JP2017098919A - Image encoder, image encoding method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image encoder capable of irreversible encoding in a manner that the image quality in a light scattering area is improved in a processing image which has been subjected to an image processing on a decoded image to reduce influences light scattering.SOLUTION: An imaging unit 101 on an image encoder 100 acquires an image. An encoding control unit 103 identifies a light scattering area in the image acquired by the imaging unit 101 and determines a parameter used for irreversible encoding so that the code amount in the identified area is larger than the code amount in the area when the area is not identified. An encoding part 104 irreversibly encodes the image acquired by the imaging unit 101 using the parameter determined by the encoding control unit 103.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for controlling a code amount in image encoding.

  When shooting outdoors with an imaging device, the clarity of captured images may be impaired due to the effect of light scattering due to fog, smoke, or floating substances in the atmosphere. Patent Document 1 describes a technique for reducing the influence of light scattering in an image by image processing.

  On the other hand, as an encoding method used for compressed recording of moving images and distribution via a network, H.264 is used. H.264 / MPEG-4 AVC (hereinafter referred to as H.264) is known. H. In H.264, an image is encoded in units of blocks called macroblocks. The quantization parameter is variable for each macroblock, and the quantization step size can be controlled by changing the quantization parameter. Patent Document 2 describes that the image quality is controlled by changing the code amount allocated to the macroblock by controlling the quantization step size.

  Specifically, in the encoding control method described in Patent Document 2, evaluation of the luminance average value, the color difference average value, the luminance variance value, the motion vector amount average value, and the like of each macroblock of the image to be encoded is performed. The encoding difficulty level is calculated by multiplying the values, and a code amount is assigned to each macroblock. The quantization step size is controlled according to the allocated code amount, and lossy encoding is performed. In this method, assuming that the average value of color differences, the variance value of luminance, and the average value of motion vector amounts are the same, the code amount to be allocated is reduced as the macroblock has a higher luminance average value. This is because it is difficult for human eyes to recognize encoding noise in a high luminance region. Therefore, for example, when there are high-intensity light scattering regions in the image affected by light scattering due to fog, smoke, floating objects, etc., the amount of code assigned to these regions is reduced.

US Pat. No. 8,340,461 JP-A-9-18872

  However, when image processing that reduces the influence of light scattering after decoding an irreversible encoded image is performed, sufficient image quality may not be obtained in the light scattering region in the processed image. For example, when an image that has been irreversibly encoded by the method described in Patent Document 2 is decoded and image processing described in Patent Document 1 is performed, block noise due to irreversible encoding in a light scattering region in the processed image And false colors may be noticeable.

  The present invention has been made in view of the above problems, and the image quality of the light scattering region in the processed image in which the image processing for reducing the influence of light scattering on the image after decoding is improved is improved. An object of the present invention is to provide a technique for performing lossy encoding.

  In order to solve the above problems, an image encoding apparatus according to the present invention has, for example, the following configuration. That is, an acquisition unit that acquires an image, a specifying unit that specifies a light scattering region in the image acquired by the acquiring unit, and a code amount of the region specified by the specifying unit is not specified by the specifying unit. A determination unit that determines a parameter used for lossy encoding so that the code amount of the region is larger, and a code that performs lossy encoding of the image acquired by the acquisition unit using the parameter determined by the determination unit Means.

  According to the present invention, it is possible to perform lossy encoding so that the image quality of a light scattering region in a processed image obtained by performing image processing for reducing the influence of light scattering on a decoded image is improved. it can.

It is a block diagram which shows the structure of the image coding apparatus 100 based on embodiment. It is a flowchart for demonstrating operation | movement of the image coding apparatus 100 based on Embodiment. It is a block diagram which shows the structure of the image coding apparatus 100 in the case of specifying an important area | region based on embodiment. It is a flowchart for demonstrating operation | movement of the image coding apparatus 100 in the case of specifying an important area | region based on embodiment. It is a figure for demonstrating the relationship between the input image and important area based on embodiment. It is a block diagram which shows the hardware structural example of the image coding apparatus 100 in the case of performing the computer program based on embodiment.

  Hereinafter, the present invention will be described in detail based on the embodiments with reference to the drawings. The following embodiments do not limit the present invention according to the scope of claims, and all combinations of features described in the following embodiments are not necessarily essential to the present invention.

  FIG. 1 is a block diagram illustrating a configuration of an image encoding device 100 according to the present embodiment. As illustrated in FIG. 1, the image encoding device 100 includes an imaging unit 101, a reference image generation unit 102 (hereinafter, generation unit 102), an encoding control unit 103, an encoding unit 104, and a bit rate setting unit 105. Each processing unit in FIG. 1 may be configured by a single physical circuit or may be configured by a plurality of circuits. Note that it is not essential that the image encoding device 100 includes all of the above-described components.

  An image captured by the imaging unit 101 is input to the generation unit 102 and the encoding unit 104. The generation unit 102 generates a reference image for encoding control based on the image captured by the imaging unit 101 and outputs the reference image to the encoding control unit 103. The reference image generated by the generation unit 102 is, for example, an image representing the degree of light scattering, such as an image showing the concentration of fog, smoke, or suspended matter. The encoding control unit 103 refers to the input reference image and determines a quantization parameter. The encoding unit 104 performs lossy encoding on the image input from the imaging unit 101 based on the quantization parameter determined by the encoding control unit 103. The encoded image data (encoded stream) output from the encoding unit 104 is transmitted via a network or stored in various storage media. The bit rate setting unit 105 sets an upper limit of the bit rate of the encoded stream output from the encoding unit 104 via a network or a user interface included in the bit rate setting unit 105. The bit rate setting unit 105 notifies the set upper limit bit rate to the encoding control unit 103, and the encoding control unit 103 controls the encoding unit 104 according to the notified upper limit bit rate.

  The image encoding device 100 in the present embodiment is configured as a network camera. Here, consider a case where the image captured by the image encoding device 100 includes a light scattering region. The light scattering region in the present embodiment is a region where the influence of light scattering due to fog, smoke, suspended matters, etc. in the atmosphere, or the influence of light scattering in water appears. In the light scattering region in the image, image quality deterioration such as a decrease in contrast and a decrease in resolution occurs. Such image processing that reduces the influence of light scattering in the image is referred to as light scattering removal in this embodiment.

  If the image coding apparatus 100 performs coding after removing light scatter from the captured image and can transmit the coded image to another receiving apparatus, the receiving apparatus decodes the received image. Thus, an image in which the influence of light scattering is reduced can be acquired. However, if the image encoding apparatus 100 performs all of image capturing, light scattering removal, encoding, and transmission processing, the processing amount of the image encoding apparatus 100 increases. Further, the image encoding device 100 may not have a light scattering removal function.

  On the other hand, when the image coding apparatus 100 performs lossy coding of a captured image as it is and transmits it, and the receiving apparatus receives and decodes the captured image, block noise and false color in the light scattering area are conspicuous. In some cases, sufficient image quality cannot be obtained. In view of this, the image encoding device 100 according to the present embodiment has a sufficient code amount for a captured image so that the image quality of the light scattering region is improved when the reception device performs light scattering removal on the decoded image. Is encoded and transmitted to the receiving apparatus. However, the image encoding device 100 is not limited to a network camera. For example, the image encoding apparatus 100 may not include the imaging unit 101 and may perform an encoding process on an image acquired from an external apparatus via a network.

  Hereinafter, the operation of the image encoding device 100 of the present embodiment will be described in detail. FIG. 2 is a flowchart for explaining the operation of the image coding apparatus 100. The process of FIG. 2 is started at a timing when an instruction for starting imaging is given to the image encoding device 100. However, the start timing of the processing in FIG. 2 is not limited to the above timing.

  In S201, the imaging unit 101 acquires an image by imaging. In the present embodiment, the imaging unit 101 captures a moving image, and hereinafter, each frame of the moving image captured by the imaging unit 101 is referred to as an input image. However, the present invention is not limited to this, and the imaging unit 101 may capture a still image. In this case, the still image captured by the imaging unit 101 becomes the input image. The input image acquired by imaging may be a color image in a format such as RGB or YUV, or may be a monochrome image.

  In S <b> 202, the generation unit 102 generates a reference image from the input image acquired by the imaging unit 101. In the present embodiment, for each of a plurality of processing target pixels in the input image acquired by the imaging unit 101, the generation unit 102 at least includes a plurality of color component values in the processing target pixel and the brightness of the processing target pixel. The evaluation value based on which is determined. Then, the generation unit 102 generates a reference image using the determined evaluation value as a pixel value.

  For example, the generation unit 102 determines the evaluation value of the processing target pixel in the input image according to the minimum value among the R value, the G value, and the B value in the pixel existing within a predetermined range from the processing target pixel. . A reference image having an evaluation value determined by this method as a pixel value is called a dark channel image. Pixels in the input image (pixels with large evaluation values) corresponding to pixels with large pixel values in the dark channel image have large R values, G values, and B values in neighboring pixels, and the influence of light scattering appears. There is a high possibility. For example, the generation unit 102 determines the evaluation value of the processing target pixel in the input image according to the luminance of the pixel existing within a predetermined range from the processing target pixel. A reference image having an evaluation value determined by this method as a pixel value is called a luminance image. A pixel in the input image corresponding to a pixel having a large pixel value in the luminance image has a high luminance in the neighboring pixels and is highly likely to be affected by light scattering. The predetermined range may be a rectangular range including a plurality of pixels on one side, or may have other shapes. For example, the pixel existing within a predetermined range from the processing target pixel may be only the processing target pixel.

  The reference image is not limited to these, and may be an image called a transmission image having a pixel value determined based on, for example, the pixel value of the dark channel image and the intensity of the ambient light, and may be an R value, a G value, and It may be an image having pixel values based on other evaluation values such as a difference in B values. In the present embodiment, the reference image is a monochrome image, but is not limited thereto. For example, each pixel of the reference image may include both a component corresponding to the dark channel image and a component corresponding to the intensity of the ambient light. In the present embodiment, the reference image is described as having the same resolution as the input image, but the resolution of the input image and the reference image may be different.

  In S <b> 203, the encoding control unit 103 specifies a light scattering region in the input image acquired by the imaging unit 101 based on the reference image based on the evaluation value determined by the generation unit 102. In the present embodiment, the image encoding device 100 divides an input image acquired by the imaging unit 101 into a plurality of divided regions (macroblocks), and performs encoding for each divided region. Therefore, in order to specify the light scattering region, a pixel value of 16 × 16 pixels in the reference image corresponding to the position of each macroblock in the input image is used. In this embodiment, each divided region is a 16 × 16 pixel macroblock. However, the size of the divided region is not limited to this, and may be, for example, 8 × 8 pixels or 32 × 32 pixels. It may be asymmetric like 16 pixels. Further, when the reference image has a resolution smaller than that of the input image, appropriate measures are taken. For example, when the reference image has half the resolution of the input image, 8 × 8 pixels in the reference image correspond to a 16 × 16 pixel macroblock in the input image.

  The encoding control unit 103 compares each pixel value of 16 × 16 pixels of the reference image corresponding to the processing target macroblock of the input image with the threshold value T1, and counts the number of pixels that satisfy the comparison result. To do. The contents of the conditions vary depending on the reference image generation method. The count value at the time when the comparison with the threshold value T1 is completed in all the pixels of 16 × 16 pixels is set as a value S1. Furthermore, the encoding control unit 103 compares the value S1 with the threshold value T2. When the comparison result with the threshold value T2 satisfies the condition, it is determined that the macroblock is included in the light scattering region.

  For example, consider a case where the reference image is a dark channel image or a luminance image. At this time, the encoding control unit 103 determines a predetermined number of pixels whose evaluation value determined by the generation unit 102 is equal to or more than the threshold T1 among a plurality of divided regions (macroblocks) obtained by dividing the input image acquired by the imaging unit 101 ( The divided region including the threshold value T2) or more is specified as the light scattering region. That is, in a dark channel image or a luminance image, a pixel having a pixel value equal to or greater than a threshold is highly likely to be affected by light scattering. Therefore, a macro corresponding to 16 × 16 pixels including a predetermined number or more of such pixels. Let the block be a light scattering region. However, the present invention is not limited to this, and depending on the evaluation value determination method, the number of pixels having a pixel value equal to or less than the threshold value T1 in the reference image may be set as the value S1. May be used as a light scattering region.

  The method for specifying the light scattering region is not limited to this. For example, the encoding control unit 103 may use a statistical value such as an average or variance of evaluation values for pixels in a divided region (in a macroblock) as a value S1 corresponding to the divided region. For example, when S1 is an average value, a divided region where S1 is a predetermined value or more (threshold value T2 or more) may be specified as a light scattering region. According to this method, it is also possible to identify a region where the influence of light scattering appears strongly. In addition, a value obtained by combining the above statistical values with the result of size comparison between the pixel value of the reference image and the threshold value T1 or a value obtained from a plurality of statistical values may be used as the value S1. In addition, the encoding control unit 103 may specify the light scattering region based on the frequency characteristics of the input image without using the reference image.

  In S204, the encoding control unit 103 determines a quantization parameter used for lossy encoding of the macroblock based on the result of specifying the light scattering region. Here, the encoding control unit 103 uses the quantization step size in the encoding of the same region when the quantization step size in the region specified as the light scattering region is not specified as the light scattering region. The quantization parameter is determined so as to be smaller. Thereby, the code amount of the region specified as the light scattering region is larger than the code amount of the same region when it is not specified as the light scattering region. An image in a region to which a large amount of code is allocated has little loss of information due to lossy encoding, and thus becomes a high-quality image with little coding noise when decoded.

As a specific quantization parameter determination method, for example, the encoding control unit 103 stores a value corresponding to each of cases where the encoding control unit 103 is different from the light scattering region in a lookup table, and sets the table for each macroblock. The quantization parameter may be determined with reference to FIG. In addition, the method is not limited to the method of determining the quantization parameter based on the binary determination as to whether or not the macroblock is included in the light scattering region, but stores a plurality of values in the lookup table, and the value obtained in S203 The quantization parameter may be determined by referring to the table according to S1. By this method, the amount of light scattering is divided into a plurality of stages and the quantization parameter is determined, so that the code amount can be controlled in more detail. Furthermore, the quantization parameter may be determined by other methods such as a method of calculating the quantization parameter without using a lookup table. In this embodiment, the case where the encoding control unit 103 controls the quantization parameter in units of macroblocks will be mainly described. However, the encoding control unit 103 controls the quantization parameter for a block in which a plurality of macroblocks are collected. May be.
Also, the parameters determined by the encoding control unit 103 are not limited to quantization parameters, but may be parameters that can be used for lossy encoding and control the amount of codes. For example, the encoding control unit 103 may determine the value of the quantization table based on the result of specifying the light scattering region. Further, for example, the encoding control unit 103 may determine a parameter related to the frequency range, and the encoding unit 104 may perform encoding by removing information related to frequency components within the range indicated by the parameter from information included in the image. Good.

  In S <b> 205, the encoding unit 104 performs lossy encoding on the input image acquired by the imaging unit 101 using the quantization parameter determined by the encoding control unit 103. Then, the encoding unit 104 transmits the encoded image (encoded stream) to an external device or a storage medium. In this embodiment, the encoding unit 104 uses H.264 as an encoding method. H.264 is used, however, the encoding method is not limited to this, and any method that can perform lossy encoding may be used.

  The bit rate setting unit 105 may notify the encoding control unit 103 of the upper limit bit rate. At this time, the encoding control unit 103 controls the encoding unit 104 so that the bit rate of the encoded stream output from the encoding unit 104 falls within the notified upper limit bit rate. This control is performed by adjusting the quantization parameter determined in S204 for each macroblock. However, the present invention is not limited to this, and the control may be performed by recalculating a lookup table used for determining the quantization parameter for each frame of the moving image according to the upper limit bit rate.

  As described above, the image encoding device 100 according to the present embodiment acquires an image and identifies a light scattering region in the acquired image. Furthermore, the image encoding apparatus 100 determines parameters used for lossy encoding so that the code amount of the region specified as the light scattering region is larger than the code amount of the same region when not specified as the light scattering region. . Then, the image encoding device 100 performs lossy encoding of the acquired image using the determined parameters. Thereby, a large amount of code is assigned to the light scattering region such as the fog region and the smoke region at the time of irreversible encoding. As a result, the image quality of the light scattering region in the processed image that has been subjected to the image processing for reducing the influence of light scattering after the decoding of the image is improved.

  Note that the image coding apparatus 100 may identify an important region in the input image and control the coding amount in the coding based on the identification result. Hereinafter, the configuration and operation of the image encoding device 100 in this case will be described. FIG. 3 is a block diagram illustrating a configuration of the image encoding device 100 when an important region is specified according to the present embodiment. Blocks having the same functions as those in FIG. 1 are denoted by the same reference numerals. The difference from FIG. 1 is that the image encoding device 100 includes an important region specifying unit 301 (hereinafter, specifying unit 301).

  The specifying unit 301 specifies an important region in the input image acquired by the imaging unit 101. The important region is, for example, a region of interest (ROI: Region of Interest) or a region determined by a map representing importance for each position in the image. In the following description, it is assumed that the specifying unit 301 specifies a region of interest in the input image.

  The attention area is specified based on the result of analysis performed on the input image by the specifying unit 301, for example. The content of the result of this analysis is a result of detection processing for detecting a predetermined object such as a moving object or a person in the input image, for example. An area where a predetermined object such as a moving object or a person is detected may be desired to have high image quality after decoding and light scattering removal. Therefore, the identification unit 301 identifies these areas as attention areas. However, the contents of the analysis results are not limited to these. The specifying unit 301 may specify a region of interest based on a user input via a setting function on the image encoding device 100 or an input from an external device via a network.

  Next, the operation of the image coding apparatus 100 when an important region is specified will be described using the flowchart of FIG. The start timing of the process in FIG. 4 is the same as that in FIG. Steps that perform the same processing as in FIG. 2 are given the same reference numerals. Hereinafter, the difference from the process of FIG. 2 will be mainly described.

  In S201, the imaging unit 101 acquires an input image. In S202, the generation unit 102 generates a reference image, and in S203, the encoding control unit 103 specifies a light scattering region in the input image. In S401, the specifying unit 301 specifies a region of interest in the input image. Then, the encoding control unit 103 corrects the light scattering region specifying result in S203 based on the attention region specified by the specifying unit. Note that the region of interest may be specified before the light scattering region is specified, or may be performed in parallel.

  A method of correcting the specific result will be described with reference to FIG. In FIG. 5, a plurality of macroblocks 501 and a region of interest 502 are shown inside the input image 500 to be encoded. The encoding control unit 103 determines whether each macroblock is located in the attention area based on the attention area specified by the specifying unit 301. At this time, the encoding control unit 103 does not change the identification result in S203 for the macroblock located in the attention area 502. On the other hand, for a macroblock not located in the attention area 502, if the macroblock is included in the light scattering area specified in S203, the specifying result is corrected, and the macroblock is not included in the light scattering area. Treat as a thing. That is, as a result of correcting the identification result, the encoding control unit 103 identifies the light scattering region within the attention region identified by the identifying unit 301.

  The correction method for the specific result is not limited to this. For example, the encoding control unit 103 selects one of the different coefficients W1 and W2 depending on whether or not the macroblock is in the attention area 502, and corrects the value S1 obtained in S203 using the coefficient. Also good. In this case, the encoding control unit 103 re-determines whether or not the macroblock is included in the light scattering region using the corrected value S1. Although FIG. 5 illustrates a case where there is one region of interest, there may be a plurality of regions of interest, and in that case, a different coefficient for each region of interest may be used for correction.

  In addition, the encoding control unit 103 does not correct the result of specifying the light scattering region later, but performs the process of S203 only on the macroblock in the attention region to determine the light scattering region in the attention region. You may specify. In this embodiment, when all the pixels in the macroblock are located in the attention area, it is determined that the macroblock is located in the attention area. However, the present invention is not limited to this. For example, when a predetermined number of pixels in the macroblock are located in the attention area, it may be determined that the macroblock is located in the attention area.

  In S204, the coding control unit 103 generates a macroblock quantization parameter based on the light scattering region specification result corrected in S401. In S205, the encoding unit 104 encodes the macroblock of the input image and transmits the encoded stream.

  As described above, the image coding apparatus 100 according to the present embodiment identifies a predetermined region (region of interest) in the input image, and the irreversible code so that the code amount of the light scattering region in the predetermined region increases. The parameters used for conversion may be determined and encoding may be performed. As a result, image processing that reduces the influence of light scattering on the decoded image by allocating a large amount of code to the light scattering area in the important area while suppressing an increase in the code amount of the entire image. It is possible to improve the image quality of important areas in the processed image.

  In the present embodiment, the description has focused on the case where the encoding unit 104 starts encoding the input image after the encoding control unit 103 has determined all the quantization parameters corresponding to each macroblock in the input image. Not limited to this. For example, the encoding control unit 103 determines whether one processing target macroblock corresponds to the light scattering region based on the reference image, and determines a quantization parameter based on the determination result. The encoding unit 104 encodes the processing target macroblock using the quantization parameter. The image encoding apparatus 100 may take a method of repeating the above processing while changing the processing target macroblock. According to this method, when the encoding control unit 103 and the encoding unit 104 can perform processing in parallel, the delay associated with encoding can be shortened.

  In this embodiment, the encoding control unit 103 determines whether or not the macroblock is included in the light scattering region based on the evaluation values of all the pixels in the macroblock. The determination may be performed based on an evaluation value of a specific pixel in the block. The encoding control unit 103 may determine whether a specific macroblock is included in the light scattering region instead of all the macroblocks in the input image. In the present embodiment, the case where the processing of FIG. 2 or 4 is performed on each frame of the moving image captured by the imaging unit has been mainly described, but the present invention is not limited to this. For example, the image coding apparatus 100 may determine the quantization parameter for each predetermined number of frames, and may encode all the predetermined number of frames using the same quantization parameter. As a result, the processing load on the image encoding device 100 can be reduced.

  In the above-described embodiment, each processing unit illustrated in FIGS. 1 and 3 has been described as being configured by hardware. However, the image encoding apparatus 100 may implement the processing shown in FIGS. 2 and 4 performed by some or all of the processing units shown in these drawings by executing a computer program. Hereinafter, a hardware configuration example of the image encoding device 100 in this case will be described with reference to FIG.

  The CPU 601 controls the entire apparatus using computer programs and data stored in the RAM 602 and the ROM 603, and executes each process performed by the image encoding apparatus 100 in the above-described embodiment. That is, the CPU 601 functions as each processing unit shown in FIGS.

  The RAM 602 has an area for temporarily storing computer programs and data loaded from the external storage device 606 and data acquired from the outside via an I / F (interface) 607. Further, the RAM 602 has a work area used when the CPU 601 executes various processes. For example, the RAM 602 is used as a picture memory that stores images.

  The ROM 603 stores setting data of the image encoding device 100, a boot program, and the like. The operation unit 604 includes a keyboard, a mouse, and the like, and inputs various instructions to the CPU 601 in response to user operations. The output unit 605 outputs and displays the processing result by the CPU 601. The output unit 605 includes a display unit such as a liquid crystal display.

  Computer programs and data stored in the external storage device 606 are appropriately loaded into the RAM 602 under the control of the CPU 601 and are processed by the CPU 601. The I / F 607 can be connected to a network such as a LAN or the Internet, and other devices such as a projection device and a display device, and the image encoding device 100 can acquire various information via the I / F 607. Can be sent out. The bus 608 connects the above-described units and transmits information.

  When the image encoding apparatus 100 is configured as shown in FIG. 6, the processing described with reference to FIGS. 2 and 4 is performed by the CPU 601 executing a control program stored in the ROM 603, calculating and processing information, This is realized by executing hardware control.

<Other embodiments>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions. Further, the program may be provided by being recorded on a computer-readable recording medium.

DESCRIPTION OF SYMBOLS 100 Image coding apparatus 101 Imaging part 103 Coding control part 104 Coding part

Claims (14)

An acquisition means for acquiring an image;
Specifying means for specifying a light scattering region in the image acquired by the acquiring means;
A determining unit that determines a parameter used for lossy encoding so that a code amount of the region specified by the specifying unit is larger than a code amount of the region not specified by the specifying unit;
An image encoding apparatus comprising: encoding means for irreversibly encoding the image acquired by the acquisition means using the parameter determined by the determination means. For each of a plurality of processing target pixels in the image acquired by the acquisition unit, an evaluation value based on at least one of a plurality of color component values in the processing target pixel and brightness of the processing target pixel is determined. 2 determination means,
The image coding apparatus according to claim 1, wherein the specifying unit specifies the light scattering region based on the evaluation value determined by the second determining unit.   The second determining means determines an evaluation value of a processing target pixel according to a minimum value among R values, G values, and B values in pixels existing within a predetermined range from the processing target pixel. The image encoding device according to claim 2.   The image coding apparatus according to claim 2, wherein the second determination unit determines an evaluation value of a processing target pixel according to a luminance of a pixel existing within a predetermined range from the processing target pixel.   The specifying unit includes a plurality of divided regions obtained by dividing the image acquired by the acquiring unit, and a divided region including a predetermined number or more of pixels whose evaluation value determined by the second determining unit is equal to or greater than a threshold value. The image encoding device according to claim 3 or 4, wherein the image encoding device is specified as a region.   The specifying unit is a divided region obtained by dividing the image acquired by the acquiring unit, and an average of evaluation values determined by the second determining unit in pixels in the divided region is a predetermined value or more. 5. The image encoding device according to claim 3, wherein the image encoding device is specified as the light scattering region.   The light scattering region is a region in which an influence of light scattering due to at least one of fog, smoke, and suspended matter in the atmosphere, or an influence of light scattering in water appears. 7. The image encoding device according to any one of items 1 to 6.   The deciding means is an irreversible code so that a quantization step size in encoding of the area specified by the specifying means is smaller than a quantization step size in encoding of the area when not specified by the specifying means. The image encoding apparatus according to claim 1, wherein a quantization parameter used for conversion is determined. Second specifying means for specifying a predetermined area in the image acquired by the acquiring means based on at least one of an input by a user, an input from an external device, and an analysis result on the image acquired by the acquiring means Have
9. The image encoding device according to claim 1, wherein the specifying unit specifies the light scattering region in the predetermined region specified by the second specifying unit. 10.   The image encoding apparatus according to claim 9, wherein the result of analysis on the image acquired by the acquisition unit is a result of detection processing for detecting a predetermined object in the image. An imaging means for capturing an image;
Transmission means for transmitting the image encoded by the encoding means to an external device,
The image encoding apparatus according to claim 1, wherein the acquisition unit acquires an image captured by the imaging unit. An acquisition process for acquiring images;
A specific step of identifying a light scattering region in the image acquired in the acquisition step;
A determining step for determining parameters used for lossy encoding so that the code amount of the region specified in the specifying step is larger than the code amount of the region not specified in the specifying step;
An image encoding method comprising: an encoding step of irreversibly encoding the image acquired in the acquisition step using the parameter determined in the determination step. For each of a plurality of processing target pixels in the image acquired in the acquisition step, an evaluation value based on at least one of a plurality of color component values in the processing target pixel and a brightness of the processing target pixel is determined. Having a second determination step;
13. The image encoding method according to claim 12, wherein the specifying step specifies the light scattering region based on the evaluation value determined in the second determination step.   The program for operating a computer as an image coding apparatus of any one of Claims 1 thru | or 11.

Images