JP3165461B2 - Image processing method, image reading method and image reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for scanning a recording medium on which an image is recorded with a light beam, and photoelectrically detecting a signal light generated from the scanned portion of the recording medium by a photodetector. TECHNICAL FIELD The present invention relates to an image processing method, an image reading method, and an image reproducing method in an image reading and reproducing system that obtains an image signal by performing image processing on the image signal and reproduces an image.

[0002]

2. Description of the Related Art In various fields, a recorded image is read, an image signal is obtained, and after the image signal is subjected to appropriate image processing, the image is reproduced and displayed. For example, an X-ray image is recorded using an X-ray film having a low gamma value designed to be compatible with the subsequent image processing, and the X-ray image is read from the film on which the X-ray image is recorded, and an electric signal ( After converting the image signal into an image signal and subjecting the image signal to image processing, the image signal is reproduced as a visible image in a copy photograph or the like, thereby obtaining a reproduced image having good image quality performance such as contrast, sharpness, and graininess. (See Japanese Patent Publication No. 61-5193).

[0003] Further, the applicant of the present invention has proposed that radiation (X-ray, α
Radiation, 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, the accumulated light shows stimulable emission according to the accumulated energy. Using stimulable phosphor (stimulable phosphor)
Radiation image information of a subject such as a human body is temporarily recorded on a sheet-shaped stimulable phosphor, and the stimulable phosphor sheet is scanned with excitation light such as laser light to generate stimulated emission light. A radiation image recording / reproducing system has already been proposed in which the emitted light is photoelectrically read to obtain an image signal, and based on the image signal, a radiation image of the subject is output as a visible image to a recording material such as a photographic photosensitive material or a CRT display device. (JP-A-55-12429, JP-A-56-11395, and JP-A-55-1)
63472, 56-104645, 55-116340, etc.).

[0004] This system has the practical advantage of being able to record images over a very wide radiation exposure area compared to conventional radiographic systems using silver halide photography. That is, in the case of the stimulable phosphor, it has been recognized that the amount of emitted light that is stimulated by excitation after accumulation is proportional to the radiation exposure amount over an extremely wide range. Even if fluctuates considerably, the amount of photostimulated light emitted from the stimulable phosphor sheet is read by the photoelectric conversion means with the reading gain set to an appropriate value and converted into an electric signal (image signal). By using this image signal to output a radiation image as a visible image on a recording material such as a photographic photosensitive material or a display device such as a CRT display device, a radiation image which is not affected by a change in radiation exposure amount can be obtained.

[0005] In the above system, before the image signal is obtained by reading under the optimum reading conditions in accordance with the dose of the radiation applied to the stimulable phosphor sheet or the like, the stimulable phosphor sheet is previously irradiated with a low-level light beam. Perform a pre-read to scan and read the outline of the radiation image recorded on this sheet, analyze the pre-read image signal obtained by this pre-read,
After that, there is a system configured to scan the sheet by irradiating the sheet with a high-level light beam and read the radiation image under optimum reading conditions to obtain an image signal to perform a main reading.

Here, the reading condition is a general term for various conditions that affect the relationship between the amount of stimulated emission light in reading and the output of the reading device. It means the scale factor or the power of the excitation light in reading.

[0007] The high level / low level of the light beam means the magnitude of the energy of the light beam applied per unit area of the sheet or the energy of the photostimulated light emitted from the sheet, respectively. When it depends on the wavelength of the light beam (has a wavelength sensitivity distribution), the weight of the energy of the light beam irradiated per unit area of the sheet is weighted by the wavelength sensitivity. In other words, the method of changing the level of the light beam includes a method of using light beams of different wavelengths, a method of changing the intensity of a light beam emitted from a laser light source or the like, and inserting and removing an ND filter or the like on an optical path of the light beam. Known methods such as a method of changing the intensity of the light beam, a method of changing the scanning density by changing the beam diameter of the light beam, and a method of changing the scanning speed The method of people can be used.

[0008] Regardless of whether the system performs the pre-reading or the system which does not perform the pre-reading, the obtained image signal (including the pre-reading image signal) is analyzed, and the optimum image when the image signal is subjected to the image processing is analyzed. In some systems, processing conditions are determined. Here, the image processing condition is a general term for various conditions when a process that affects the gradation and sensitivity of a reproduced image based on an image signal is performed on the image signal. The method for determining the optimum image processing conditions based on this image signal is not limited to a system using a stimulable phosphor sheet, and obtains an image signal from a radiation image recorded on a recording sheet such as a conventional X-ray film. It is also applied to the system.

[0009]

As described above, in a system for obtaining an image signal and obtaining a visible image based on the image signal as described above, the observation target area ranges from a low density area to a high density area. In cases such as when it is not clear which density range is to be observed, the image processed so that the high density range of the original image has a density suitable for observation and the low density range of the original image are observed. Both images and images that have been subjected to image processing so as to have a density suitable for the image are reproduced side by side.

However, when a plurality of images are arranged and reproduced, there is a problem that the size of each image is reduced and it is difficult to see.

Further, in order to widen the observation target density range in one image, the contrast between the high density range or the low density range or the whole image is reduced so as to narrow the difference between the maximum density and the minimum density, that is, the dynamic range. Have been.

For example, consider a case where a radiation image of a human spine as shown in FIG. 4 is recorded on a long stimulable phosphor sheet. As described above, the stimulable phosphor sheet can obtain a radiation image that is not affected by the fluctuation of the radiation exposure amount,
As in the image of the vertebral column, the head section A, the cervical vertebra section B, and the vertebral body section C are irradiated with the same radiation dose to the subject, but the portions having different radiation exposure doses to the stimulable phosphor sheet are integrated. Even when the stimulable phosphor sheet is recorded, it is possible to express the entire subject by performing gradation processing to reduce the contrast when performing image processing on the stimulable phosphor sheet.

However, when the contrast is lowered, there arises a problem that the fine structure in the region where the contrast is lowered becomes difficult to see.

Further, in the head section A, the cervical vertebra section B and the vertebral body section C shown in FIG. 4, if the contrast of one section is increased, the image of another section becomes difficult to see. For example, when reproducing the vertebral body section C as usual,
The cervical vertebra section B, which has more radiation exposure than the vertebral body section C, has a very high density, making it impossible to observe an image.

In order to solve this problem, according to the present applicant, a function f (Sus) (f ₁ ) that monotonically decreases as the value of the blur mask signal Sus in which the low spatial frequency component of the original image signal Sorg is emphasized increases. (Sus) and _{f 2}
(Including both Sus) and Sproc = Sorg + f (Sus) to obtain a processed image signal Sproc subjected to dynamic range compression, thereby maintaining the contrast of the fine structure portion. A compression processing method has been proposed (Japanese Patent Application No. 2-18206).

However, in the dynamic range compression processing method disclosed in Japanese Patent Application No. 2-18206, the calculation for obtaining the function f (Sus) is complicated, and special hardware for performing this calculation is required. The configuration for implementing is large.

In view of the above problems, the present invention provides an image processing method which expands an appropriate observation region in an image with a simple configuration, and also ensures observation suitability of a fine structure in each region.
It is an object to provide an image reading method and an image reproducing method.

[0018]

According to an image processing method of the present invention, a recording medium on which a radiation image of a subject is recorded is scanned by a light beam in a predetermined direction and a direction substantially perpendicular to the direction of the main scanning. The recording medium is two-dimensionally scanned by sub-scanning, and signal light generated from a portion of the recording medium that has undergone these scans is photoelectrically detected by a photodetector to form an image signal. An image processing method in an image reading / reproducing system for performing a process and then reproducing an image based on the image signal, wherein the portions of the subject having different desired reproduced image densities are substantially parallel to the main scanning direction. A boundary line is defined, the image is divided into a plurality of ranges by the boundary line, and the image signals for each of the plurality of ranges are applied to the plurality of ranges so that the desired reproduced images have substantially the same density. It is characterized in adding a respective different correction.

Here, the "desired reproduced image" means an image of a portion corresponding to the subject in the image obtained by reproducing the radiation image.

An image reading method according to the present invention is the image reading method in the above-described image reading / reproducing system, wherein the portions of the subject having different desired reproduced image densities are substantially parallel to the main scanning direction. Is determined, the image is divided into a plurality of ranges by the boundary line,
The level of the light beam is changed for each of the plurality of ranges so that the desired reproduced images in the plurality of ranges have substantially the same density.

Further, in the image reproducing method according to the present invention, a recording medium on which a radiation image of a subject is recorded is main-scanned by a light beam in a predetermined direction and sub-scanned in a direction substantially perpendicular to the main scanning direction. In this way, 2
Dimensionally scanned and subjected to image processing on an image signal obtained by photoelectrically detecting a signal light generated from a portion of the scanned recording body by a photodetector, and then modulated by the image signal An image reproducing method in an image reading / reproducing system that reproduces an image by scanning of a reproducing light, wherein the portions of the subject have different desired reproduced image densities,
A boundary line that is substantially parallel to the direction of the main scanning is determined, and the image is divided into a plurality of ranges by the boundary line. Wherein the level of the reproduction light is changed for each range.

[0022]

According to the image processing method of the present invention, a boundary line which is substantially parallel to the main scanning direction of a light beam is determined between portions of a subject having different desired reproduced image densities, and a plurality of images are defined by the boundary line. The image signal is divided into ranges, and different corrections are applied to the image signals for each of the plurality of ranges so that the desired reproduced images in the plurality of ranges have substantially the same density.

Further, in the image reading method according to the present invention, when reading an image with a light beam, the level of the light beam in each of the plurality of ranges is adjusted so that the desired reproduced images in the plurality of ranges have substantially the same density. Was changed.

Further, according to the image reproducing method of the present invention, when reproducing an image by scanning the reproduced light which has been subjected to the image processing and modulated, the desired reproduced images in the above-mentioned plurality of ranges have substantially the same density. Thus, the level of the reproduction light is changed for each of the plurality of ranges.

Therefore, by implementing the image processing method, the image reading method and the image reproducing method according to the present invention, it is possible to use an apparatus used in a conventional image reading / reproducing system as it is and to use a simple configuration to obtain an image. Even when the observation target area extends from a low-density area to a high-density area, the appropriate observation area in the image is expanded while maintaining the contrast of the whole image, and the fine structure in each area is observed. Can be secured.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. In this case, as shown in FIG. 2, a subject is used for a human body by using a long stimulable phosphor sheet 11 in which the length b in the longitudinal direction is twice or more the length a in the short direction. An example in which the spine is used will be described.

FIG. 1 is a schematic view of an example of an X-ray imaging apparatus.

The X-ray source 1 of the X-ray imaging apparatus 10
Is irradiated toward the subject 3, and the X-rays transmitted through the subject 3 are irradiated on the stimulable phosphor sheet 11, whereby the transmitted X-ray image of the subject 3 is accumulated and recorded on the stimulable phosphor sheet 11.

FIG. 3 is a perspective view showing an example of an X-ray image reading and reproducing apparatus incorporating the image processing method according to the first embodiment of the present invention.

An image is taken by the X-ray imaging apparatus shown in FIG. 1, and the stimulable phosphor sheet 11 on which the X-ray image is recorded is set at a predetermined position of the reading means 100.

When the stimulable phosphor sheet 11 is set at a predetermined position of the reading means 100, the sheet 11 is conveyed (sub-scan) in the direction of arrow Y by an endless belt 13 driven by a motor 12. On the other hand, the light beam 15 emitted from the laser light source 14 is reflected and deflected by the rotating polygon mirror 16 driven by the motor 23 and rotating at high speed in the direction of the arrow, and fθ
After passing through a focusing lens 17 such as a lens, the optical path is changed by a mirror 18 to be incident on the sheet 11, and the main scanning is performed in an arrow X direction substantially perpendicular to the sub-scanning direction (arrow Y direction). Sheet 11
From the portion irradiated with the excitation light 15, the stimulated emission light 19 of a light amount corresponding to the accumulated and recorded X-ray image information is diverged, and the stimulated emission light 19 is guided by the light guide 20, and It is photoelectrically detected by a multiplier (photomultiplier tube) 21. The light guide 20 is formed by molding a light-guiding material such as an acrylic plate, and is arranged such that a linear incident end face 20a extends along a main scanning line on the stimulable phosphor sheet 11. Injection end face 20b
The light receiving surface of the photomultiplier 21 is connected to the photomultiplier 21.
Stimulated luminescence light 19 entering the light guide 20 from the incidence end face 20a
Travels through the interior of the light guide 20 while repeating total reflection, exits from the exit end face 20b, is received by the photomultiplier 21, and the photostimulable light 19 representing the X-ray image is converted into an electric signal by the photomultiplier 21. Is converted.

The analog output signal S output from the photomultiplier 21 is logarithmically amplified by a logarithmic amplifier 26,
The digital signal is digitized by the A / D converter 27, whereby the image signal _SQ is obtained and input to the computer system 40. The computer system 40 includes a main body 41 having a built-in CPU, an internal memory, an interface, etc., a floppy disk drive 42 in which a floppy disk is loaded and driven, and information required for inputting information necessary for the X-ray image reading apparatus. It comprises a keyboard 43 and a CRT display 44 for reproducing and displaying a visible image.

[0033] When the image signals S _Q which carries the X-ray image of the object 3 in the computer system 40 is input, the image processing described below is performed on the image signal S _Q.

FIG. 4 is a diagram showing an X-ray image of the spine of a human body.

[0035] First, the computer system 40, from the value of the input image signal S _Q, the difference in the site of the object 3 between the radiation exposure amount different sites boundaries, i.e. between the head section A and the cervical vertebrae section B Boundary 50a and cervical spine section B
The boundary 50b between the vertebral body section C and the vertebral body section C is recognized. The computer system 40 includes different look-up tables LT1, LT2, and LT3 for the head section A, the cervical vertebra section B, and the vertebral body section C of the subject 3, respectively.
a, after recognizing the 50b, the lookup table LT1 to the image signal S _A of the head section A, a lookup table LT2 to the image signals S _B of the cervical vertebrae Section B, the image signal of the vertebral unit section C look-up table LT to S _C
3 to perform image processing. That is, as shown in FIG. 5, the image signal S _A of the head section A, the image signal S B of the cervical vertebral section _B , and the vertebral body section C, which have different densities, respectively.
Image signal _{S C} to performing image processing by different lookup table LT1, LT2, LT3 respective image signals _S A of substantially the same density level _{', S} B',
Obtain S _C ′. These image signals S _A ′, S _B ′, S
_{When a} visible image is reproduced and displayed on the CRT display 41 based on _C ′, this visible image is an image in which there is no difference in density due to the difference in the part of the subject 3 and the contrast of the fine structure is maintained.

In the first embodiment of the present invention, image processing is performed using three types of look-up tables. The image between the parts may be continuously changed using a table.

In the first embodiment, the image processing is performed using the lookup table. However, the image signal may be corrected by performing the following operation. That is, a correction value is determined for each section of each part (Δ ₁ for the head section A, Δ ₂ for the cervical vertebra section B, Δ ₃ for the vertebral body section C), _{S a '= S a + Δ} 1 S B' = S B + Δ 2 S C '= performs operation _{S C} + _{Δ 3,} the image signal _S a of substantially the same density _{obtained', S B ', S C} ' the By playing,
As in the above-described embodiment, an image in which the contrast is maintained can be obtained.

Next, an image reading method according to a second embodiment of the present invention will be described.

FIG. 6 is a perspective view showing an example of an X-ray image reading and reproducing apparatus including an image reading method according to a second embodiment of the present invention. Note that the pre-reading means 100 is the same as the reading means of the first embodiment of the present invention,
The same numbers as in the embodiment are assigned.

First, in the X-ray imaging apparatus as shown in FIG. 1, a transmission X-ray image of the vertebral column of the human body is stored in the long stimulable phosphor sheet 11 as in the first embodiment of the present invention. Be recorded. The stimulable phosphor sheet 11 on which the X-ray image is recorded is first scanned by a weak light beam to emit only a part of the radiation energy stored in the sheet 11 and read by the pre-reading means 100 for pre-reading. Set to position.
The stimulable phosphor sheet 11 set at this predetermined position is
Image is read by the same operation as in the first embodiment of the present invention shown in FIG. 3, the preliminary read-out image signal S _P is obtained.

The preliminary read-out image signals S _P obtained is input to the computer system 40 '. The computer system 40 'includes an example of the image reading method according to the present invention, and includes a main body unit including a CPU and an internal memory.
41 ', a drive unit 42' into which a floppy disk as an auxiliary memory is inserted and driven, a keyboard 43 'for an operator to input necessary instructions to the computer system 40', and a display for necessary information It comprises a CRT display 44 '.

[0042] In a computer system 40 'in, due to differences in the site of the object 3 from the input pre-reading image signals S _P, the boundary 50a shown in FIG. 4, 50b is recognized, then the head section A, the cervical vertebrae section B And the vertebral body section C is recognized.

Further, the level of the image signal for each section of this portion is recognized, and the light beam 1 at the time of the main reading is thereby obtained.
5 'power is controlled. For example, since the cervical vertebra section B in FIG. 4 has a high density, when reading the cervical vertebra section B, the power of the light beam 15 'is reduced so that the density becomes substantially the same as the density of other parts, and the image signal of the main reading is obtained. Lower the level.

Simultaneously with the recognition of this part, in the computer system 40 ', the reading conditions at the time of the main reading, that is, the sensitivity Sk and the latitude Gp at the time of the main reading, are obtained by a method such as a neural network or histogram analysis. For example, the voltage value applied to the photomultiplier 21 'and the amplification factor of the logarithmic amplifier 26' are controlled in accordance with the sensitivity Sk and the latitude Gp.

Here, the latitude Gp corresponds to the light quantity ratio of the strongest stimulated emission light to the weakest stimulated emission light which is converted into an image signal at the time of main reading.
The sensitivity Sk is a photoelectric conversion rate that determines a level of an image signal of a predetermined amount of stimulated emission light.

The stimulable phosphor sheet 11 'for which pre-reading has been completed.
Is set at a predetermined position of the main reading means 100 ', and a light beam 15' which is stronger than the light beam used for the pre-reading is used as shown in FIG.
The sheet 11 'is scanned by changing the laser power of the laser beam for each section of the portion as shown in (a), and an image signal is obtained under the reading conditions determined as described above. Since the structure of 100 'is substantially the same as the structure of the look-ahead means 100, the components corresponding to the constituent elements of the look-ahead means 100 are indicated by adding dashes to the numbers used in the look-ahead means 100, Description is omitted.

The A / D converter 27 'image signals S _Q obtained by being digitized, the computer again system 40' is input to. Computer system 40 '
Appropriate image processing on the image signal S _Q is the inner is applied, the image signal subjected to the image processing is sent to a not-shown reproducing apparatus, X-rays image based on the image signal is reproduced and displayed in the reproducing apparatus.

As in the first embodiment of the present invention, the reproduced and displayed X-ray image is an image in which there is no difference in density due to the difference in the site of the subject 3 and the contrast of the fine structure is maintained.

In the second embodiment of the present invention, when controlling the power of the light beam 15 ', the power is changed intermittently as shown in FIG. 7 (a). Alternatively, the power may be changed continuously as shown in FIG. 7 (b) so that there is no step between the parts.

Next, an image reproducing method according to a third embodiment of the present invention will be described.

FIG. 8 is a perspective view showing an example of an X-ray image reading and reproducing apparatus including an image reproducing method according to a third embodiment of the present invention. Since the reading means 100 is the same as in the first and second embodiments of the present invention, the same reference numerals as in the first and second embodiments are given.

First, in the X-ray imaging apparatus as shown in FIG. 1, a transmission X-ray image of the vertebral column of the human body is formed on the long stimulable phosphor sheet 11 as in the first and second embodiments of the present invention. It is stored and recorded. The stimulable phosphor sheet 11 on which the X-ray image is recorded is read by the reading means 100 in the same manner as in the above-described first embodiment of the present invention, and therefore detailed description is omitted. The read analog output signal S is logarithmically amplified by a logarithmic amplifier 26 and digitized by an A / D converter 27, whereby an image signal _SQ is obtained and input to a computer system 40 ″. Reference numeral 40 "includes an example of the image reproducing method of the present invention. The main unit 41" includes a CPU and an internal memory, a drive unit 42 "in which a floppy disk as an auxiliary memory is inserted and driven, and an operator. Comprises a keyboard 43 "for inputting necessary instructions and the like to the computer system 40" and a CRT display 44 "for displaying necessary information.

[0053] In the computer system 40 ", the difference in the site of the object 3 based on the value of the input image signal S _Q, the boundary 50a shown in FIG. 4, 50b is recognized, then the head section A, the cervical vertebrae section B and the vertebral body section C are recognized, and the level of the image signal in each section is recognized, whereby the light modulator 63 of the image reproducing unit 60 described later is recognized.
Is controlled.

[0054] Simultaneously with recognition sites described above, in the computer system 40 ", image processing necessary for the image signal S _Q is applied, the image signal subjected to the image processing is transferred to the image reproducing unit 60 8, the image reproducing section 60 includes a light beam image reproducing means for reproducing a visible image on a recording sheet by scanning with a light beam.
Here, a light beam is generated from the light beam generating means 62, and when this light beam is projected onto the recording sheet 66 by the scanning mirror 65, the main scanning is performed by the vibration of the scanning mirror 65, and the recording sheet 66 is moved to the main scanning. Sub-scanning is performed by moving in a direction perpendicular to the sub-scanning direction.
The movement of the recording sheet 66 in the sub-scanning direction may be performed by a planar movement, or may be performed by winding the recording sheet 66 around a drum and rotating the drum. In addition, a known scanning method other than these can be used.

The image signal subjected to the image processing in the image reproducing section is first subjected to digital / analog conversion and then sent to the drive circuit 61, where it is placed on the optical path of the light beam emitted from the light beam generating means 62. The optical signal is converted into an optical signal by driving the optical modulator 63. Here, the computer system 40 ″ recognizes the difference in the level of the image signal due to the difference in the region, and recognizes the cervical vertebra section B shown in FIG.
When reproducing the cervical vertebra section B, the modulation level of the light modulator 63 is reduced or the modulation levels of the head section A and the vertebral body section C are changed, so that the entire reproduced image is substantially reproduced. The drive circuit 61 is controlled so as to have the same density.

By controlling the drive circuit 61 and scanning the recording sheet 66 using the optical signal obtained as described above, there is no difference in density due to the difference in the part of the subject 3 and the contrast is maintained. Images can be played.

In the third embodiment of the present invention, the modulation level of the optical modulator 63 is changed by controlling the drive circuit 61 by the computer system 40 ". By changing the voltage level of the means 62, a difference in density due to a difference in a part in a reproduced image may be corrected. In this case, as in the cervical vertebra section B shown in FIG. 4, the voltage level of the light beam generating means 62 is lowered in the section of the high density part, or the voltage level of the light beam generating means 62 is lowered in the section of the low density part. Control to raise. Further, the optical signal modulation means 64 shown in FIG.
The optical signal modulating means 64 may be controlled at 40 "to change the level of the optical signal modulated by the optical modulator 63 to correct the difference in the density of the reproduced image.

In the third embodiment, when the modulation level is changed, it may be continuously changed so that a step due to the change in the modulation level is not displayed on the reproduced image.

[0059] The first described above, in the second and third embodiments, although to recognize based on a site of the subject 3 to the image signal S _Q or preliminary readout image signals S _P,
When the site of the subject 3 is always obtained at a fixed position on the stimulable phosphor sheet 11, for example, when the head is always shot at a fixed position when shooting the spine as in the above-described embodiment, the shooting is performed. It is not necessary to perform the part recognition every time, and sections having different parts may be determined in advance, and image reading, image processing, and image reproduction may be performed as described above.

Although each of the above embodiments is a system for obtaining an image signal by reading an X-ray image recorded on a stimulable phosphor sheet, the present invention is not limited to a system using a stimulable phosphor sheet. The present invention can be widely applied to a system for reading an X-ray image recorded on an X-ray film or the like and other general images recorded on a recording sheet to obtain an image signal and reproducing the image.

Further, in the present invention, in order to prevent erroneous diagnosis due to artifacts or the like, each section of a different portion is clearly indicated by different reading, image processing, or reproduction, so as to clearly indicate that each portion has been read, image processed or reproduced. A mark such as an arrow may be provided on the boundary line of each section.

[0062]

As described in detail above, the image processing method, the image reading method and the image reproducing method according to the present invention correct the difference in density due to the difference in the part of the subject with the conventional hardware configuration. Even when the observation area extends from the low density area to the high density area, the simple configuration allows the appropriate observation area in the image to be expanded while maintaining the contrast of the entire image. The observation aptitude of the microstructure can be secured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an example of an X-ray imaging apparatus.

FIG. 2 shows an example of a long stimulable phosphor sheet.

FIG. 3 is a perspective view showing an example of an X-ray image reading / reproducing apparatus incorporating the image processing method of the present invention.

FIG. 4 is a diagram showing an example of a radiation image of a spine of a human body.

FIG. 5 is a diagram schematically illustrating image processing using a lookup table.

FIG. 6 is a perspective view showing an example of an X-ray image reading and reproducing apparatus including the image reading method of the present invention.

FIG. 7 is a diagram showing an example of a change in power of a light beam according to the image reading method of the present invention.

FIG. 8 is a perspective view showing an example of an X-ray image reading and reproducing apparatus incorporating the image reproducing method of the present invention.

[Explanation of symbols]

 10 X-ray imaging apparatus 11, 11 'Storage phosphor sheet 19, 19' Stimulated luminescence 21, 21 'Photomultiplier 26, 26' Logarithmic amplifier 27, 27 'A / D converter 40, 40', 40 ″ Computer system

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 42/02 G06T 1/00 H04N 1/407

Claims (3)

(57) [Claims] 1. A recording medium on which a radiation image of a subject is recorded is main-scanned by a light beam in a predetermined direction and sub-scanned in a direction substantially perpendicular to the main scanning direction, so that the recording medium is scanned by a light beam. Scans two-dimensionally, performs image processing on an image signal obtained by photoelectrically detecting a signal light generated from a portion of the recording body that has undergone these scans with a photodetector, and then reproduces an image based on the image signal. An image processing method in an image reading and reproducing system, wherein a boundary line that is substantially parallel to the main scanning direction is defined between portions of the subject having different densities of a desired reproduced image,
Dividing the image into a plurality of ranges by the boundary line, and applying different corrections to the image signals in the plurality of ranges so that the desired reproduced images in the plurality of ranges have substantially the same density. Characteristic image processing method. 2. A recording medium on which a radiation image of a subject is recorded is scanned by a light beam in a predetermined direction in a main scanning direction, and is sub-scanned in a direction substantially perpendicular to the main scanning direction. Scans two-dimensionally, performs image processing on an image signal obtained by photoelectrically detecting a signal light generated from a portion of the recording body that has undergone these scans with a photodetector, and then reproduces an image based on the image signal. An image reading method in an image reading / reproducing system, wherein a boundary line that is substantially parallel to the main scanning direction is defined between portions of the subject having different densities of a desired reproduced image,
The image is divided into a plurality of ranges by the boundary line, and the level of the light beam is changed for each of the plurality of ranges so that the desired reproduced images in the plurality of ranges have substantially the same density. Image reading method. 3. A main body is scanned by a light beam in a predetermined direction on a recording body on which a radiation image of a subject is recorded, and sub-scanning is performed in a direction substantially perpendicular to the main scanning direction, so that the recording body is covered with a light beam. Dimensionally scanned and subjected to image processing on an image signal obtained by photoelectrically detecting a signal light generated from a portion of the scanned recording body by a photodetector, and then modulated by the image signal An image reproducing method in an image reading and reproducing system for reproducing an image by scanning of a reproducing light, wherein a boundary line substantially parallel to the main scanning direction is defined between portions of the subject having different densities of a desired reproduced image. ,
The image is divided into a plurality of ranges by the boundary line, and the level of the reproduced light is changed for each of the plurality of ranges so that the desired reproduced images in the plurality of ranges have substantially the same density. Image reproducing method.