[0043]
Note that the imaging apparatus according to the present embodiment can provide the same effects as those of the imaging apparatus according to the second embodiment.
[0044]
Note that the image capturing apparatus according to the present embodiment ends the continuous shooting when the code data for seven images is acquired, but the number of continuous shooting can be increased or decreased according to the capacity of the memory. In the imaging apparatus according to the present embodiment, code data for two images is stored in the CCD area of the memory, and code data for three image images is stored in the code area. Depending on the amount of data, the number of code data that can be stored in each region can also be changed.
[0045]
In the imaging device according to the present embodiment, new code data is written in the code area of the memory after the first code data is read, but if code data after the second code data is read, It is also possible to write new code data sequentially in accordance with the reading speed.
[0046]
【The invention's effect】
With the imaging apparatus of the present invention, the amount of code after compression can be kept constant even when a subject with changes is continuously shot.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to the present invention.
FIG. 2 is a timing chart showing the operation of the imaging apparatus according to the first embodiment.
FIG. 3 is a timing chart showing the operation of the imaging apparatus according to the second embodiment.
4 is a timing chart showing the operation of the imaging apparatus according to Embodiment 3. FIG.
FIG. 5 is a timing chart showing the operation of a conventional imaging device.
[Explanation of symbols]
2 Digital still camera
4 Optical lenses
6 CCD
8 Analog circuit
10 A / D converter
12 Digital signal processor
14 SDRAM
16 Microcomputer
18 Timing pulse generator
20 SDRAM interface
22 CCD writing memo control
24 YC processing Memocon
26 YC processing circuit
28 Compression processing Memocon
30 Compression circuit
32 card controller
34 IC card

Claims (1)

An imaging device that compresses continuously captured images in real time,
An imaging data output unit that continuously captures images, sequentially converts the captured images into digital data, and outputs the data as imaging data;
A memory for storing the imaging data;
Memory writing means for sequentially writing imaging data output from the imaging data output unit to a memory;
YC processing means for sequentially reading out the imaging data from the memory, generating YC data comprising a luminance signal and a color difference signal using the imaging data, and writing the YC data into the memory;
Compression means for sequentially reading out the YC data from the memory, compressing the YC data, writing code data obtained by the compression into the memory, and calculating a compression parameter based on the compression result; Prepared,
The compression means includes
When the first YC data corresponding to the first captured image is read, the first YC data is compressed using a predetermined compression parameter, and the first compression parameter is determined based on the compression result. Next, the first YC data is read again from the memory, and the read first YC data is compressed using the first compression parameter and obtained by compression. Write the code data to the memory, further calculate a new compression parameter based on the compression result,
When YC data corresponding to the second and subsequent images is read, the YC data is obtained by compressing the YC data using the compression parameters calculated based on the compression result of the immediately preceding image. writes are code data in said memory, further, on the basis of the compression result to calculate a new compression parameters, whereby
When the first YC data corresponding to the first captured image is read out, the purpose is to generate final compressed data after performing preliminary compression, which is compression not intended to generate final compressed data. While performing the main compression,
When the YC data corresponding to the second and subsequent images is read, the main compression is performed without performing the preliminary compression.
Imaging device.

Images