JP3439585B2 - Image display method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display method and apparatus for displaying an image on a light emitting display means such as a CRT, and more particularly to an image display method and an image display method for gradation-converting an image signal to display on the light emitting display means. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, when an image is displayed on a light emitting display means such as a CRT, the gradation characteristic of the light emitting display means (the relationship between the image signal value and the logarithmic value of the brightness on the light emitting display means) is made linear. A gradation conversion table is provided, and the image signal is subjected to gradation conversion in accordance with this gradation conversion table before the image is displayed.

[0003]

However, the luminance of the light emitting display means is deteriorated due to the deterioration of the display surface of the light emitting display means (for example, the tube surface of the CRT) or the deterioration of the electron gun for performing the light emitting display. Sometimes. That is, as shown in FIG. 8A, in the luminance characteristic representing the relationship between the image signal and the luminance, the luminance characteristic Lorg before deterioration and the luminance characteristic Ldep after deterioration express the same luminance even if the same voltage is applied. I will not be able to. If the luminance of the light emitting display means is deteriorated in this way, even if the gradation of the image signal is converted by the gradation conversion table, the gradation characteristic reproduced by the light emitting display means as shown in FIG. However, the high density portion (low luminance portion) A is crushed as shown by the characteristic γdep after deterioration, and the contrast of this portion A cannot be reproduced. As described above, if the low luminance (high density) portion of the image is not reproduced, the image information is lost, and further, the appearance of the image is changed.

In view of the above circumstances, the present invention provides a light emitting display means.
Brightness can be corrected and images can be displayed well.
An object of the present invention is to provide an image display method and apparatus.
Of.

[0005]

[0006]

An image display method according to the present invention is an image display method for performing gradation conversion processing on an image signal and displaying the image signal on a light emitting display means,
The light and dark pattern near the lowest brightness of the light emitting display means is
Displayed on the light emitting display means, a bright and dark pattern near the lowest brightness
The light emission based on whether the contrast of the
Enter the judgment as to whether the brightness of the display is deteriorated.
It is characterized in that the brightness deterioration of the light emitting display means is corrected when the brightness deterioration is advanced .

The image display device according to the present invention is an image display device which performs gradation conversion processing on an image signal and displays the image signal on the light emitting display means.
The light and dark pattern near the lowest brightness of the
Shows the contrast of the light and dark patterns near the lowest brightness
Brightness of the light emitting display means based on whether or not the
Detector that accepts input to determine whether or not
And a correction unit that corrects the luminance deterioration of the light emitting display unit when the luminance deterioration is progressing .

[0008]

According to the image display method and apparatus of the present invention , the light emitting display means such as a CRT has the lowest brightness.
Displays a pattern of light and dark near the brightness, and light and dark near the lowest brightness
Based on whether the contrast of the pattern is visible
It is necessary to enter a judgment as to whether or not the brightness of the light emitting display means has deteriorated.
Force is received and the luminous display
Since the brightness deterioration of the step is corrected, the light emitting display means
Even if the deterioration occurs, the desired gradation can be obtained by correcting the gradation.
Can be set.

[0009]

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an image display device according to the present invention. The illustrated display device is a display device that displays a medical image, and a gradation correction unit 1 that corrects the gradation of the image signal S and an image signal based on the image signal that has been gradation-corrected by the gradation correction unit 1. A CRT 2 as an example of a light emitting display means for displaying an image to be carried, and a CRT
No. 2 deterioration detecting unit 3, a storage unit 4 storing a plurality of correction gradation conversion tables predetermined according to the deterioration amount of the CRT 2, and the CRT detected by the detecting unit 3.
The table selecting unit 5 selects a desired correction gradation conversion table from a plurality of correction gradation conversion tables stored in the storage unit 4 according to the deterioration amount of 2.

In the normal gradation conversion, the image signal S is first input to the gradation correction means 1. The image signal S is gradation-converted by the gradation conversion table shown by the broken line in the fourth quadrant of FIG. 2 and further CRT shown by the broken line in the first quadrant.
It is converted by the gradation characteristic of No. 2 and displayed as a visible image on the CRT 2, and finally exhibits the gradation characteristic shown by the broken line in the second quadrant. .

Next, the operation of the image display device according to the present invention will be described. First, the detecting means 3 detects the deterioration of the brightness of the CRT 2. The detection of the deterioration of the brightness is performed as follows. FIG. 3 is a schematic diagram showing the configuration of the CRT 2. As shown in FIG. 3, in the CRT 2, the electron beam emitted from the electron gun 11 is accelerated by the grid 12 and deflected by the deflection yoke 13 to collide with the phosphor screen 10, and the phosphor screen emits light according to the intensity of the beam. It is a thing. The luminance deterioration of the CRT 2 is almost always due to the deterioration of the electron gun 11 (mainly cathode emission). Here, the deterioration of the cathode can be monitored by a decrease in the anode current amount (cathode current amount). Therefore, the luminance deterioration of the CRT 2 can be monitored by constantly monitoring the amount of anode current (cathode current). In the present embodiment, the deterioration of the brightness of the CRT 2 is detected by comparing the anode current value corresponding to the pixel value indicating the maximum brightness value with the initial value.

When the detecting means 3 detects the deterioration of the brightness of the CRT 2, the table selecting means 5 selects a desired correction gradation conversion table from the plurality of correction gradation conversion tables stored in the storage means 4. select. The selection of this correction gradation conversion table is performed as follows. FIG. 4 is a diagram showing an example of gradation characteristics of the CRT 2 after conversion by the correction gradation conversion table. In FIG. 4, Lorg is the initial value of the luminance characteristic of CRT2, γorg is the initial value of the gradation characteristic, and Ldep is C
Brightness characteristics after deterioration of RT2, γdep is gradation characteristics after deterioration, L ′ is brightness characteristics after conversion by the correction gradation conversion table, and γ ′ is gradation characteristics after conversion by the correction gradation conversion table. Show.

When the region of interest in the image represented by the image signal S is in the high density region, that is, in the low luminance region such as the chest image or the mammo image, the gradation characteristic of the broken line shown in the fourth quadrant of FIG. Is changed as shown by the solid line, or a desired table is selected from the CRT gradation correction tables predetermined according to the luminance deterioration as shown in the fourth quadrant of FIG. 2 and shown in FIG. A gradation characteristic that maintains the gradation in the low luminance (high density) range is realized. By setting the gradation as shown in FIG. 4, γ ′ <γorg and L ′ <Lorg in the high luminance (low density) region, and the gradation characteristic is softened. To γ ′ = γorg, L ′ = Lorg in the low brightness (high density) range
Therefore, it is possible to obtain the same gradation characteristic and the same luminance characteristic as before the luminance of the CRT 2 is deteriorated.
Even if the CRT 2 deteriorates, it is possible to obtain a high-quality reproduced image in which the gradation in the low-luminance (high-density) region does not collapse. In this case, the correction gradation conversion table that can make the gradation of the low luminance (high density) area or the middle density area substantially the same as the gradation before deterioration, or the gradation of the image signal in the entire band of the image signal It is also possible to store a correction gradation conversion table that linearizes the values in the storage means 4 and select these correction gradation conversion tables according to the density range in which the gradation should be maintained. is there.

In the above-described embodiment, the detecting means 3 detects the deterioration of the brightness of the CRT 2 by monitoring the anode current of the CRT 2, but the deterioration of the CRT 2 turns on the switch of the CRT 2. The process progresses during that period, that is, the luminance deterioration of the CRT 2 and the time when the switch of the CRT 2 is on correspond to each other as shown in FIG. Therefore, the time when the switch of CRT2 is on is monitored by the timer,
The gradation of the CRT 2 may be corrected by the gradation correction unit 1 after a lapse of time when the luminance deterioration of the CRT 2 exceeds a certain value.

Further, it is not necessary to automatically detect the luminance deterioration of the CRT 2, but it may be detected manually. For example, the luminance level of the CRT 2 is measured using a luminance meter, the degree of luminance deterioration of the CRT 2 is measured based on the measurement result, and the gradation correction unit 1 is adjusted to correct the gradation of the CRT 2. You may

Further, in the above-mentioned embodiment,
Although the deterioration of the brightness of the CRT 2 is detected by detecting the anode current on the tube surface of the CRT 2, the invention is not limited to this. Since the luminance deterioration often appears as the gradation of the low-luminance portion (high-density portion) is flattened as shown in FIG. 8, an image having a small contrast in the low-luminance portion, such as an SMPTE pattern, is displayed. In this case, the luminance deterioration may be monitored depending on whether or not the contrast of the low luminance portion can be visually recognized. Here, the SMPTE pattern means a pattern as shown in FIG. 6, which is the Society of Mot.
ion Picture and Television Engineers (name of society)
The recommended test pattern for quality control of medical images is ratified by the Radiological Society of North America and recommended for quality control of diagnostic CRTs. Then, the portion representing the 0 to 5% contrast of this SMPTE pattern is the target of the determination of the luminance deterioration of the CRT2. Correct luminance deterioration. In this way, the luminance deterioration of the CRT 2 can be measured by displaying the SMPTE pattern on the CRT 2 and observing whether the bright and dark patterns are hard to see.

In the above-described embodiment, the correction gradation conversion table stored in the storage means 4 is selected by the table selection means 5 based on the detection result of the detection means 3, and the gradation conversion means 1 is selected. 7, the gradation conversion is performed, but as shown in FIG. 7, without providing the pattern selecting means and the storage means, the gradation converting means 1 increases the cathode potential or the cathode potential so that the anode current amount of the CRT 2 increases. The grid potential may be increased. By increasing the cathode potential or the grid potential in this manner, it is possible to increase the luminance of the CRT 2 and correct the luminance deterioration. In this case, it is necessary to leave some margin in the means for applying a voltage to the cathode or grid so that the cathode potential or grid potential in the CRT 2 can be adjusted. When the luminance deteriorates beyond the adjustment range based on this margin, it is preferable to notify the user that the luminance deterioration of the CRT 2 has reached the limit by issuing a warning sound or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image display device according to the present invention.

FIG. 2 is a graph showing gradation characteristics of a gradation conversion table and a CRT.

FIG. 3 is a schematic diagram showing the configuration of a CRT of the image display device according to the present invention.

FIG. 4 is a graph showing an example of gradation characteristics of a corrected CRT.

FIG. 5 is a graph showing the relationship between CRT luminance deterioration and time.

FIG. 6 is a diagram showing an SMPTE pattern.

FIG. 7 is a block diagram showing another embodiment of the image display device according to the present invention.

FIG. 8 is a graph showing a state of deterioration of gradation characteristics due to deterioration of CRT.

[Explanation of symbols]

1 gradation correction means 2 Luminous display means (CRT) 3 detection means 4 storage means 5 Table selection means S image signal

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Claims (2)

(57) [Claims] 1. An image display method for performing gradation conversion processing on an image signal and displaying the image signal on a light emitting display means, wherein a bright and dark pattern near the lowest brightness of the light emitting display means is provided.
The turn is displayed on the light emitting display means, and the light near the minimum brightness is displayed.
Based on the visibility of the dark pattern contrast
It is possible to determine whether or not the brightness of the light emitting display means has deteriorated.
An image display method characterized by receiving a disconnection input and correcting the luminance deterioration of the light emitting display means when the luminance deterioration is progressing . 2. An image display device for subjecting an image signal to gradation conversion processing to display the image signal on a light emitting display means, wherein a bright and dark pattern near the lowest brightness of the light emitting display means is provided.
The turn is displayed on the light emitting display means, and the light near the minimum brightness is displayed.
Based on the visibility of the dark pattern contrast
It is possible to determine whether or not the brightness of the light emitting display means has deteriorated.
The detection means that accepts the disconnection input,
And a correction unit that corrects the luminance deterioration of the light emitting display unit.