JP2002209113A - Image processing apparatus, its method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively convert the image component of each frequency band by each area. SOLUTION: An original image is divided into tiles and the ratios of overlapping of a target area and the tiles are calculated by each tile. When the value of this overlapping degree is larger than a fixed threshold Th, the tile is given frequency resolution by using the first DWT transformation circuit. When the value is not larger than Th, the tile is given frequency resolution by using the second DWT transformation circuit. Then, a DWT transformation circuit decided by each tile is selected and two-dimensional discrete wavelet conversion processing is given to an image signal within the tile to calculate and output the image component. Next, a transformation curved line is prepared by each frequency band and the picture component is transformed. Then, the inverse transformation of the discrete wavelet transformation is performed by each tile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and method for performing image processing on an image including a region of interest, and a storage medium.

[0002]

2. Description of the Related Art Recent advances in digital technology have made it possible to convert a radiographic image into a digital image signal, perform image processing such as frequency processing on the digital image signal, and display or print out the image on a CRT or the like. Have been done.
By the way, such frequency processing is performed by separating into image components of a plurality of frequency bands and increasing or attenuating the image components for each frequency band.

[0003]

However, in the above-described method, since the same frequency separation processing is performed on the entire image, uniform frequency decomposition processing is performed even when the frequency characteristics of each area are different. Therefore, there has been a problem that frequency processing suitable for each area cannot be efficiently performed.

[0004] In addition, although the frequency component contained in each area of the image is different, there is a problem that if the same filter is applied to all the areas, the compression efficiency is not good.

The present invention has been made to solve the above-described problems, and has as its object to effectively convert image components for each frequency band for each region.

[0006]

In order to achieve the object of the present invention, for example, an image processing apparatus of the present invention has the following arrangement.

That is, an image processing apparatus for performing image processing on an image including a region of interest, comprising: a dividing unit that divides the image into tiles of a predetermined size; Frequency conversion means for performing the frequency conversion performed on the tile of interest, and component conversion means for performing component conversion on the conversion coefficient included in the tile of interest in the tile of interest frequency-converted by the frequency conversion means. An inverse frequency conversion unit that performs an inverse conversion of the frequency conversion unit on the tile of interest that has been subjected to the component conversion by the component conversion unit.

[0008] Further, an image pickup means for picking up an image is provided, and the image including the attention area is picked up by the image pickup means.

The frequency conversion means may further comprise a calculation means for calculating the ratio of the attention area included in the tile of interest, and a plurality of frequency conversion parts for performing different frequency conversions. Selecting means for selecting, and performs frequency conversion on the tile of interest using the frequency conversion unit selected by the selecting means.

In order to achieve the object of the present invention, for example, an image processing apparatus of the present invention has the following arrangement.

That is, an image processing apparatus for performing image processing on an image including a region of interest, comprising: a dividing unit that divides the image into tiles of a predetermined size; Frequency conversion means for performing frequency conversion on the tile of interest in accordance with the frequency conversion plan, and, in the tile of interest, which has been frequency-converted by the frequency conversion means, performs component conversion on a conversion coefficient included in the tile of interest. And a reverse frequency conversion unit that performs a reverse conversion to the frequency conversion unit on the tile of interest that has been subjected to the component conversion by the component conversion unit.

Further, there is provided an image pickup means for picking up an image, and the image including the attention area is picked up by the image pickup means.

The frequency conversion means may further comprise: calculation means for calculating a ratio of the region of interest included in the tile of interest; and a plurality of frequency conversion units for performing different frequency conversions.
From a plan of frequency conversion performed by using some frequency conversion units, a selection unit that selects a plan according to the calculation unit, wherein the frequency conversion is performed on the tile of interest according to the plan selected by the selection unit. Do.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to preferred embodiments with reference to the accompanying drawings. [First Embodiment] FIG. 1 is a block diagram showing an X as an image processing apparatus according to the present embodiment.
FIG. 1 is a diagram illustrating a configuration of a line imaging apparatus 100. That is, the X-ray imaging apparatus 100 is an X-ray imaging apparatus having a function of performing processing on a captured image for each frequency band, and includes a preprocessing circuit 106, a CPU 108, a main memory 109, an operation panel 110, and an image display. Unit 111, image processing circuit 11
2 for exchanging data with each other via the CPU bus 107.

The X-ray imaging apparatus 100 includes a pre-processing circuit 1
06, the two-dimensional X-ray sensors 104 and X connected to the data collection circuit 105.
A line generating circuit 101, and each of these circuits
It is also connected to the PU bus 107.

The components of the X-ray imaging apparatus 100 having the above configuration will be described. First, the main memory 109 stores C
It stores various data necessary for processing in the PU 108 and includes a work memory for the CPU 108 to work with.

The CPU 108 uses the main memory 109 to control the operation of the entire apparatus in accordance with an operation from the operation panel 110. Thereby, the X-ray imaging apparatus 100
It works as follows.

First, the X-ray generation circuit 101 emits an X-ray beam 102 to a subject (test object) 103.
X-ray beam 102 emitted from X-ray generation circuit 101
Is transmitted through the test object 103 while being attenuated.
The light reaches the line sensor 104 and is output as an X-ray image by the two-dimensional X-ray sensor 104. Here, the X-ray image output from the two-dimensional X-ray sensor 104 is, for example, a human body image or the like.

The data collection circuit 105 converts the X-ray image output from the two-dimensional X-ray sensor 104 into an electric signal and supplies the electric signal to the preprocessing circuit 106. The preprocessing circuit 106 performs preprocessing such as offset correction processing and gain correction processing on the signal (X-ray image signal) from the data collection circuit 105. The X-ray image signal subjected to the pre-processing by the pre-processing circuit 106 is used as an original image under the control of the CPU 108.
The data is transferred to the main memory 109 and the image processing circuit 112 via the PU bus 107.

In the circuit 112, an area dividing circuit 113 divides an image into small areas and determines a wavelet transform method by a discrete wavelet transform circuit 114 described later for each small area (hereinafter referred to as a tile). A discrete wavelet transform circuit having a method, performing a discrete wavelet transform on the original image,
Image components (wavelet transform coefficients) of each frequency band are obtained.

Reference numeral 118 denotes a discrete wavelet transform circuit 11
4 is an image component conversion circuit for converting the image components of each frequency band obtained in step 4, and 115 is an inverse component for inversely converting the image components converted by the image component conversion circuit 118 and synthesizing the image by a plurality of inverse DWT conversion methods. This is a DWT conversion circuit.

In the present embodiment having the above configuration, X
The processing performed by the line imaging apparatus 100 will be described below with reference to flowcharts of the processing shown in FIGS.

The original image preprocessed by the preprocessing circuit 106 is transferred to the image processing circuit 112 via the CPU bus 107 (step S200). Here, the original image is shown in FIG.
Assume that the front chest image shown in FIG. Image processing circuit 11
In 2, in step S201, the area dividing circuit 113 divides the original image into tiles and determines a wavelet transform method (filter) for each of the divided areas. Details of this processing will be described with reference to the flowchart shown in FIG.

First, as shown in FIG. 5B, the area dividing circuit 113 divides an original image into small squares of a predetermined size (step S301). Next, as a target area,
For example, as illustrated in FIG. 5B, an anatomically distinctive region such as the lung is extracted as the target region 501 (step S302). As a method for extracting such a target region 501, a known method is used, but this method is not particularly limited.

Next, the area dividing circuit 113 calculates an overlapping ratio between the target area and the tile for each tile (step S).
303). Then, the ratio of the area of the target region included in the tile is calculated as the degree of overlap (step S30).
3). Specifically, the ratio of the number of pixels constituting the target area to the number of pixels in the tile is calculated. If the value of the degree of overlap is greater than a predetermined threshold value Th (step S304), the tile is subjected to frequency decomposition using a first DWT conversion circuit (this processing is referred to as a first DWT).
WT conversion) (step S306), and Th
If this is the case (step S304), frequency decomposition (this processing is called second DWT conversion) is performed using the second DWT conversion circuit (step S305).

Here, the difference in the characteristics of each DWT conversion circuit is the difference in the type of filter used, and each has a characteristic in the resolution characteristic of the frequency band. For example, the first DWT conversion circuit has a feature of finely separating high-frequency components (for example, 9-7).
Type filter: Details are publicly known and will be omitted. )
In the second DWT conversion circuit, the separation width of the frequency band is wide, and a filter (for example, Harr) capable of performing decomposition processing down to a lower frequency than the first DWT conversion circuit in the same dimension decomposition processing is possible.
Type filter: Details are publicly known and will be omitted. ) Is used.
A plurality of DWT conversion circuits having a characteristic in such a frequency band decomposition characteristic are prepared, and are selectively used according to the region and the region.

Then, the DWT conversion circuit 114 performs a frequency decomposition process for each tile in accordance with the tile and the wavelet conversion method determined by the region division circuit 113 (step S202).

Next, the details of the processing in step S202 will be described with reference to the flowchart shown in FIG. The DWT transform circuit 114 selects a DWT transform circuit determined by the region dividing circuit 113 for each tile, performs a two-dimensional discrete wavelet transform process on the image signal in the tile, and calculates an image component (transform coefficient). Output. In addition,
When the conversion coefficient for each tile is obtained, a flag indicating which DWT conversion circuit was used (DWT conversion circuit selection flag) is attached to each tile.

The DWT conversion circuit 114 in the present embodiment
6A is shown in FIG. In the circuit having the configuration shown in the figure, an input image signal is separated into an even address signal and an odd address signal by a combination of a delay element and a downsampler, and is subjected to filter processing by two filters p and u. s and d respectively represent a low-pass coefficient and a high-pass coefficient when one-level decomposition is performed on a one-dimensional image signal, and are calculated by the following equations.

D (n) = x (2n + 1) −floor ((x (2n) + x (2n + 2)) / 2) (Equation 1) s (n) = x (2n) + floor ((d (n−1 ) + D (n)) / 4) (Expression 2) where x (n) is an image signal to be converted. With the above processing, one-dimensional discrete wavelet transform processing is performed on the image signal. In addition, as described above, each DWT
The conversion circuit uses a different filter.

In the two-dimensional discrete wavelet transform, one-dimensional transform is sequentially performed in the horizontal and vertical directions of an image. FIG. 6B shows a 2D image obtained by a two-dimensional conversion process.
5 is a configuration example of a level conversion coefficient group, in which image signals are image components HH1, HL1, and LH of different frequency bands.
1,. . . , LL (step S401).
In FIG. 6B, HH1, HL1, LH1,. . . ,
LL (hereinafter referred to as a sub-band) indicates an image component for each frequency band.

Next, the image component conversion circuit 118 creates, for example, a conversion curve shown in FIG. 7 for each frequency band (step S4).
02), the image components are converted (step S403). That is, the scaling according to the curve 702 is performed on the conversion coefficient (input coefficient in the figure) whose value is equal to or greater than Th1.

FIG. 7 is an example of a conversion curve created by the image component conversion circuit 118. The horizontal axis indicates the input coefficient (input image component), and the vertical axis indicates the output coefficient (output image component).

Here, in the conversion curve shown in FIG. 7, the slope of the conversion curve 702 and the threshold 701 used are those created in step S402 for each small area and each subband. For example, even when the same DWT conversion circuit is used, a different conversion curve shape for each frequency is used for each tile. The shape of the conversion curve is changed according to, for example, the anatomical region and the pixel value of the original image.
As a result, it is possible to perform fine frequency processing for each tile.

The inverse DWT conversion circuit 115 refers to the aforementioned DWT conversion circuit selection flag attached to the tile, and
The filter used in the three-dimensional discrete wavelet transform process is specified, the filter used for the inverse DWT transform according to the specified filter is specified, and the inverse DWT is determined for each tile as follows.
WT conversion is performed (step S404). The configuration of the inverse DWT conversion circuit 115 is as shown in FIG. The input image components are subjected to two filter processes of u and p, are upsampled and then superimposed to output an image signal x ′. These processes are performed by the following equations.

X ′ (2n) = s ′ (n) −floor ((d ′ (n−1) + d ′ (n)) / 4) (Equation 3) x ′ (2n + 1) = d ′ (n) + floor ((x ′ (2n) + x ′ (2n + 2)) / 2) (Equation 4) With the above processing, one-dimensional inverse discrete wavelet transform processing is performed on the transform coefficients. In the two-dimensional inverse discrete wavelet transform, one-dimensional inverse transform is sequentially performed in the horizontal and vertical directions of an image, and details thereof are publicly known, and thus description thereof is omitted here. In addition, each DWT conversion circuit has a different filter type. For example, the first inverse DWT conversion circuit uses a filter corresponding to the 9-7 type filter, and for example, the second inverse DWT conversion circuit uses Harr.
A filter corresponding to the type filter is used.

When the image is stored, the image data before the inverse conversion is stored. In this case, the image data before the conversion process for each image component may be stored. Alternatively, the image data after the component conversion processing may be stored.
When the image before the component conversion is stored, the component conversion process is performed before performing the inverse conversion process. Accordingly, when the image before the component conversion is stored, the original image can be restored, but the component conversion process needs to be performed in the restoration process.

On the other hand, when the image data is stored after the component conversion, the original image cannot be restored, but there is an effect that the compression efficiency is increased by cutting off the high frequency components. Further, the image conversion processing does not have to be performed during the restoration processing. Furthermore, by using a high-frequency separable filter in a region containing a large amount of high-frequency components (for example, a lung part), the degree of correlation between the image data and the filter is increased, and the number of data for representing the image is reduced. This has the effect of increasing the rate. Similarly, by using a low-frequency high-frequency filter with good separability in a region containing a large amount of low-frequency components (eg, abdomen), the degree of correlation between the image data and the filter increases, and the number of data for representing the image decreases. As a result, there is an effect that the compression ratio increases. Therefore, using a different filter for each area rather than applying a uniform filter as a whole has an effect of increasing the compression ratio of the entire data. In particular, in the case of a human body, if the anatomical regions such as the chest and abdomen are different, the frequency components are different, and using different filters for each anatomical region has an effect of improving the efficiency such as the data compression ratio.

By the way, in the lung, blood vessels and fine trabecular bones are composed of high-frequency components, and it is necessary to convert high-frequency components in order to emphasize these parts. However, in the present embodiment, the target high frequency component can be accurately emphasized by using a DWT conversion circuit that can finely separate the high frequency component in the lung.

On the other hand, organ parts such as the abdomen are composed of low and medium frequencies, and in order to emphasize the organ parts, it is necessary to emphasize a wide range of low and medium frequencies. However, in the present embodiment, the width of the separation frequency band is wide in the abdomen, and a filter type that can separate up to the low frequency with the number of low-order separations is used, so that the low and middle frequency image components can be accurately emphasized. As described above, by properly using the DWT circuit according to the characteristics of each region, there is an effect that the target region can be efficiently emphasized efficiently.

As described above, in the present embodiment, the use of the DWT conversion circuit having different decomposition characteristics for each region has an effect that the intended frequency decomposition can be performed efficiently. Further, by performing frequency number decomposition for each region with a target frequency bandwidth, there is an effect that a target frequency component can be emphasized finely. Furthermore, by using a different DWT conversion circuit for each anatomical region,
The frequency processing can be performed finely for each anatomical region, and the effect that the frequency processing of the entire image can be performed accurately can be achieved. Further, since the method and intensity of frequency emphasis are changed for each small area, it is possible to perform fine frequency processing over the details of the image, and it is possible to perform optimal frequency processing on the entire image.

[Second Embodiment] An X-ray imaging apparatus as an image processing apparatus according to the present embodiment is different from the X-ray imaging apparatus according to the first embodiment in that a DWT conversion circuit and an inverse DWT conversion circuit are added. And a configuration similar to that of the first embodiment.
It has a function of selecting a DWT conversion plan according to the ratio of the target area to each tile, and performing a two-dimensional discrete wavelet transform on each tile according to the selected conversion plan as in the first embodiment. After the discrete wavelet transform, the component transform is performed in the same manner as in the first embodiment, and the inverse transform of the discrete wavelet transform performed on each tile is performed.

Hereinafter, the X-ray imaging apparatus according to the present embodiment will be described. FIG. 8 shows the configuration of the X-ray imaging apparatus according to the present embodiment. The same parts as those in the apparatus shown in FIG. 1 are indicated by the same numbers. The difference from the device shown in FIG.
The difference is that a WT conversion circuit and an inverse DWT conversion circuit are added, and a storage circuit 117 is added.

Hereinafter, the processing in the present apparatus will be described with reference to flowcharts of the processing shown in FIGS.

The original image preprocessed by the preprocessing circuit 106 is transferred to the image processing circuit 112 via the CPU bus 107 (step S900). Here, the original image is shown in FIG.
Assume that the front chest image shown in FIG. Image processing circuit 11
In 2, the area dividing circuit 113 divides the original image into tiles, and determines a DWT conversion plan for each of the divided areas (tiles) (step S901). Details of this processing will be described with reference to the flowchart shown in FIG.

First, the area dividing circuit 113 divides the original image into tiles of a predetermined size as illustrated in FIG. 5B (step S1001). Next, as shown in FIG. 5B, a region having an anatomical characteristic such as a lung is extracted as a target region 501 as a target region 501 (step S1002). Such a target area 501
A known method is used as a method for extracting, but this method is not particularly limited.

Next, the area dividing circuit 113 calculates the overlapping ratio of the target area and the tile for each tile (step S).
1003). Then, the ratio of the area of the target region included in the tile is calculated as the degree of overlap (step S100).
3). Specifically, the ratio of the number of pixels constituting the target area to the number of pixels in the tile is calculated. If the value of the degree of overlap is greater than a predetermined threshold value Th (step S1004), the tile is subjected to frequency decomposition by selecting the first DWT conversion plan (step S10).
06), if it is equal to or less than Th (step S1004), the second DWT conversion plan is selected and frequency decomposition is performed (step S1005).

Here, the first DWT conversion plan includes, for example, the first DWT conversion in the first and second decomposition levels of the DWT conversion.
The second DWT conversion circuit (type 5-3) is used at the third and fourth decomposition levels using the conversion circuit (type 9-7).
In the decomposition level of, the third DWT conversion circuit (Harr type)
Is used. Here, the third DWT conversion circuit is
D newly provided in the X-ray imaging apparatus in the first embodiment
A WT conversion circuit, which has a wide frequency band separation width and is capable of performing decomposition processing down to a lower frequency than the second DWT conversion circuit in the same dimension decomposition processing. In this embodiment, the Harr type is used as the third DWT conversion circuit, but the present invention is not limited to this.

On the other hand, as the second DWT conversion plan, for example, in the first and second decomposition levels of the DWT conversion, the second DWT conversion plan
A conversion circuit (5-3 type) is used, and a third DWT conversion circuit (Harr type) is used at the third and fourth decomposition levels. The contents of the first and second DWT conversion plans are stored in the main memory 109.

Here, the decomposition level is the number of times the DWT conversion processing is performed. For example, the second DWT conversion processing is called a second decomposition level.

As a result, the first DWT conversion plan is selected for the chest and the second DWT conversion plan is selected for the abdomen. There are fine blood vessels, fine organs, medium blood vessels, medium organs, ribs, and the like in the chest. In the chest, fine blood vessels, fine organs, and the like have high frequency as the main component, and medium blood vessels, medium organs, ribs, and the like have high and medium frequency as the main component. The ribs are mainly composed of middle and low frequencies. Therefore, it is efficient to use a suitable filter for each frequency band in order to adjust the sharpness of the entire chest image. For example, 9-7 to emphasize high frequency
It is preferable to use a filter having excellent separation characteristics of high-frequency components such as a type. In order to emphasize an image component over a high-middle frequency band, the frequency band is wider than that of the 9-7 type and the separation characteristics of high-middle frequencies are excellent. -3 type is preferably used. In order to emphasize an image mainly including middle and low frequencies like ribs, it is efficient to use a Harr type which has a wider frequency band and has excellent low frequency component separation characteristics.

For example, in order to separate the frequency resolution down to a low frequency with a single 9-7 type filter, a high-order resolution level is required, and the efficiency is reduced. Further, for example, in order to emphasize the image components in the low frequency band in the 9-7 type having a narrow frequency band, it is necessary to adjust the image components over a plurality of decomposition levels, which is inefficient.

On the other hand, since the abdomen is mainly composed of middle and low frequency components, it is more efficient to decompose in the order of 5-3 type and Harr type filters. 9 in the area without high frequency components
This is because applying a -7 type filter is not good for the above-mentioned reason. Further, the second DWT conversion plan uses a filter having a wide frequency band, so that the decomposition level can be suppressed to a low number of times. Further, using a filter suitable for each decomposition level has the effect of improving the image compression efficiency.

Then, the DWT conversion plan for each tile determined by the region dividing circuit 113 and the filter used for this plan are stored in the storage circuit 117 (step S902). Then, the DWT conversion circuit 114 performs a frequency decomposition process for each tile according to the DWT conversion plan and the filter stored in the storage circuit 117 (step S903). At this time, D
The contents of the WT conversion plan are also read from the main memory 109. The frequency decomposition process uses the same two-dimensional discrete wavelet transform process as in the first embodiment. In the present embodiment, in the frequency decomposition processing, for example, taking the first DWT conversion plan as an example, for example, at the first decomposition level, a 9-7 type filter is used for the frequency decomposition processing, and HH1, HL1, L
Decompose into four subbands, H1 and LL1. In the second decomposition level, LL1 is further subjected to frequency decomposition processing using a 9-7 type filter, and HH2, HL2,
Decompose into four subbands LH2 and LL2. Then, at the third decomposition level, LL2 is further subjected to frequency decomposition processing using a 5-3 type filter, and HH3, HL
3, LH3, and LL3. Hereinafter, the same processing is repeated.

Then, the image component is converted for each tile (step S904). This processing is the same as the processing of step S403 in the first embodiment.

The inverse DWT conversion circuit 115 determines in step S9
02, the filter used for the DWT conversion plan for each tile stored in the storage circuit 117 is read, and the filter used in the two-dimensional discrete wavelet transform processing is specified, and the filter is used for the inverse DWT conversion according to the specified filter. A filter is specified, and inverse DWT conversion is performed for each tile (step S
905). The method of the inverse DWT transform is the same as the method described in the first embodiment.

[Other Embodiments] Even if the present invention is applied to a system constituted by a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (one device) For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

Another object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiment is recorded to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. It is needless to say that the present invention can also be achieved by a CPU or an MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Also,
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the operating system (OS) running on the computer based on the instructions of the program code.
It goes without saying that a case where the functions of the above-described embodiments are implemented by performing some or all of the actual processing, and the processing performs the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, the CPU included in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the above-mentioned storage medium, the storage medium has the above-described storage medium (FIG. 2, and / or FIG. 3, and / or FIG. 4, and / or FIG. 9, and / or FIG. 9). 1
(Shown as 0) will be stored.

[0061]

As described above, according to the present invention, it is possible to effectively convert an image component for each frequency band for each region.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an X-ray imaging apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a process performed by the X-ray imaging apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an area division processing procedure according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure of area division according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of area division.

FIG. 6 is a diagram illustrating a DWT conversion circuit.

FIG. 7 is a diagram showing a conversion curve and a threshold.

FIG. 8 is a diagram illustrating a configuration of an X-ray imaging apparatus according to a second embodiment of the present invention.

FIG. 9 is a flowchart of a process performed by the X-ray imaging apparatus according to the second embodiment of the present invention.

FIG. 10 is a flowchart illustrating in detail a process of step S901 in a process performed by the X-ray imaging apparatus according to the second embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/18 A61B 6/00 350Z H04N 7/133 Z (72) Inventor Makoto Sato 3 Shimomaruko, Ota-ku, Tokyo F-term (reference) at Chome 30-2 Canon Inc. LC04 MA24 PP01 SS20 SS23 TA69 TB08 TC24 TC34 TD08 TD12 UA02 UA11 5C078 BA44 BA53 CA14

Claims (29)

[Claims] 1. An image processing apparatus for performing image processing on an image including a region of interest, comprising: a dividing unit configured to divide the image into tiles of a predetermined size; Frequency conversion means for performing the frequency conversion performed on the tile of interest, and component conversion means for performing component conversion on the conversion coefficient included in the tile of interest in the tile of interest frequency-converted by the frequency conversion means. An image processing apparatus comprising: an inverse frequency conversion unit that performs an inverse conversion of the frequency conversion unit on the tile of interest that has been subjected to the component conversion by the component conversion unit. 2. The image processing apparatus according to claim 1, further comprising an imaging unit that captures an image, wherein the image including the attention area is captured by the imaging unit. 3. The image processing apparatus according to claim 2, wherein the imaging unit captures an image of a subject by X-rays. 4. The frequency conversion unit further includes: a calculation unit that calculates a ratio of the region of interest included in the tile of interest; and a plurality of frequency conversion units that perform different frequency conversions.
And selecting means for selecting a frequency conversion unit according to the calculation means, wherein the frequency conversion is performed on the tile of interest using the frequency conversion unit selected by the selection means. 4. The image processing device according to any one of 3. 5. The frequency conversion unit, which performs frequency conversion on the tile of interest according to whether or not a ratio of a region of interest included in the tile of interest is equal to or greater than a certain threshold, The image processing apparatus according to claim 4, wherein the image processing apparatus is selected from the means. 6. The selecting unit selects a first frequency conversion unit having a function of finely separating a high-frequency component in the tile of interest when a ratio of a region of interest included in the tile of interest is equal to or greater than a certain threshold. However, when the ratio of the attention area included in the attention tile is smaller than a certain threshold, the separation width of the frequency band is wide, and the decomposition processing up to a lower frequency than the first frequency conversion unit is performed in the same dimension decomposition processing. The image processing apparatus according to claim 5, wherein a second frequency converter having a possible function is selected. 7. The image processing apparatus according to claim 6, wherein the first frequency converter uses a 9-7 type filter. 8. The image processing apparatus according to claim 6, wherein the second frequency converter uses a Harr type filter. 9. The component conversion unit further includes a curve creation unit that creates a conversion curve for each tile and each frequency band, and performs component conversion on a conversion coefficient included in the frequency band using the curve. The image processing apparatus according to claim 1, wherein: 10. The image processing apparatus according to claim 9, wherein the curve creating unit creates the curve according to an anatomical region and a pixel value of an original image. 11. The image processing apparatus according to claim 1, wherein the frequency conversion unit performs a two-dimensional discrete wavelet transform on the tile. 12. The image processing apparatus according to claim 1, wherein the region of interest is an anatomically characteristic region such as a lung. 13. An image processing apparatus for performing image processing on an image including a region of interest, comprising: a dividing unit configured to divide the image into tiles of a predetermined size; Frequency conversion means for performing frequency conversion on the tile of interest in accordance with the frequency conversion plan, and, in the tile of interest, which has been frequency-converted by the frequency conversion means, component conversion is performed on the conversion coefficients included in the tile of interest. An image processing apparatus comprising: a component conversion unit that performs component conversion; and an inverse frequency conversion unit that performs a reverse conversion of the frequency conversion unit with respect to the tile of interest that has undergone component conversion by the component conversion unit. 14. The image processing apparatus according to claim 13, further comprising an image pickup unit for picking up an image, wherein the image including the attention area is picked up by the image pickup unit. 15. The image processing apparatus according to claim 14, wherein the imaging unit captures an image of a subject by X-rays. 16. The frequency conversion unit further includes: a calculation unit that calculates a ratio of the region of interest included in the tile of interest; and a plurality of frequency conversion units among a plurality of frequency conversion units that perform different frequency conversions. Selecting means for selecting a plan according to the calculation means from a plan of frequency conversion to be performed using the frequency conversion, and performing frequency conversion on the tile of interest according to the plan selected by the selection means. Item 16. The image processing apparatus according to any one of Items 13 to 15. 17. The method according to claim 1, wherein the selecting unit selects a plan for performing frequency conversion on the tile of interest according to whether or not a ratio of a region of interest included in the tile of interest is equal to or greater than a certain threshold. The image processing apparatus according to claim 16, wherein: 18. The method according to claim 18, wherein the selecting unit sets the first conversion plan when the ratio of the region of interest included in the tile of interest is equal to or greater than a certain threshold. 17. The image processing apparatus according to claim 16, wherein the second conversion plan is selected when the size is smaller. 19. The first conversion plan uses a frequency converter using a 9-7 type filter at the first and second decomposition levels of frequency conversion, and uses a 5-3 type at the third and fourth decomposition levels. 19. The image processing apparatus according to claim 18, wherein a frequency converter using a filter is used, and a frequency converter using a Harr type filter is used at the fifth and sixth decomposition levels. 20. The second conversion plan uses a frequency conversion unit using a 5-3 type filter at the first and second decomposition levels of the frequency conversion, and Harr at the third and fourth decomposition levels.
19. The image processing apparatus according to claim 18, wherein a frequency conversion unit using a type filter is used. 21. The image processing apparatus according to claim 19, wherein the decomposition level is the number of times of frequency conversion. 22. An image processing method for performing image processing on an image including a region of interest, comprising: a dividing step of dividing the image into tiles of a predetermined size; A frequency conversion step of performing a frequency conversion on the tile of interest, and a component conversion step of performing a component conversion on a conversion coefficient included in the tile of interest in the tile of interest that has been frequency-converted in the frequency conversion step. And an inverse frequency conversion step of performing a reverse conversion of the frequency conversion step on the tile of interest subjected to the component conversion in the component conversion step. 23. The frequency conversion step, further comprising: a calculation step of calculating a ratio of the attention area included in the tile of interest; and a plurality of frequency conversion units each performing different frequency conversion.
A selection step of selecting a frequency conversion unit according to the result of the calculation step, wherein the frequency conversion unit selected in the selection step is used to perform frequency conversion on the tile of interest. Item 23. The image processing method according to Item 22. 24. An image processing method for performing image processing on an image including a region of interest, comprising: a dividing step of dividing the image into tiles of a predetermined size; A frequency conversion step of performing frequency conversion on the tile of interest according to the frequency conversion plan, and, in the tile of interest that has been frequency-converted in the frequency conversion step, component conversion is performed on the conversion coefficient included in the tile of interest. An image processing method, comprising: performing a component conversion step; and performing an inverse frequency conversion step of performing a reverse conversion to the frequency conversion step on the tile of interest that has been subjected to the component conversion in the component conversion step. 25. The frequency conversion step, further comprising: a calculation step of calculating a ratio of the region of interest included in the tile of interest; and a plurality of frequency conversion units of a plurality of frequency conversion units performing different frequency conversions. A selecting step of selecting a plan according to the result of the calculation step from a plan of the frequency conversion to be performed using the frequency conversion, and performing a frequency conversion on the tile of interest according to the plan selected in the selecting step. Claim 24
The image processing method according to 1. 26. A computer-readable storage medium storing a program code for performing image processing on an image including a region of interest, the program code for a dividing step of dividing the image into tiles of a predetermined size. A program code of a frequency conversion step of performing frequency conversion on the tile of interest according to a ratio of the region of interest included in the tile of interest; And a program code of a component conversion step of performing a component conversion on a conversion coefficient included in the component conversion step, and an inverse frequency conversion step of performing a reverse conversion of the frequency conversion step on the target tile subjected to the component conversion in the component conversion step. A storage medium comprising a program code. 27. The program code of the frequency conversion step further includes: a program code of a calculation step of calculating a ratio of the region of interest included in the tile of interest; and a plurality of frequency conversion units performing different frequency conversions.
And a program code of a selection step of selecting a frequency conversion unit according to the result of the calculation step, wherein the frequency conversion unit selected in the selection step performs frequency conversion on the tile of interest. The storage medium according to claim 26, wherein 28. A computer-readable storage medium storing a program code for performing image processing on an image including a region of interest, the program code for a dividing step of dividing the image into tiles of a predetermined size. A program code of a frequency conversion step of performing a frequency conversion on the tile of interest according to a frequency conversion plan according to a ratio of the region of interest included in the tile of interest; and the tile of interest converted in the frequency conversion step A program code of a component conversion step of performing a component conversion on a conversion coefficient included in the tile of interest, and performing a reverse conversion of the frequency conversion step on the tile of interest that has been component-converted in the component conversion step And a program code for an inverse frequency conversion step. 29. The program code of the frequency conversion step further includes: a program code of a calculation step of calculating the ratio of the region of interest included in the tile of interest; and a program code of a plurality of frequency conversion units for performing different frequency conversions. A program code for a selection step of selecting a plan according to the result of the calculation step from a plan of the frequency conversion performed using the frequency conversion unit, and the tile of interest according to the plan selected in the selection step. 29. Frequency conversion is performed on the data.
A storage medium according to claim 1.