JP2006000187A - Display method of test pattern, and medical image displaying apparatus and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the precision of visibility of an operator to execute a calibration more precisely by the visual observation of the operator. <P>SOLUTION: When the calibration processing is executed, one pattern of N test patterns [n] is switched and displayed on one screen of a display section 13 respectively. Also, a visual characteristic of an observer and the information of an observation condition which are preset and stored in a storing section 16 are read out and the line pair density in the test patterns [n] is determined on the basis of the above readout information. Then, when the one test pattern is displayed on the one screen, the individual test patterns [n] are displayed with the determined line pair density. Also, for all the test patterns [n], the background region is displayed and driven by a driving level DDL<SB>0.2</SB>corresponding to the intensity level of 20% of the maximum intensity level so that it has the intensity level corresponding to 20% of the maximum intensity level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a test pattern display method used when correcting display gradation characteristics of a medical image display device by visual observation by an observer, a medical image display device that displays a test pattern, and a program.

  In the medical field, monitor diagnosis in which a patient's medical image obtained by various examination imaging such as X-ray imaging, MRI (Magnetic Resonance Imaging) imaging, ultrasonic imaging, etc. is displayed on a monitor for interpretation is widespread. . In addition, with the development of networks inside and outside hospitals, it is possible to interpret the same image on monitors at different locations. However, if the monitor used for interpretation is of different types such as LCD (Liquid Crystal Display), CRT (Cathode Ray Tube), etc., the display characteristics will be different, so the appearance of the image will be different, and the same type of monitor. However, the appearance of the image may still differ depending on the degree of deterioration due to its use and the installation environment.

  In this way, if there are variations in the appearance of images on individual monitors, the diagnostic accuracy will be affected. Therefore, correction of display tone characteristics (hereinafter referred to as calibration) is performed to change the appearance of images on each monitor. It is necessary to unify. Conventionally, calibration is performed using a luminance meter. However, since the luminance meter is generally expensive, calibration using the luminance meter is expensive. In addition, when there are a number of monitors for image interpretation, the work of calibrating each monitor with a luminance meter one by one is very troublesome and complicated.

On the other hand, a method is also proposed in which an operator visually confirms a calibration result after performing calibration using a luminance meter (see, for example, Patent Document 1). In the calibration method described in Patent Document 1, as shown in FIG. 12, a plurality of test patterns displayed at different brightness levels are displayed on a monitor, and the brightness of each test pattern is displayed to an operator (observer). The level is confirmed visually.
JP-A-11-327501

  However, as shown in FIG. 12, when calibration is performed by displaying a plurality of test patterns on one screen, the test pattern adjacent to the judgment target test pattern and the adjacent test pattern are in the operator's field of view. As a result, it becomes difficult to perform accurate calibration.

  An object of the present invention is to improve the accuracy of visual recognition by an operator and make it possible to perform calibration by visual observation of the operator more accurately.

The invention according to claim 1 is a test pattern display method,
A test pattern display method for displaying a plurality of test patterns for correcting display gradation characteristics of a medical image display device on a display unit of the medical image display device,
The plurality of test patterns are switched to one screen one pattern at a time and displayed on the display unit, and the display conditions of the test patterns displayed on the one screen are based on information on the visual characteristics and observation conditions of the observer set in advance. And the test pattern is displayed under the determined display condition.

The invention described in claim 2 is the test pattern display method according to claim 1,
The background area of the test pattern displayed on each switching screen is displayed at a constant luminance level.

The invention described in claim 3 is the test pattern display method according to claim 1,
The background area of the test pattern displayed on each switching screen is displayed at a luminance level corresponding to the luminance level of the test pattern on each switching screen.

The invention according to claim 4 is the test pattern display method according to any one of claims 1 to 3,
The test pattern is formed of a plurality of line pairs in which two line-shaped display areas displayed at different luminance levels are used as a pair of line pairs,
When displaying a test pattern on each switching screen, the density of the line pairs formed in the pattern is determined based on the visual characteristics of the observer and information on the observation conditions as the display conditions, and the determined line pairs The test pattern is displayed at a density of.

The invention according to claim 5 is the test pattern display method according to any one of claims 1 to 4,
The observation conditions are an observation distance from an observer to a display screen and a pattern size of a test pattern to be observed.

The invention according to claim 6 is a medical image display apparatus,
Display means for displaying medical images;
A plurality of test patterns for correcting display gradation characteristics in the display means are switched one pattern at a time to be displayed on the display means, and display conditions of test patterns to be displayed on the one screen are set in advance. Control means for determining based on the observer's visual characteristics and information on the observation conditions, and displaying the test pattern under the determined display conditions;
It is characterized by providing.

The invention described in claim 7
On the computer,
A plurality of test patterns for correcting display gradation characteristics of the medical image display device are switched on a screen one by one and displayed on the display means, and display conditions for the test patterns displayed on the one screen are set in advance. And a program for realizing a function of displaying the test pattern under the determined display conditions.

  According to the first, sixth, and seventh aspects of the invention, when the test pattern is displayed, the display is switched and displayed one pattern at a time on the screen. When the test pattern is inserted, it is possible to prevent the visual accuracy from being lowered. In addition, since the test pattern is displayed under display conditions based on the visual characteristics of the observer and the observation conditions, the observer's visibility with respect to the test pattern is improved, and the display gradation characteristics can be corrected more accurately.

  According to the invention described in claim 2, since the luminance level of the background area of the test pattern is unified at a constant luminance level in each switching screen, the luminance level of the background area for the test pattern displayed on each switching screen is The influence on the visibility can be reduced, and stable display gradation characteristics can be corrected.

  According to the third aspect of the present invention, the luminance level of the background area of the test pattern displayed on each switching screen changes according to the luminance level when each test pattern is displayed. When a background area having a brightness level that is the same as or similar to the brightness level of the pattern enters the viewer's field of view, the viewer adapts to the brightness level and the visual accuracy improves. Therefore, the display gradation characteristic can be corrected more accurately.

  According to the invention described in claim 4, as the display condition, the density of the line pairs formed in the test pattern is determined so as to improve the observer's visibility based on the observer's visual characteristics and the observation condition. As a result, the display gradation characteristics can be corrected more accurately.

  According to the fifth aspect of the present invention, it is possible to determine the test pattern display conditions that improve the observer's visibility based on the observation conditions of the observation distance and the pattern size of the test pattern.

First, the configuration will be described.
FIG. 1 shows an internal configuration of a medical image display apparatus 10 in the present embodiment.
As illustrated in FIG. 1, the medical image display apparatus 10 includes a control unit 11, an operation unit 12, a display unit 13, a communication unit 14, a RAM (Random Access Memory) 15, and a storage unit 16.

  The control unit 11 develops various control programs such as a system program stored in the storage unit 16 and a calibration processing program according to the present invention in the RAM 15, and centrally controls the operation of each unit according to the control program.

  In the calibration process, the level range of the drive level that can be displayed and driven by the medical image display device 10 is divided into N equal parts, and each of the N test patterns in which the N equally divided drive levels are set has the drive level. The information is output to the display unit 13 together with the information, and each test pattern is displayed and driven at a set drive level. That is, each test pattern is displayed at a luminance level corresponding to each drive level divided into N equal parts. Each test pattern is formed by a plurality of pairs of a pair of line-like regions (referred to as line pairs) in which different drive levels are set so as to be displayed at different luminance levels.

  When displaying the N test patterns on the display unit 13, the control unit 11 outputs screen data in which one test pattern is arranged on one screen to the display unit 13 together with information on the drive level set in the test pattern. As a result, one pattern is switched and displayed on one screen. Also, information on the visual characteristics and observation conditions of the observer set in advance and stored in the storage unit 16 is read out, and the line pair density in the test pattern is determined based on the read out information (line pair density). The line pair density information is output to the display unit 13 as test pattern display condition information. Then, each test pattern is displayed at the line pair density determined on each switching screen. In each switching screen, the background area of the test pattern is driven and displayed at a driving level of 20% of the maximum driving level. The display condition of the background area is based on DICOM (Digital Imaging and Communication in Medicine) standard. That is, the control means can be realized by the cooperation of the control unit 11 and the calibration processing program.

  When the brightness level adjustment operation is performed on the displayed test pattern via the operation unit 12, the drive level in the test pattern is changed according to the operation instruction and the display unit 13 drives the display. When the adjustment operation is completed, a correction curve for correcting the display gradation characteristics of the medical image display device 10 is obtained based on the drive level value of each line constituting the line pair in each test pattern. Then, an LUT (Look Up Table) that defines an output value for the input value of the correction curve is created and stored in the storage unit 16.

  The display characteristic refers to the correlation between the drive level and the luminance level, and the display gradation characteristic refers to the correlation between the input level of the pixel value in the image data to be displayed and the luminance level when the image data is displayed and output. Say.

  The operation unit 12 includes a keyboard and a mouse. When these keyboard and mouse are operated, an operation signal corresponding to the operation is generated and output to the control unit 11. The operation unit 12 may have a touch panel formed integrally with the display unit 13.

  The display unit 13 is a display unit having a monitor such as an LCD or a CRT, and drives the monitor according to control by the control unit 11. When each test pattern [n] is displayed, the monitor is displayed and driven at a drive level designated according to the drive level information input together.

  The communication unit 14 has communication interfaces such as a NIC (Network Interface Card), a modem, and a router, and performs data communication with external devices on a LAN (Local Area Network) provided in the hospital via these communication interfaces. I do. For example, a medical image data is acquired by accessing an image server in which medical images of patients are managed in a database.

  The RAM 15 forms a work area for temporarily storing various programs executed by the control unit 11 and data processed by these programs.

  The storage unit 16 is configured by a magnetic or optical recording medium, a semiconductor memory, or the like, and stores various control programs such as a system program and a calibration processing program. Also, as parameters used during the calibration process, the observation conditions of the observer set in advance via the operation unit 12 (observation distance from the observer to the display screen, pattern size of the test pattern to be observed, etc., here. The observation distance is set to 500 mm, and the pattern size is set to 17.5 mm × 17.5 mm.), The visual characteristics of the observer (for example, the number of line pairs per viewing angle when the visibility is the highest, here. In this case, it is assumed that four line pairs are set per viewing angle, and information such as the display screen size of the display unit 13 is stored. The created LUT for correcting the display gradation characteristics of the medical image display device 10 is stored.

  The observer means a person who observes the medical image when the medical image is displayed, and may be the same person as the operator who performs the calibration or another person. Further, in this embodiment, the visual characteristics of the set observer are characteristics common to those who make such observation, and the display condition of the test pattern [n] is determined based on the general visual characteristics. However, the visual characteristics of each observer may be obtained by measurement, and the display condition of the test pattern [n] may be determined according to the visual characteristics of the individual observer.

The storage unit 16 stores a plurality of test pattern data used in the calibration process.
FIG. 2 shows an example test pattern.
As shown in FIG. 2, the test pattern [n] (n in parentheses indicates a pattern number assigned to identify each test pattern. N = 1,..., N) is driven on the display unit 13. The level range of possible drive levels, that is, 0 to the maximum drive level DDL _max is divided into N equal parts, and the drive level is created corresponding to each of the N drive levels. In the present embodiment, an example of dividing into eight parts is shown, but it is assumed that the number of N to be equally divided can be appropriately set depending on the accuracy of calibration. When it is desired to perform calibration with high accuracy, it is preferable to increase the N number.

In each test pattern [n], as shown in FIG. 3, a plurality of line pairs are formed by using two lines with different drive levels as a pair of line pairs. A drive level in which the maximum drive level DDL _max is equally divided into N is set in one line of the line pair, and a drive level higher than the drive level set in the one line is set in the other line. Yes. The line in which the drive level divided into N is set is referred to as a reference target, and the line in which the drive level is set to be higher than the reference target is referred to as an adjustment target.

When the drive level of the reference target is DDLK [n] and the drive level of the adjustment target is DDLT [n], the drive level DDLK [n] is expressed by the following formula 1, and DDLT [n] is expressed by the following formula 2.

Hereinafter, a calibration process executed by the medical image display apparatus 10 of the present embodiment using the test pattern [n] will be described.
FIG. 4 is a flowchart for explaining the calibration process. This process is started when calibration is selected from the environment setting menu.

  In the calibration process shown in FIG. 4, first, information on the observation conditions and visual characteristics of the observer is read from the storage unit 16, and lines for displaying each test pattern [n] based on the read information are displayed. The pair density J is determined (step S1).

A method for determining the line pair density will be described.
As shown in FIG. 5, C (unit; lp / deg) is the number of line pairs (hereinafter, the unit of the number of line pairs is indicated by lp) and the observation distance is X (unit; mm), when the viewing distance at the viewing distance X is Y (mm), the line pair density J (lp / mm) that is most easily recognized can be obtained from the following equation 3.

  In the case of a line pair test pattern, it is known that the human visibility rate is highest when the viewing angle is 3 to 5 line pairs per 1 degree viewing angle (hereinafter referred to as deg). In the present embodiment, the line pair density J is calculated by applying C = 4 (lp / deg). A parameter set in advance in the storage unit 16, that is, X = 500 mm is applied to the observation distance X, and the line pair density J = 0.46 lp / mm is calculated from the above equation 3.

  In this embodiment, the observation distance is set to 500 mm in advance, and the line pair density J having the highest recognition rate is set when the observation distance is 500 mm. However, the present invention is not limited to this, and calibration is performed. When performing, it is good also as calculating the line pair density J in the control part 11 based on the information of the number of line pairs with the highest visual recognition rate per 1 degree of viewing distance and viewing angle input each time.

  Next, the pattern number n of the test pattern to be displayed is set to an initial value n = 1 (step S2). When the pattern number n is set, the data of the test pattern [n] of the pattern number n is read from the storage unit 16 and data processing is performed, and a line pair is formed with the determined line pair density J. . Then, the test pattern [n] in which the line pair is formed with the determined line pair density is displayed on the display unit 13 with a preset pattern size of 17.5 mm × 17.5 mm. (Step S3).

FIG. 6A shows a display example of the test pattern [2].
As shown in FIG. 6A, only one pattern is displayed on the screen as the test pattern [2], the pattern size is 17.5 mm × 17.5 mm, and the line pair density in the pattern is 0.46 lp. In other words, the data is processed and displayed in the control unit 11 so that 17.5 mm × 0.46 lp / mm = 8.05 lp is formed in the pattern of the above size. The pattern size is not limited to 17.5 mm × 17.5 mm and can be set to other sizes.

The background area of the test pattern [n] is display-driven at a drive level DDL _0.2 corresponding to a luminance level of 20% of the maximum luminance level so that the background level corresponds to 20% of the maximum luminance level according to the DICOM standard. Is done. The drive level of this background area is common to all test patterns [n], and the brightness levels of the background areas of each test pattern [n] are all the same. For example, when the display is switched to the test pattern [6], the brightness level of the background area is the same as the brightness level of the background area of the test pattern [2] shown in FIG. It becomes.

  Note that the test pattern [n] may be arranged in a horizontal line as shown in FIG.

  When the test pattern [n] is displayed in this way, the operator can make the minimum luminance level difference between the adjustment target and the reference target in the test pattern [n] visually visible via the operation unit 12. Until the brightness level of the adjustment target is increased or decreased. The minimum visually recognizable luminance level difference is a luminance level difference at the limit where the luminance level difference can be visually recognized as a result of the operator adjusting the luminance level of the adjustment target in accordance with the luminance level of the reference target. Specifically, when the luminance level of the adjustment target is lowered by one more level, the luminance level is adjusted until the operator cannot distinguish the luminance level difference between the adjustment target and the reference target.

  In the medical image display device 10, when an operation for adjusting the luminance of the adjustment target is performed via the operation unit 12, the operation signal is analyzed, and it is determined whether an operation instruction has been given to increase or decrease the luminance level. (Step S4). When an operation instruction is given to increase the luminance level (step S4; up), the drive level DDLT [n] of the adjustment target is increased by one level, and the adjustment level being displayed is increased by the drive level DDLT [n]. The display is driven (step S5). On the other hand, when an operation instruction is given to reduce the luminance (step S4; down), the drive level DDLT [n] of the adjustment target is lowered by one level, and the drive level DDLT [n] in which the adjustment target being displayed is lowered. The display is driven (step S6). That is, the luminance level is raised and lowered by one drive level according to one operation. Even if the operation to lower the luminance level of the adjustment target is repeated, the adjustment operation that is lower than the drive level of the reference target is disabled so that the luminance level of the adjustment target does not become lower than the luminance level of the reference target. The adjustment operation is limited.

When the drive level adjustment operation is performed, it is determined whether or not the adjustment operation has been completed (step S7). If the adjustment operation is still being performed via the operation unit 12 (step S7; N), step Returning to the process of S4, the luminance level is adjusted in accordance with the input operation instruction. On the other hand, when the adjustment operation is completed (step S7; Y), the drive level DDLT ′ [n] of the adjustment target of the test pattern [n] at the end of the adjustment is determined, and the drive level DDLT ′ [n] and the reference target are determined. A difference ΔDDL _jnd [n] from the driving level DDLK [n] is calculated (step S8). This ΔDDL _jnd [n] corresponds to the minimum luminance level difference visible to the operator in the test pattern [n].

  Next, it is determined whether or not the adjustment operation described above has been completed for all test patterns [n] (step S9). If the adjustment operation has not been completed for all the test patterns (step S9; N), the pattern number n is incremented by 1 (step S10), the process returns to step S3, and the adjustment operation is performed for the next test pattern [n]. Is repeated. That is, only one test pattern [n] is displayed on one screen, and each test pattern [n] is sequentially switched and displayed in the order of the pattern numbers.

When all the test patterns [n] are displayed and the adjustment operation is completed (step S9; Y), as shown in FIG. 8, the reference target drive level DDLK [n] for each test pattern [n] is displayed. ΔDDL _jnd [n] calculated in this way is plotted, and an approximate function g (DDL) of each plotted point is calculated (step S11). That is, each ΔDDL _jnd [n], which is a discrete value, is interpolated to obtain a continuous value corresponding to the drive level DDL in the entire level range. That is, the approximate function g (DDL) is a function indicating the correspondence between the drive level DDL and the minimum drive level difference ΔDDL _jnd [n].

Next, a function h (DDL) obtained by integrating the calculated function g (DDL) for each drive level DDL is calculated by the following expression 4 (step S12). The g (DDL) indicates the slope of h (DDL).

FIG. 9 is a diagram illustrating h (DDL). The X axis represents the drive level DDL, and the Y axis represents h (DDL) with respect to the drive level DDL. At this time, if the value of h (DDL) at the maximum drive level DDL _max that can be driven by the medical image display device 10 is I _max , h (DDL) so that this I _max corresponds to the maximum drive level DDL _max. Is normalized, and f (DDL) indicating normalized h (DDL) is calculated by the following equation 5 (step S13).

Then, the drive level DDL, which is the unit of the X axis in FIG. 9, is replaced with the input level of the image value (P _max in the figure indicates the maximum gradation that can be expressed by the medical image display device 10), and in the unit of the Y axis. A curve as shown in FIG. 10 is created by replacing a certain h (DDL) with the calculated f (DDL). With this curve, it is possible to obtain a drive level that realizes a corresponding luminance level from the input level of the pixel value so that the input level of the pixel value is finally displayed at a luminance level visually linear to the input level. it can. That is, this curve is a correction for correcting display gradation characteristics (that is, the relationship between the input level of the pixel value and the luminance level when actually displayed according to the input level) according to the display characteristics of the medical image display device 10. It is a curve. In the control unit 31, an output value for the input value of the correction curve is calculated and tabulated, and an LUT is created (step S14). When the created LUT is stored in the storage unit 16 as an LUT for correcting the display gradation characteristics of the medical image display device 10, this processing is terminated.

  When displaying a medical image, the created LUT is referred to, a drive level (output value) corresponding to the input level (input value) of the pixel value of the medical image is obtained, and display drive is performed at the drive level. . Since the drive level obtained by the LUT is a drive level that is corrected so that the luminance level when the drive display is performed at the drive level has a linear relationship with the input level of the pixel value, the medical image display The display gradation characteristics of the medical image display apparatus 10 are corrected according to the display characteristics of the apparatus 10 and the visual characteristics of the operator.

  As described above, in the present embodiment, when the test pattern for calibration is displayed, the pattern is switched and displayed one pattern at a time. Therefore, it is possible to prevent the visual recognition accuracy from being lowered by entering a test pattern other than the test pattern to be visually recognized in the visual field of the operator. Therefore, more accurate calibration can be performed.

  Further, as the display condition of the test pattern [n], the line pair density is determined so as to obtain the best visual recognition rate based on the visual characteristics of the observer and the observation condition, and each test pattern [n ] Is displayed, the visibility of the test pattern [n] is improved, and more accurate calibration can be performed.

Furthermore, even when the test pattern [n] to be visually recognized is switched and displayed, the background area of each test pattern [n] has a constant luminance level (20% of the maximum luminance level) in accordance with the DICOM standard. The driving level of the background area is unified and set to the driving level DDL _0.2 corresponding to the luminance level of 20% of the maximum luminance level, so that the influence of the background area on the test pattern [n] is reduced. And stable calibration can be performed.

  In addition, the description content in this embodiment is a suitable example of the medical image display apparatus 10 to which the present invention is applied, and is not limited to this.

For example, in the above description, when each test pattern [n] is switched and displayed for each screen, the background area of the test pattern is the same drive level (maximum luminance level) in any test pattern [n]. Display driving is performed at a driving level DDL _0.2 corresponding to 20%), but the present invention is not limited to this, and the background area is changed according to the driving level (luminance level) set in each test pattern [n]. Also good. For example, when the test pattern [1] is displayed as shown in FIG. 11, the background area is displayed and driven at the same drive level as the drive level DDLK1 of the reference target, and the test pattern 3 is displayed. When the test pattern [5] is displayed and driven at the reference target drive level DDLK [3], the background area is displayed and driven at the reference target drive level DDLK [5]. The display is made such that the luminance level of the background area of the test pattern [n] is the same as the luminance level of the reference target of the test pattern [n].

  In this way, by displaying the background area at a luminance level corresponding to each test pattern [n], the background area close to the luminance level together with the test pattern [n] enters the visual field, so that the operator's eyes have the luminance. The accuracy of visual recognition improves. Therefore, more accurate calibration can be performed. Note that the above description is an example, and if the display gradation of the background area changes according to the test pattern [n], for example, the driving level of the background area is set to the average value of DDLT [n] and DDLK [n]. For example, other values may be set.

It is a figure which shows the internal structure of the medical image display apparatus 10 in this Embodiment. It is a figure which shows the test pattern [n] displayed at the time of a calibration process. It is a figure explaining the line pair which forms test pattern [n]. 5 is a flowchart for explaining calibration processing executed by the medical image display apparatus 10. It is a figure which shows the visual field range Y when the viewing angle is 1 degree and the observation distance X. It is a figure which shows the example by which the test pattern [n] and the background area | region were display-driven by the fixed drive level. It is a figure which shows the example of a display arrange | positioned so that the line of a test pattern [n] may become a horizontal line. It is a figure which shows the function g (DDL). It is a figure which shows the function h (DDL). 4 is a diagram illustrating a correction curve for correcting display gradation characteristics of the medical image display apparatus 10; FIG. It is a figure which shows the example by which the background area | region of test pattern [n] was display-driven by the same drive level as the reference | standard target in test pattern [n]. It is a figure which shows the example of a display of the conventional test pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Medical image display apparatus 11 Control part 12 Operation part 13 Display part 14 Communication part 15 RAM
16 Memory unit

Claims (7)

A test pattern display method for displaying a plurality of test patterns for correcting display gradation characteristics of a medical image display device on a display unit of the medical image display device,
The plurality of test patterns are switched to one screen one pattern at a time and displayed on the display unit, and the display conditions of the test patterns displayed on the one screen are based on information on the visual characteristics and observation conditions of the observer set in advance. And displaying the test pattern under the determined display conditions.   2. The test pattern display method according to claim 1, wherein the background area of the test pattern displayed on each switching screen is displayed at a constant luminance level.   2. The test pattern display method according to claim 1, wherein the background area of the test pattern displayed on each switching screen is displayed at a luminance level corresponding to the luminance level of the test pattern on each switching screen. The test pattern is formed of a plurality of line pairs in which two line-shaped display areas displayed at different luminance levels are used as a pair of line pairs,
When displaying a test pattern on each switching screen, the density of the line pairs formed in the pattern is determined based on the visual characteristics of the observer and information on the observation conditions as the display conditions, and the determined line pairs The test pattern display method according to claim 1, wherein the test pattern is displayed at a density of 5.   The test pattern display method according to claim 1, wherein the observation conditions are an observation distance from an observer to a display screen and a pattern size of a test pattern to be observed. Display means for displaying medical images;
A plurality of test patterns for correcting display gradation characteristics in the display means are switched one pattern at a time to be displayed on the display means, and display conditions of test patterns to be displayed on the one screen are set in advance. Control means for determining based on the observer's visual characteristics and information on the observation conditions, and displaying the test pattern under the determined display conditions;
A medical image display device comprising: On the computer,
A plurality of test patterns for correcting display gradation characteristics of the medical image display device are switched on a screen one by one and displayed on the display means, and display conditions for the test patterns displayed on the one screen are set in advance. A program for realizing the function of determining based on the visual characteristics of the observer and information on the observation conditions and displaying the test pattern under the determined display conditions.