High-frequency emphasis control device

Abstract

This invention provides a high-frequency enhancement control device that can automatically enhance the high-frequency components of an image with an appropriate amount of enhancement. [Solution] The first discrete Fourier transform unit 11 performs a two-dimensional discrete Fourier transform on the input image signal to generate a first frequency spectrum. The second discrete Fourier transform unit 21 performs a two-dimensional discrete Fourier transform on the output image signal output from the high-frequency enhancement circuit 30 to generate a second frequency spectrum. The first and second high-frequency component index generation units (summation calculation units 13 and 23) each generate first and second high-frequency component indexes, respectively, based on the first and second frequency spectra, indicating the total amount of high-frequency components. The high-frequency component index is generated. The high-frequency component emphasis ratio calculation unit 4 calculates the high-frequency component emphasis ratio, which is the ratio of the first high-frequency component index to the second high-frequency component index. The emphasis amount control unit 5 generates an emphasis amount control value according to the comparison result between the high-frequency component emphasis ratio and the target emphasis ratio and supplies it to the high-frequency emphasis circuit 30.

Description

Technical Field

[0001] The present invention relates to a high-frequency emphasis amount control device.

Background Art

[0002] In order to improve the sharpness of an image displayed on an image display device, a high-frequency emphasis circuit that emphasizes the high-frequency components of the image is used (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When emphasizing the high-frequency components of an image by a high-frequency emphasis circuit, an appropriate emphasis amount varies depending on the content of the image. The user of the image display device manually sets the emphasis amount of the high-frequency components while viewing the image displayed on the image display device. For the user, manually setting the emphasis amount is troublesome. Also, when the user manually sets the emphasis amount, it is difficult to set an appropriate emphasis amount because the high-frequency components may be overemphasized or the degree of emphasis may be too little. Therefore, the emergence of a high-frequency emphasis amount control device that can automatically emphasize the high-frequency components with an appropriate emphasis amount is desired.

[0005] <LID=46> An object of the present invention is to provide a high-frequency emphasis amount control device that can automatically emphasize the high-frequency components of an image with an appropriate emphasis amount.

[0006] ​​​​​​​​This invention performs a two-dimensional discrete Fourier transform on an input image signal to produce a first frequency spectrum. The first discrete Fourier transform section and the output image signal output from the high-frequency enhancement circuit are then processed in two dimensions. A second discrete Fourier transform unit that performs a discrete Fourier transform to generate a second frequency spectrum, and Based on the first frequency spectrum, a first high-frequency component index is used to indicate the total amount of high-frequency components. A first high-frequency component index generation unit generates, and based on the second frequency spectrum, the high-frequency component A second high-frequency component index generation unit that generates a second high-frequency component index that shows the total amount of minutes, and the first The high-frequency component is calculated as the ratio of the high-frequency component index to the second high-frequency component index. The enhancement ratio calculation unit and the enhancement amount control value according to the comparison result between the high-frequency component enhancement ratio and the target enhancement ratio. The present invention provides a high-frequency enhancement control device comprising an enhancement amount control unit that supplies an enhancement amount to the aforementioned high-frequency enhancement circuit. [Effects of the Invention]

[0007] According to the high-frequency enhancement control device of the present invention, the high-frequency components of an image are automatically enhanced by an appropriate amount. It is possible. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing a high-frequency emphasis control device according to the first embodiment. [Figure 2] Figures 1, 9, and 12 are conceptual diagrams showing weighted filters that multiply the frequency spectrum by weighted calculation units 12 and 22. [Figure 3A] This is a diagram showing a frame for displaying a circular zone plate. [Figure 3B] This figure shows a partial region extracted from the central part of Figure 3A. [Figure 3C] Figure 1 shows the frequency spectrum obtained by the discrete Fourier transform unit 11 in Figure 3B performing a two-dimensional discrete Fourier transform on the subregion. [Figure 3D] It is a diagram showing a weighting filter that the weighting operation unit 12 in FIG. 1 multiplies with the frequency spectrum. [Figure 3E] It is a diagram showing a frequency spectrum map obtained by multiplying the frequency spectrum shown in FIG. 3C by the weighting filter shown in FIG. 3D by the weighting operation unit 12 in FIG. 1. [[ID=⑤]] [[ID=⑥]] [Figure 4A] [[ID=⑦]]It is a diagram showing a frame in which a circular zone plate is reduced and arranged at the center. [[ID=⑧]] [[ID=⑨]] [Figure 4B] [[ID=⑩]]It is a diagram showing a partial region extracted from the central part of FIG. 4A. [[ID=⑪]] [[ID=⑫]] [Figure 4C] [[ID=⑬]]It is a diagram showing a frequency spectrum obtained by performing a two-dimensional discrete Fourier transform on the partial region of FIG. 4B by the discrete Fourier transform unit 11 in FIG. 1. [[ID=⑭]] [[ID=⑮]] [Figure 4D] [[ID=⑯]]It is a diagram showing a weighting filter that the weighting operation unit 12 in FIG. 1 multiplies with the frequency spectrum. [[ID=⑰]] [[ID=⑱]] [Figure 4E] [[ID=⑲]]It is a diagram showing a frequency spectrum map obtained by multiplying the frequency spectrum shown in FIG. 4C by the weighting filter shown in FIG. 4D by the weighting operation unit 12 in FIG. 1. [[ID=⑳]] [[ID=㉑]] [Figure 5] [[ID=㉒]]It is a block diagram showing a schematic configuration example of the high-frequency emphasis circuit 30 in FIGS. 1, 9, and 12. [[ID=㉓]] [[ID=㉔]] [Figure 6] [[ID=㉕]]It is a characteristic diagram showing the time constant when the high-frequency emphasis circuit 30 in FIGS. 1, 9, and 12 changes the emphasis amount control value. [[ID=㉖]] [[ID=㉗]] [Figure 7] [[ID=㉘]]It is a characteristic diagram showing the hysteresis characteristics when the high-frequency emphasis circuit 30 in FIGS. 1, 9, and 12 changes the emphasis amount control value. [[ID=㉙]] [[ID=㉚]] [Figure 8] [[ID=㉛]]It is a diagram showing an example of a medical image displayed on a medical monitor by a DICOM viewer. [[ID=㉜]] [[ID=㉝]] [Figure 9] [[ID=㉞]]It is a block diagram showing the high-frequency emphasis amount control device of the second embodiment. [[ID=㉟]] [[ID=㊱]] [Figure 10A] [[ID=㊲]]It is a diagram showing an example of a frequency spectrum map output from the weighting operation unit 12 in FIG. 9. [[ID=㊳]] [[ID=㊴]] [Figure 10B]FIG. 9 is a diagram showing an example of a frequency spectrum map from which horizontal and vertical frequency components are removed by the horizontal / vertical frequency component removing unit 14. [Figure 11A] FIG. 9 is a diagram showing an example of a frequency spectrum map output from the weighting calculation unit 22. [Figure 11B] FIG. 9 is a diagram showing an example of a frequency spectrum map from which horizontal and vertical frequency components are removed by the horizontal / vertical frequency component removing unit 24. [Figure 12] FIG. 9 is a block diagram showing a high-frequency emphasis amount control device according to the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, the high-frequency emphasis amount control device according to each embodiment will be described with reference to the accompanying drawings.

[0010] <First Embodiment> FIG. 1 shows a high-frequency emphasis amount control device 101 according to the first embodiment. The high-frequency emphasis amount control device 10 1 includes a discrete Fourier transform unit 11 (first discrete Fourier transform unit), a weighting calculation unit 12 (first weighting calculation unit), and a sum calculation unit 13 (first sum calculation unit). Further, the high-frequency emphasis amount control device 101 includes a discrete Fourier transform unit 21 (second discrete Fourier transform unit), a weighting calculation unit 22 (second weighting calculation unit), a sum calculation unit 23 (second sum calculation unit), a high-frequency component emphasis ratio calculation unit 4, and an emphasis amount control unit 5. The high-frequency emphasis amount control device 101 controls the emphasis amount when the high-frequency emphasis circuit 30 emphasizes the high-frequency component of the input image signal.

[0011] The high-frequency emphasis amount control device 101 and the high-frequency emphasis circuit 30 shown in FIG. 1 can be mounted on any image display device. As an example, the image display device is a device such as an X-ray imaging device, a computed tomography device (CT), or a magnetic resonance imaging device (MRI) used by a doctor to image the human body It is a medical monitor that diagnoses patients by looking at the captured images. The images used will be referred to as medical images.

[0012] Medical images are stored on a PACS (Picture Archiving and Communication System) server. The workstation reads medical images from the PACS server and displays them on the medical monitor. Display. Medical images are typically in DICOM format (Digital Imaging and Communications in Media). It complies with the cine standard and medical models are viewed using software called a DICOM viewer. It will be displayed on Nita.

[0013] In Figure 1, the discrete Fourier transform unit 11 processes the input medical image displayed on the medical monitor. The force image signal is subjected to a two-dimensional discrete Fourier transform. The discrete Fourier transform unit 21 is a high-frequency enhancement circuit 3 The output image signal, which is output from 0, is subjected to a 2D discrete Fourier transform. Typically, discrete Fourier transforms are performed. The transformation units 11 and 21 each perform the Fast Fourier Transform (FFT). The input and output image signals are subjected to a discrete Fourier transform using the rm algorithm.

[0014] The weighting calculation units 12 and 22 output from the discrete Fourier transform units 11 and 21, respectively. The resulting two-dimensional frequency spectrum is multiplied by a weighted filter that extracts high-frequency components. Generate a frequency spectrum map for evaluation. The frequency spectrum output from the discrete Fourier transform unit 11 The wavenumber spectrum is the first frequency spectrum, which is output from the Discrete Fourier Transform unit 21. The resulting frequency spectrum is the second frequency spectrum, generated by the weighting calculation unit 12. The resulting frequency spectrum map is the first frequency spectrum map, and the weighting calculation unit The frequency spectrum map generated by 22 is the second frequency spectrum map. .

[0015] Figure 2 shows the weighted filter that the weighting calculation units 12 and 22 multiply by the frequency spectrum. This is conceptually illustrated. As shown in Figure 2, the weighted filter uses the input image signal and the output An inverted circle where the center of frame F of the image signal has a value of 0, and the value increases as you move away from the center. A cone-shaped filter is preferable.

[0016] The weighting calculation units 12 and 22 multiply the frequency spectrum by the inverted cone-shaped filter shown in Figure 2. In calculation, the low-frequency components in the frequency spectrum are removed, and the high-frequency components increase. This process yields a frequency spectrum map processed so that high-frequency components are dominant. It is possible.

[0017] Using Figures 3A to 3E and Figures 4A to 4E, the weighting calculation units 12 and 22 generate The resulting frequency spectral map is explained. Figure 3A shows an image with relatively few high-frequency components. As an example, a frame that displays a Circular Zone Plate (CZP) Figure 4A shows an example of an image with a relatively large amount of high-frequency components, specifically a circular zone plate. This shows frame F with the element reduced and placed in the center. The frames shown in Figures 3A and 4A The 'F' resolution is Full HD, with 1920 pixels horizontally and 1080 pixels vertically. This example illustrates the case where image quality is involved.

[0018] Figure 3B shows the central part of frame F shown in Figure 3A, with approximately 800 pixels horizontally and vertically. Figure 3C shows a subregion extracted from an area with approximately 800 pixels in the direction. The Fourier transform unit 11 performs a two-dimensional discrete Fourier transform on the subregion of Figure 3B to obtain the frequency spectrum. This is shown. In the frequency spectrum shown in Figure 3C, the center represents the low-frequency components, and the periphery represents the high-frequency components. This indicates the minutes. In the peripheral area, the value increases as the frequency increases, and the display appears whiter. ru.

[0019] Figure 3D shows the weighted filter that the weighting calculation unit 12 multiplies by the frequency spectrum. Figure 3D corresponds to the weighted filter shown in Figure 2. In Figure 3D, the dark areas are The closer the value is to 0, the whiter it becomes, and the larger the value. Figure 3E shows the weighting calculation unit 1 Figure 2 is the frequency spectrum obtained by multiplying the frequency spectrum shown in Figure 3C by the weighted filter shown in Figure 3D. This shows a spectrum map. The low-frequency components in the center of the frequency spectrum have been removed. The value has become smaller and is displayed in a dark color.

[0020] Figure 4B shows the center of frame F shown in Figure 4A, with approximately 800 pixels horizontally and vertically... This shows a subregion extracted from an area with approximately 800 pixels in the direction. Figure 4C is a discrete fu The frequency spectrum obtained by the Fourier transform unit 11 performing a two-dimensional discrete Fourier transform on the subregion of Figure 4B is shown. As can be seen by comparing Figure 3C and Figure 4C, the subregion shown in Figure 4B is the same as in Figure 3B. Because there are more high-frequency components than in the subregion shown, the frequency spectrum shown in Figure 4C is as a whole The values ​​are displayed as large and white. Figure 4D shows the same weighted filter as Figure 3D. Yes, they are.

[0021] Figure 4E shows the weighting calculation unit 12 applying the weights shown in Figure 4D to the frequency spectrum shown in Figure 4C. This shows the frequency spectrum map after multiplying by the filter. Compare Figure 3E and Figure 4E. As can be seen, the frequency spectrum map shown in Figure 4E is the same as the frequency spectrum shown in Figure 3E. The value is larger than that of Lumap and is displayed in a lighter color.

[0022] Thus, the frequency spectrum map generated by the weighting calculation unit 12 is the input The more high-frequency components are present in the image signal, the larger the value will be at each pixel. Similarly, the frequency spectral map generated by the weighting calculation unit 22 is used in the output image signal. The more high-frequency components a pixel contains, the larger its value will be in each pixel.

[0023] Returning to Figure 1, the sum calculation units 13 and 23 are located within frame F, and the weighting calculation unit is located within frame F. The sum of the values ​​of each pixel in the frequency spectrum map output from 12 and 22 is calculated. The sum calculation unit 13 is the first sum calculation unit, and the sum calculation unit 23 is the second sum calculation unit. The sum of the values ​​of each pixel in the frequency spectrum map calculated by the sum calculation units 13 and 23 is This is a high-frequency component index that shows the total amount of high-frequency components in the frequency spectrum map.

[0024] The sum calculation unit 13 calculates based on the frequency spectrum output from the discrete Fourier transform unit 11. It functions as a first high-frequency component index generation unit that generates a high-frequency component index (first high-frequency component index). The summation unit 23 calculates based on the frequency spectrum output from the discrete Fourier transform unit 21. As a second high-frequency component index generation unit that generates a high-frequency component index (second high-frequency component index), It works.

[0025] While it is not essential to provide weighting calculation units 12 and 22, it is preferable to do so. When weighting calculation units 12 and 22 are provided, the sum calculation units 13 and 23 are dominated by high-frequency components. Since the high-frequency component index is generated based on a frequency spectrum map that has been processed in such a way, The high-frequency enhancement circuit 30 makes it easier to determine the degree to which the high-frequency components of the input image signal are enhanced.

[0026] The high-frequency component emphasis ratio calculation unit 4 calculates the high-frequency component index output from the summation calculation unit 13 and the summation calculation unit The high-frequency component emphasis ratio is calculated as the ratio to the high-frequency component index output from 23. The ratio calculation unit 4 outputs the high-frequency component index output from the sum calculation unit 23 from the sum calculation unit 13. It is best to calculate the high-frequency component emphasis ratio by dividing by the high-frequency component index. The high-frequency component emphasis ratio is The high-frequency enhancement circuit 30 enhances the high-frequency components of the input image signal. This shows the proportion of high-frequency components that have been increased by the enhancement. The high-frequency component enhancement ratio is controlled by the amount of enhancement. It will be supplied to the 5th division.

[0027] The enhancement control unit 5 receives the target enhancement ratio set by the user. The target enhancement ratio is, for example, The target enhancement ratio is 1.1. The target enhancement ratio of 1.1 means that the high-frequency enhancement circuit 30 enhances the high frequencies of the input image signal. This means that the component is emphasized by 1.1 times. The emphasis amount control unit 5 controls the high-frequency component emphasis ratio calculation unit 4. A control value for the amount of enhancement is generated based on the comparison result between the supplied high-frequency component enhancement ratio and the target enhancement ratio. The signal is then supplied to the high-frequency enhancement circuit 30.

[0028] Taking a target enhancement ratio of 1.1 as an example, the enhancement amount control unit 5 sets the high-frequency component enhancement ratio to the target enhancement ratio of 1. If the value is less than 1, the high-frequency enhancement circuit 30 controls the amount of emphasis on high-frequency components to increase. The emphasis control value is supplied to the high-frequency emphasis circuit 30. The circuit controls the emphasis amount of the high-frequency components to increase. The enhancement control value is, for example, a positive value that increases as the degree of enhancement increases. You should use this value.

[0029] The enhancement control unit 5, if the high-frequency component enhancement ratio is greater than the target enhancement ratio of 1.1, will activate the high-frequency enhancement circuit. The emphasis control value of the high-frequency emphasis circuit 30 controls the amount of emphasis of high-frequency components to decrease. It supplies to the following. The emphasis control value that controls the amount of emphasis on high-frequency components is, for example, It should be a negative value, where the smaller the value, the greater the degree of reduction.

[0030] If the emphasis control unit 5 matches the target emphasis ratio of 1.1, the emphasis control unit 5 will then activate the emphasis circuit 3. The high-frequency enhancement circuit 30 controls the enhancement amount so as not to change the amount of emphasis on high-frequency components when set to 0. It supplies power to the system. The emphasis control value, which controls the amount of emphasis on high-frequency components so as not to change, is set to, for example, 0. That's all you need to do.

[0031] The high-frequency enhancement circuit 30 controls the input image according to the enhancement amount control value supplied from the enhancement amount control unit 5. The amount of emphasis on the high-frequency components of the signal is controlled. The high-frequency emphasis circuit 30 enhances the output of the signal. The force image signal is input to the Discrete Fourier Transform unit 21. Therefore, the high-frequency enhancement control device 10 1 is the amount of high-frequency component emphasis by the high-frequency emphasis circuit 30, which is set by the user in the emphasis amount control unit 5. It includes a feedback control loop that automatically controls the amount of enhancement to correspond to the target enhancement ratio.

[0032] The high-frequency enhancement circuit 30 automatically adjusts the amount of enhancement of high-frequency components to an amount equivalent to the target enhancement ratio. The controlled output image signal is supplied to and displayed on a liquid crystal panel (not shown). (Medical monitor) It may be equipped with an organic EL panel instead of an LCD panel, and any display panel can be used. good.

[0033] Figure 5 shows a schematic example of the high-frequency enhancement circuit 30. The high-frequency enhancement circuit 30 is a high-frequency enhancement circuit. It comprises a pass filter (HPF) 31, a coefficient multiplier 32, a delay unit 33, and an adder 34. The HPF31 extracts the high-frequency components of the input image signal. The coefficient multiplier32 then processes the extracted high-frequency components. The high-frequency components are emphasized by multiplying the low-frequency components by a coefficient. The delay element 33 is a combination of the HPF 31 and the coefficient multiplier. The input image signal is delayed for a time corresponding to the processing by 32. Adder 34 is a delay unit. The high-frequency component output from coefficient multiplier 32 is added to the input image signal delayed by 33. Then, it generates the output image signal.

[0034] The coefficient multiplier 32 controls the emphasis amount of the high-frequency components to increase the emphasis amount of the emphasis amount of the emphasis amount control unit 5. If a metering control value is supplied, the value of the coefficient multiplied by the high-frequency component is increased. Coefficient multiplier 32 The enhancement control unit 5 supplies an enhancement control value that controls the enhancement amount of high-frequency components to decrease. If so, the coefficient value is reduced. The coefficient multiplier 32 does not change the amount of emphasis on high-frequency components. If a controlled enhancement value is supplied, the coefficient value will not change.

[0035] The configuration example of the high-frequency enhancement circuit 30 shown in Figure 5 is merely one example, and the high-frequency enhancement circuit 30 is input Any configuration is acceptable as long as it emphasizes the high-frequency components of the image signal. The high-frequency enhancement circuit 30 is: This circuit may also be called an edge enhancement circuit, a contour correction circuit, or an enhancer.

[0036] According to the high-frequency enhancement control device 101 described above, the high-frequency components of the image are automatically enhanced to an appropriate level. It can be emphasized through metering.

[0037] In the high-frequency emphasis control device 101, the emphasis control unit 5 changes the emphasis control value in a short time. When this happens, the enhancement control value changes frequently around the target enhancement control value (target enhancement control value). A phenomenon called "moving hunting" can occur. To avoid the occurrence of hunting... Therefore, the enhancement control unit 5 generates and outputs a target enhancement control value in a feedback control loop. The system is configured to have a time constant and output the target enhancement control value after a predetermined time. That's good.

[0038] Figure 6 shows the state before the enhancement control unit 5 changes the enhancement control value, with the enhancement control value set to 0. This shows how the enhancement control value changes when it is changed to a predetermined target enhancement control value. As shown by the solid line, reducing the time constant allows the target enhancement control value to be reached in a short time. As shown, setting the time constant to a moderate level allows for target emphasis over a longer period than when the time constant is small. This becomes the quantity control value. As shown by the dashed line, increasing the time constant allows for long-term control of the target enhancement amount. The value is determined. The enhancement control unit 5 changes the enhancement control value by setting a predetermined time constant.

[0039] The enhancement amount control unit 5 generates and outputs an enhancement amount control value, and the feedback control loop is hiss It may also have hysteresis properties. Figure 7 shows an example of hysteresis properties. Feedback By incorporating hysteresis characteristics into the control loop, the occurrence of hunting can be avoided. It is possible.

[0040] As shown in Figure 7, when the high-frequency component emphasis ratio initially increases in the positive direction from 0, The metering control unit 5 sequentially increases the emphasis control value as shown by the dashed line. When the high-frequency component emphasis ratio decreases after reaching the maximum value, the emphasis control unit 5 adjusts the emphasis control value to the maximum value If the high value is maintained for a while and the high-frequency component emphasis ratio decreases further, the emphasis control value will be gradually reduced. The emphasis control value reaches its minimum, and then when the high-frequency component emphasis ratio increases, the emphasis control Section 5 maintains the minimum value of the emphasis control value for a while, and when the high-frequency component emphasis ratio increases further, The emphasis control value is increased sequentially.

[0041] In this manner, the emphasis control unit 5 controls the emphasis at a predetermined time constant to avoid hunting. Either change the meter control value, or change the emphasis control value according to a predetermined hysteresis characteristic. It is preferable.

[0042] <Second Embodiment> Figure 8 shows an example of a medical image displayed on a medical monitor by a DICOM viewer. Yes. When a medical image is displayed on a medical monitor using a DICOM viewer, the medical monitor will display... In addition to medical images, graphical user interface images such as window frames and menus are also included. (The GUI image below is displayed.) Since the GUI image is a geometric shape, steep edges It contains many high-frequency components. Therefore, when a medical image like the one shown in Figure 8 is input as an image signal, Furthermore, the high-frequency enhancement circuit 30 enhances the high-frequency components of the input image signal to produce the output image signal. Therefore, the frequency spectrum map will contain many high-frequency components originating from the GUI image.

[0043] Even though the original medical image does not contain many high-frequency components, the high-frequency component index If this value becomes too large, the high-frequency component enhancement ratio will not reflect the ratio of high-frequency components in the original medical image. The emphasis control value may not be an appropriate value. High-frequency emphasis amount of the second embodiment shown in Figure 9 The control device 102 can also perform appropriate actions even if the input image signal contains high-frequency components originating from the GUI image. It is configured to generate a value for controlling the amount of emphasis of the value. In Figure 9, the same part as in Figure 1 is the same A symbol may be added, and its explanation may be omitted.

[0044] GUI images are often composed of a combination of horizontal and vertical lines, while medical images are natural Since it is a drawing, it contains almost no horizontal or vertical lines. Therefore, it is included in the frequency spectrum map. The horizontal and vertical frequency components present are mostly unwanted high-frequency components originating from the GUI image. ru.

[0045] In Figure 9, horizontal and vertical frequency component removal units 14 and 24 (first and second horizontal and vertical The frequency component removal unit respectively processes the frequency components output from the weighting calculation units 12 and 22. Removes horizontal and vertical frequency components from the vector map. Horizontal / Vertical Frequency Component Removal Unit 1 4 and 24 are cross-shaped in the frequency spectrum map, removing horizontal and vertical frequency components. Multiply by the filter.

[0046] Figure 10A shows the frequency spectrum map output from the weighting calculation unit 12. Figure 10B shows the frequency spectrum map output from the horizontal / vertical frequency component removal unit 14. This shows that the horizontal and vertical frequency components are removed by the cross-shaped filter of the horizontal and vertical frequency component removal unit 14. The direct frequency component has been removed. Figure 11A shows the frequency output from the weighting calculation unit 22. The spectral map is shown. Figure 11B shows the output from the horizontal / vertical frequency component removal unit 24. The frequency spectrum map is shown. Cross-shaped horizontal / vertical frequency component removal section 24. The horizontal and vertical frequency components are removed by the filter.

[0047] In Figure 9, the horizontal and vertical frequency component removal units 14 and 24 are connected to the weighting calculation unit 12 and Although it is located after the 22 stage, it may also be located before the weighting calculation units 12 and 22. The functions of the horizontal and vertical frequency component removal units 14 and 24 are provided in the weighting calculation units 12 and 22. Alternatively, the weighting calculation units 12 and 22 may perform the discrete Fourier transform on the discrete Fourier transform units 11 and 21. The resulting frequency spectrum is then filtered using the inverted cone-shaped filter and the cross-shaped filter shown in Figure 2. You can also multiply by a filter that is a multiplication of and .

[0048] According to the high-frequency enhancement control device 102 described above, the high-frequency components of the image are automatically enhanced to an appropriate level. It can be emphasized by adjustment. According to the high-frequency emphasis control device 102, the input image signal is high frequency Geometric shapes containing horizontal and vertical lines, such as GUI images, that should not be emphasized. When doing so, unwanted high-frequency components caused by geometric shapes are removed, and the high-frequency components of the image are appropriately processed. It can be emphasized with a moderate degree of emphasis.

[0049] In the high-frequency emphasis control device 102, the emphasis control unit 5 controls the emphasis amount at a predetermined time constant. It is good to change the amount of emphasis control value according to a predetermined hysteresis characteristic. good.

[0050] <Third Embodiment> The high-frequency emphasis control device 103 of the third embodiment shown in Figure 12 is the same as the high-frequency emphasis control device of the second embodiment. In a different manner from the control device 102, the input image signal contains high-frequency components originating from the GUI image. However, it is configured to generate an appropriate emphasis control value. In Figure 12, Figure 1 Parts identical to those of the same character are given the same reference numeral, and their explanations may be omitted.

[0051] As shown in Figure 8, GUI images are placed at the top / bottom or left / right edges of the frame, and medical images It is often located in the center of the frame. Therefore, as shown in Figure 12, high frequency The metering control device 103 has a trimming unit 10 and a preceding discrete Fourier transform unit 11 and 21. It comprises 20 (first and second trimming sections).

[0052] The trimming unit 10 removes the top, bottom, left, and right edges of each frame in the input image signal. The central part is cropped. The cropping unit 20 processes each part of the output image signal. Trim the frame by removing the top, bottom, left, and right edges, leaving the central portion. The regions from which the input image signal and output image signal are extracted by the 10 and 20 sections are the same. The extent to which the trimming sections 10 and 20 extend horizontally and vertically from the center of each frame. You can set whether to crop the area to the center as needed.

[0053] The discrete Fourier transform units 11 and 21 are trimmed by the trimming units 10 and 20. The central image signal of each frame is subjected to a two-dimensional discrete Fourier transform. Therefore, the discrete Fourier transform is performed. The frequency spectra output from the E conversion units 11 and 21 are GUI images (geometric shapes). It contains almost no unwanted high-frequency components caused by ).

[0054] According to the high-frequency enhancement control device 103, the high-frequency components of the image are automatically enhanced by an appropriate amount. This allows for the removal of unwanted high-frequency components caused by geometric shapes, thereby reducing the high-frequency components of the image. It can be emphasized with an appropriate level of emphasis.

[0055] In the high-frequency enhancement control device 103, the enhancement control unit 5 controls the enhancement amount at a predetermined time constant. It is good to change the amount of emphasis control value according to a predetermined hysteresis characteristic. good.

[0056] The present invention is not limited to the first to third embodiments described above, and the gist of the present invention is as follows: Various modifications are possible as long as they do not deviate from the norm. [Explanation of Symbols]

[0057] 4. High-frequency component emphasis ratio calculation section 5. Enhancement Control Unit 10,20 Trimming section 11,21 Discrete Fourier Transform section 12,22 Weighting calculation unit 13,23 Sum Calculation Unit 14,24 Horizontal and Vertical Frequency Component Removal Section 30. High-frequency enhancement circuit 101, 102, 103 High-frequency emphasis control device

Claims

[Claim 1] The first method generates a first frequency spectrum by performing a two-dimensional discrete Fourier transform on the input image signal. The discrete Fourier transform part of and The output image signal from the high-frequency enhancement circuit is subjected to a two-dimensional discrete Fourier transform to obtain the second frequency. A second discrete Fourier transform unit that generates a number spectrum, Based on the first frequency spectrum, a first high-frequency component index indicating the total amount of high-frequency components is obtained. The first high-frequency component index generation unit generates, Based on the second frequency spectrum, a second high-frequency component index is used to indicate the total amount of high-frequency components. The second high-frequency component index generation unit generates, The high-frequency component emphasis ratio, which is the ratio of the first high-frequency component index to the second high-frequency component index, is calculated. A high-frequency component enhancement ratio calculation unit, The amount of emphasis control value corresponding to the comparison result between the aforementioned high-frequency component emphasis ratio and the target emphasis ratio is the high-frequency emphasis rate. A control unit for supplying the amount of enhancement to the path, A high-frequency enhancement control device equipped with the following features.

Images