JP2000342567A - Method and device for image processing and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly execute image processing to synthetic image data obtained by dividedly photographing a subject such as the whole lower limb. SOLUTION: This processing method synthesizes divided image data S1 to S3 obtained by dividedly photographing by using a synthesizing means 3 to obtain synthetic image data G0. On the other hand, based on all the data S1 to S3, an image processing condition deciding means 4 decides a image processing condition J for executing to the data G0. Based on the decided condition J, a processing means 5 executes image processing to the data G0 to obtain processed image data G1, which is reproduced by a reproducing means 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a long synthetic image by synthesizing divided images obtained by dividing and photographing a subject such as a radiation image of the entire spine and lower limbs. More particularly, the present invention relates to an image processing method and apparatus for performing image processing on composite image data representing a composite image, and a computer-readable recording medium storing a program for causing a computer to execute the image processing method.

[0002]

2. Description of the Related Art In various fields, reading a radiation image recorded on a recording sheet or the like to obtain image data, performing appropriate image processing on the image data, and reproducing / recording the image is performed in various fields. . For example, a radiation image recording / reproducing system using a stimulable phosphor sheet, which has been filed by the present applicant, is one of them.

In such a system, there has been known a system in which image data obtained from a stimulable phosphor sheet is analyzed and optimum image processing conditions when image processing is performed on the image data are known. ing. 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 the image data is performed on the image data. As an algorithm for obtaining such an image processing condition, there is known a method of obtaining a histogram of image data and obtaining an image processing condition based on the histogram. Specifically, the maximum value and the minimum value of the range required as image information are obtained from the histogram in the image data, and the image processing conditions are set so that the image information within the range between the maximum value and the minimum value can be obtained with high accuracy. Method (for example, Japanese Patent Application Laid-Open No. 60-15655)
No.) etc. are known.

On the other hand, in the above-mentioned radiation image recording / reproducing system, in order to diagnose scoliosis, a long stimulable phosphor having a recording area corresponding to the length of the entire vertebral column of a subject to be imaged is used. A radiographic image of the entire spine is taken using a sheet, and the radiographic image of the entire spine is reproduced and recorded for use in diagnosis (Japanese Patent Laid-Open No. 3-287).
248). However, a long stimulable phosphor sheet is not easy to handle, and a dedicated reader is required to obtain image data from such a long sheet. For this reason, a plurality of divided images are obtained by dividing a radiation image of the same subject in the longitudinal direction of the subject using a plurality of stimulable phosphor sheets to obtain a plurality of divided images. There has been proposed a radiation image information recording / reading apparatus which obtains combined image data representing a combined image by combining (Japanese Patent Laid-Open No. 3-287249).
issue).

However, when photographing the entire spine, the subject thickness differs between the neck and abdomen of the subject, and when photographing the entire lower limb, between the thigh and the ankle. There is a problem that the amount of radiation transmitted through the subject differs for each portion of the subject, and as a result, the density of the portion where the subject is thin is higher than the density of the portion where the subject is thick in the obtained composite image.

For this reason, for example, when performing divisional photography of all the lower limbs using three stimulable phosphor sheets, the thickness of the subject gradually decreases from the thigh to the ankle. The image processing conditions are obtained based on the divided image data obtained from the stimulable phosphor sheet located in the middle between the stimulable phosphor sheet and the ankle, and the image processing is performed on all the divided image data based on the image processing conditions. There has been proposed a method of performing image processing so that an appropriate density is obtained over the entire area in the scale direction.

[0007]

However, in such an image processing method, when a divided image is read from a stimulable phosphor sheet, the stimulable phosphor obtains divided image data for determining image processing conditions. Since it is necessary to specify the sheet or to determine the order of the stimulable phosphor sheets and perform the reading, if an incorrect sheet is specified or the reading order is incorrect, an appropriate image processing condition is obtained. You will not be able to do it. In the above-described image processing method, since the image processing condition is calculated from one piece of the divided image data, the image is blackened in the divided image having a high density (for example, the ankle side of all the lower limbs), or the density is low. In a thin divided image (for example, the thigh side of all the lower limbs), the image flies white, resulting in a problem that image information is lost.

Further, in the case of performing the divided photographing, the photographing of the subject is performed by overlapping a part of the stimulable phosphor sheet.
The obtained divided image data is synthesized based on the information of the overlapping portion to obtain the synthesized image data. The overlapping portion of the sheet on the side distant from the subject at the time of shooting is compared with the portion other than the overlapping portion. Therefore, if image processing is performed under inappropriate image processing conditions and the image information of that part is lost, it becomes impossible to synthesize the divided image data.

The present invention has been made in view of the above circumstances, and has an image processing method and apparatus capable of appropriately performing image processing on synthesized image data, and a program for causing a computer to execute the image processing method. It is an object of the present invention to provide a computer-readable recording medium according to the present invention.

[0010]

An image processing method according to the present invention combines divided image data representing each divided image obtained by dividing and photographing the same subject to form a composite image representing a composite image of the subject. An image processing method for obtaining data, performing image processing on the composite image data under predetermined image processing conditions to obtain processed composite image data,
The image processing condition is determined based on information on all the divided image data.

Here, "divisional photographing" refers to the whole spine,
As with all lower limbs, all upper limbs, etc., for a relatively long subject, it means that the subject is divided and photographed in the longitudinal direction, but the mode of division is not limited to this. For example, the object may be photographed by dividing the subject into four parts vertically and horizontally.

In the image processing method according to the present invention, it is preferable that the information regarding the divided image data is the divided image data itself or a feature amount of each of the divided image data. May be calculated based on

Here, the "feature value" includes a histogram of divided image data, a minimum data value and a maximum data value of a histogram, a histogram of composite image data, a minimum data value and a maximum data value of a histogram of composite image data, and the like. No.

The image processing apparatus according to the present invention is a synthesizing means for synthesizing divided image data representing each divided image obtained by dividing and photographing the same subject to obtain composite image data representing a composite image of the subject. Processing means for performing image processing on the composite image data to obtain processed composite image data, wherein the image processing conditions are determined based on information on all of the divided image data. An image processing condition determining means is provided.

In the image processing apparatus according to the present invention, it is preferable that the information on the divided image data is the divided image data itself or a characteristic amount of each of the divided image data. May be calculated based on

The image processing method according to the present invention may be provided by being recorded on a computer-readable recording medium as a program for causing a computer to execute the method.

[0017]

According to the present invention, the image processing conditions for performing the image processing on the composite image data are determined based on the information regarding all the divided image data. It is necessary to specify the stimulable phosphor sheet for obtaining the divided image data for determining the image processing condition and to determine the order of reading the stimulable phosphor sheet, as compared with the conventional method of determining the image processing condition from Thus, the image processing conditions can be determined without performing a troublesome operation. Further, since it is possible to determine the image processing conditions reflecting all the divided image data, the image is lost due to the image being blackened or flying white in the specific divided image as in the above-described conventional method. As a result, it is possible to obtain processed composite image data that has been optimally subjected to image processing. Further, since the image information is not lost, even when a part of the stimulable phosphor sheet is overlapped and the subject is photographed to obtain a composite image, the information of the overlapped portion is not lost. Thus, the divided image data can be accurately combined to obtain the combined image data.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of an image synthesizing system using an image processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image synthesizing system according to the present embodiment is a photographing means 1 for dividing and photographing all the lower limbs as a subject in the longitudinal direction thereof and recording the divided images of all the lower limbs on three stimulable phosphor sheets. And a reading unit 2 that photoelectrically reads the stimulable phosphor sheet on which the divided images are recorded to obtain divided image data S1, S2, and S3 representing the divided images, and combines the divided image data S1 to S3. Combining means 3 for obtaining combined image data G0 by means of a combination, and combining image data G0 based on information on all divided image data S1 to S3.
Image processing condition determining means 4 for determining an image processing condition J when image processing is performed on image data, and performing image processing on the composite image data G0 based on the image processing condition J determined by the image processing condition determining means 4. And a reproducing unit 6 for recording and reproducing the processed composite image data G1 on a film. In the present embodiment, the information regarding all the divided image data S1 to S3 is the divided image data S1.
S3 itself is used.

In the photographing means 1, three stimulable phosphor sheets are accommodated in a long cassette so that each of the stimulable phosphor sheets is partially overlapped or the ends thereof are aligned, and the radiation transmitted through the subject is transmitted. Is irradiated onto each of the sheets stored in the long cassette, so that the radiation images of all the lower limbs of the subject are divided into the respective sheets and recorded.

In the reading means 2, first, the sheet stored in the long cassette and on which the divided image is recorded is replaced with a standard cassette suitable for the size of each sheet, and then the divided image is read to obtain divided image data S1. To S3 are obtained.

In the synthesizing means 3, the divided image data S1
To S3 are combined to obtain combined image data G0. In this synthesis, the correlation values of the divided image data S1 to S3 in the overlapping portion or the contact portion on the sheet are obtained,
The divided image data S1 to S when the correlation value becomes maximum
3, the amount of translation, the amount of rotation, and the amount of enlargement / reduction are determined as the amount of positional deviation, the affine transformation coefficient is determined based on the amount, and the divided image data S1 to S3 are affine-transformed based on these coefficients. .

The image processing condition determining means 4 first
As shown in (a) to (c), each divided image data S1 to
The histograms H1 to H3 of S3 are obtained, and these histograms H1 to H3 are added to create a combined histogram HG as shown in FIG. Note that in FIG. 2D, the frequency of the combined histogram HG is obtained by reducing the actual frequency. Then, when the combined histogram HG is created in this manner, the lowest data value of the combined histogram HG is set as the minimum data value Smin, and in the combined histogram HG, the peak of the histogram representing the main subject and the direct radiation are irradiated. The data value at the boundary between the histogram and the peak representing the high density portion is obtained as the maximum data value Smax. Note that the maximum data value Sma
As a method for obtaining x, for example, Japanese Patent Laid-Open No. 6-13051
As described in No. 7, a data value (for example, SmaxK) exceeding a predetermined threshold value is determined only from the highest data value in the composite histogram HG, and the following equation (1) is minimized with the data value SmaxK as a starting point. A method of setting the data value S to be the maximum data value Smax may be used.

HG (S) / (SmaxK−S) (1) where HG (S) is the frequency of the composite histogram at an arbitrary data value S and thus the minimum data value Smin and the maximum data value of the composite histogram HG When Smax is obtained, the shift amount of the gradation curve for converting the combined image data G0 as shown in FIG. 3 so that the image data in the range of the data values Smin and Smax is reproduced in an appropriate density range ( Up and down arrows), scale factor change (point K
) Is input to the processing unit 5 as an image processing condition J for performing image processing on the composite image data G0. Specifically, the data value S
min and Smax are predetermined concentration values Qmin
And the image processing condition J is determined so as to be converted into Qmax. In FIG. 3, the combined image data G
Although the conversion characteristic for converting 0 is a curve, this characteristic may be a straight line.

In the processing means 5, the shift amount and the scale factor of the gradation curve as shown in FIG. 3 are adjusted based on the input image processing condition J, and the synthesized image data G0 is formed by the adjusted gradation curve. The converted composite image data G1 is obtained by the conversion.

Next, the operation of this embodiment will be described. FIG. 4 is a flowchart showing the operation of the first embodiment. First, the photographing means 1 performs divided photographing of all the lower limbs as a subject using three stimulable phosphor sheets (step S1). Then, the reading means 2 reads the divided image data S1 to S3 representing the divided image from the three stimulable phosphor sheets (step S2). The divided image data S1 to S3 are synthesized by the synthesizing means 3 to obtain synthesized image data G0, which is input to the processing means 5 (step S3). On the other hand, the divided image data S1 to S3 are also input to the image processing condition determining means 4, where the image processing condition J is determined and input to the processing means 5 as described above (step S4). The processing in step S4 may be performed before step S3, or may be performed in parallel.

The processing means 5 performs image processing on the composite image data G0 based on the input image processing condition J to obtain processed composite image data G1 (step S5). The processed composite image data G1 is reproduced by the reproducing means 6 (step S6), and the processing is terminated.

As described above, in the present embodiment, the image processing condition J for performing the image processing on the composite image data G0 is determined based on all the divided image data S1 to S3. In comparison with the conventional method of determining the image processing condition J from only one divided image data (for example, S2), the stimulable phosphor sheet for obtaining the divided image data for determining the image processing condition J is designated or stored. There is no need to determine the order in which the luminescent phosphor sheets are read, so that the image processing condition J can be determined without performing a troublesome operation. Also, all the divided image data S1
Since the image processing condition J that reflects S3 can be determined, the image information is not lost due to the image being blackened or blackened in the specific divided image as in the above-described conventional method. Thereby, it is possible to obtain the processed composite image data G1 on which the image processing is optimally performed. Further, since the image information is not lost, even when a part of the stimulable phosphor sheet is overlapped and the subject is photographed to obtain a composite image, the information of the overlapped portion is not lost. Divides image data S
1 to S3 can be accurately synthesized.

In the above embodiment, the image processing condition J is determined based on the combined histogram HG obtained by combining the histograms H1 to H3 of the divided image data S1 to S3. a) to (c), the minimum data value S of each of the histograms H1 to H3.
min1 to Smin3 and the maximum data value Smax1
Smax3 may be obtained as a feature amount of the divided image data S1 to S3, and the image processing condition J may be determined based on this. Specifically, the minimum data values Smin1 to Smin3 and the maximum data value S
The average value of max1 to Smax3 is calculated as a minimum data value Smin and a maximum data value Smax, which are references for determining the image processing condition J, and this minimum data value Sm is calculated.
and the image processing condition J by determining the shift amount and the scale factor of the gradation curve based on the maximum data value Smax.
May be determined. Note that each histogram H
The minimum data values Smin1 to Smin3 are defined as minimum data values Smin and maximum data values Smax1 to Smax3 serving as references for determining the image processing condition J.
May be determined as the maximum data value Smax serving as a reference for determining the image processing condition J.

After obtaining the composite image data G0,
The histogram of the composite image data G0 may be obtained, and the minimum data value Smin and the maximum data value Smax may be determined based on the histogram of the composite image data G0 to determine the image processing condition J.

Further, in the above embodiment, the correction of the composite image data G0 representing the radiation image of all the lower limbs is described. However, if the image is divided and photographed, such as the whole spine or the upper limb, The present invention can be applied to any radiographic image. Further, the mode of the divided photographing is not limited to the one in which the subject is divided in the longitudinal direction. For example, the subject may be photographed by dividing the subject into four parts vertically and horizontally.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram illustrating a configuration of an image composition system to which an image processing device according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a histogram of divided image data;

FIG. 3 is a diagram showing a gradation curve.

FIG. 4 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photographing means 2 reading means 3 synthesizing means 4 image processing condition determining means 5 processing means 6 reproducing means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) // H04N 1/04 G06F 15/62 390A H04N 1/04 EF term (reference) 4C093 AA28 CA04 CA10 FF05 FF08 FF11 FF19 FF35 5B057 AA08 CA08 CB08 CE10 CE11 DC23 5C072 AA01 UA17 VA01 5C076 AA19 5C077 LL04 PP10 PQ19

Claims (12)

[Claims] 1. Combining divided image data representing each divided image obtained by dividing and photographing the same subject to obtain combined image data representing a combined image of the subject, and performing predetermined processing on the combined image data. An image processing method for obtaining processed composite image data by performing image processing according to the image processing condition of claim 1, wherein the image processing condition is determined based on information on all of the divided image data. 2. The image processing method according to claim 1, wherein the information on the divided image data is the respective divided image data itself. 3. The image processing method according to claim 1, wherein the information on the divided image data is a feature amount of each of the divided image data. 4. The image processing method according to claim 1, wherein the information on the divided image data is calculated based on the composite image data. 5. A combining means for combining divided image data representing each divided image obtained by dividing and photographing the same subject to obtain combined image data representing a combined image of the subject; An image processing condition determining unit that determines the image processing condition based on information on all of the divided image data. An image processing apparatus comprising: 6. The image processing apparatus according to claim 5, wherein the information on the divided image data is the respective divided image data itself. 7. The image processing apparatus according to claim 5, wherein the information on the divided image data is a feature amount of each of the divided image data. 8. The image processing apparatus according to claim 5, wherein the information on the divided image data is calculated based on the composite image data. 9. Combining divided image data representing each divided image obtained by dividing and photographing the same subject to obtain combined image data representing a combined image of the subject, and performing predetermined processing on the combined image data. A computer-readable recording medium that records a program for causing a computer to execute an image processing method of performing image processing according to the image processing conditions to obtain processed composite image data, wherein the program includes all of the image processing conditions. A computer-readable recording medium having a procedure for making a decision based on information on the divided image data. 10. The information on the divided image data,
10. The computer-readable recording medium according to claim 9, wherein each of the divided image data itself is used. 11. The information on the divided image data,
10. The computer-readable recording medium according to claim 9, wherein the recording medium is a feature amount of each of the divided image data. 12. The information on the divided image data,
10. The computer-readable recording medium according to claim 9, wherein the recording medium is calculated based on the composite image data.