JP2004229314A - Image decoding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a conventional problem that when a video is reproduced in real time, a high-speed image decoding apparatus is generally required, which is a disadvantage in terms of cost and power consumption. <P>SOLUTION: A decoding unit 12 decodes an image according to JPEG2000. A simplified unit 30 includes a compulsory converter 32 for comparing elapsed time with a time limit in each stage of image decoding, and switching a decoding processing to a simplified processing when needed. For example, when the time for reproducing one frame of the video is expected to exceed a 1/30 second, the compulsory converter 32 performs the simplified processing in which, for example, only low frequency components are decoded. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an image decoding technique, and more particularly to a method and apparatus for decoding encoded image data.

  2. Description of the Related Art In recent years, with the spread of various information devices represented by PCs (personal computers), the popularization of digital cameras and color printers, and the explosion of the Internet population, the culture of digital images has deeply penetrated into ordinary people's daily life. . Under these circumstances, encoding and compression techniques such as JPEG (Joint Photographic Expert Group) and MPEG (Motion Picture Expert Group) have been standardized for still images and moving images, respectively, and recording media such as CD-ROMs, networks or broadcast The convenience of distributing and reproducing images via transmission media such as waves has been improved. In the JPEG series, JPEG 2000, which can be called an advanced version of JPEG, has been announced, and a medium-to-long term goal has been set for MPEG.

For example, taking a single digital camera, recently, the movie shooting function has been enhanced and the unique area of the movie camera has been narrowed. The number of pixels of a CCD (Charge Coupled Device) is also on the order of millions, and some have a high-speed continuous shooting function. While some users have been stuck with silver halide cameras, the wave of digitization has never stopped, just as it has replaced music records with compact discs.
JP-A-11-225337

  However, with the development of consumer electronics, functions, operability and cost must always be considered together. Enhancement of functions creates expectations for operability and cost. For example, when a digital camera is equipped with a moving image playback function and a high-speed continuous shooting function, image data that has been compressed and coded and stored in a memory card or the like must be read out and decoded and decompressed at a timing suitable for display. . For this purpose, a high-speed image decoder must be mounted, which is generally disadvantageous in terms of cost, power consumption, mounting area, and the like.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an image decoding technique that is advantageous in terms of cost, power consumption, and the like.

  Patent Literature 1 discloses a technique in which a transmission source of image data appropriately stops data transmission in consideration of variations in transmission line speed. It also discloses that a wavelet transform to which the present invention can be applied is used. This technique is designed mainly to operate when the transmission path is normal. On the other hand, the present invention aims to reduce the cost on the decoding side irrespective of the transmission path.

  One embodiment of the present invention relates to an image decoding method. In this method, when the decoding of the encoded image data is not completed within a specified time, the subsequent decoding is switched to a simplified process. Therefore, it is possible to prevent undesired reproduction such as dropped frames while maintaining a certain image quality without performing complicated or high-speed processing. The term “when the state of completion is not completed” includes not only the case where the completion is not actually completed, but also the case where it is predicted with a high probability that the completion is not determined based on the progress.

  Note that this aspect includes a step of acquiring the encoded image data, a step of inputting the acquired encoded image data to the decoding processing, a step of monitoring the elapsed time of the decoding processing, a result of the monitoring, and a step in the middle of the decoding processing. When the elapsed time at the check point exceeds a predetermined time limit, the subsequent decoding process may be switched to the simplified process.

  Another embodiment of the present invention relates to an image decoding device. The apparatus includes a decoding unit that decodes encoded image data, and a simplification unit that switches the subsequent decoding to a simplified process when decoding of the encoded image data is not completed within a specified time. . The simplification unit may execute the simplified decoding itself instead of the decoding unit, or may simply instruct the decoding unit to perform the simplification processing.

  Still another preferred embodiment according to the present invention relates also to an image decoding apparatus. The apparatus includes an imaging block, a mechanism control block that controls the mechanism in terms of a mechanism, and a processing block that processes a digital image obtained by imaging, wherein the processing block includes an encoding unit that is generated from the digital image. A decoding unit for decoding the image data; and a simplification unit for switching the subsequent decoding to a simplification process when the decoding of the encoded image data is not completed within a prescribed time.

  Still another preferred embodiment according to the present invention relates also to an image decoding apparatus. The apparatus includes a receiving block, a processing block for processing a received signal, and a reproduction block for reproducing the processed signal, wherein the processing block decodes encoded image data of a digital image extracted from the reception signal. And a simplification unit that switches the subsequent decoding to a simplification process when the decoding of the encoded image data is not completed within a specified time.

  Note that any combination of the above-described components and any conversion of the expression of the present invention between a method, an apparatus, a system, a computer program, a recording medium, and the like are also effective as embodiments of the present invention.

  According to the present invention, a relatively high-quality image can be decoded with a relatively small-scale configuration.

  Hereinafter, preferred embodiments of the present invention will be described. This embodiment relates to an apparatus for decoding image data encoded by JPEG2000.

  FIG. 1 is a diagram for explaining a decoding process based on JPEG2000. As shown in the figure, first, coded image data CI (Coded Image) is input, and after being subjected to processing such as arithmetic decoding and pit plane decoding as described later, it is subjected to inverse quantization processing. At this stage, an image obtained by performing the wavelet transform twice on the original image (hereinafter, referred to as an image WI2 of the second hierarchy) is obtained. Subsequently, the image is subjected to inverse wavelet transform to generate a first-layer image WI1. Further, this image is subjected to another inverse wavelet transform to obtain a decoded image DI (Decoded Image).

  If an encoding procedure is shown for easy understanding, it can be said that this is an inverse transformation of the processing of FIG. That is, the portion that is designated as the decoded image DI in FIG. 1 is the original image, which is subjected to wavelet transform once to generate the first hierarchical image WI1. The filter of the wavelet transform used in JPEG2000 is a Daubechies filter, and its essence is to apply a high-pass filter and a low-pass filter simultaneously to the vertical and horizontal directions of an image. Therefore, the image resulting from the conversion has an LL subband having low frequency components in both x and y directions, an HL subband having a low frequency component in one direction of x and y, and a high frequency component in the other direction, and It is divided into a total of four bands, an LH subband and an HH subband having high frequency components in both the x and y directions. This filter also has the effect of reducing the number of pixels in both the x and y directions by half. Therefore, as shown in FIG. 1, in the image WI1 of the first hierarchy, four schematically illustrated subbands (here, denoted by LL1, HL1, LH1, and HH1) are generated.

  In the wavelet transform in encoding, filtering is performed a predetermined number of times. In FIG. 1, the wavelet transform is performed twice, and an image WI2 of the second hierarchy is generated. The second and subsequent wavelet transforms are performed only on the LL subband components in the image of the immediately preceding layer. Therefore, in the image WI2 of the second hierarchy, the LL1 subband of the image WI1 of the first hierarchy is decomposed into four subbands LL2, HL2, LH2, and HH2. In the encoding process, the encoded image data CI is finally obtained through quantization and other processes.

  One thing to note about the layered image is that the low frequency components in the original image appear at the upper left in FIG. In the case of FIG. 1, the LL2 sub-band at the upper left corner of the image WI2 of the second hierarchy has the lowest frequency. Conversely, if only the LL2 sub-band can be obtained, the most basic property of the original image is obtained. Can be reproduced. This finding is used in the following embodiments.

  FIG. 2 shows the configuration of the image decoding device 10. This configuration can be realized in hardware by a CPU, a memory, or another LSI of an arbitrary computer, and is realized in software by a program having an image decoding function loaded in the memory. The functional blocks realized by their cooperation are drawn. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  The image decoding device 10 mainly includes a decoding unit 12 and a simplification unit 30. The decoding unit 12 receives the coded image data CI, analyzes the data stream, a stream analyzer 14, performs an arithmetic decoding on a data sequence to be decoded which is found as a result of the analysis, and A bit plane decoder 18 for decoding the obtained data in the form of a bit plane for each color component, an inverse quantizer 20 for inversely quantizing the result, and an image of the n-th layer obtained as a result of the inverse quantization An inverse wavelet transformer 24 that performs inverse wavelet transform on WIn is included. The wavelet inverse transformer 24 uses the frame buffer 22 as a work area. Finally, the decoded image DI obtained by completing the decoding is output from the frame buffer 22 for an arbitrary purpose.

  On the other hand, the simplification unit 30 monitors the progress of decoding, and when the elapsed time exceeds a predetermined time limit, the forcible converter 32 that forcibly switches the decoding process to the simplified process, and the forcible converter 32. It includes a time limit table 34 for storing time limits to be referred to, and a playback stop detection unit 36 for detecting when a user instructs stop during playback of a moving image. When the user instructs to pause or end playback while playing back a moving image, the frame that has been decoded and played back at that moment is effectively released from the time limit for decoding. Therefore, when such an instruction is detected by the reproduction stop detecting unit 36, the simplification processing by the compulsory converter 32 is avoided for the frame, and complete decoding and reproduction are performed as usual. However, there may be a case where the simplification process by the forcible converter 32 has already started, and in that case, the subsequent decoding process may be performed by a normal method as much as possible.

  The compulsory converter 32 refers to the clock CLK in order to measure the elapsed time. The clock CLK is frequency-divided as necessary inside the compulsory converter 32, counted by a counter (not shown), and a predetermined time is measured. However, instead of using the clock CLK, the compulsory converter 32 may refer to an external clocking means such as a PIT (programmable interrupt timer). Also, here, the coercive converter 32 monitors the progress of the processing in the wavelet inverse transformer 24, but this need not be the case, and any step from the stream analyzer 14 to the wavelet inverse transformer 24 is performed. May be monitored. Hereinafter, the process to be monitored is simply represented by “decoding”.

  FIG. 3 shows the relationship between the time limit and the elapsed time at each stage of the decoding process, and the activation of the simplification process. As shown in the drawing, the frame period is set to Tf, and in the case of decoding a moving image, for example, Tf is set to 1/24, 1/30 seconds, and the like. Three time limits are set according to the processing stage. The decoding in JPEG2000 independently processes each of the color components luminance Y, color difference Cb, and Cr. In the drawing, the time limit for decoding the luminance Y is set to Ty, the time limit for decoding the color difference Cb is set to Tb, and similarly, the time limit for decoding the color difference Cr is set to Tr. These time limits are stored in the time limit table 34 in advance. By setting the time limit for each color component, the reproduction of an unnatural image such that only a certain color component is decoded and other components are not decoded at all is prevented. The ratio of the time limit may be set based on the ratio of the average time required for each processing stage, may be allocated to an important color component, for example, the luminance Y, or may be set to a larger value through experiments. It can be set arbitrarily.

  In JPEG2000, decoding is performed on images of the same layer in the order of LL, HL or LH, and HH subbands. Accordingly, four sub-bands are first decoded for luminance Y in this order, and then four sub-bands for chrominance Cb and Cr are decoded.

  Now, it is assumed that the processing of the three sub-bands LL, HL, and LH has been completed normally in the decoding processing of the luminance Y, but the time limit Ty has passed during the processing of the last HH sub-band. In this case, the decoding process relating to the luminance Y is interrupted, and the process shifts to a simplification process denoted as “process A” in FIG. Subsequently, it is assumed that the decoding process of the color difference Cb is started and the decoding of the LL sub-band is completed normally, but the time limit Tb has passed in the middle of the decoding of the next HL sub-band. In this case, the decoding process for the color difference Cb is stopped, and the process shifts to a simplification process denoted as “process B” in FIG. Next, the decoding process proceeds to the color difference Cr. In this decoding process, it is assumed that the time limit Tr has passed during the processing of the first subband LL. At this time, the decoding process is stopped, and the process shifts to a simplification process denoted by “Processing C” in FIG. The processes A, B, and C are all activated by comparing the time limit of the forcible converter 32 with the elapsed time actually taken for the process.

  FIGS. 4A, 4B, and 4C schematically show the contents of processes A, B, and C by the forced converter 32, respectively. As shown in FIG. 4A, as the process A, the forcible converter 32 invalidates the coefficients of the HH subbands that have been cut off during the decoding. That is, all components of the HH subband are replaced with 0. The coercive transformer 32 cooperates with the wavelet inverse transformer 24 for this processing, and the wavelet inverse transformer 24 stores the HH subband components that would otherwise have been stored after the inverse transform. The compulsory converter 32 stores “0”. According to this simplification process, the decoding of the luminance Y can be kept within the time limit Ty, and the fact that the human eye is generally not very sensitive to high frequency components can be used to minimize the deterioration of image quality. .

  FIG. 4B shows a simplification process performed by the forcible converter 32 as the process B. As shown in the figure, in the decoding process of the color difference Cb, only the subband LL was successfully decoded. Therefore, as shown in the figure, the coefficients of all three sub-bands other than the LL sub-band are invalidated and padded with zeros. Also in this case, the purpose is to leave the low frequency component. Generally, a filter for wavelet transform adopted in JPEG2000 is designed with an emphasis on image quality at a low bit rate, and can maintain a relatively high image quality even when an image is reproduced using only the LL subband. Here, the property is used.

  FIG. 4C shows the processing by the compulsory converter 32. In the processing of the chrominance Cr, even the first subband, LL, was not completely finished. For this reason, as shown by LL 'in the figure, processing is performed on the data of the LL subband. Specifically, the processing time is reduced by skipping the processing of the lower bit plane among the plurality of bit planes forming the LL sub-band.

  FIG. 5A shows the relationship between the LL2 subband and the bit plane in the second hierarchy WI2. As shown in the figure, in the image WI2 of the second hierarchy, first, the LL2 subband is decoded in such a manner as to traverse all the bit planes as shown by the rectangular parallelepiped 50 in the figure. Therefore, by skipping from the bit plane closer to the LSB (least significant bit), it is possible to reduce the processing time while minimizing the deterioration of the image quality.

  In FIG. 5B, the rectangular parallelepiped 50 relating to the LL2 subband is divided into a portion 52 formed by a valid bit plane and a portion 54 to be skipped. Here, one least significant bit plane is discarded in relation to the time limit Tr.

  As described above, since one frame can be reproduced for each frame period Tf by the simplification processing of the simplification unit 30, particularly the compulsory converter 32, a moving image or a continuously shot image can be reproduced at a desired speed without dropping frames. . Also, at this time, since consideration is given to prevention of deterioration in image quality, a relatively natural image can be obtained. Further, since the time limit is allocated to each color component, there is a low possibility that color variation occurs between frames. Therefore, according to this embodiment, a very small configuration can produce a very great advantage in practical use.

  In such a case, a case has been considered in which a time limit elapses during decoding of an image. However, depending on the situation, conversely, a time limit may be left. FIG. 6 shows how to reschedule the time limit in such a situation.

  In this figure, the frame period Tf is the same as in FIG. 3, and the three time limits Ty, Tb, Tr are also the same as in FIG. In this state, first, it is assumed that the decoding process of the luminance Y is started and all the four sub-bands LL, HL, LH, and HH are completed within the time limit Ty. In the figure, there is a time margin Tm with respect to the time limit Ty. In this case, the margin Tm can be included in decoding the color differences Cb and Cr. Therefore, as shown in the figure, the time limits Tb and Tr for the color differences Cb and Cr are alleviated, and are changed to longer time limits Tb 'and Tr'.

  According to this method, when decoding of a certain color component is completely completed, there is a time margin in decoding other color components as a ripple effect, and as a result, the number of color components that are completely decoded increases. Therefore, the overall image quality is improved while maintaining the color balance.

  When all or any of the three color components is decoded within the time limit, the decoding time of the entire frame may be shorter than the frame period Tf which is the originally specified time. In this case, the same concept of rescheduling is extended between frames. That is, if a time margin occurs when a certain frame is decoded, this margin may be added to the next frame period Tf. According to this method, a larger number of frames can be reproduced completely or with higher image quality. Further, according to this embodiment, a desired reproduced image can be obtained at low cost and low power consumption without imposing an excessive burden on the image decoding device 10.

  FIG. 7 shows a configuration of a digital camera 200 according to another embodiment. The digital camera 200 includes an imaging block 202, a mechanism control block 204, a processing block 206, an LCD monitor 208, and an operation button group 210.

  The imaging block 202 includes a lens, an aperture, an optical low-pass filter, a CCD, a signal processing unit, and the like (not shown). Electric charges are accumulated in the CCD according to the amount of light of the subject image formed on the light receiving surface of the CCD, and read out as a voltage signal. The voltage signal is decomposed into R, G, and B components by a signal processing unit, and white balance adjustment and gamma correction are performed. Thereafter, the R, G, and B signals are A / D converted and output as digital image data to the processing block 206.

  The mechanism control block 204 controls the optical system of the imaging block 202, that is, controls driving such as zoom, focus, and aperture. The processing block 206 includes a YC processing unit 226, a card control unit 228, and a communication unit 224, in addition to the CPU 220 and the memory 222 used for controlling the entire digital camera 200. Of these, some of the functions of the CPU 220 and the image decoding program loaded into the memory 222 correspond to the image decoding device 10 in FIG. The frame buffer 22 in FIG. 2 can also be realized by using a part of the memory 222. In the digital camera 200, an image encoding device (not shown) is also realized by the CPU 220 and the memory 222 in order to store image data in the memory card 230. Therefore, the following description will be made on the assumption that the encoding and the decoding are possible.

  The YC processing unit 226 generates a luminance Y and color differences Cb and Cr from the digital image data. Luminance and chrominance are coded independently and sequentially. The encoded image data CI is output to the outside via the communication unit 224 or written into the memory card 230 via the card control unit 228.

  The communication unit 224 controls protocol conversion and the like in accordance with standard communication specifications, and in addition, exchanges data with an external device such as a printer or a game machine through an individual interface.

  The LCD monitor 208 displays photographed moving images, high-speed continuous shot images, still images, and the like, in addition to the photographing / playback mode, zoom magnification, date and time, and the like. Therefore, when a user shoots a moving image, the moving image is first encoded and compressed, and is recorded on, for example, the memory card 230. When the user reproduces the moving image, simplification processing characteristic of the embodiment is performed as necessary. Note that the operation button group 210 includes a power switch, a release switch, and the like for the user to take a picture or set various operation modes.

  With the above configuration, the following effects occur.

  1. When capturing and reproducing a still image, there is no physical time limit for decoding. Therefore, decoding is not simplified, and reproduction with the highest image quality is performed. However, even for a still image, a decoding time that is too long can be problematic, so the simplification processing according to the embodiment may be performed.

  2. When a moving image is captured and reproduced, a simplification process is performed in some cases because the frame rate is fixed. For this reason, the image quality can be maintained and the drop of frames can be prevented without increasing the speed of the image decoding apparatus 10. Since high specifications are not required for the image decoding apparatus 10, there are advantages in cost and power consumption.

  3. When stop or temporary stop is instructed during the reproduction of a moving image, the simplification process is not performed on the last frame, so that the image quality is the highest or close to it. In particular, since the frame is visible to the user as a still image for a relatively long time, the merit of this is great.

  FIG. 8 shows a configuration of a television receiver 300 according to still another embodiment. The television receiver 300 includes an antenna 302, a reception block 304 that receives broadcast waves via the antenna 302, a processing block 306 that processes image and audio data obtained as a result of processing by the reception block 304, and a processing block 306. A reproduction block 308 for reproducing the decoded audio and image is included. Further, the interface block 336 outputs the decoded image data obtained by the processing block 306 to an external device as appropriate.

  The reception block 304 includes a tuner 320 and a packet separation unit 322. Tuner 320 selects a transponder including the channel selected by the user and performs QPSK demodulation. A stream including a plurality of transport packets obtained by demodulation is sent to packet separation section 322. The packet separation unit 322 is a demultiplexer that separates a packet corresponding to a desired channel and outputs the packet to the processing block 306.

  The image / audio decoder 334 of the processing block 306 cooperates with the CPU 330 and the memory 332 to decode the image and audio data encoded and transmitted by the broadcasting station. The image / audio decoder 334 decodes the input packet, and outputs audio data to the audio output unit 340 and image data to the display device 344, respectively. The audio output unit 340 performs a predetermined process on the input audio data, and finally outputs the audio to the speaker 342. The configuration of the processing block 306, that is, the portion related to image decoding among the image / audio decoder 334, the CPU 330, and the memory 332 corresponds to the image decoding device 10 in FIG. According to the above configuration, a so-called digital television can be realized with very low cost and power consumption. This television can be mounted on a small device such as a mobile phone, for example.

  The present invention has been described based on the embodiments. These embodiments are exemplifications, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. By the way. Hereinafter, modified examples will be described.

  In the process B of FIG. 4B, all the components of the three subbands other than the LL subband are invalidated. However, as a method other than this, a scale-up process may be performed in which components other than the LL sub-band are not considered, and the LL sub-band is simply doubled vertically and horizontally. In this case, a process of interpolating between pixels is used. When the characteristics of the filter used for this process are the same as those used for the inverse JPEG2000 wavelet transform, the same image as when the components of the three subbands are invalidated is used. Is obtained.

  In the embodiment, a time limit is assigned to each color component. However, the time limit may be allocated in accordance with other attributes of the image. For example, when an image is divided into a plurality of regions and decoding processing is performed for each region, a time limit may be assigned to each region. In that case, time is allocated in proportion to the area of the region, a relatively long time is allocated to a region near the center of the image, a relatively long time is allocated to a region that is conspicuous in the image, for example, a region with high brightness, For example, a method of allocating a relatively long time to a region having a large motion, for example, a region having a large motion vector component, or a method of allocating a long time to a region having a high importance as an object, for example, a human face region in a videophone can be considered. . In JPEG2000, a method of dividing an image into tiles in advance is also possible. In that case, the same assignment may be made for each tile. Also in this case, if the processing of a certain area is completed within the time limit, the time limit of another area may be rescheduled.

  In FIG. 4C, the processing of the lower bit plane of the LL subband is omitted. As another method, the LL sub-band of the image of the layer that has been decoded earlier may be used. For example, in FIG. 1, when the decoding of the LL1 subband of the image WI1 of the first layer is not completed, the LL2 subband of the image WI2 of the second layer which is the immediately preceding layer is enlarged and used. Good.

  In FIG. 4C, the processing time is reduced by omitting the processing of the lower bit plane for the LL subband. As another decoding method, four subbands may be processed in bit plane units in order from the most significant bit plane. That is, for a certain bit plane, processing is performed in the order of LL, HL or LH, and HH subbands, and then processing is performed in the same order for the next lower bit plane. Also in this decoding method, when the time limit has elapsed, the decoding process can be simplified by omitting the processing of the unprocessed lower bit plane. In this case, unlike the case shown in FIGS. 5A and 5B, the processing of the lower bit plane is omitted for all four subbands.

FIG. 9 is a diagram illustrating a series of procedures for decoding encoded image data according to JPEG2000. FIG. 2 is a configuration diagram of an image decoding device according to an embodiment. FIG. 14 is a diagram illustrating a relationship between a frame period, a time limit, and actual decoding processing in the embodiment. FIGS. 4A, 4B, and 4C are diagrams showing the simplification processing performed by the simplification unit, respectively. FIGS. 5A and 5B are diagrams showing the relationship between the LL subband of a certain layer and a bit plane in JPEG2000. FIG. 10 is a diagram illustrating a case where a time margin occurs in a certain decoding process in the embodiment and the time limit of another decoding process is rescheduled. FIG. 1 is a configuration diagram of a digital camera according to an embodiment. It is a block diagram of the television receiver concerning embodiment.

Explanation of reference numerals

  Reference Signs List 10 image decoding device, 12 decoding unit, 14 stream analyzer, 16 arithmetic decoder, 18 bit plane decoder, 20 inverse quantizer, 22 frame buffer, 24 wavelet inverse transformer, 30 simplification unit, 32 forced converter , 34 time limit table, 36 playback stop detection unit, 200 digital camera, 202 imaging block, 204 mechanism control block, 206 processing block, 208 LCD monitor, 210 operation button group, 220 CPU, 222 memory, 224 communication unit, 226 YC Processing unit, 228 card control unit, 230 memory card, 300 television receiver, 302 antenna, 304 reception block, 306 processing block, 308 reproduction block, 320 tuner , 322 packet separation unit, 330 CPU, 332 memory, 334 image / sound decoder, 336 interface block, 340 sound output unit, 342 speaker, 344 display device.

Claims (4)

In a method for decoding encoded image data,
When the decoding of the encoded image data is not completed within a prescribed time, the subsequent decoding is switched to a simplified process to perform the decoding. A decoding unit for decoding encoded image data;
When the decoding of the encoded image data is not completed within the specified time, a simplification unit that switches the subsequent decoding to the simplification processing,
An image decoding device comprising: Including an imaging block, a mechanism control block that controls it mechanically, and a processing block that processes a digital image obtained by imaging,
The processing block comprises:
A decoding unit for decoding encoded image data generated from the digital image,
When the decoding of the encoded image data is not completed within the specified time, a simplification unit that switches the subsequent decoding to the simplification processing,
An image decoding device comprising: A receiving block, a processing block for processing the received signal, and a reproduction block for reproducing the processed signal,
The processing block comprises:
A decoding unit for decoding encoded image data of a digital image extracted from the received signal,
When the decoding of the encoded image data is not completed within the specified time, a simplification unit that switches the subsequent decoding to the simplification processing,
An image decoding device comprising:

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