JPH06259543A - Picture processor - Google Patents

Abstract

PURPOSE:To improve operability by eliminating the necessity of operation for switching the gradation conversion between the whole picture and a picture in a specific area. CONSTITUTION:This picture processor 30 is characteristically provided with a lookup table(LUT) 8b to be used for the gradation conversion of a picture in a specific area which is inputted from a console 11, an LUT 8a to be used for the gradation conversion of the whole picture and a means 10 for synthesizing these LUTs 8a, 8b to execute gradation conversion by using the synthesized LUT. Since the gradation of the whole picture is always held by executing gradation conversion by the synthesized LUT, the positional relation of a picture in a specific area on the whole picture can be grasped, so that switching operation can be made unnecessary and operability can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus using means for converting the gradation of an image using a look-up table displayed on a display controller of the image processing apparatus in a medical image diagnostic apparatus.

[0002]

2. Description of the Related Art In an image processing apparatus, it is necessary to adjust the gradation of an image displayed on a display device in order to interpret a specific area of the whole or a part of an image to be displayed. As a method therefor, the average value, the maximum value, and the minimum value of the numerical values of the pixels forming the specific area of the image are calculated, and the lookup table (L
UT), and the gradation of the specific area is converted using this LUT.

Next, a conventional image processing apparatus will be described with reference to the drawings. FIG. 3 is a block diagram showing a configuration of a digital radiography apparatus (DR) as an example of a medical image diagnostic apparatus adopting an image processing apparatus, and FIG.
It is a figure which shows each gradation conversion of the whole image and a specific area | region using UT. First, the configuration of the image processing apparatus and the positioning of the medical image diagnostic apparatus will be described with reference to FIG. Here, DR is used as an example of the medical image diagnostic apparatus. The DR is an X-ray tube 21 that irradiates X-rays, an X-ray 22 that is incident on the subject 24 supported by the bed 23 from the X-ray tube 21, and the incident X-ray 22 is the subject 2
X-rays 25 transmitted through the X-ray 4, X-ray detectors 26 that collect the transmitted X-rays 25 and convert them into visible light, and a TV camera 27 that forms an image of the visible light converted by the X-ray detector 26.
Measurement system 20 consisting of, and image memory 7 for storing images
A means 9 for converting the image in the image memory 7 into an arbitrary gradation by using the LUT 8, a display controller 12 for displaying the image whose gradation is converted by the gradation converting means 9, and this display control. The image processing device 30 is provided with an image displayed on the device 12 and a console 11 for inputting a specific area of the image memory 7 corresponding to the image. DR like this
In, the image processing device is positioned as shown.

Next, an LUT used for gradation conversion in a conventional image processing apparatus will be described with reference to FIG. First, the LUT used for gradation conversion of the entire image is shown in FIG.
This will be described using (a). Overall 4 of DR image shown in the figure
Looking at 0, various organs of the subject are displayed. Further, due to the difference in the X-ray absorption amount of these organs, the numerical values of the pixels forming the image have a wide range. In the middle of the figure, the distribution is shown by taking the pixel value in the horizontal axis direction and the frequency in the vertical axis direction. From this distribution, the minimum value M _i0 , the average value A _v0 , and the maximum value M _a0
Ask for. From these _calculated M _i0 , A _v0 , and M _a0 , as shown in the lower part of the figure, the pixel value is in the horizontal axis direction and the LU is in the vertical axis direction.
Taking the relative value indicating the output value of T as a percentage, the points are arranged in correspondence with 0 (point A ₀ ), M _v0 50 (point B ₀ ) and M _a0 100 (point C ₀ ) for M _i0. , The LUT is created with the slope represented by the line segment connecting these points.

Next, an LUT used for gradation conversion of an image in a specific area will be described with reference to FIG. Looking at the image of the DR specific region 50 shown in the figure, attention is paid to one organ of the subject. Also, it is common for many diagnostics to be interested in a specific organ in this way. The specific region 50 having only one organ is distributed in a narrower range than the distribution of the numerical values of the pixels in FIG. In the figure, the distribution of the entire image is shown by a dotted line for comparison. This LU
In FIG. 4A, the minimum value M _i0 is replaced by M _i1 (point A ₁ ), the average value A _v0 is replaced by A _v1 (point B ₁ ), and the maximum value M _a0 is replaced by M _a1 (point C ₁ ). And created in the same manner as in FIG. With the LUT for the specific area, the gradation of the image other than the specific area is impaired.

[0006]

According to the above-mentioned prior art, when the gradation conversion of the entire image is performed by the LUT for the specific area of the image, the gradation of the image other than the specific area is lost. This makes the positional relationship between the entire image and the specific area image unclear. In order to confirm this positional relationship, when moving the specific area while diagnosing, it is necessary to repeat the gradation conversion for the entire image and the gradation conversion for the specific area alternately, which causes a problem of operability.
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide an image processing apparatus capable of displaying the gradations for the entire image and for the specific area without repeating the gradation conversion alternately.

[0007]

In order to achieve the above object, the present invention provides an LUT used for gradation conversion of an image of a specific area input on a console in an image processing apparatus, and a floor of the entire image. Means for synthesizing the LUT used for the key conversion,
Grayscale conversion is performed using this synthesized LUT.

[0008]

The LUT synthesizing means is a polygonal line connecting the minimum value M _i0 and the maximum value M _a0 of the pixels in the entire image, and the minimum value M _i1 and the maximum value M _a1 of the pixels in the image of the specific area. From the LUT. Grayscale conversion is performed using the synthesized LUT.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Gradation conversion using an LUT in the image processing apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an image processing apparatus of the present invention, and FIG. 2 is a diagram showing an example of creating an LUT used for gradation conversion of the present invention.

First, the configuration of the image processing apparatus of the present invention is shown in FIG.
Will be described using. The image processing apparatus of the present invention comprises an image memory 7 for storing images, a means 10 for synthesizing an image in the image memory 7 with a LUT 8a for the entire image, and a LUT 8b for a specific area, and this LUT synthesizing means 10. Means 9 for converting to an arbitrary gradation using the LUT created in step 1, a display controller 12 for displaying an image whose gradation is converted by the gradation converter 9, and a display controller 12 for displaying the image. Image and a console 11 for inputting a specific area of the image memory 7 corresponding to this image.

Next, creation of an LUT used for gradation conversion in the image processing apparatus of the present invention will be described with reference to FIG. In the upper part of the figure, the pixel values of the entire image are shown in the horizontal axis direction,
The frequency is plotted along the vertical axis, and the solid line shows the pixel value distribution of the image in the specific region, and the dotted line shows the pixel value distribution of the entire image. From this distribution, the minimum value M _i0 , the average value A _v0 , and the maximum value M _a0 are obtained in the entire image, and the minimum value M _i1 , the average value A _v1 , and the maximum value M _a1 are obtained in the image of the specific region. . From these calculated values, as shown in the lower part of the figure, X
Pixel values are taken in the axial direction, and LUT is taken as a relative value in the Y-axis direction as a percentage. Here, in the entire image, points are arranged by associating M _i0 with 0, A _v0 with 50, and M _a0 with 100, and the LUT is created with the inclination represented by the line segment connecting these points (in the figure). (A)). In the image of the specific area, M _{i1 is set} to 0,
A point is arranged by associating A _v1 with 50 and M _a1 with 100, and an LUT is created with an inclination represented by a line segment connecting these points ((b) in the figure). From this figure the lower, LUT used for gradation conversion of the specific region, LUT values 0, LUT value between M _a0 -M _a1 100 next between M _i0 -M _i1 pixel values, these gradation Understand that it is damaged. Therefore, in order not to impair the gradation of the entire image, the LUT value needs to be a value that follows a certain slope. Therefore, first, M _i0 −M
_In order to have the gradation between _i1, the pixel value in the lower part of the figure-LUT
When a dotted line parallel to the vertical axis is drawn on M _i1 of the graph of and the distance to the intersection (point A ₂ ) with (a) is h ₁ , 0 <P <h ₁ is obtained on this dotted line. Place point p, point P and point A
_{Connect 0} and draw a line segment. Next, in order to provide gradation between M _a0 -M _a1, M of the graph of pixel values -LUT of the lower in Fig.
Pull the vertical axis and parallel dotted lines in _a1, when the (a) h _2, the distances to the intersection (point B ₂₎ with (b) h ₃ a distance to the intersection of the (= 100), this H ₂ <Q <h ₃ on the dotted line
Then, a point Q is set so that a line segment connecting the point Q and the point P is drawn. Finally, draw a dotted line parallel to the vertical axis on M _a0 , and
Draw a line segment connecting the intersection point (point C ₀ ) with the point Q and the line segment from the point A ₀ to the point C ₀ connected by such a polygonal line.
T is created.

The steps of displaying an image on the display control device 12 by gradation conversion of the image stored in the image memory 7 using the LUT created by the LUT synthesizing means 10 as described above are shown in FIGS. It will be described with reference to FIG. Note that one frame of the DR image is stored in the image memory.

Step 501. For the DR image in the image memory 7, the gradation conversion unit 9 performs gradation conversion of the image using the LUT 15 of the entire LUT 8 a, and the image is input to the display control device 12.

Step 502. The operator of the image processing device 30 observes the image of the display control device 12 in step 501 to determine a specific area, designates a box-shaped cursor as shown in the upper right part of FIG. I do. At this time, the input 1 corresponding to the above is also stored in the image memory 7.
4 is played.

Step 503. The LUT 8b for the specific area is used to create an LUT for the specific area determined by the corresponding input 14 to the image memory 7 in step 502.

Step 504. The LUT for the entire image created in step 501 and the LUT for the specific area created in step 503 are combined by the LUT combining means 10 to create an LUT. Note that this synthesizing method is similar to that shown in FIG.
It is performed according to the explanation using.

Step 505. The gradation conversion means 9 performs gradation conversion on the image in the image memory 7 using the LUT 16 synthesized in step 504.

Step 506. The image subjected to the gradation conversion in step 505 is displayed on the display control device 12. In the present embodiment, the case in which there is one specific area has been described. However, even if there are a plurality of specific areas, there are as many points as the specific areas corresponding to the points P and Q of the polygonal line. It goes without saying that the LUT is created from the line segment connecting the points corresponding to the points P and Q.

[0019]

The present invention has the following effects.
LUT used for gradation conversion in the image processing apparatus of the present invention
Since the image other than the specific region in the entire image can be provided with the gradation, the tone of the image other than the specific region is not impaired. Therefore, since the positional relationship between the entire image and the image of the specific region becomes clear, when moving the specific region while diagnosing, it is not necessary to repeat the gradation conversion for the entire image and the gradation conversion for the specific region alternately. Has the effect of improving.

[Brief description of drawings]

FIG. 1 is a block diagram of an image processing apparatus of the present invention.

FIG. 2 is a diagram showing a method of creating an LUT used for gradation conversion in an image processing apparatus for explaining an embodiment of the present invention.

FIG. 3 shows DR as a typical example of a conventional medical image diagnostic apparatus, the positioning of the image processing apparatus in this DR, and a block diagram of this image processing apparatus.

FIG. 4 is a diagram showing a method of creating an LUT used for gradation conversion in a conventional image processing apparatus.

FIG. 5 is a flowchart showing a gradation conversion process using an LUT in the image processing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 7 image memory 8 LUT 8a whole image LUT 8b image LUT for specific area 9 gradation conversion means 10 LUT synthesizing means 11 operator console 12 display control device 21 X-ray tube 22 incident X-ray tube 23 bed 24 subject 25 Transmission X-ray 26 X-ray detector 27 TV camera 30 Image processing device 40 Whole image 50 Image of specific region

Claims (1)

[Claims] 1. An image memory for storing an image, a means for converting an image in the image memory into an arbitrary gradation using a look-up table, and an image whose gradation is converted by the gradation converting means. In the image processing apparatus including the display control device, the image displayed on the display control device, and the operation console for inputting the specific region of the image memory corresponding to the image, the specific region input on the operation console is displayed. A lookup table used for image gradation conversion on the screen of the display control device;
An image processing apparatus comprising: a lookup table used for tone conversion of an entire image; and means for synthesizing these lookup tables, and performing tone conversion using the synthesized lookup table.