JP2019075685A - Image encoding apparatus, image encoding method, and program - Google Patents

Abstract

To reduce image quality deterioration at a time of changing a position of a partial image corresponding to a partial region of a captured image.SOLUTION: The image encoding apparatus includes: encoding means for encoding a frame of a partial image corresponding to a partial area of a captured image captured by imaging means using at least either of intra-frame encoding and inter-frame encoding; and output means for outputting the partial image encoded by the encoding means. The encoding means encodes a second partial image without using the inter-frame encoding when a state is changed from a state where a first partial image is output by the output means to a state where the second partial image of a region different form the first partial image is output by the output means.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image coding apparatus, an image coding method, and a program.

  2. Description of the Related Art Conventionally, there is known a monitoring system which controls a monitoring camera by remote control via a network or a dedicated line to monitor an image. Among such monitoring systems, there are systems for encoding moving images to realize reduction of the distribution data size in order to perform long-time recording and smooth video distribution. As a coding method, for example, an intra-frame coding method using an intra-frame correlation (coding method using intra prediction) and an inter-frame coding method using an inter-frame correlation (inter prediction) Encoding method using the.

  In this video delivery method, a group consisting of at least one intraframe encoded I frame and a plurality of interframe encoded P frames and B frames is called a group of pictures (GOP), and each GOP is Output. Also, I-frames are decoded alone, but P-frames are decoded based on I-frames and P-frames prior to this. B frames are decoded based on I frames and P frames before and after. Furthermore, when the GOP length is short, it is possible to smoothly perform seek such as reproduction or stop of video, but the data size becomes large because the interval of I frames having a large amount of information becomes short. Therefore, there is a function to make the data size smaller by lengthening the GOP length to several tens of seconds.

  In the monitoring system having such a function, the data size of the video to be distributed can be suppressed, and smooth video distribution becomes possible. However, if a scene change or the like occurs in the P frame and the image changes significantly, it is not possible to maintain the high compression rate of the interframe coding scheme. As a result, the amount of data may increase and the image quality may also deteriorate. On the other hand, Patent Document 1 discloses a technique for compressing an image by intraframe coding instead of interframe coding when a scene change is detected.

Unexamined-Japanese-Patent No. 10-51784

  However, when the frame after the scene change is a B frame, the technique disclosed in Patent Document 1 changes to an I frame or a P frame that appears later, so the video itself immediately after the scene change is an I frame. It does not. Therefore, the video immediately after the scene change can not be distributed. Further, in the case of the P frame, since the image is distributed as it is, the video having a large difference becomes the P frame, and the problem of the image quality deteriorating remains. In particular, when the position of the digital PTZ image in the omnidirectional camera is continuously changed, there is a problem that many P frames having a large difference immediately after the position change are transmitted.

  The present invention has been made in view of such problems, and it is an object of the present invention to reduce image quality deterioration when switching from a partial image corresponding to a partial region of a captured image to a partial image corresponding to another region. .

  Therefore, the present invention is an image coding apparatus, which uses at least one of intraframe coding and interframe coding for a frame of a partial image corresponding to a partial region of a captured image captured by an imaging unit. Encoding means for encoding the image and output means for outputting the partial image encoded by the encoding means, the encoding means outputting the first partial image by the output means When the state is changed to a state in which a second partial image of an area different from the first partial image is output by the output unit, the second partial image may be output without using the interframe coding. It is characterized by encoding.

  According to the present invention, it is possible to reduce image quality deterioration at the time of changing the position of a partial image corresponding to a partial region of a captured image.

FIG. 1 is an overall view of a camera system according to a first embodiment. It is a hardware block diagram of a camera server apparatus. It is a function block diagram of a camera server apparatus. It is a figure which shows an example of a viewer. It is a flow chart which shows coding method decision processing in the case of position specification. It is a flow chart which shows coding method decision processing in the case of direction specification. It is a flowchart which shows the encoding method decision processing which concerns on 2nd Embodiment. It is a flow chart which shows coding method decision processing concerning a 3rd embodiment. It is a figure which shows an example of a threshold value table.

  Hereinafter, embodiments of the present invention will be described based on the drawings. In the embodiment, an I frame is a frame encoded using only intra prediction without using inter prediction in each block in the frame. Such a frame is also called an intra frame or a key frame. In addition, P frame and B frame are frames encoded using inter prediction in at least a part of the frame. Such a frame is also called an inter frame.

First Embodiment
FIG. 1 is an overall view of a camera system according to the first embodiment. The camera system includes a camera server device 100 and a client device 110. The camera server apparatus 100 and the client apparatus 110 are mutually connected via the network 120. The camera server device 100 is an example of an image coding device. The camera server device 100 includes a camera with a variable shooting angle of view, and distributes a captured image via the network 120. The client device 110 accesses the camera server device 100, controls image quality parameters such as pan (P) / tilt (T) / zoom (Z) and focus and exposure while acquiring an image, and performs preset setting. The details of each will be described later. In addition, although the camera server apparatus 100 is set to one for simplification of description, two or more may be sufficient. In addition to the client device 110, there may be other clients that access the camera server device 100 to receive and store images. The network 120 is configured of a plurality of routers, switches, cables, and the like that satisfy communication standards such as Ethernet (registered trademark). The communication standard, the scale, and the configuration of the network are not limited to the embodiment. As another example, the network 120 may be the Internet, a LAN (Local Ara Network), or the like.

  FIG. 2 is a hardware configuration diagram of the camera server device 100. As shown in FIG. A CPU 200, a primary storage device 201, a secondary storage device 202, an image capture I / F 203, a camera platform control I / F 204, and a network I / F 205 are mutually connected via an internal bus 210. The primary storage device 201 is a writable high-speed storage device represented by a RAM. The primary storage device 201 is loaded with an OS, various programs and various data, and is also used as a work area of the OS and various programs. The secondary storage device 202 is a non-volatile storage device represented by an HDD, a flash memory, an SSD (Solid State Drive), etc., and is used as a permanent storage area of the OS, various programs and various data. The secondary storage device 202 is also used as a storage area for various types of data in the short term. The functions and processing of the camera server device 100 described later are realized by the CPU 200 reading a program stored in the secondary storage device 202 and executing this program.

  Connected to the image capture I / F 203 is an image sensor 206 composed of a CCD or CMOS. The image capture I / F 203 performs image processing on the image data acquired from the image sensor 206 according to the image quality parameter, converts it into a predetermined format, compresses it, and transfers it to the primary storage device 201. A lens / head unit 207 is connected to the head control I / F 204. A pan head control I / F 204 controls a pan / tilt / zoom mechanism to change a shooting position and a shooting angle of view. A network I / F 205 is an I / F for connecting to the above-described network 120, and is responsible for communication with the client apparatus 110 or the like via a communication medium such as Ethernet.

  FIG. 3 is a functional block diagram of the camera server apparatus 100. As shown in FIG. The camera server device 100 includes an imaging processing unit 300, a PTZ processing unit 301, a preset control unit 302, and a communication processing unit 303. The imaging processing unit 300 acquires image data generated by the image sensor 206 via the image capture I / F 203. In the present embodiment, the image data is moving image data. However, the image data may be continuous still images. The imaging processing unit 300 further performs image processing and encoding processing in accordance with the image quality parameters specified by the preset control unit 302, and stores the image processing and encoding processing in the primary storage device 201. In addition, the imaging processing unit 300 cuts out part of the image data before performing encoding processing, thereby generating a digital PTZ image of the specified cutout position and cutout angle of view. Further, in the case of an omnidirectional camera equipped with an all-around fisheye lens as the lens / head unit 207, the camera server apparatus 100 can capture a fisheye image such as a 360 degree circular or circular shape. In this case, the imaging processing unit 300 can convert the captured fisheye image into a panoramic developed image or a planar perspective projection image by performing a geometric conversion process.

  The PTZ processing unit 301 acquires information on the cutout position and cutout angle of view of the digital PTZ image designated by the viewer or the like on the client device 110 via the network 120, and sets the information in the imaging processing unit 300. Thereby, the camera server apparatus 100 can generate a predetermined digital PTZ image. The imaging processing unit 300 generates a digital PTZ image of the cutout position and the cutout angle of view set previously, until the PTZ processing unit 301 resets the cutout position and the cutout angle of view to the imaging processing unit 300. In addition, the PTZ processing unit 301 determines whether the frame coding method is intraframe coding or interframe coding, and sets the determined coding method in the imaging processing unit 300. When the camera server apparatus 100 is an omnidirectional camera, the PTZ processing unit 301 generates a digital PTZ image cut out from a fisheye image.

  The preset control unit 302 controls the lens / camera platform 207 via the camera platform control I / F 204 in accordance with a preset position and preset traveling setting preset from the client apparatus 110 or a preset movement setting based on an event. Thereby, the pan, tilt and zoom positions can be controlled. The preset control unit 302 also sets image quality parameters, such as focus, exposure, white balance, darkening, dark area correction, noise reduction, sharpness, and color saturation, stored in the preset, in the imaging processing unit 300.

  The communication processing unit 303 controls the network I / F 205 and transmits the image data stored in the primary storage device 201 to the various clients via the network 120 in response to requests from the various clients. Further, the communication processing unit 303 transmits pan / tilt / zoom positions and image quality parameters sent from various clients to the preset control unit 302, and stores the received preset settings and preset tour settings in the secondary storage device 202.

  FIG. 4 is a view showing an example of a viewer displayed on the client device 110. As shown in FIG. By operating the viewer 400, the user can set the cut-out position and the angle of view of the digital PTZ, cut out a part of the captured image as a digital PTZ image, and display it on the viewer 400. Here, the digital PTZ image is an example of a partial image corresponding to a partial area of a captured image. By operating the viewer 400 on the client device 110, the user can change the cutout position and the cutout angle of view of the digital PTZ.

  As a method of changing the cutout position and cutout angle of view of the digital PTZ, “position specification” mainly specifying the cutout position and cutout angle after movement, “direction specification” to specify movement direction, zoom magnification ( There is a "zoom specified" to change the angle of view. When a “position designation” command is received from the client device 110 via the network 120, the PTZ processing unit 301 sets the designated cutout position and cutout angle in the imaging processing unit 300. Thereby, the imaging processing unit 300 immediately generates an image of the specified cutout position and cutout angle of view.

  When the received command is “direction designation”, the PTZ processing unit 301 sets the cutout position moved in the designated direction in the imaging processing unit 300 at a constant interval. The PTZ processing unit 301 calculates the size to be moved from the speed value acquired from the client apparatus 110 via the network 120. Then, when the PTZ processing unit 301 receives the stop command from the client device 110, the PTZ processing unit 301 stops the movement of the cutout position in the designated direction. Thus, the imaging processing unit 300 can generate a continuous digital PTZ image (video) in which the cutout position gradually moves for each frame.

  When the received command is “zoom designation”, the PTZ processing unit 301 sets the cutout view angle in the imaging processing unit 300 at a constant interval according to the designated change amount. When the PTZ processing unit 301 receives the stop command from the client device 110, the PTZ processing unit 301 stops the change of the magnification with the specified change amount. Thereby, the imaging processing unit 300 can generate a continuous digital PTZ image (video) in which the zoom magnification gradually increases or decreases for each frame.

  Next, a method of performing position specification, direction specification, and zoom specification using the viewer 400 will be described. Below the viewer 400, a fisheye image 410 is displayed. Furthermore, on the upper side of the viewer 400, the digital PTZ image 420 cut out at the cut-out position 411 in the fisheye image 410 is displayed. Here, the digital PTZ image 420 is a partial image corresponding to a partial area of the fisheye image 410 as a captured image.

  The user can change the pan and tilt positions of the digital PTZ image 420 by changing the cutout position 411. Further, by changing the size of the circle at the cutout position 411, the zoom of the digital PTZ image 420 can be changed. The user can change the pan and tilt positions of the digital PTZ image 420 by moving the slider 431 of the pan position specification bar 430 and the slider 441 of the tilt position specification bar 440. Also, the user can change the zoom of the digital PTZ image 420 by moving the slider 451 of the zoom position specification bar 450. When the slider 451 is moved upward, it zooms in, and when it is moved downward, it zooms out. Position specification can be performed by the above method.

  Although not shown, position designation may be performed by another method. For example, by surrounding the position to be displayed on the digital PTZ image 420, the cutout position and the cutout angle of view may be specified. Further, the PTZ processing unit 301 may set the preset position notified from the preset control unit 302 in the imaging processing unit 300.

  Next, the method of direction specification will be described. The user can specify the moving direction of the digital PTZ image 420 by specifying the direction of the vector 460. Also, the user can specify a speed value by changing the length of the vector 460. Although the direction specification can be performed by the above method, other methods may be used. For example, instead of the vector 460, a button capable of specifying the pan and tilt directions and a slider capable of specifying the speed value may be prepared. Further, in the case of zoom designation, a button capable of designating magnification and a slider capable of designating a speed value can be prepared, and the change amount (speed) of magnification can be designated by using these.

  FIG. 5 is a flowchart showing the coding method determination process by the camera server apparatus 100 when the user specification method is position specification. In S500, the PTZ processing unit 301 confirms whether or not the received command is position specification. In the case of position designation (YES in S500), the PTZ processing unit 301 advances the process to S501. If the PTZ processing unit 301 does not specify a position (NO in S500), the process ends. The case where the received command is direction designation will be described later with reference to FIG. In step S501, the PTZ processing unit 301 sets the frame coding method to intraframe coding simultaneously with the setting of the cutout position and cutout angle of the digital PTZ in the imaging processing unit 300. In response to this, the imaging processing unit 300 encodes the digital PTZ image relating to the position specification using intra-frame coding. That is, the imaging processing unit 300 encodes the digital PTZ image relating to the position specification without using interframe coding.

  As described above, the camera server apparatus 100 switches to intraframe coding simultaneously with setting of the cutout position and the cutout angle of view. Therefore, when the cutout position and the cutout angle of view of the digital PTZ where the scene is often largely changed, the image after the change is not the P frame of inter-frame coding with a large difference, but the I frame of intra-frame coding Can be generated as

  FIG. 6 is a flowchart showing a coding method determination process performed by the camera server apparatus 100 when the user specification method is direction specification. In S600, the PTZ processing unit 301 confirms whether or not the received command is direction specification. Here, the direction specification is an example of a movement instruction to gradually move the position of a partial area to be a digital PTZ image. In the case of direction specification (YES in S600), the PTZ processing unit 301 advances the process to S601. If the received command is not direction designation (NO in S600), the PTZ processing unit 301 ends the process. In step S601, the PTZ processing unit 301 saves the image quality parameters at the time of processing in the primary storage device 201, and then changes the image quality parameters set in the imaging processing unit 300 so as to degrade the image quality. In the present embodiment, the PTZ processing unit 301 changes the image quality parameter so as to reduce the image quality by 10% from the image quality at the time of processing. The method of changing the image quality parameter is not limited to the embodiment. As another example, the PTZ processing unit 301 may leave the image quality as it is when the image quality at the processing time is already less than a certain level. In the process of S601, the image quality of the digital PTZ image output after the timing at which the direction designation as the movement instruction is accepted is changed to be lower than that of the digital PTZ image output before the timing at which the direction designation is accepted. Image quality change processing.

  Next, in S602, the PTZ processing unit 301 obtains a difference between the cutout position of the digital PTZ image after movement at the processing time of S602 and the cutout position of the digital PTZ image at the start of movement according to direction specification. . Also, the PTZ processing unit 301 cuts out the digital PTZ image as the I-frame, which is output at the timing closest to the processing time of the processing timing of S602 and the processing position of the digital PTZ image after movement at the processing time of S602. Find the difference between position and Here, the I frame is an example of a partial image subjected to intraframe coding. In the following, the I frame output at the timing closest to the processing time of S602 will be referred to as the previous I frame. Then, the PTZ processing unit 301 selects a smaller difference, and compares the selected difference with a preset threshold. Here, it is assumed that the threshold is preset in the primary storage device 201. If the difference is equal to or larger than the threshold (YES in S602), the PTZ processing unit 301 advances the process to S603. If the difference is smaller than the threshold (NO in S602), the PTZ processing unit 301 advances the process to S605.

  In step S603, the PTZ processing unit 301 determines whether or not a predetermined time or more has elapsed from the previous generation timing of the I frame at the processing time of step S603. Here, it is assumed that the predetermined time is set in advance in the primary storage device 201. Note that the fixed time is a period shorter than the I-frame interval preset by the PTZ processing unit 301. If the predetermined time or more has elapsed (YES in S603), the PTZ processing unit 301 advances the process to S604. The PTZ processing unit 301 advances the process to step S605 when the predetermined time or more has not elapsed (NO in step S603). In S604, the PTZ processing unit 301 sets the frame coding method to intraframe coding.

  Next, in step S605, the PTZ processing unit 301 determines whether an instruction to stop movement according to direction specification has been received from the client device 110. If the PTZ processing unit 301 receives a stop instruction (YES in S605), the PTZ processing unit 301 advances the process to S606. If the PTZ processing unit 301 does not receive the stop instruction (NO in S605), the PTZ processing unit 301 advances the process to S602. In step S606, the PTZ processing unit 301 obtains the image quality parameter stored in the primary storage device 201, and sets the image quality processing parameter to the original value by setting in the imaging processing unit 300, thereby restoring the image quality to the basis. Next, in S607, the PTZ processing unit 301 sets the frame coding method to intraframe coding at the time of video generation at the time of stop. Thus, the process ends. As a result, the PTZ processing unit 301 can simultaneously perform the change to restore the image quality and the change to generate the I frame. If there is a limitation in the area from which the digital PTZ image is cut out, the PTZ processing unit 301 advances the process to step S606 when the end of the area is reached.

  The coding method determination process in the case of zoom specification is substantially the same as the coding method in the case of direction specification described with reference to FIG. In the case of zoom specification, in S602, the difference between the magnification (field angle) and the threshold value may be compared with the difference between the cutout positions.

  As described above, in the case of direction specification, the camera server apparatus 100 can generate an I frame at an appropriate timing while suppressing the data size for a moving image in a direction that is considered to be of low importance. it can. Then, the camera server apparatus 100 can clearly display the video with high importance by returning the image quality at the time of stopping and generating the I frame. In the present embodiment, the I frame is generated when a predetermined time has elapsed in S603, but the PTZ processing unit 301 may further change the predetermined period according to the moving speed.

  As described above, the camera server apparatus 100 according to the first embodiment sets the encoding scheme to intraframe encoding according to the change of the cutout position and the cutout angle of view. Therefore, in the camera server apparatus 100, a state in which a first partial image (digital PTZ image) corresponding to a partial area of a captured image is output and a second partial image corresponding to another area is output It is possible to reduce the image quality deterioration when changing to another.

  As a first modified example of the first embodiment, the process of reducing the image quality in the coding method determination process in the case of direction specification described with reference to FIG. 6 may not be performed. For example, it is effective when moving images are also important.

  Also, as a second modification, the PTZ processing unit 301 performs switching to the I frame at the time of movement or stop while executing the function of switching to the I frame using the difference of the video information. It is good not to execute.

  As a third modification, the PTZ processing unit 301 cuts out the digital PTZ image cutout position after movement and the digital PTZ image at movement start time at the processing point of S602 in accordance with the direction specification in S602. Only the difference between the position and may be obtained. Then, the PTZ processing unit 301 may compare this difference with a threshold. Also, as another example, the PTZ processing unit 301 determines the cut-out position of the digital PTZ image after movement at the processing time of S602 and the cut-out position of the digital PTZ image as the previous I frame according to direction specification. It is also possible to obtain only the difference of. Then, the PTZ processing unit 301 may compare this difference with a threshold.

Second Embodiment
Next, differences of the camera system according to the second embodiment from the camera system according to the first embodiment will be mainly described. FIG. 7 is a flowchart showing coding method determination processing in the case of position specification by the camera server device 100 according to the second embodiment. Among the processes shown in FIG. 7, the same processes as the processes of the encoding method determination process according to the first embodiment described with reference to FIG. 5 are assigned the same reference numerals. In S500, in the case of position designation (YES in S500), the PTZ processing unit 301 advances the process to S700. In S700, the PTZ processing unit 301 compares the area of the overlapping portion of the digital PTZ image relating to the position designation and the digital PTZ image displayed immediately before the position designation with the threshold. If the area is equal to or larger than the threshold (YES in S700), PTZ processing unit 301 advances the process to S501. If the area is smaller than the threshold (NO in S700), the PTZ processing unit 301 ends the process. The remaining configuration and processing of the camera system according to the second embodiment are the same as the configuration and processing of the camera system according to the first embodiment.

  By the above processing, the camera server apparatus 100 according to the second embodiment generates a P frame when the amount of change in the digital PTZ image before and after movement according to the position designation is less than the threshold, and the amount of change is equal to or more than the threshold Will generate an I frame. Therefore, the camera server apparatus 100 according to the second embodiment can reduce image quality deterioration when switching from a partial image corresponding to a partial area of a captured image to a partial image corresponding to another area.

  As a first modification of the second embodiment, the camera server apparatus 100 may set the threshold used in S700 according to the distance from the center of the fisheye image 410.

  As a second modification, the camera server apparatus 100 uses the digital PTZ image encoding method for position specification based on the digital PTZ image for position specification and the digital PTZ image displayed immediately before. You should decide. That is, the specific process is not limited to the embodiment. For example, the camera server apparatus 100 may set the encoding scheme to intraframe encoding when the difference between the cutout angle of view of both images is equal to or greater than a threshold. Further, as another example, the camera server apparatus 100 may set the encoding method to intra-frame encoding when the difference between the cutout positions of both images is equal to or larger than the threshold.

Third Embodiment
Next, differences of the camera system according to the third embodiment from the camera system according to the first embodiment will be mainly described. FIG. 8 is a flowchart showing a coding method determination process in the case of position specification by the camera server device 100 according to the third embodiment. Among the processes shown in FIG. 8, the same processes as the processes of the encoding method determination process according to the first embodiment described with reference to FIG. 5 are assigned the same reference numerals. In S500, in the case of position designation (YES in S500), the PTZ processing unit 301 advances the process to S800.

  In S800, the PTZ processing unit 301 acquires in advance the image quality parameter of the moving image of the digital PTZ from the image to be cut out. Next, in S801, the PTZ processing unit 301 obtains a difference between image quality parameters before and after movement, and compares the difference with a threshold. In the present embodiment, the PTZ processing unit 301 obtains, as an image quality parameter, the difference between each of the luminance value and the edge amount for the entire image of the digital PTZ, and compares each difference with the corresponding threshold. Each threshold value is assumed to be preset in the primary storage device 201.

  FIG. 9 is a diagram showing an example of the threshold value table 900 stored in the primary storage device 201. As shown in FIG. In the threshold table 900, types of image quality parameters and thresholds are associated. In the example shown in FIG. 9, the threshold value of each of the luminance value and the edge amount is set. The PTZ processing unit 301 determines whether the difference in luminance value is equal to or larger than the threshold of the luminance value and the difference in edge amount is equal to or more than the threshold of the edge amount. If the PTZ processing unit 301 satisfies the condition (YES in S801), the PTZ processing unit 301 advances the process to S501. When the condition is not satisfied (NO in S801), the PTZ processing unit 301 ends the process. The other configurations and processes of the camera system according to the third embodiment are the same as the configurations and processes of the camera system according to the other embodiments.

  By the above processing, the camera server apparatus 100 according to the third embodiment generates a P frame when the change amount of the image quality parameter of the digital PTZ image before and after movement according to the position specification is less than the threshold, and the change amount is If the threshold value is exceeded, an I frame will be generated. If the amount of change in the image quality parameter is less than the threshold, it is estimated that the scene has not changed much. On the other hand, when the change amount of the image quality parameter is equal to or more than the threshold value, it is estimated that the scene is largely changed. That is, the camera server apparatus 100 according to the third embodiment sets a coding method according to a scene change, and changes from a partial image corresponding to a partial area of a captured image to a partial image corresponding to another area. Image quality deterioration at the time of switching can be reduced.

  As a modification of the third embodiment, the type and number of image quality parameters used in S801 are not limited to those of the embodiment. As the image quality parameters, in addition to the above, an exposure correction value, a shutter speed value, an aperture value, and the like can be considered.

  Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention as set forth in the claims.・ Change is possible.

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

100 Camera server device 120 Client device 200 CPU
201 Temporary storage device 206 Image sensor

Claims (14)

Encoding means for encoding a frame of a partial image corresponding to a partial area of a captured image captured by the imaging means using at least either of intra-frame encoding and inter-frame encoding;
And output means for outputting the partial image encoded by the encoding means,
When the encoding unit changes from the state in which the first partial image is output by the output unit to a state in which a second partial image in an area different from the first partial image is output by the output unit An image coding apparatus characterized in that the second partial image is coded without using the interframe coding.   The image coding apparatus according to claim 1, wherein the coding unit codes the second partial image using the intraframe coding.   The image coding apparatus according to claim 1, wherein the first partial image and the second partial image are frames included in one moving image.   The encoding unit is configured to interframe encode the second partial image when the specification of the area corresponding to the second partial image is received in a state in which the first partial image is output. The image coding apparatus according to any one of claims 1 to 3, wherein coding is performed without using. Determining means for determining whether or not to encode the second partial image without using the interframe coding, based on the difference in position between the second partial image and the first partial image And have
The encoding means uses the inter-frame encoding when the determination means determines that the second partial image is to be encoded without using the inter-frame encoding. The image coding apparatus according to any one of claims 1 to 4, wherein the image coding is performed without coding. The output means continuously outputs a plurality of partial images corresponding to the area according to the movement instruction, when receiving a movement instruction to gradually move the position of the partial area,
The image coding apparatus according to claim 5, wherein the first partial image is a partial image output corresponding to a timing at which the movement instruction is received.   The determination means may be further configured to output the second partial image based on a difference between positions of the partial image subjected to the intraframe coding and the second partial image, which is output at a timing closest to the second partial image. 7. The image coding apparatus according to claim 6, wherein it is determined whether to encode two partial images without using the interframe coding. The output means continuously outputs a plurality of partial images corresponding to the area according to the movement instruction, when receiving a movement instruction to gradually move the position of the partial area,
The image coding according to claim 6, wherein the first partial image is a partial image on which the intraframe coding has been performed, which is output at a timing closest to the second partial image. apparatus. The apparatus further comprises image quality change means for changing the image quality of the partial image output after the timing of receiving the movement instruction to be lower than the image quality of the partial image output before the timing,
The image code according to any one of claims 6 to 8, wherein the output means outputs the partial image of the image quality after being changed by the image quality changing means when the movement instruction is received. Device.   When the output unit receives an instruction to stop movement of the partial area after receiving the movement instruction, a partial image corresponding to the area after movement corresponding to the timing at which the stop instruction is received is received. 10. The image coding apparatus according to any one of claims 6 to 9, wherein coding is performed without using the interframe coding. The image processing apparatus further includes a determination unit that determines whether the second partial image is to be encoded without using the interframe encoding, based on the second partial image and the first partial image. ,
The encoding means uses the inter-frame encoding when the determination means determines that the second partial image is to be encoded without using the inter-frame encoding. The image coding apparatus according to any one of claims 1 to 4, wherein the image coding is performed without coding.   The determination unit may encode the second partial image without using the interframe coding, based on the difference in the angle of view between the second partial image and the first partial image. The image coding apparatus according to claim 11, characterized in that: An image coding method performed by an image coding apparatus, comprising:
Encoding a frame of a partial image corresponding to a partial region of a captured image captured by the imaging unit using at least either of intra-frame encoding and inter-frame encoding;
Outputting the partial image encoded in the encoding step to an output means,
In the encoding step, the state in which the first partial image is output to the output means is changed to a state in which a second partial image of an area different from the first partial image is output to the output means. In this case, the second partial image is encoded without using the interframe encoding.   The program for functioning a computer as each means of the image coding apparatus in any one of Claims 1-12.

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