JPH07101446B2 - Image rollover determination method - Google Patents

Description

The present invention relates to a method for determining whether the orientation of an image formed by an image signal carrying image information of a human body is normal or overturned.

(Prior Art) In an X-ray tomography apparatus, an ultrasonic diagnostic apparatus, or the like, an image signal that carries image information of a human body is obtained, and various algorithms relating to image processing are applied to this image signal, or the image signal is easily viewed. Displaying has been performed conventionally. The applicant has also applied radiation (X-ray,
When irradiated with α rays, β rays, γ rays, electron rays, ultraviolet rays, etc.,
A part of this radiation energy is accumulated in the phosphor, and when irradiated with excitation light such as visible light after that, the phosphor exhibits stimulated emission according to the accumulated energy,
The radiation image information of the human body is once recorded on a sheet-shaped stimulable phosphor, and then this stimulable phosphor sheet is scanned with excitation light such as laser light to generate stimulated emission light. To obtain an image signal by photoelectrically reading the image signal, perform image processing on the image signal, and then, based on the image signal subjected to the image processing, a radiation image of a subject is recorded on a recording material such as a photographic photosensitive material or a display device such as a CRT. A radiation image information recording / reproducing apparatus for outputting as a visible image has already been proposed (Japanese Patent Laid-Open No. 55-55).
(-12429, No. 56-11395, etc.) Normally, in such a device, the relative positional relationship between the device and the human body is determined at the time of shooting, and image processing is performed on the image signal, or When displaying an image signal, the image signal was handled as being photographed in the above-mentioned determined positional relationship. In the above device proposed by the applicant,
For example, when recording (photographing) radiation image information of the chest, neck, etc. of a human body on a stimulable phosphor sheet, it is usually performed such that the longitudinal direction of the sheet is the vertical direction of the human body, and then the image is taken from the sheet. Even after the signal is read, the image formed by the image signal is handled such that the vertical direction of the sheet is the vertical direction of the image.

However, in some cases, the image is taken with the sheet oriented horizontally, that is, with the vertical direction of the sheet being the left-right direction of the human body. In that case, the image signal is read after the image signal is read. In the image displayed, the vertical direction of the image is the left-right direction of the human body.

(Problems to be Solved by the Invention) However, imaging is usually performed in a predetermined positional relationship as described above, and for example, the image processing is performed on the assumption that the vertical direction of the image is the vertical direction of the human body. Since various algorithms are set or the output process is set to output the visible image in a viewable manner in which the vertical direction of the visible image is the vertical direction of the human body, different from the above direction, for example, When the vertical direction is the horizontal direction of the human body, the fact is input to the image processing means or the image reproducing means to change the image processing algorithm, or the vertical direction in the visible image becomes the vertical direction of the human body. It is necessary to change the output process, which requires the image to be in the normal position (for example, the vertical direction of the image as described above should match the vertical direction of the human body). It is necessary to determine whether it is the normal position) or the roll position rotated 90 ° from the normal position.

In view of the above circumstances, an object of the present invention is to provide an image rollover judging method capable of judging whether the image is in a normal position or a rollover position.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an image rollover judging method according to the present invention includes a vertical direction and a horizontal direction from an image signal carrying image information of a human body, including a central portion of the image. Each of the characteristic values representing the level of the image signal magnitude of the strip-shaped region extending in the direction is obtained, the magnitudes of these characteristic values are compared, and based on the comparison result, preset according to the magnitude of the characteristic value. It is characterized by determining whether it is a normal position or a rollover position.

Here, the characteristic value representing the level of the magnitude of the image signal is 2
It means a value representing the overall signal level of the image signal in one band-shaped area, and specifically, for example, an average value or a total value of the signal levels can be adopted. Then, by comparing the magnitudes of this level, it is possible to stably determine the rollover of the image. Whether or not the image is overturned can be determined by comparing the magnitude of these characteristic values depending on which is larger, but the relationship between the magnitude and the normal position or the lateral dislocation placement is Since it depends on the type of image (region, etc.), it is necessary to set in advance the relationship between the size and the position in accordance with the type of image.

(Function) The human body is composed of various bones, muscles, and other organs, and the degree of transmission or reflection of radiation, ultrasonic waves, and the like varies depending on the organ. For example, bones that normally extend in the vertical direction of the human body generally have a property of being less likely to transmit radiation than other parts of the human body. Further, the radiation transmitted through the human body is weakened by the human body as compared with the radiation not transmitted through the surrounding human body. In addition, these images are often left-right objects (or up-down objects when the images are laid down) because the human body is left-right objects.

Therefore, in these cases, including the central part of the image,
When the characteristic values representing the level of the image signal magnitude of the strip-shaped regions extending in the vertical direction and the horizontal direction, respectively, are obtained, the characteristic values have a clear difference, and on the basis of this difference, the image depends on the magnitude of the characteristic value. It is possible to determine whether it is a preset normal position or a rollover position rotated by 90 ° from the normal position.

(Examples) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining an embodiment in which the present invention is applied to a radiographic image centered on the neck of a human body obtained by the radiographic image recording / reproducing apparatus proposed by the present applicant, using the total value as a characteristic value. It is a figure. The image 1 of the human body in this image is a portion where the radiation is absorbed by the human body and weakened as compared with the surrounding area 2. Therefore, if the image signal is formed so that the level of the image signal carrying the image information and the dose of the radiation applied to the stimulable phosphor sheet are proportional, the image signal level corresponding to the image 1 of the human body is It is lower than the image signal level corresponding to the surrounding area 2. Comparing the total values of the image signal levels of the strip-shaped regions 3 and 4 here, the strip-shaped region 3 contains a large amount of the human body image 1 and the peripheral region 2 contains only a small amount thereof, while the strip-shaped region 4 contains Since the surrounding area 2 is included in a large amount and the human body image 1 is included in a small amount, when the strip-shaped areas 3 and 4 have substantially the same area (number of pixels), the respective total values of the image signal levels are
The total value corresponding to the strip-shaped region 4 is larger than the total value corresponding to the strip-shaped region 3. Therefore, comparing each sum,
If the area corresponding to the larger value is the area extending in the left-right direction, the image is in the normal position, and if the area corresponding to the larger value is the area extending in the up-down direction, the image is in the horizontal position. Can be determined to be.

When the total value is used as the characteristic value as described above, it is preferable to make the areas of the strip-shaped regions extending vertically and horizontally substantially equal to each other. However, even if the area is different depending on the part of the human body to be imaged, etc. This does not apply when the size relationship of is stable.

FIG. 2 is an explanatory diagram for explaining an embodiment in which the present invention is applied to a radiation transmission image of a chest of a human body, and in this embodiment, an average value as a characteristic value of image signal levels extending in the vertical direction and the horizontal direction. Is used. The mediastinum 5, which extends vertically in the center, has many bones with low radiation transmittance. On the other hand, the lung field 6 has a higher radiation transmittance than the mediastinum 5 on average. Therefore, if the image signal is formed so that the amount of radiation transmitted through the human body is proportional to the image signal level, the image signal level of the mediastinum 5 is lower than the image signal level of the lung field 6 on average. Therefore, the average value of the image signal level of the zonal region 8 including a relatively large number of the lung fields 6 and a small number of the mediastinum 5 is the zonal shape having a relatively large number of the mediastinum 5 and a small number of the lung fields 6. It is larger than the average value of the image signal level of the area 7. Therefore, also in the case of this example, when the average value for the strip-shaped region extending in the left-right direction is larger than the average value for the strip-shaped region extending in the vertical direction, this image is in the normal position, and vice versa. When the average value for the strip-shaped region extending in the vertical direction is larger, it can be determined that the roll-over position is set.

The band-shaped regions 7 and 8 shown in FIG. 2 are the band-shaped regions shown in FIG.
Although the width is drawn narrower than 3 and 4, the width of this strip area depends on the part of the human body to be photographed, the relative size of the photographing screen and the part of the human body photographed, etc. It may be set in advance so that the difference between the values becomes the most stable and large.

Further, when the average value is adopted as the characteristic value, the areas of the strip-shaped regions extending in the vertical and horizontal directions may be different from each other, and the difference between the average values may be the most stable and large. The area should be set.

The characteristic values that can be adopted in the present invention are not limited to the total value and average value described in the above embodiments. Any characteristic value may be used as long as the characteristic value can be extracted from the image signals of the two strip-shaped areas and whether or not the image is overturned can be stably determined based on the extracted characteristic value. .

Further, the present invention is not limited to the parts described in the above embodiments, but is applied to all parts that can be stably determined whether or not the image is overturned based on the characteristic values of the image signal levels of the two strip-shaped areas. can do. Further, the application of the present invention is not limited to the radiation transmission image, and may be a radiation reflection image or an image obtained by irradiating the human body with ultrasonic waves, and by what means the image signal of the human body is obtained. It doesn't matter.

(Advantageous Effects of the Invention) An image rollover judging method according to the present invention obtains characteristic values representing the level of the image signal magnitude of a strip-shaped region including a central portion of the image and extending in the vertical direction and the horizontal direction,
The size of each characteristic value is compared, and based on the comparison result, it is determined whether the image is in the normal position or the overturned position set in advance according to the size of the characteristic value. , The width of each of the band-shaped regions is preset according to the relative size of the imaged part of the human body and the photographing screen, and which is the normal position based on the result of comparing the characteristic values. It is possible to easily and accurately determine whether the image is in the normal position or the rollover position by setting in advance whether or not the rollover position is the rollover position.

[Brief description of drawings]

FIG. 1 is an explanatory view for explaining an embodiment in which the present invention is applied to a radiation transmission image of a neck, and FIG. 2 is an explanatory view for explaining an embodiment in which the present invention is applied to a radiation transmission image of a chest. 1 ... Human body image, 2 ... Surrounding area 3,4,7,8 ... Strip area 5 ... Mediastinum, 6 ... Lung field

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Claims (3)

[Claims] 1. A characteristic value representing the magnitude level of an image signal of a strip-shaped region including a central portion of the image and extending in the vertical direction and the horizontal direction is obtained from the image signal carrying the image information of the human body, and the characteristic values are obtained. The size of the two characteristic values is compared, and based on the comparison result, it is determined whether the position is a normal position or a rollover position that is preset according to the size of the characteristic value. Judgment method. 2. The image rollover judging method according to claim 1, wherein the characteristic value is a total value, and the judgment is made depending on which of the total values is larger. 3. The image overturning determination method according to claim 1, wherein the characteristic value is an average value, and the determination is performed depending on which of the average values is larger.