WO2000004716A1

WO2000004716A1 - Image pickup device

Info

Publication number: WO2000004716A1
Application number: PCT/JP1998/003215
Authority: WO
Inventors: Hiroki Jinbo; Kenichi Munei; Kikuo Shioya; Hiroaki Takagishi
Original assignee: Hitachi, Ltd.; Hitachi Tohbu Semiconductor, Ltd.
Priority date: 1998-07-17
Filing date: 1998-07-17
Publication date: 2000-01-27
Also published as: TW416229B

Abstract

An image pickup device which has a compressing means (6, 9) which compresses image information obtained through an image pickup means (1) at a variable compressibility. The compressed image information outputted from the compressing means is supplied to a host device (4) through an interface means (7). The compressibility is specified by the compressing means in accordance with control information supplied by the interface means and the compression at the compressibility can be completed by the compressing means within a single image information frame. Thus the compressibility can be optimized in accordance with the decompression capability of the host device which receives different image sizes, transfer capacities and compressed image information. Further, since the compression can be completed by data in the image information frame, the cost of the hardware for compressing images can be reduced and a frame memory for compression is not necessary.

Description

Details

Technical field

The present invention relates to an imaging device such as a camera for sequentially transmitting captured moving image information to a host device. For example, in a video conference system, a television telephone, or the like, an image is captured in a limited band. In order to transfer the information, technology related to technology that is effective when applied to a data processing system such as an image compression / decompression device that compresses image information with hardware or software and decompresses compressed data with software. Things. Background art

The inventor has studied a monitor camera connected via an external interface of a personal computer. Known interfaces for connecting a personal computer and peripheral devices include a USB (Universal Serial Bus), a SCSI (Small Computer System Interface), an IrDA (Infrared Data Association), and an RS232C. For example, USB is a standard for serial data transfer, and its data transfer rate is 12 Mbps. The USB Standard (REV1.0) was published on November 13, 1995.

It is sufficient that the frame rate of the image information is about 25 Hz. For example, in the case of CIF (Common Intermediate Fonat), the image size of one frame is 352 x 2888 pixels. If the image data format is 4: 2: 0 (the luminance data per pixel is 8 bits and the color difference data per pixel is 4 bits), the amount of image information data to be transmitted Is about 29 M bps. As described above, the USB data transfer rate is 12 Mb-ps, so when transmitting image information using a USB, image data captured by a monitor camera is compressed or thinned out. And so on. For example, if the compression ratio is reduced to 1/4, the data amount will be approximately 7.3 Mbps, which can satisfy the USB data transfer rate. On the other hand, QCIF (Quarter Common Intermediate Format), where the size of one frame is 1/4 of CIF, can satisfy the USB overnight transfer rate without compression. If compression is not required, the image information can be transferred to the host device via USB as it is, and decompression processing is unnecessary on the host device side, which is preferable because the data processing time is reduced and the load on the processor is reduced. As a result, the necessity of making it possible to select the compression ratio of image information in the monitoring camera according to the study of the present inventors has been clarified.

According to the USB standard, up to 127 peripheral devices (USB devices) can be connected to one host device via a hub. According to the USB specification, when a USB device is connected to a port, various configuration information of the USB device is transferred to the host device. Then, the host device always schedules what kind of transfer and when to perform it in units of 1 ms. At this time, since the maximum data transfer rate per second is the above-mentioned 12 Mbps, multiple USB devices must be able to perform data transmission operation in time-division multiplexing without significantly impairing real-time performance. The total data transfer rate of all USB devices must be less than 12 Mbps. For this reason, in the case of a USB device having a relatively large data transfer rate, such as an imaging device, the number of other USB devices sharing the USB port and the data transfer rate are taken into consideration, and the image information is transferred. It is desirable to be able to change the compression ratio. In this regard, too, the compression ratio of the image information in the monitor camera is selected. The need to make it optional was identified. -In addition, the present inventor has studied a compression method of image data overnight in that case. For example, H.261 and the like are known as standards for compressing and expanding information in order to transfer moving image information over a telephone line. In this information compression method, a difference between a past image information frame and a current image information frame is first detected on the compression side. Since the correlation between temporally continuous image information frames in a moving image is high, the amount of information can be reduced by calculating the difference. Next, the difference is frequency-transformed by the discrete cosine transform. Generally, when an image is frequency-converted, information is concentrated on low-frequency components. The data after frequency conversion is quantized to reduce the information of high frequency components with a small amount of information. Finally, we focus on the frequency of appearance of the code, and perform variable-length coding that assigns a short code length to a code with a high appearance frequency and a long code length to a code with a low appearance frequency. On the decompression side, difference data between frames is calculated in the order of variable length decoding, inverse quantization, and inverse discrete cosine transform. The difference is added to the past image information frame to reproduce the image. Such a method is intended to reduce the amount of information by focusing on the temporal and spatial redundancy of the image.

However, such image information compression technology performs information compression using the correlation between frames, and it is necessary to accumulate image information for a plurality of frames, thus requiring a large number of frame memories. Hardware is too costly.

In the above method, the compression ratio of the information decreases when the correlation between temporally consecutive frames is low or when the frequency components of the image information are concentrated at high frequencies. In such a case, the frame rate (the number of frames per unit time) changes in order to reduce the amount of information by dropping the image during encoding, and the movement of the subject in the expanded reproduced image is unnatural. It is expected that Also, when the decompression processing is performed by software, the number of operations in the inverse discrete cosine transform becomes extremely large, and the load on the host device side increases.

An object of the present invention is to provide an image pickup apparatus capable of efficiently transmitting image information while maintaining good image quality in accordance with an image size (amount of information) and a band (a transfer capacity) of a transmission path. It is in.

Another object of the present invention is to reduce the cost of an image pickup apparatus that transmits image information efficiently and with good image quality according to the image size and the bandwidth of the transmission path.

The above and other objects and novel features of the present invention will become apparent from the following description of the present specification and the accompanying drawings. Disclosure of the invention

An image pickup apparatus according to the present invention is used for image pickup means, compression means for compressing image information acquired via the image pickup means at a variable compression rate, and data transmission of compressed image information output from the compression means. Includes an ink face means. The compression means includes a plurality of compression logic means for respectively compressing image information, means for selecting a compression rate for processing using the compression logic means, and means for indicating a compression rate selected by the selection means. . As described above, since the compression rate can be selected using a plurality of compression logic means, the compression rate is optimized according to the expansion processing capacity of the host device that receives the different image sizes, transfer capacities, and coded compressed image information. It becomes possible to do.

The compression logic is capable of completing the compression process within a single image information frame. In other words, the compression process can be completed with the data in the image information frame. Therefore, the cost of hardware for compressing an image can be reduced, and it is not necessary to have a frame memory for compression. The plurality of compression logic means includes a thinning circuit for image information, Δ Υ ΙΙ V circuit can be adopted. At this time, the selection means may select a state using only the thinning circuit, a state using only the AYUV circuit, a state using both the thinning circuit and the ΔYUV circuit, and a state using both the thinning circuit and the △ YUV circuit. One state can be selected from among the states that allow image information to pass through as unused. Thereby, regardless of the spatial or temporal redundancy of the image information, each image information can be compressed at the selected constant compression ratio, and it is easy to secure a constant frame rate. It is. As a result, it is possible to suppress the deterioration of the image quality of the image information that has undergone compression and expansion.

For the compression logic means, consideration is given to decompression processing by software, and the emphasis is on algorithm simplicity rather than compression ratio. For compression, for example, 1 / m decimation with a compression ratio of lZm, 1 / n decimation with a compression ratio of 1 / n, and a compression ratio of 1/111 ¥ 1; And compress them in series to compress l / m, l / n, l / (m'n), and 1 / (m · m). As a result, the algorithm of the compression process is easy, and the load on the software for performing the decompression process can be reduced.

The main processing of both types of 1 / m thinning and 1 / n thinning is the filter operation, so there are many common parts in the hardware, and both 1 / m thinning and 1 / n thinning should be prepared. The increase in the circuit size due to is small. The filter operation only needs to sequentially perform a product-sum operation on input image data, and the AYUV method only needs to encode the difference between the input image data. The simplicity of the algorithm allows the compression processing hardware to be realized at low cost, and reduces the load on the decompression processing software Xa.The compression means is not particularly limited to dedicated hardware. It may be realized by software. For example, an interface function conforming to USB can be adopted as the interface means. A USB port of a host device to which a USB device having a USB interface function is connected has a large number of USB ports. The maximum data transfer rate of the USB port of the host device is limited to 12 Mbps, and when multiple USB devices transfer data by time division multiplexing, At this time, since the image pickup device can select a compression ratio of image information, in the case of a USB device having a relatively high data transfer rate such as an image pickup device, The compression ratio of the image information can be varied in consideration of the number of other USB devices sharing the USB port and the data transfer rate. When the host device connected to the interface means gives the instruction, the host device refers to the compression ratio instruction at that time. The decompression process can be performed.

FIG. 1 is a block diagram showing an overall configuration of an image compression / decompression system including a monitoring camera and a host computer according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a variable compression section.

FIG. 3 is a schematic diagram illustrating a 1/2 thinning operation selected by the variable compression section.

FIG. 4 is a circuit diagram showing an example of a thinning circuit provided in the variable compression section.

Fig. 5 is a schematic diagram illustrating the 1/4 thinning operation selected by the variable compression unit. FIG. -FIG. 6 is an explanatory diagram showing a specific example of a data conversion in the compression / decompression processing by the AYUV circuit.

FIG. 7 is an explanatory diagram showing a conversion table for converting difference data between adjacent images into transmission data in the AYUV circuit.

FIG. 8 is an explanatory diagram showing a conversion table for converting a received data into a difference data from an adjacent image in the AYUV circuit.

FIG. 9 is a flowchart showing an example of a compression data decompression process performed by the host computer.

FIG. 10 is a flowchart showing an example of realizing compression processing of image data by software. BEST MODE FOR CARRYING OUT THE INVENTION

Fig. 1 shows the overall configuration of an image compression / decompression system equipped with a monitor camera and a host computer. In FIG. 1, reference numeral 4 denotes a host computer such as a personal computer, for example, which has a USB interface function as an external interface, and is connected to a USB port located on a US host hub 20. A device that supports USB (USB device) can be connected to the port. Although not specifically shown, the USB host hub 20 is connected to an interface controller inside the host computer 4 and controls data transfer instructed by a data transfer command from a processor (not shown). This is performed in accordance with the provisions of the USB Function Specification (REV1.0).

In FIG. 1, although not particularly limited, the monitoring camera 21 is one of the USB devices. The monitoring camera 21 is connected to the USB host hub 20 via an interface cable 10A. In addition, USB host To the DSU (Digital Service Unit) and TA (Terminal Adapter) 23, which are typically shown as separate USB devices, via an interface cable 10B and an external hub 22. Board 24 is connected.

The monitor camera 21 includes a charge coupled device (CCD) 1, an A / D converter (analog / digital converter) 2, and an image processing unit 3. Although not particularly limited, the image processing unit 3 is formed as one semiconductor integrated circuit. The video signal (image signal) captured by the CCD 1 is sent to the image processing unit 3 via the A / D converter 2 to output a signal (R (RED), G (G REEN), B (BLUE), etc.) (Color signal). The input image signal is converted into a luminance signal and a chrominance signal by the signal processing unit 5.c The variable compression unit 6 compresses the luminance signal and the chrominance signal by varying the compression ratio.c Compressed data (compression The image information) is transmitted from the USB interface circuit 7 to the host computer 4 via the interface cable 1 OA. The host computer 4 expands the received compressed image signal by software and displays it on a monitor.

Although not shown, the signal processing unit 5 and the variable compression unit 6 may perform each process using software such as a microcomputer.

The timing control section 8 controls the operation timing of the CCD A / D converter 2, the signal processing section 5, and the variable compression section 6. The selection of the compression ratio of the variable compression unit 6 and the setting change to the signal processing unit 5 and the timing control unit 8 according to the change of the image size to be handled are arbitrarily performed from the host computer 4 via the overall control unit 9. . Specifically, when the image processing unit 3 needs to change the setting, the host computer 4 issues an instruction or command via the transmission path 1 OA, and although not particularly limited, the instruction or command is not required. Switch the setting of the general control unit 9 according to the control information attached to You. Although the control information is not particularly limited, the control information is stored in the control register 25 of the overall control unit 9, and the compression ratio of the variable compression unit 6 is selected using the stored control information.

The CCD 1 and the A / D converter 2 operate in synchronization with a signal generated by the timing control unit 8. The image information from the CCD 1 is sequentially read out one pixel at a time for each scanning line, and supplied to the signal processing unit 5. The camera 21 does not need to have a frame memory corresponding to image information such as CIF.

FIG. 2 shows a detailed circuit example of the variable compression section 6. The variable compression section includes a 1/2 thinning circuit 11 for compressing the information amount of the captured image to 1/2, a 1/4 thinning circuit 12 for compressing the information amount of the captured image to 1/4, It has an AYUV circuit 13 for compressing the information amount of the image to half, and switch circuits 14 and 15 for selecting three kinds of compression circuits. The switch states of the switch circuit 14 and the switch circuit 15 are controlled by an instruction from the general control unit (general control circuit) 9. By switching the switches 14 and 15, it is possible to set a path for outputting the input signal without compression and a path for compressing the compression ratio of 1/2, 1/4, and 1/8.

The 1/2 thinning circuit 11 will be described. FIG. 3 schematically shows luminance (or color difference) signals arranged two-dimensionally. The 1/2 thinning circuit compresses the above information amount to 1/2 by sampling 1/2 data and thinning out 1/2 data. However, if only 1/2 of the data is thinned out, the image may be distorted due to the effect of aliasing. Therefore, before thinning, the image is subjected to a two-dimensional LPF (Low Pass Filter) operation to reduce high frequency components. Fig. 4 shows an example of LPF configuration. The horizontal storage element 16 is a 7-pin filter and the vertical storage element 17 is a 3-tap FIR (Finite Impulse Response) type filter. You. A luminance (or color difference) signal is input one pixel at a time in the horizontal direction, a product-sum operation is performed using coefficients 1 & A to 18J, and the operation result is replaced with the data of the center pixel. The selection circuit 19 performs the thinning according to FIG. 3 to compress the information amount to half.

The 1/4 thinning circuit 12 will be described. As shown in FIG. 5, the 1/4 thinning circuit 12 samples 1/4 data and thins out 3/4 data to compress the information amount to 1/4. Here, LPF calculation is performed before thinning. The filter configuration is exactly the same as in FIG. 4, but the values of the coefficients 18 A to 18 J are different from those of the 1/2 thinning circuit 11. 1/2 decimation circuit 1 Since 1 and 1/4 decimation circuit 12 do not operate at the same time, only two types of coefficients, 18 A to l8 J, are prepared, and the other circuit parts are 1/2 decimation circuit 1 Shared with 1 and 1/4 thinning circuit 12.

The ΔYUV circuit 13 will be described. The AYUV method is a compression technology that has been put to practical use in car navigation and the like. Figure 6 shows an example of conversion from original data to compressed data. The dynamic range of luminance (or color difference) signal 0 to 255 is compressed to 16 to 235 by the conversion formula Υ2 (y / 255) · 219 + 16. As the predicted value Pn, Yn—Predicted value Pn = Difference Dn is obtained. The difference Dn is encoded according to the conversion table shown in FIG. 7, and the obtained ΔΥn is transmitted. Δ Yn is re-converted according to the conversion template shown in Fig. 8, and D'n is added to the predicted value Pn to obtain the next predicted value Pn + 1 (Pn + l = Pn + D 'n). If P n + 1 is 16 or less or 235 or more, clip to 16 or 235. The AYUV circuit 13 also reduces the amount of information by half.

On the receiving side, the received ΔΥη is decoded into the difference D′ η from the conversion table shown in FIG. 8, and D′ n is added to the immediately preceding decompressed data Υ′η−1, and the range compression data is decompressed. , N. Furthermore, the dynamo is calculated by the conversion formula y, = (Υ, -16) · 255/219. Expand the mic range and get y'n.

As described above, in the variable compression section 6, the processing is completed in the image information frame, and there is no need to use a frame memory in the compression / expansion processing, and the cost of the image compression / expansion apparatus can be reduced. it can. Furthermore, there is no change in the number of processes due to the redundancy of the image information, the frame rate can be kept constant, and the smooth operation of the object of the reproduced image is guaranteed.

The case where the functions of the signal processing unit 5 and the variable compression unit 6 are processed by software will be described with reference to the flowchart of FIG.

The digitalized video signals of R, G, B, etc., input from the A / D converter 2, are converted into a luminance signal and a color difference signal (S9). Next, if compression processing is necessary (S10), it is determined whether or not compression by thinning is possible (S11) based on the compression ratio instructed from the host computer. When performing compression by thinning, determine whether it is 1/2 thinning or 1/4 thinning (S12), and select either 1/2 thinning processing (S13) or 1/4 thinning processing (S14). Or execute. Further, when compression by AYUV is required (S15), AYUV compression processing is performed (S16). If neither compression is necessary, the luminance (color difference) signal is output through.

For example, when the compression ratio is 1/4, there are two methods: thinning 1/4 and thinning 1/2 and AYUV. Either method can be selected depending on the image quality and the processing capability of the decompressing software.

△ If only 1/4 decimation is performed without performing YUV compression, the compressed image information is displayed as it is from the interface cable 10 on the display means (host computer 4). , It is possible to display reduced-size images without using YUV decoding means.

Host computer 4 can be connected via interface cable 1 OA The control information is given to the variable compression section 6 to indicate the compression ratio. The host computer 4 stores the control information and, when decompressing the received compressed data, refers to the stored control information and performs processing according to the flowchart of FIG. .

The host computer 4 refers to the control information to determine whether compression by AYUV has been performed (S1), and if compression by AYUV has been performed, performs expansion processing by ΔYUV (S2). . Next, the host computer 4 refers to the control information to determine whether compression by thinning has been performed (S3), and if so, determines whether it is 1/2 thinning or 1/4 thinning. Yes (S4). If 1/2 has been thinned out, a filter operation for interpolating the data thinned out in the double interpolation processing (S5) is performed. If 1/4 thinning has been performed, it is determined whether decompression processing is possible (S6). If the display screen size by the host computer 4 is 1/4 of the screen size before compression, the decompression process is omitted. Performs a filter calculation. When the decompression process is completed, the image is displayed (S8).

Since the compression method of image information is a variable compression ratio, it is possible to cope with a case where priority is given to either the compression ratio or the image quality, which are in opposite relations. Since each frame is compressed at a predetermined compression ratio, the amount of operation of each compression algorithm is small, and multiple frame memories are not required, the USB port of the _c host computer 4 that can realize a system at low cost has many USB devices share. The maximum data transfer rate of the USB port of the host computer 4 has a limit of 12 Mbps, and when multiple USB devices transfer data by time division multiplexing, the limit must be satisfied. . At this time, since the monitor camera 21 can select the compression ratio of the image information, the USB data having a relatively large data transfer rate like the camera camera 21 is used. In the case of a device, the compression rate of image information can be varied in consideration of the transfer rate of several USB devices sharing the USB port. For example, if the imaging frame rate of CCD 1 is 25 Hz, the image data format is 4: 2: 0, and the image size is CIF, the number of USB devices connected to the USB host hub 20 When the number of other USB devices is increasing, the compression ratio can be set to 1/8.

When the frame rate of imaging with CCD 1 is 25 Hz, the image data format is 4: 2: 0, and the image size is QCIF, the data is passed through the variable Select the ratio 0), and when the number of other USB devices increases, the compression ratio can be set to 1/2 or 1/4.

The compression ratio setting control as described above may be performed by the host computer with reference to the configuration information acquired from each USB device.

As described above, since the monitor camera 21 having the USB interface function has a large data transfer amount, the number of other USB devices sharing the USB port and the data transfer rate are taken into consideration. The compression ratio of image information can be varied, making it ideal for USB interface.

The invention made by the present inventor has been specifically described based on the embodiments, but the present invention is not limited thereto, and can be variously modified without departing from the gist thereof.

For example, the interface means is not limited to USB, but may be another serial interface or a parallel interface. The image format of the luminance signal and the color difference signal may be 4: 2: 2. Further, the image frame rate of the image information picked up by the image pickup means is not limited to 25 Hz, but may be 30 Hz or the like. Further, the image size of the image information imaged by the imaging means is not limited to CIF and QCIF. The settings of the overall control unit 9 are set from the host computer 4, but items that do not require external setting changes may be fixed in advance. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a monitor camera, a video conference system, a video phone, and the like which are used by being connected to a personal computer.

Claims

The scope of the claims -

1. Imaging means, compression means for compressing image information obtained via the imaging means at a variable compression rate, and an image used for one-time transmission of compressed image information output from the compression means And face means,

The compression unit includes: a plurality of compression logic units for respectively compressing image information; a unit for selecting a compression ratio for processing using the compression logic unit; and a unit for indicating a compression ratio selected by the selection unit. Imaging device including.

2. The imaging device according to claim 1, wherein said compression logic means is capable of completing a compression process within a single image information frame.

3. The plurality of compression logic means includes a thinning circuit for image information and a ΔΥυV circuit, and the selecting means includes a state using the thinning circuit, a state using the ΔYUV circuit, and a thinning circuit and an AYUV circuit. 3. The imaging device according to claim 2, wherein one state can be selected from a state in which image information is passed through by disabling both of them.

The plurality of compression logic means includes a 1 / m thinning circuit for image information, a 1 / n thinning circuit for image information, and an AYUV circuit;

The selecting means includes: a state using the l / m thinning circuit; a state using the 1 / n thinning circuit; a state using the △ YUV circuit; a state using the 1 / m thinning circuit and the AYUV circuit; The imaging apparatus according to claim 2, wherein one state can be selected from a state in which the n-thinning circuit and the AYUV circuit are used, and a state in which image information is passed without using all compression logic means. .

5. The imaging device according to claim 3, wherein the interface means has an interface function conforming to USB.

6. The instruction means includes control information supplied from the interface means. 6. The imaging device according to claim 5, wherein the instruction is given according to:

7. Imaging means, compression means for compressing the image information obtained via the imaging means at a variable compression rate, and interface means used for data transmission of the compressed image information output from the compression means And

An image pickup apparatus wherein the compression means is instructed on a compression ratio in accordance with control information supplied from the interface means, and is capable of completing compression processing within a single image information frame.

8. The image pickup apparatus according to claim 7, wherein the interface means has an interface function conforming to USB.

9. A data processing system including an imaging device and a host device, wherein the imaging device includes an imaging unit, and a compression unit that compresses image information acquired via the imaging unit at a variable compression ratio. And an interface means used for data transmission of the compressed image information output from the compression means, wherein the compression means has a compression rate according to the control information supplied from the interface means. Instructed to complete the compression process within a single image information frame,

A decompression processing system comprising: a decompression unit that can decompress the compressed image information transmitted from the interface unit with reference to the control information indicating the compression ratio.

10. The data processing system according to claim 9, wherein said interface means has an interface function conforming to USB, and said host device is a personal computer.

11. An image sensor for capturing image information, a variable compressor for compressing image information obtained via the image sensor at a variable compression rate, and a compressed image output from the variable compressor. And an interface circuit used for data overnight transmission, The variable compression unit includes a plurality of compression logic circuits for compressing image information, a switch circuit for selecting a compression ratio for processing using the compression logic circuit, and a compression ratio for the switch circuit. 12. The imaging apparatus according to claim 11, wherein the compression logic circuit can complete the compression processing within a single image information frame.

13. The plurality of compression logic circuits include a thinning circuit for image information and a ΔΥUV circuit, wherein the switch circuit is in a state using the thinning circuit, a state using the △ YUV circuit, and a thinning circuit and a ΔΥυν circuit. 13. The imaging device according to claim 12, wherein one state can be selected from a state in which image information is passed through by disabling both.

14. The plurality of compression logic circuits include a 1 / m thinning circuit for image information, a 1 / n thinning circuit for image information, and an AYUV circuit,

The switch circuit includes a state using the 1 / m thinning circuit, a state using the 1 / n thinning circuit, a state using the YUV circuit,

One of a state in which the 1 / m thinning circuit and the AYUV circuit are used, a state in which the 1 / n thinning circuit and the AYUV circuit are used, and a state in which all the compression logic circuits are not used and the image information is passed. 13. The imaging device according to claim 12, wherein a state can be selected.

15. The imaging apparatus according to claim 13, wherein the interface circuit has an interface function of serial data transfer.

16. The imaging device according to claim 15, wherein the control unit gives the instruction according to control information supplied from the interface circuit.

17. An image sensor, a variable compression unit that compresses image information obtained via the image sensor at a variable compression rate, and an imager used for data transmission of compressed image information output from the variable compressor. And a face circuit, An imaging apparatus in which the variable compression section is instructed on a compression ratio in accordance with control information supplied from the interface circuit, and is capable of completing a compression process within a single image information frame.

8. The imaging device according to claim 17, wherein the interface circuit has an interface function of serial data transfer.

9. A data processing system including an imaging device and a host device, wherein the imaging device includes: an imaging device; and a compression unit configured to compress image information acquired via the imaging device at a variable compression rate. An interface circuit used for data transmission of compressed image information output from the compression unit, wherein the compression unit is instructed on a compression ratio according to control information supplied from the interface circuit, The compression process can be completed within a single image information frame,

A decompression processing system comprising: a decompression circuit that can decompress the compressed image information transmitted from the interface circuit with reference to the control information indicating the compression ratio.

10. The data processing system according to claim 19, wherein said interface circuit has an interface function of serial data transfer, and said host device is a personal computer.