JP3645249B2 - Electronic still camera - Google Patents

Description

The present invention is an imaging element, AD conversion unit, a frame memory, an electronic still camera provided with a data compression unit and the like.

Some conventional electronic still cameras can record about 20 frame images on a 2-inch magnetic disk. When recording 20 or more images with this camera, the new magnetic disk is replaced and recorded. That is, the magnetic recording format is a floppy disk format, and the disk can be exchanged (see Patent Document 1).
JP 63-122392 A

  Although an electronic still camera is inferior to a silver salt camera in terms of resolution, it is superior in terms of immediacy playback, electrical transmission, editing, searchability, and the like. The fact that high-speed continuous shooting is possible is said to be one of the excellent points of an electronic still camera, and the user needs for this are high. However, at present, the recording speed of this magnetic disk is limited to 15 frames / second. Moreover, since the recording capacity (number of sheets) is about 20, continuous shooting is completed in about 1 second. Thus, from the viewpoint of recording speed and recording time, it is difficult to take a single golf swing for continuous shooting with the current electronic still camera. In addition, it seems that the number of pixels will increase in the future in order to increase the resolution. For example, when the number of pixels of the HDTV system is reached, considering the amount of data, the number of continuous shots and the recording speed are further increased. It decreases and decreases to about 1/5.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic still camera suitable for recording and reproduction by increasing the recordable number of continuous shots in an electronic still camera capable of single-frame recording and continuous recording .

  In order to achieve the above object, the electronic still camera of the present invention has the following characteristic configuration. In addition, about the characteristic structure of this invention other than the following, it clarifies in embodiment.

The electronic still camera of the present invention is capable of generating image data subjected to intra-frame compression, and generating image data subjected to inter-frame compression and image data subjected to at least one frame intra-frame compression. In the camera, image data compression means adapted to perform intra-frame compression or inter-frame compression on the supplied image signal, and image recording on an applied recording medium are possible, and the image data compression means It is possible to identify whether the image data compressed by the above is image data generated by generating the image data subjected to the inter-frame compression and the image data subjected to the intra-frame compression of at least one frame. A recording means for recording; and the image data recorded on the recording medium can be decoded, and the image data In the case of image data generated by generating image data subjected to inter-frame compression and image data subjected to at least one frame intra-frame compression, the image data subjected to inter-frame compression is subjected to inter-frame decoding, The image data subjected to the intra-frame compression is connectable to a TV monitor, a decoding unit that performs intra-frame decoding, a conversion unit that converts the image data decoded by the decoding unit into a state that can be reproduced on a TV monitor, and the TV monitor. The first output means for outputting the image data converted by the conversion means to the TV monitor and the electronic album apparatus can be connected, and the image data recorded in the recording means is stored in the electronic album apparatus. A second output means for outputting, from the second output means to the electronic album device without the conversion means. Is characterized in that image data recorded in the recording means are output.

According to the present invention, in an electronic still camera capable of single frame recording and continuous recording, it is possible to provide an electronic still camera suitable for recording and reproduction by increasing the recordable number of continuous shots.

(One embodiment)
FIG. 1 is a block diagram showing a part of the configuration of an electronic still camera using an image data recording system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the remaining part of the configuration of the electronic still camera. . The configuration of this embodiment will be described below with reference to FIGS. Subject image incident through the lens 50 with respect to an imaging element 1 is converted into a video signal in this IMAGING element 1. The video signal is amplified by the preamplifier 2, converted to a digital signal by the A / D converter 3, and temporarily stored in the frame memory 4. The frame memory 4 is for performing time conversion, data string conversion, and the like for subsequent various signal processing. The video signal is converted into sequential signals of Y, RY, and BY by the frame memory 4 and the video process circuit 5. Further, in order to perform data compression, which will be described later, in the subsequent data compression section 6, the sequential signals (Y, RY, BY) are output as image data for each block of 8 × 8 pixels. The image data compressed by the data compression unit 6 is recorded on the recording medium 8 through the recording unit 7. When the recording medium 8 is a magnetic disk, a magnetic tape, or the like, the recording unit 7 includes an error correction encoding circuit and a recording modulation circuit. This is not particularly necessary when the recording medium 8 is a semiconductor memory such as a memory card.

  Next, the data compression circuit 6 will be described. This data compression circuit 6 is configured so that compression within a frame and compression between frames can be performed simultaneously. It is also possible to set only compression within a frame by switching. Data compression within a frame is performed by an ADCT (Adaptive Discrete Cosine Transformer) system as shown in Japanese Patent Application No. 01-283761, which has a high image quality and a high compression rate. For inter-frame data compression, motion compensation inter-frame prediction is performed for each block using the previous frame, and a prediction error is obtained by taking the difference from the current frame, and this value prediction is performed by quantizing the prediction error signal. Done in a manner.

  First, the operation of the data compression circuit 6 when shooting one frame will be described. The camera 24 has a changeover switch 36 for selecting one frame shooting or continuous shooting. When this is set to single frame shooting, the changeover switch 10 is switched to the terminal 11 side through the control unit 9, and the subtraction circuit 12 only passes the video signal. At this time, the inverse quantization circuit (representative value setting circuit) 13, the inverse DCT circuit 14, the adder circuit 15, the frame memory 16, the frame memory control unit 17, and the motion vector detection unit 18 are not used. For this reason, the power supply is set to the OFF state through the power supply control unit 19. The Y, RY, BY sequential signals converted into 8 × 8 pixel blocks by the frame memory 4 and the video process circuit 5 are converted into two-dimensional DCT coefficients (8 by the DCT circuit 20 for each block. X8 coefficient). Next, the quantization circuit 21 divides this two-dimensional DCT coefficient by a quantization width (quantization matrix) assigned in advance for each frequency component, thereby performing linear quantization corresponding to each frequency component. This quantization width is usually increased as it approaches the high frequency component. This is because high frequency components have a low frequency of occurrence and a small amplitude, so that even if some omissions occur due to visual characteristics, the image quality is hardly affected. By using this and performing the above quantization, the compression effect in the subsequent encoding circuit 22 can be significantly increased. In other words, the encoding circuit 22 zigzags the quantized 8 × 8 system matrix from the upper left low frequency component to the lower right high frequency component to increase the frequency of the zero value component to increase 2 Perform dimensional Huffman coding. For this reason, by performing the quantization as described above, the high-frequency component is almost zero, and the compression effect by the two-dimensional Huffman coding can be greatly increased. The above detailed description of the ADCT system is described in Japanese Patent Application No. 01-283761. The two-dimensional Huffman coding is a variable length code, but it is desirable that the code amount of one screen is constant in consideration of search, editing and the like. A method of using a two-dimensional Huffman code and making the code amount per screen constant is also described in the above application.

  Next, the operation of the data compression circuit 6 when performing continuous shooting, that is, continuous shooting will be described. First, when the changeover switch 36 is set to continuous shooting and the shutter 26 is pressed, the power of each necessary circuit enters an operating state through the power control unit 19. In particular, the subtraction circuit 12, the inverse quantization circuit 13, the inverse DCT circuit 14, the addition circuit 15, the frame memory 16, the frame memory control unit 17, and the motion vector detection unit 18 are different from each other when shooting one frame. It is set to the operating state differently. Then, after autofocus operation, photometry, etc. are performed, continuous shooting is started. For the first image frame after the continuous shooting is started, the changeover switch 10 is switched to the terminal 11 side, and the same compression (intra-frame compression by ADCT) as that for the one-frame shooting described above is performed, and recording is performed. Recorded on the medium 8. At the same time, the output of the quantization circuit 21 is decoded into the original image by the inverse quantization circuit 13 and the inverse DCT circuit 14 and stored in the frame memory 16 as the first frame data. However, the frame data at this time is stored as a form including a quantization error by the quantization circuit 21. At the same time, this frame data is subjected to a correlation operation with the second frame signal (current frame signal 25) output from the video process circuit 5 in the motion vector detection unit 18, and each block of the second frame (current frame) is calculated. A reference motion vector is detected. Then, data for 8 × 8 pixels of the first frame (previous frame) at the position corresponding to the motion vector is read from the frame memory 16 through the memory control unit 17. Then, the difference from the image data 25 of the second frame (current frame) is obtained by the subtraction circuit 12. The difference is compressed by the above-described ADCT method. That is, the DCT circuit 20 performs DCT conversion within the frame, the quantization circuit 21 performs predetermined quantization, the encoding circuit 22 performs Huffman encoding, and the recording medium 8 stores the result. . At this time, the motion vector signal 28 is also encoded by the encoding circuit 22 and recorded together with the block data. Since the difference data amount has a high correlation between frames, if the motion compensation inter-frame prediction is performed, the amount of data becomes very small, and after the encoding circuit 22, compression of about 1/100 is possible. Now, when a 2M BYTE memory card is used as a recording medium, the continuous shooting duration can be about 16 to 20 seconds. When the difference between the image data of the first frame and the second frame is taken by the subtraction circuit 12, the changeover switch 10 is naturally switched to the terminal 23 side. This data difference is immediately decoded through the circuits 20, 21, 13, 14 and the adder circuit 15 and stored in the frame memory 16 and the buffer memory in the motion vector detection unit 18. Since writing to and reading from the frame memory 16 has a time delay due to the processing of the circuits 20, 21, 13, and 14, data at the same address will not be shared, and writing and reading can be performed in a time-sharing manner for each clock. Can be accessed simultaneously. When data is shared, a delay circuit having an appropriate delay amount may be inserted after the adder circuit 15. The delay amount of the delay circuit is such that the motion vector is detected from the time when the current frame signal 25 is input to the motion vector detecting unit 18 and the data of the previous frame is read from the frame memory 16 through the memory control unit 17 correspondingly. The subtraction circuit 12 can be processed in real time. The compression after the third frame is also performed by repeating the above-described operation. The image data includes address information (for searching and editing), ID information (date, etc.), a continuous shooting identification signal 29 for identifying single frame shooting and continuous shooting, and a control circuit 9. Added through the circuit 22. Incidentally, as shown in the figure, in the data compression circuit 6, a local decoder 27 is purposely provided to detect a prediction error from the previous frame to form a feedback configuration, and the DCT circuit 20 and the quantum are included in this feedback loop. A circuit 21 is inserted. The reason is that the prediction error is quantized while taking into account the integrated value of the quantization noise caused by the quantization, so that the accumulation of noise during decoding is avoided.

  Next, an operation for reproducing an image will be briefly described. First, when performing one-frame playback, the changeover switch 10 is set to the terminal 11 side. Then, the compressed image data is read from the recording medium 8 in accordance with the set address. When the recording medium 8 is a magnetic disk or a magnetic tape, the recording unit 7 demodulates the recording code and corrects the error. Then, it is input to the encoding circuit 22 and two-dimensional Huffman is decoded. Then, the image data is restored through the inverse quantization circuit 13 and the inverse DCT circuit 14. The restored image data is converted into a parallel signal of Y, RY, BY by the serial / parallel converter 30 and converted into an NTSC signal by the NTSC circuit 31. Then, it is converted into an analog signal by the D / A converter 32 and displayed on the TV monitor 33.

  Next, continuous shooting reproduction will be described. In this case, the changeover switch 10 is set to the terminal 23 side after the first image is restored by the same process as the one-frame reproduction and stored in the frame memory 16. This is controlled by the control section 9 after the continuous shooting identification signal 29 added to the head of the compressed data is determined by the encoding circuit 22. After that, the continuous shot image is reproduced by the same operation as that of the continuous decoding local decoder 27. By the way, in the continuous shooting system of the present invention, in addition to intra-frame compression (ADCT), inter-frame compression is performed by a previous value prediction system. For this reason, even if normal playback is possible, trick playback such as reverse playback and search playback for each frame become difficult. Therefore, when changing to an electronic album device 60 such as a magnetic disk, an optical disk, or a digital VTR, the compression (ADCT) in the frame is performed again by the circuit 34 and then recorded in the mass storage 35. In this way, trick playback, searching and editing are possible.

Since this electronic still camera is capable of single-frame recording and continuous recording and is suitable for recording and reproduction, it is extremely useful, for example, when performing continuous shooting .

1 is a block diagram showing a part of a configuration of an electronic still camera according to an embodiment of the present invention. The block diagram which shows the remaining part of the structure of the electronic still camera which concerns on one Embodiment of this invention.

Explanation of symbols

1 ... imaging element, 3 ... A / D converter, 4 ... frame memory, 6 ... data compression unit, 9 ... control unit, 36 ... one frame / continuous shooting switch switch.

Claims (2)

In an electronic still camera capable of generating image data subjected to intra-frame compression, and generating image data subjected to inter-frame compression and image data subjected to intra-frame compression of at least one frame.
Image data compression means adapted to perform intra-frame compression or inter-frame compression on the supplied image signal;
The image data can be recorded on the applied recording medium, and the image data compressed by the image data compression means is the image data subjected to the inter-frame compression and the image data subjected to the intra-frame compression of at least one frame. Recording means for recording in an identifiable state whether or not the image data is generated by generating
Image data that is decodable in the image data recorded on the recording medium, and the image data is generated by generating the image data subjected to the inter-frame compression and the image data subjected to the intra-frame compression of at least one frame. In this case, the image data subjected to the inter-frame compression performs inter-frame decoding, and the image data subjected to the intra-frame compression performs decoding within the frame;
Conversion means for converting the image data decoded by the decoding means into a state reproducible on a TV monitor;
A first output means that is connectable to a TV monitor and outputs the image data converted by the conversion means to the TV monitor;
A second output means connectable to the electronic album device and outputting the image data recorded in the recording means to the electronic album device;
Comprising
An electronic still camera , wherein the image data recorded in the recording means is output from the second output means to the electronic album apparatus without going through the converting means . The electronic still camera according to claim 1, wherein the electronic album device includes any one of a magnetic disk device, an optical disk device, and a digital VTR device.

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