JPH01106275A - Method and device for processing radiograph - Google Patents

Abstract

PURPOSE:To effectively attenuate the granular noise of a radiograph and to suppress the deterioration of picture quality performance by attenuating a space frequency component higher than a space frequency component included in a vignette masking signal obtained by averaging image signals. CONSTITUTION:An accumulative fluorescent sheet 2 on which the radiograph information signal of an object is accumulated is scanned by laser beams projected from a laser light source 4 and stimulated luminous light 9 radiated from a sheet 1 is converged by a converging body 10 and detected by a photomultiplier 11. The output of the photomultiplier 11 is inputted to an operation part 18 through an amplifier 16 and an A/D converter 17. The operation part 18 averages image signals in a prescribed range to find out a vignette masking signal and attenuates the space frequency component higher than the one included in the vignette masking signal from the original image signal. The operated image signal is stored in a memory 19, and when it is necessary, is displayed on an image display device 20.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to frequency processing of radiographic image signals, and in particular to frequency processing for suppressing deterioration of graininess of reproduced images due to reduction of radiation dose irradiated to a subject. The present invention relates to a radiation image processing method and an apparatus for implementing this method.

(Prior art) When a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is accumulated in the phosphor, and this It is known that when a phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy. It is called an exhaustible phosphor).

Using this stimulable phosphor, a subject such as a human body is irradiated with radiation and photographed, the radiation image information of this subject is temporarily recorded on a stimulable phosphor sheet, and this stimulable phosphor sheet is exposed to laser light. The stimulated luminescent light is generated by scanning two-dimensionally with excitation light such as the above, and the resulting stimulated luminescent light is photoelectrically read by a photodetector to obtain an image signal, and based on this image signal, the photographic light-sensitive material is processed. The applicant has already proposed a radiographic image information recording and reproducing system that outputs a radiographic image of a subject as a visible image to a display device such as a CRT. (Unexamined Japanese Patent Publication No. 55-12429, No. 56-1139
No. 5 etc. ) This system has the practical advantage of being able to record images over a much wider range of radiation exposure compared to conventional radiographic systems using silver halide photography. In other words, in a stimulable phosphor, it is recognized that the amount of emitted light that is stimulated to emit light due to excitation after accumulation is proportional to the amount of radiation exposure over an extremely wide range.
Therefore, even if the amount of radiation exposure varies considerably due to various imaging conditions, the amount of stimulated luminescence emitted from the stimulable phosphor sheet can be read by setting the gain to an appropriate value and using the photoelectric conversion means. By reading the data and converting it into an electrical signal, and using this electrical signal to output the radiographic image as a developable image to a recording material such as a photographic light-sensitive material or a display device such as a CRT, it is possible to produce a radiographic image that is not affected by fluctuations in radiation exposure. Obtainable.

(Problems to be Solved by the Invention) When the radiation image information recording and reproducing system described above is used for diagnosing the human body, the radiation dose to the human body can be significantly reduced compared to conventional X-ray imaging diagnostic systems.

However, as the amount of radiation irradiated to the subject during imaging is reduced, the effects of radiation quantum noise and other factors on the radiographic image become greater, resulting in degraded image granularity, resulting in a reproduced image with a coarse and grainy impression.

Among the ways to improve this graininess, there are ways to improve the device quality by making the stimulable phosphor sheet thicker or by increasing the size of the stimulable phosphor particles used in this sheet, so that images that are blurred during shooting can be stored and recorded. Possible methods include increasing the diameter of scanning excitation light to blur the image during reading, or inputting the read analog image signal to an analog filter to blur it. Although delicate control is required to improve graininess and minimize deterioration of other image quality performance such as sharpness, each of the above methods requires increasing the number of sheet types. Even if the number of pixels is increased, the degree of freedom that can be controlled is limited.Despite the complexity of the mechanism, the degree of freedom that can be controlled is extremely low.The direction of the flow of time-series image signals (main scanning direction)
There are problems such as only being able to control the system. In addition, as a method to improve this graininess by image processing, FFT
(Past Fourier Transfer
), or digitally calculate the average value of image signals around each scanning point for each scanning point to blur the image. Although the method using FFT has a very large degree of freedom in control, it has problems such as the processing speed is too slow to be applied to large-capacity image signals, and increasing the processing speed involves a large increase in cost. Although the digital blurring method described above is fast in processing time, it does not allow delicate control and usually results in excessive blurring.

In view of the above-mentioned problems, the present invention is capable of improving the graininess of radiographic images and minimizing the deterioration of other image quality performance, without complicating the apparatus, and within a sufficiently allowable range of calculation time. The object of the present invention is to provide a radiographic image processing method and an apparatus capable of implementing this method.

(Means for Solving the Problems) The radiation image processing method of the present invention scans a stimulable phosphor in which radiation image information is accumulated and recorded with excitation light, and the luminescence emitted from each scanning point by the excitation light is After obtaining an original image signal by photoelectrically reading the exhaustion light, in order to reproduce the radiation image as a visible image on a recording medium, the original image signal within a predetermined surrounding area corresponding to each scanning point or this original One blur mask signal obtained by averaging the image signal obtained by performing intermediate processing on the image signal or a plurality of blur mask signals obtained by changing the above predetermined range is S
u-, * (k=1.2.-, nun is an integer indicating the number of blur mask signals), the original image signal or the image signal obtained by performing intermediate processing on the original image signal is S b
l+sb2, one or more attenuation coefficients corresponding to the one or more blur mask signals, respectively, are β
, (k=1, 2,..., n), and when the image signal after calculation processing is S', the attenuation coefficient βk (k=1, 2,
..., n) at least one damping coefficient βl (i
is a constant in the range from 0 to βl (where βl≠1), and using this attenuation coefficient βl, calculation is performed according to the formula, and the blur mask signal corresponding to the attenuation coefficient βl is obtained. It is characterized by attenuating spatial frequency components higher than those of Sun and L.

Further, the radiation image processing apparatus of the present invention for implementing the radiation image processing method described above scans the stimulable phosphor in which radiation image information is stored and recorded with excitation light, and emit light from each scanning point by the excitation light. After obtaining an original image signal by photoelectrically reading the stimulated luminescence light emitted, this original image signal is processed by a calculation unit, and a radiation image is reproduced as a visible image on a recording medium based on the processed image signal. In a radiation image processing device in a radiation image recording and reproducing system, the calculation unit averages original image signals within a predetermined surrounding area corresponding to each scanning point or image signals obtained by performing intermediate processing on the original image signals. Sum, k (k = 1, 2, ..., nun is an integer indicating the number of blur mask signals), the original image signal or a plurality of blur mask signals obtained by changing the predetermined range. An image signal obtained by performing intermediate processing on the original image signal is 8111+Sb2, one or more attenuation coefficients corresponding to the one or more blur mask signals are βk (k=1, 2,..., n), When the image signal after the arithmetic processing is S', at least one attenuation coefficient βl (Q is an integer within 1 to n) among the attenuation coefficients βi (k=1, 2,..., n) or It is a constant in the range of 0 to βl (where βl≠1), and is characterized by using this attenuation coefficient β to perform calculations according to the following formula.

(Function) As described above, in the radiation image processing method of the present invention, at least one of the attenuation coefficients βk (k=1, 2,..., n) is 0 and βl (βl≠1). It is a constant within the range of , and the calculation is performed according to the formula of .

When the above (1) is modified, it becomes S' -8bl-βl (Sbz Sua, L).

Focusing on the second term βl (Sb2Sus,L) of this equation (2), by subtracting the blur mask signal Sus,L from the original image signal Sb2, for example, Sb2Sum,L in parentheses of this term, S, The low spatial frequency component of the blur mask signal S-m,g is subtracted from 2.This Sb2 Sus,l is multiplied by the attenuation coefficient βl of 0 × βl (βl≠1).
By further subtracting (Sb2Sus,t) from, for example, the original image signal Sb,
The high spatial frequency components of S b2S us,l can be attenuated from the signal of S b2S us,l . This high spatial frequency component is matched with image granular noise, and the attenuation coefficient βl
By setting βl to an appropriate value (βl≠1), it is possible to attenuate image granular noise and minimize deterioration in image quality performance such as sharpness. Furthermore, the radiation image processing apparatus for carrying out this calculation method is disclosed in Japanese Patent Laid-open No. 55-12429 and No. 5B-
Compared to the radiation image processing device in the radiation image information recording and reproducing system proposed by the present applicant in No. 11395 etc., it is possible to realize a device for implementing the above radiation image processing method without complicating the device in particular, Furthermore, the calculation time can be kept within a sufficiently permissible range.

As the image signal Sbl+s,2, an original image signal read photoelectrically may be used for both,
The original image signal may be subjected to intermediate image processing, and the signal subjected to this image processing may be used for one or both of the signals.

Next, the third and fourth terms of the above equation (2) will be explained. Grain noise has a fairly wide range of spatial frequency components.

Therefore, if the granular noise cannot be suppressed sufficiently by the combination of the first and second terms of equation (2) above, the same calculation as the second term can be performed by changing the spatial frequency band from the second term. This can be done in Section 4 or Section 4. In addition, in the third and fourth terms, the damping coefficient β, (
m-I-9J) to β. For example, JP-A-55-
The calculations proposed by the present applicant in No. 1133472 for emphasizing specific spatial frequency components may be combined.

Here, the above-mentioned image processing method has been proposed by the present applicant or
The non-sharp mask signal proposed in No. 5-183472 etc. is S. 1. When the original image signal is Sll+g1, the emphasis coefficient is β, and the processed signal is S', S' m S ,,,+β(S,,,-S.,)...
The basic difference from the case where calculation is performed to emphasize a specific spatial frequency component according to equation (3) will be explained.

The simplest equation for the present invention is the first equation (2) above.
Only the term and the second term, that is, S'=Sb+-βl(Sbz Sus, t)...(
4).

As described above, this equation (4) indicates that the spatial frequency component of granular noise is actively attenuated.

However, the inventors of the above-mentioned Japanese Patent Application Laid-Open No. 55-163472 have revealed that the spatial frequency of particle noise overlaps with the spatial frequency that affects image quality performance such as sharpness. It can be easily imagined that actively attenuating the spatial frequency component of particle noise would irreparably degrade other image quality performance. Image quality is improved by emphasizing spatial frequency components whose contribution rate to image quality performance is relatively greater than that of sharpness.

As a result of examining the properties of granular noise in more detail, the present inventors have determined that the spatial frequency to be attenuated and the degree to which this spatial frequency is attenuated are delicately selected to actively suppress the spatial frequency components of granular noise. They have discovered that by doing so, it is possible to make grainy noise less noticeable and to minimize deterioration in image quality performance such as sharpness. The optimal value of the attenuation coefficient βl for performing the above-mentioned attenuation varies depending on the type of radiation image, etc., but this optimal value often exists within the range of 0 to β and <1.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a perspective view showing an example of a radiation image processing apparatus using the radiation image processing method of the present invention.

A stimulable phosphor sheet 1 on which radiation image information of a subject is accumulated and recorded is conveyed (sub-scanned) in the direction of arrow Y by a sheet conveying means 3 such as an endless belt driven by a motor 2. On the other hand, the excitation light 5 emitted from the laser light source 4 is reflected and deflected by a rotating polygon mirror 6 that is driven by a motor 13 and rotates at high speed in the direction of the arrow, and after passing through a focusing lens 7 such as an fθ lens, the optical path is changed by a mirror 8. and enter the sheet 1 in the sub-scanning direction (direction of arrow Y)
The main scan is performed in the direction of the arrow X, which is substantially perpendicular to the main image. From the part of the sheet 1 irradiated with this excitation light 5, stimulated luminescence light 9 is emitted in an amount corresponding to the radiographic image information stored and recorded.
This stimulated luminescence light 9 is collected by a condenser IO, and a photomultiplier (photomultiplier tube) serves as a photodetector.
11, it is detected optically and electrically. The light condenser 10
is made by molding a light-guiding material such as an acrylic plate, and is arranged such that the linear entrance end surface 10a extends along the main scanning line on the stimulable phosphor sheet 1, and the annular shape The light-receiving surface of the photomultiplier 11 is coupled to the output end surface 10b formed in the photomultiplier 11. The above-mentioned entrance end surface 10
The stimulated luminescent light 9 that enters the light collector 10 from the light collector 10 travels through the interior of the light collector 10 by repeating total reflection, and reaches the output end face 10.
b and is received by the photomultiplier 11, and the amount of stimulated luminescence light 9 carrying the radiation image information is detected by the photomultiplier 11.

The analog output signal S output from the photomultiplier 11 is amplified by the amplifier 1B, and digitized by the A/D converter 17 at a predetermined recording scale factor.

The digitized original image signal S01. obtained in this way. is input to the calculation unit 18, and the calculation unit 18
Then, a blur mask signal S is obtained by averaging image signals within a predetermined range around each scanning point. ,, k
(k=1, 2, . . . , nun is the number of blur mask signals obtained by changing the above predetermined range) is obtained, and the original image signal S or□ or this original image signal S01. The signal that has undergone intermediate processing is S
blI Sb2 and the blur mask signal S us
, k (k=1, 2, . . . n), respectively, with damping coefficients βk (k=1, .
2,...,n), S' m S, , -Σ β, (S, 2-8., ,
, , )...The image signal S' after the arithmetic processing is obtained according to the equation (5). The simplest calculation process among the calculation processes shown in equation (5) above is for one blur mask signal Su*,
Using Ls damping coefficient βl (0 × βl (βl≠1)), S' 11111 S b I-βl (S'b
2 S 111. This is an arithmetic processing according to the formula of This calculation process is performed using the blur mask signal Sua, l.
By appropriately selecting the spatial frequency components to be attenuated and the degree of attenuation, it is possible to improve the apparent graininess of the image and improve sharpness, etc. It is possible to minimize the deterioration of the image quality performance of the ground.

The image signal S' subjected to the above calculation in the calculation unit 18 is stored in the memory 19, and a radiation image based on this image signal is reproduced and displayed on the image display device 20 as necessary.

FIGS. 3A to 3C each show the calculation unit 18 shown in FIG.
FIG. 3 is a block diagram showing different configuration examples.

In the configuration example of FIG. 3A, the original image signal S02 is input to the storage means 21 from the left side of the figure and is stored at - time. Original image signal S temporarily stored in storage means 21
01 is directly input to a subtracting means 24, which will be described later, and n blur mask signal calculation means 22a such as a first blur mask signal calculation means 22a.

22b, . . . , 22n are input in parallel. These blur mask signal calculation means 22a, 22b,...
, 22n, the surrounding Nl corresponds to each scanning point, respectively.
1 XN.

A blur mask signal S is obtained by averaging the image signals of N2×N2, . . . , N, XN scanning points. @, +1 S
un, 2+..., Sum,. is required. These blur mask signals S us, l+ S us, 2
+ ”'+ S us, n is n attenuation term calculation means 23a, 23, such as the first attenuation term calculation means 23a, respectively.
b, ..., 23n, each with a damping term βl
(Sang Sum, l) + β2 (S,
,,S,,,2),...,β,(S,,,-S,
, , ) are calculated. These attenuation terms and the original image signal S01 are input to the subtraction means 24, and S′ −30,, −Σ β, (S, , −S, , ,
, )・−(6) is calculated, and the image signal S′ after the arithmetic processing is
is required.

FIG. 3B is a block diagram showing an example of the configuration of the arithmetic unit 18 different from that shown in FIG. 3A. The same parts as in FIG. 3A are given the same numbers as in FIG. 3A, and explanations thereof will be omitted.

In this configuration example, the blur mask signal calculation means 22' first calculates the average value of 3x3 scanning points centering on each scanning point, and then calculates the average value of these average values to obtain 9x9, 15x15 Each attenuation term calculating means 23a, 23b, . . .
..., 23n, and each attenuation term calculation means 23a, 23b, .

23n. By doing so, the blur mask signal can be calculated efficiently.

FIG. 3C is a block diagram showing a further different configuration example of the calculation unit 18 shown in FIG. 2.

Original image signal S01. is temporarily stored in the storage means 21'' and then sent to the blur mask signal calculation means 22'.The blur mask signal calculation means 22' generates a blur mask signal S corresponding to the attenuation coefficient β1 based on the original image signal 5021. is calculated.This blur mask signal S
us, l are sent to the attenuation term calculation means 23', where βl (log-S ua, l) is calculated and sent to the subtraction means 24''.

The subtraction means 24' receives the original image signal S. , 1 are subjected to intermediate processing, and the image signals S, -S. 1, -β1(S,,
, -8, , , ) are calculated.

The image signal S1 resulting from this calculation is returned to the storage means 21', and the original image signal S01. will be remembered instead. This image signal S1 is sent to the blur mask signal calculation means 22'', which calculates a blur mask signal Sus, 2° corresponding to the attenuation coefficient β2 based on the image signal S1, and this blur mask signal Sus
, 2 are sent to the attenuation term calculation means 23', and β2(S, -3
゜1.2) is calculated. This calculation result is sent to the subtraction means 24'', and the image signal S1 is further subjected to second intermediate processing to produce an image signal 52-3l-β2 (SI S,
-, 2) are calculated.

By repeating the above loop n times, the final arithmetic-processed signal S' becomes S' w 3 , L , -β, (S, -1-S
,, fi) ・(Find as 71.

In this way, the image signal S l +S2 subjected to intermediate processing
,...,5n-1 is used to generate the blur mask signal Sua,l+S
us, 2+...S, 1. . Also by performing the calculation represented by equation (7), it is possible to effectively attenuate granular noise while minimizing deterioration of image quality performance such as sharpness.

・Compared with the above-mentioned equation (5), the above equation (7) uses the same image signal 5a-1 as the image signals S, , S, □, but the attenuation shown in FIG. 3C, for example, The original image signal S02 is also directly input and stored in the term calculation means 23'', and the image signals S, S2, ..., Sゎ-, after intermediate processing are calculated in the attenuation term calculation means 23'. without using the original image signal S, rg, calculate β, (S, , -S, , ,) β2 (S, , S us, 2), etc., and finally S' m S, -, -β11 (Slitg
The image signals S jll+ sb2 may be different, such as by performing the calculation of (8).

FIG. 1 shows the results obtained by using the radiation image processing method of the present invention.
(Bokeh mask signal and two attenuation coefficients) is a graph showing an example of calculation in the spatial frequency domain.

The horizontal axis shows the spatial frequency, and the vertical axis shows the relative value with the DC component being 1. For simplicity, a signal obtained by Fourier transforming the image signal S' after the arithmetic processing and expressed in the spatial frequency domain is also expressed as S'.

Graph A is an ideal graph showing the optimal spatial frequency characteristic for suppressing granular noise and minimizing deterioration of image quality performance in areas such as sharpness for a certain radiation image. In contrast to graph A, graph A' uses the average values of 15×15 and 5×5 scanning points surrounding each scanning point as the blur mask signals S us, In S us, 2, respectively, and the attenuation coefficient β2. β2 as β, −0,
1, S'! using β2-0.4. S, , ,
-β+ (So-1Sus, +)-β2 (S,,
,S,,,2)...This is a graph showing the calculation result of (9) in the spatial frequency domain.1. It is sufficiently similar to graph A.

Graph B is an ideal graph showing optimal spatial frequency characteristics for other radiation images. In contrast to this graph B, graph B' is the blur mask signal S usll Su, .
2, 15 x 15 around each scanning point, 3 x 3
Using the average value of the scanning points, the attenuation coefficient β2. Using β+"0.1.β2=0.8 as β2, 5' m S, , -βs (S----3u
−;+)−β2 (S−−−S ua, 2)”
"" is a graph showing the calculation result of (10) in the spatial frequency domain. In this case as well, graph B' closely approximates graph B.

In this way, radiation images are classified according to the type of subject, the intensity of the radiation irradiated to the subject, etc., and the calculation method of the blur mask signal and the value of the attenuation coefficient are determined to suit each radiation image. By performing arithmetic processing according to the method, it is possible to effectively attenuate the granular noise of the radiation image and obtain a reproduced image in which deterioration in image quality performance such as sharpness is minimized.

(Effects of the Invention) The present invention scans a stimulable phosphor on which radiation image information is accumulated and recorded with excitation light, and photoelectrically reads the stimulated luminescence light emitted from each scanning point by the excitation light to create an original image. After obtaining the image signal, the attenuation coefficient βk (k=1, 2,
...In), the attenuation coefficient βl is a constant within the range of 0 to βl (βl≠1), and the calculation is performed according to the formula, so that the blur mask signal S, L is valid. It is possible to attenuate spatial frequency components higher than the spatial frequency components currently being used, and it is possible to effectively attenuate granular noise in radiographic images and to minimize deterioration of other image quality performance. Furthermore, the apparatus for carrying out this method is not particularly complicated (and the calculation time can be kept within a sufficiently tolerable range).

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of calculation using the radiation image processing method of the present invention in the spatial frequency domain, and FIG. 2 shows an example of a radiation image processing apparatus implementing the radiation image processing method of the present invention. The perspective views and FIGS. 3A to 3C are block diagrams showing different configuration examples of the calculation section shown in FIG. 2. 1... Stimulable phosphor sheet 2.13... Motor 3... Sheet conveying means 4... Laser 6... Rotating polygon mirror 9
... Stimulated luminescence light 10. ...Concentrator 11...
・Photomultiplier 16...Amplifier 17...A/D converter 18...Arithmetic unit 19...Memory 2
0...Image display device No. I N-No. m Figure 2

Claims (6)

[Claims] (1) After scanning the stimulable phosphor on which radiation image information is stored and recorded with excitation light and photoelectrically reading the stimulated luminescence light emitted from each scanning point by the excitation light to obtain an original image signal. When reproducing a radiation image as a visible image on a recording medium, by averaging the original image signal within a predetermined surrounding area corresponding to each scanning point or the image signal obtained by performing intermediate processing on this original image signal. The obtained one or a plurality of blur mask signals obtained by changing the predetermined range are applied to S_u_a_. ＿k(k=1, 2,
..., n; n is an integer indicating the number of blur mask signals), the original image signal or an image signal obtained by performing intermediate processing on this original image signal are S_b_1, S_b_2, respectively corresponding to the one or more blur mask signals. One or more damping coefficients are β_k (k=1, 2,
..., n), and when the image signal after arithmetic processing is S', at least one attenuation coefficient β_l (l is within 1 to n) among the attenuation coefficients β_k (k=1, 2, ..., n) ) is a constant in the range of 0<β_l (however, β_l≠1), and using this attenuation coefficient β_l, perform calculations according to the formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ to obtain the above-mentioned attenuation coefficient. Blur mask signal S_u_ corresponding to β_l
s_. A radiation image processing method characterized by attenuating spatial frequency components higher than spatial frequency components of _l. (2) The radiation image processing method according to claim 1, wherein the attenuation coefficient β_l is a constant in the range of 0<β_l<1. (3) Image signals S_b_1, S_b obtained by performing intermediate processing on the original image signal or this original image signal
3. The radiation image processing method according to claim 1 or 2, wherein _2 are the same original image signals. (4) Image signals S_b_1, S_b obtained by performing intermediate processing on the original image signal or this original image signal
The radiation image processing method according to claim 1 or 2, wherein _2 are the same image signals obtained by performing the same intermediate processing on the original image signals. . (5) Image signals S_b_1, S_b obtained by performing intermediate processing on the original image signal or this original image signal
_2, one of which is the original image signal or an image signal obtained by performing first intermediate processing on the original image signal, and the other is an image signal obtained by performing second intermediate processing on the original image signal. A radiation image processing method according to claim 1 or 2, characterized in that: (6) After scanning the stimulable phosphor on which radiation image information is stored and recorded with excitation light and photoelectrically reading the stimulated luminescence light emitted from each scanning point by this excitation light to obtain an original image signal. , in a radiation image processing apparatus in a radiation image recording and reproducing system that processes this original image signal in a calculation unit and reproduces a radiation image as a visible image on a recording medium based on the processed image signal, the calculation unit includes each One image signal obtained by averaging an original image signal within a predetermined range surrounding the scanning point or an image signal obtained by performing intermediate processing on this original image signal, or a plurality of image signals obtained by changing the predetermined range. The blur mask signal is S_u_s_. _k (k=1, 2,..., n;
(n is an integer indicating the number of blur mask signals), the original image signal or an image signal obtained by performing intermediate processing on the original image signal, S_b_1, S_b_2, one or more signals corresponding to the one or more blur mask signals, respectively. β_k (k=1, 2,..., n)
, when the image signal after the arithmetic processing is S', at least one attenuation coefficient β_l (l is an integer within 1 to n) among the attenuation coefficients β_k (k=1, 2, ..., n) is It is a constant in the range of 0<β_l (however, β_l≠1), and is characterized by using this attenuation coefficient β_l to perform calculations according to the formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Radiographic image processing device.