JP2002281271A - Image processing method and image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always display an image in a suitable state even if the display area of an original image is changed in an image processor. SOLUTION: When the image is displayed, at display area setting means 11a sets an area where display in the original image is desired. An image processing condition setting means 12a calculates the area of the display area. A multiplier value adjusting the inclination of a reference gradation correction curve G based on a ratio between the area of the display area and that of the original image is decided. The reference gradation correction curve G is rotated on a point Gc on the curve based on the multiplier value, the inclination of the reference gradation correction curve G is adjusted and a gradation correction curve G' applied when the display area is displayed is generated. An image processing means 13a performs a gradation processing based on the gradation correction curve G' and data is outputted to a display means 20a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus for displaying an image of a display area, which is a partial area on an original image, by using an image signal representing the image of the display area. The present invention relates to an image processing method and apparatus for performing processing.

[0002]

2. Description of the Related Art Radiation (X-ray, α-ray,
(β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is accumulated, and then, when irradiated with excitation light such as visible light, stimulable fluorescence that shows stimulated emission according to the accumulated energy Using a body (stimulable phosphor), a radiation image of a subject such as a human body is once photographed and recorded on a sheet-shaped stimulable phosphor, and the stimulable phosphor sheet is scanned with excitation light such as laser light. The photostimulated emission light is photoelectrically read to obtain an image signal, and a radiation image of the subject is output as a visible image on a photosensitive film or a monitor based on the image signal. A radiographic image recording / reproducing system for displaying images has been proposed.
-12429).

In the above-described system, when each photographed image is output as a visible image, gradation processing for correcting an image signal value is performed so as to output a visible image having appropriate density and contrast. In this gradation processing, for example, a plurality of gradation processing characteristics (signal conversion characteristics), for example, a plurality of gradation correction curves according to the type of the photographing object (subject) and the photographing purpose are prepared, and the prepared gradation is prepared. An optimal gradation correction curve is selected from the correction curves according to the photographing target and the photographing purpose of each photographing, and the correction is performed based on the selected gradation correction curve, or one of the axes of the rectangular coordinates is used. A reference gradation correction curve is set in a coordinate system in which the level of the image signal before conversion is set on the other axis and the level of the image signal after conversion is set on the other axis. By rotating and / or moving in parallel about one point, a gradation correction curve corresponding to a photographing target and a photographing purpose is obtained, and the correction is performed based on the gradation correction curve.

In the above system, in order to improve the diagnostic performance of a radiographic image, a frequency enhancement process or a dynamic range compression process using an unsharp mask image signal (hereinafter referred to as a blur image signal) is performed on the image signal. (JP-A-55-163472, JP-A-55-87953, JP-A-3-222577, JP-A-10-75395, JP-A-10-75364, JP-A-10-1
71983). For example, in the frequency emphasis processing, a predetermined spatial frequency component of the original image signal is enhanced by adding a value obtained by subtracting the blurred image signal Sus from the original image signal Sorg and an enhancement coefficient β to the original image signal Sorg. Is what you do. This can be expressed by the following equation (1).

Sproc = Sorg + β × (Sorg−Sus) (1) (Sproc: signal subjected to frequency emphasis processing, Sorg: original image signal, Sus: blurred image signal, β: emphasis coefficient) A frequency emphasis processing method in which the value of the emphasis coefficient β is negative has also been proposed by the present applicant (Japanese Patent Laid-Open No.
1-106277, 1-239681). Thus, the enhancement coefficient β
By setting the value of to be negative, high frequency noise can be removed from the original image.

As described above, when outputting a visible image based on an image signal generally obtained, the image signal is subjected to various types of image processing and then output as a visible image. Further, when such a visible image is output, not only the case where the entire original image is output as a visible image, but also the case where only an image of a partial region in the original image is output as a visible image is often present. When only an image of a partial area in the original image is output as a visible image, the image signal representing the image of the partial area is output after performing various image processing. Conventionally, the image processing conditions usually set based on the original image,
For example, in the case of gradation processing, image processing is performed based on the gradation processing characteristics, and in the case of frequency processing, image processing is performed based on the degree of frequency emphasis.
That is, for a certain original image, image processing conditions are set based on the original image, and whether to output the entire original image as a visible image or to output an image of a partial area as a visible image is determined. Instead, the image processing is performed according to image processing conditions set based on the original image, and then output as a visible image.

[0007]

However, under the image processing conditions set on the basis of the above-mentioned original image, it may be possible to output the entire original image as an appropriate visible image. When only an image of a partial region of an image is output as a visible image, the visible image cannot always be displayed in an appropriate state.

For example, when a partial area of an original image is used as a display area, and an image in this display area is enlarged and displayed on a display screen of a monitor, if the enlargement ratio becomes large, that is, the size of the display area on the original image Is smaller, a blurred image may be displayed even when image processing is performed under image processing conditions set based on the original image.

Further, since the display area is a partial area on the original image, the maximum value and the minimum value of the image signal value representing the image of the display area are equal to the maximum value and the minimum value of the image signal value representing the original image. Or the position of the display area is different, the maximum value and the minimum value of the image signal value representing those images are different for each display area, and as a result, the image processing is performed under the image processing conditions set based on the original image. However, a visible image cannot always be displayed in an appropriate state.

The present invention has been made in view of the above-mentioned problems of the prior art, and when an image of a display area, which is a partial area on an original image, is displayed as a visible image, the image of the display area is used as a visible image. It is an object of the present invention to provide an image processing method and apparatus for performing image processing so that an image can be appropriately displayed.

[0011]

An image processing method according to the present invention performs image processing on an image signal representing an image of a display area to display an image of the display area which is a partial area on an original image. An image processing method to be performed, wherein image processing conditions are set based on information about a display area, and image processing is performed on an image signal representing an image of the display area based on the set image processing conditions. Is what you do.

An image processing apparatus according to the present invention is an image processing apparatus that performs image processing on an image signal representing an image of a display area in order to display an image of a display area which is a partial area on an original image. Image processing condition setting means for setting image processing conditions based on information about the display area; and performing image processing on an image signal representing an image of the display area based on the image processing conditions set by the image processing condition setting means. And an image processing means for performing the image processing.

Here, "image processing" means processing such as gradation processing and frequency emphasis processing performed on an image signal representing an image in a display area in order to appropriately display a display image.

[0014] "Information on the display area" means various information related to the display area, such as the size of the display area or an image signal representing an image of the display area.

Further, the image processing apparatus according to the present invention includes a display area setting means for setting a display area on the original image, and the image processing condition setting means sets the display area every time a different display area is set by the display area setting means. Automatically setting an image processing condition based on the information about the display area, and each time the image processing condition is set by the image processing condition setting means, the image processing means sets an image of the display area based on the image processing condition. May be subjected to image processing.

In the image processing apparatus according to the present invention, the image processing condition setting means sets a gradation processing characteristic based on a ratio between the size of the original image and the size of the display area. The means may perform gradation processing on an image signal representing an image in the display area based on the gradation processing characteristics set by the image processing condition setting means.

Here, "size" refers to various types of the size of the original image and the display area, such as the length in the vertical direction, the length or the area in the horizontal direction, or the length of the diagonal line of the original image and the display area. Mean value.

The image processing condition setting means may set a gradation processing characteristic based on a maximum value and a minimum value of an image signal value representing an image in the display area.
Tone processing may be performed on an image signal representing an image of the display area based on the tone processing characteristics set by the image processing condition setting means.

Further, the image processing condition setting means sets the frequency emphasis degree based on a ratio between the size of the original image and the size of the display area.
A frequency emphasis process may be performed on an image signal representing an image of the display area based on the frequency emphasis degree set by the image processing condition setting means.

[0020]

The image processing method and apparatus according to the present invention configured as described above perform image processing by setting image processing conditions in accordance with changes in the display area on the original image. The image of the display area can always be displayed with a suitable image quality even when the display area changes due to the change of the parameter, or when the position of the display area on the original image is changed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the image processing apparatus according to the present invention will be described. FIG. 1 is a block diagram of the image processing apparatus according to the first embodiment, and FIG. 2 is a diagram of a gradation correction curve representing characteristics of an output signal with respect to an input signal. In the description of the present embodiment, an image processing apparatus that performs gradation processing will be described as an example of the image processing apparatus according to the present invention.

Image processing apparatus 10a according to the present embodiment
Is a display area setting means 11a for setting a display area (a partial area on the original image) on an original image to be displayed, and an image processing condition setting for setting an image processing condition based on information on the set display area. Means 12a, and image processing means 13a for performing image processing on an image signal representing an image in the display area based on the set image processing conditions.
0a.

The display area setting means 11a sets a range of an area to be displayed as a display area on the basis of a predetermined point with respect to the original image. Usually, it is based on the upper left point of the original image,
Any reference may be used.

Further, the display area setting means 11a includes an input device such as a keyboard and a mouse, not shown, for changing the position of the display area on the original image in accordance with a command input from the user via the input device. It has functions to perform processing such as changing the display magnification of the original image (enlargement / reduction processing of the image) and changing the size of the display area. With these functions, the display area in the original image is changed and a new display area Can be set. A detailed description of these functions is omitted because it is a technique generally used in image processing software and the like currently in practical use.

The image processing condition setting means 12a obtains the area of the display area set by the display area setting means 11a, and, based on the ratio between the area of the original image and the area of the display area,
A multiplier value for adjusting the slope of the reference tone correction curve G when performing the tone processing is determined, and the slope of the reference tone correction curve G is adjusted in accordance with the multiplier value, so that the tone correction curve G for the display area is determined. ´
(Image processing conditions) is set.

Here, instead of the ratio of the area of the display area to the area of the original image, the ratio of the vertical length of the display area to the vertical length of the original image or the horizontal length of the display area to the original image is calculated. The multiplier value may be determined based on either the ratio to the horizontal length of the image.

That is, the multiplier value can be determined based on the size ratio between the original image and the display area, such as the area between the original image and the display area, the ratio of the vertical length or the horizontal length.

The multiplier value may be determined using a table in which the ratio between the size of the display area and the original image and the multiplier value for adjusting the slope of the reference gradation correction curve G are associated with each other, Alternatively, it may be determined using a function such as the equation (2).

F (multiplier value) = (preset value) −ratio × (preset value−1) (2) This function sets the multiplier value to 1 as the ratio of the size of the display area to the size of the original image approaches 1. As the ratio approaches, the multiplier value approaches a predetermined preset value as the ratio approaches 0, but any other function may be used.

As shown in FIG. 2, based on the multiplier value obtained by the above table or function, the reference gradation correction curve G is rotated by an angle according to the multiplier value with the point Gc above it as the center of rotation. Thus, the inclination of the reference gradation correction curve G is adjusted, and the gradation correction curve G ′ applied to the gradation processing when displaying the image in the display area is set. The rotation center point Gc may be set in advance, or may be set according to the gradation range of the display area.

The image processing means 13a, based on the gradation correction curve set by the image processing condition setting means 12a,
A gradation process is performed on an image signal representing an image in the display area.

As a display means 20a for displaying an image processed by the image processing apparatus 10a, a monitor is usually used, but it may be output to any device such as a printer.

Next, the operation of the image processing apparatus according to the present embodiment configured as described above will be described.

With respect to the original image input to the image processing apparatus 10a, the display area setting means 11a sets a displayable area on the display means 20 based on the upper left point of the original image as a display area. Here, the size of the original image is
If the size of the original image is smaller than the size that can be displayed, the entire original image is set as the display area.

The image processing condition setting means 12a acquires area information of the display area set by the display area setting means 11a, and sets a multiplier based on the ratio of the area of the display area to the area of the original image. A gradation correction curve G 'is set based on the multiplier value.

The image processing means 13a performs gradation processing based on the gradation correction curve G 'set by the image processing condition setting means 12a, and outputs the result to the display means 20a.

When the user inputs a command to enlarge the original image using the input device, the display area setting means 11a
The original image is enlarged based on the command, and a size that can be displayed on the display means 20 is set as a display area based on the upper left point of the enlarged original image.

Here, when a command to change the position or size of the display area on the original image is input instead of the enlargement processing on the original image, the area desired by the user to be displayed based on the input command. Is set as the display area.

When the display area is changed by the display area setting means 11a, the area of the display area is newly calculated by the image processing condition setting means 12a, and based on the ratio between the area of the display area and the area of the original image. A multiplier value is set, and a gradation correction curve G 'is set based on the multiplier value.
At 3a, gradation processing is performed based on the gradation correction curve G 'set by the image processing condition setting means 12a, and output to the display means 20a.

According to the image processing apparatus of the present invention configured as described above, it is possible to perform gradation processing according to the display area on the original image, so that a suitable image can always be displayed. It is possible.

Next, a second embodiment of the present invention will be described. This embodiment is obtained by changing the method of generating the gradation correction curve in the first embodiment. Since the basic configuration of the device is the same as that of the first embodiment shown in FIG. 1, in this embodiment, a number is used in which the number a at the end of the number in FIG. Will be explained. Also,
Except for the method of generating the gradation correction curve, the configuration and operation of the first embodiment are the same as those of the first embodiment. FIG. 3 is a diagram of a gradation correction curve representing characteristics of an output signal with respect to an input signal.

The image processing apparatus 10b includes a display area setting means 11b for setting a display area on an original image to be displayed.
Image processing condition setting means 12b for setting image processing conditions based on information on the set display area; and image processing for performing image processing on an image signal representing an image of the display area based on the set image processing conditions A display device 20b for displaying an image is connected to the image processing device 10b.

In the present embodiment, the image processing condition setting means 12b obtains the maximum value and the minimum value of the image signal value representing the image in the display area set by the display area setting means 11b, and obtains the obtained display area. A tone correction curve is generated based on the maximum value and the minimum value of the image signal values in the image data.

The method of generating the gradation correction curve G 'is, for example, as shown in FIG. 3, the maximum value Sin of the image signal value in the display area.
max is the maximum density value of the desired display density range, for example, the image signal value Sout max corresponding to the maximum displayable density value.
The minimum value Sin min of the image signal value in the display area is set to the minimum density value of the desired display density range, for example, the image signal value Sout min corresponding to the minimum displayable density value, and the characteristic between the two is linear. Set as a characteristic.

In addition to the above method, the maximum value and the minimum value of the image signal value in the display area are image signal values corresponding to arbitrary displayable density values. It is also possible to set a gradation correction curve as a characteristic.

In the image processing apparatus according to the present invention configured as described above, since gradation processing can be performed according to the display area on the original image, a suitable image can always be displayed. It is.

Next, a third embodiment of the present invention will be described. This embodiment is obtained by changing the gradation processing to the frequency emphasizing processing in the first embodiment. In addition,
Since the basic configuration of the apparatus is the same as that of the first embodiment shown in FIG. 1, in the present embodiment, the description will be made using the number in which the letter a at the end of the number in the figure is changed to c. Since the configuration and operation of the first embodiment are the same as those of the first embodiment except that the gradation processing is changed to the frequency processing, the description thereof will be omitted unless particularly necessary.

The image processing apparatus 10c includes a display area setting means 11c for setting a display area on an original image to be displayed.
Image processing condition setting means 12c for setting an image processing condition based on information on the set display area; and image processing for performing image processing on an image signal representing an image of the display area based on the set image processing condition A display device 20c for displaying an image is connected to the image processing device 10c.

The image processing condition setting means 12c obtains the area of the display area set by the display area setting means 11c, and calculates the area based on the ratio between the area of the original image and the area of the display area.
The frequency emphasis coefficient β representing the frequency emphasis degree in the frequency processing of the equation (1) is determined.

Here, instead of the ratio of the area of the display area to the area of the original image, the ratio of the vertical length of the display area to the vertical length of the original image or the horizontal length of the display area and the original The multiplier value may be determined based on either the ratio to the horizontal length of the image.

That is, the multiplier value can be determined based on the size ratio between the original image and the display area, such as the area between the original image and the display area, the ratio of the vertical length or the horizontal length.

The emphasis coefficient β may be determined using a table in which the size ratio between the display area and the original image and the emphasis coefficient β are described in association with each other, or, for example, as shown in equation (3). The determination may be made using a function.

Β (emphasis coefficient) = (preset value) −ratio × (preset value−1) (3) This function sets the emphasis coefficient β to 1 as the ratio of the size of the display area to the size of the original image approaches 1. And the enhancement coefficient β approaches a predetermined preset value as the ratio approaches 0, but any other function may be used.

In the image processing apparatus according to the present invention configured as described above, since gradation processing can be performed according to the display area on the original image, a suitable image can always be displayed. It is.

Further, the image processing apparatus according to the present invention can perform both gradation processing and frequency processing on the same image.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image processing apparatus according to a first embodiment.

FIG. 2 is a diagram of a gradation correction curve according to the first embodiment.

FIG. 3 is a diagram of a gradation correction curve according to a second embodiment.

[Explanation of symbols]

 10a, 10b, 10c Image processing device 11a, 11b, 11c Display area setting means 12a, 12b, 12c Image processing condition setting means 13a, 13b, 13c Image processing means 20a, 20b, 20c Display device

Continued on the front page F-term (reference) 5B057 AA08 BA03 BA29 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB16 CC03 CE03 CE11 DA17 DB02 DB05 DB09 DC22 5C076 AA17 AA21 AA27 BA06 CA01 CA02 CB01 5C077 LL19 MP01 NN03 PP03 BA15 A30 CA34 CA54 CA81 CB01 MM10

Claims (6)

[Claims] 1. An image processing method for performing image processing on an image signal representing an image of a display area in order to display an image of a display area which is a partial area on an original image, the image processing method comprising: An image processing method comprising: setting an image processing condition based on information; and performing image processing on an image signal representing an image of the display area based on the set image processing condition. 2. An image processing apparatus for performing image processing on an image signal representing an image of a display area in order to display an image of a display area which is a partial area on an original image, the image processing apparatus comprising: Image processing condition setting means for setting image processing conditions based on information; image processing for performing image processing on an image signal representing the image of the display area based on the image processing conditions set by the image processing condition setting means And an image processing apparatus. 3. A display area setting means for setting the display area on the original image, wherein the image processing condition setting means sets the display area each time a different display area is set by the display area setting means. Automatically setting an image processing condition based on the information about the image processing unit, wherein the image processing unit sets the image of the display area based on the image processing condition each time the image processing condition is set by the image processing condition setting unit. 3. The image processing apparatus according to claim 2, wherein image processing is performed on the represented image signal. 4. The image processing condition setting means sets a gradation processing characteristic based on a ratio between a size of the original image and a size of the display area. 4. The image processing apparatus according to claim 2, wherein a gradation process is performed on an image signal representing an image of the display area based on a gradation processing characteristic set by a condition setting unit. 5. The image processing condition setting means for setting a gradation processing characteristic based on a maximum value and a minimum value of an image signal value representing an image of the display area, wherein the image processing means comprises: 4. The image processing apparatus according to claim 2, wherein a gradation process is performed on an image signal representing an image of the display area based on a gradation processing characteristic set by an image processing condition setting unit. . 6. The image processing condition setting means sets a frequency emphasis degree based on a ratio between a size of the original image and a size of the display area. 4. The image processing apparatus according to claim 2, wherein a frequency enhancement process is performed on an image signal representing an image of the display area based on the frequency enhancement degree set by the setting unit.