JPH1091131A - Image display method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a gradation characteristic to desired one more precisely than conventional one, in an image display device. SOLUTION: From plural gradation correction tables 111, 112,... stored in a storage part 110, a selecting part 120 selects a gradation correction table suitable for correcting a gradation characteristic C of a display part 150 to be approximately linear, and an adjusting part 130 corrects the gradation characteristic C more precisely to desired one by adjusting a rotation value, a center of the rotation, and a parallel shift value of the correction curve expressing the selected gradation correction table.

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, and more particularly to an image display method and apparatus. It relates to improvement of gradation characteristics.

[0002]

2. Description of the Related Art A radiographic image recorded on an X-ray film or a stimulable phosphor sheet is read to obtain an image signal, and after subjecting this image signal to appropriate image processing, a visible image represented by the image signal is converted to a CRT. Display on an image display device such as a liquid crystal display or a liquid crystal display is performed in various fields including the field of medical images.

Here, when a visible image is displayed on an image display device, a gradation characteristic of the image display device (input image signal and brightness on the image display device (including brightness corresponding to the brightness in a liquid crystal display)) is paired. Relationship with numerical values) becomes important.

That is, for two or more image display devices,
Those having completely the same gradation characteristics and the same output luminance with respect to a predetermined input image signal can display a visible image having the same gradation by the predetermined input image signal. Due to differences in manufacturers and models, manufacturing variations, aging of the electron beam and phosphor screen, etc., these gradation characteristics are different, and the same gradation image is displayed even when the same image signal is input. It is a well-known fact that you cannot do that.

Conventionally, therefore, each image display device has a plurality of tone correction tables capable of correcting a plurality of types of tone characteristics to predetermined characteristics, respectively. It is possible to arbitrarily select a table that is most suitable for correcting the gradation characteristics to the predetermined characteristics.

[0006] With this, even if a plurality of image display devices of different manufacturers or the like are input with the same image signal, a visible image of the same gradation can be displayed. Particularly in the field of medical images, When one image signal is displayed on two or more displays and a plurality of doctors observe the images displayed on each display, or when the image signals are converted into digital data and recorded on a recording medium such as a floppy disk or optical disk. In the case where the image is represented by the digital data on a display installed in each place by carrying the recording medium to a plurality of different places and displaying the image represented by the digital data, accurate diagnosis without being confused by individual differences of the display Is very useful.

[0007]

However, as described above, the gradation characteristics of an image display device are slightly different for each image display device, whereas a plurality of gradation correction tables prepared in advance are used. Is set uniformly based on the average gradation characteristics of a large number of image display devices, or the gradation characteristics of individual image display devices are somewhat regular to predetermined gradation characteristics. Are set uniformly in view of the fact that there are significant differences or changes, it is assumed that all of the image display devices can be completely corrected to a predetermined gradation characteristic depending on these gradation correction tables. However, the present invention is not limited to this, and in many cases, even if the tone correction table is used, a predetermined tone characteristic is not obtained.

In particular, when correcting changes over time, it is conceivable to prepare a plurality of finite tables in advance. However, while changes over time are continuous changes, they are prepared in advance. The gradation correction table is discrete, so that when the change over time matches a change that can be corrected by the gradation correction table, the gradation characteristics can be made completely linear, but not so. In other words, if the change in the gradation characteristics does not match any of the changes in the gradation characteristics that can be corrected in the prepared plurality of gradation correction tables, even after the correction in any of the gradation correction tables, The unique gradation characteristics remain.

The present invention has been made in view of the above circumstances, and an image display method for displaying an image by correcting the gradation characteristics of an image display device having individual differences to desired gradation characteristics with higher accuracy. It is intended to provide a device.

[0010]

SUMMARY OF THE INVENTION An image display method and apparatus according to the present invention include a plurality of gradations prepared in advance so that the gradation characteristics of a display section of an image display device can be corrected to a predetermined gradation characteristic to some extent. By rotating a correction curve (including a straight line as one form of the curve) representing the selected table among the correction tables around an arbitrarily selectable rotation center and / or by parallel shifting, the selected gradation is selected. The correction table can be adjusted to a table that can correct the gradation characteristics of the display unit to predetermined gradation characteristics.

That is, according to the image display method of the present invention, a plurality of different tone corrections prepared in advance, which respectively correct the plurality of different tone characteristics to predetermined tone characteristics. Selecting means for setting a desired gradation characteristic and a gradation correction table suitable for correcting a unique gradation characteristic from the plurality of gradation correction tables to the desired gradation characteristic. And the gradation correction table selected by the selection unit so that the gradation characteristic corrected by the gradation correction table matches the desired gradation characteristic. The rotation amount, the rotation center, and the parallel shift amount of the correction curve to be represented are individually adjusted, and according to the gradation correction table obtained by the adjustment and the unique gradation characteristics,
It is characterized in that an input image signal is displayed as a visible image.

Further, the image display apparatus of the present invention corrects a plurality of different gray-scale characteristics to predetermined gray-scale characteristics corresponding to the plurality of different gray-scale characteristics, respectively. Selecting means for setting a desired gradation characteristic and a gradation correction table suitable for correcting a unique gradation characteristic from the plurality of gradation correction tables to the desired gradation characteristic. An image display device comprising: a gradation correction table selected by the selection unit such that a gradation characteristic corrected by the gradation correction table matches the desired gradation characteristic. Adjusting means for individually adjusting the rotation amount, the rotation center, and the parallel shift amount of the correction curve to be represented, and correction means for correcting the unique gradation characteristics by using the gradation correction table obtained by the adjustment. For example, according to the gradation characteristic corrected by the gradation correction table, an image signal input is characterized in that the display as a visible image.

[0013]

According to the image display method and apparatus of the present invention, a correction curve representing a table selected from a plurality of gradation correction tables prepared in advance is arbitrarily selected around a rotation center which can be arbitrarily selected. Rotate by the amount of rotation obtained, and / or
Alternatively, by performing a parallel shift by an arbitrary amount, the selected gradation correction table is converted into a table that can correct the gradation characteristics of the image display device to desired gradation characteristics.

With this operation, even if any of the plurality of gradation correction tables prepared in advance cannot correct the gradation characteristic of the image display device to the desired gradation characteristic, the gradation correction table is prepared. One of the tables
The gradation characteristics of the image display device can be converted into a gradation correction table that can correct the gradation characteristics of the image display device to the desired gradation characteristics. Can be corrected.

By storing the gradation correction table obtained by the above conversion, the adjustment on the input signal side is not required until the gradation characteristic of the image display device changes again. Therefore, there is also an effect that such adjustment does not need to be performed each time an image signal is input.

That is, when an image signal is input to an image display device, pre-processing for inputting the read image signal to each image display device is performed in accordance with the content of an image represented by the input image signal (for example, an imaged part). The image signal is converted by the image processing device. Here, regarding the conversion according to the content of the image, it is assumed that the optimal conversion pattern for displaying the content of the image on the image display device is that the tone characteristics of the image display device are predetermined tone characteristics. Below, it is fixed for each content of the image. That is, the conversion pattern according to the content of the image is a fixed pattern under the assumption that the gradation characteristics of the image display device are completely corrected to the predetermined gradation characteristics by the gradation correction table. Is stored within.

However, the gradation characteristics of the image display device may not actually be completely corrected to the desired gradation characteristics even by the gradation correction table. It is necessary to perform the conversion processing of the image signal.

In such a case, in the image processing section for processing the gradation of the image so as to improve the diagnostic performance of the image, the desired gradation characteristic of the image display device can be obtained. It is necessary to correct even the deviation.

That is, the image processing device performs correction on the image signal before being input to the image display device in consideration of the gradation characteristics of the image display device.

However, according to this method, every time an image is output to an image display device, image processing is performed in consideration of a difference between a gradation characteristic of the image display device and a desired gradation characteristic. , Very time-consuming.

On the other hand, according to the present invention, since the tone correction table of the image display device itself is directly corrected, until the original tone characteristics of the image display device are further changed, the corrected tone characteristics are not changed. The gradation characteristic can always maintain a predetermined gradation characteristic. Therefore, each time an image signal is input,
There is no need to perform a troublesome operation of adjusting the gradation correction table.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the image display device of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an image processing and display system including an embodiment of the image display device of the present invention. The illustrated image processing and display system displays an image processing device 200 that performs gradation processing on an input image signal S0, and an image signal S1 processed by the image processing device 200 as a visible image. Image display device 10 according to one embodiment of the present invention
0.

Here, the image signal S0 input to the image processing apparatus 200 is generated by irradiating excitation light to a stimulable phosphor sheet on which image information representing a radiation image of a predetermined patient is accumulated and recorded. This is an image signal obtained by photoelectrically reading the stimulated emission light thus obtained and then converting the digitally converted light.

More specifically, the image processing apparatus 200 includes a temporary storage section 210 for temporarily storing the input image signal S0, and information on the input image signal, specifically, a portion represented by the image signal S0. An information input unit 220 for inputting information to be input and the like, and an input is performed so that an image signal of each part is displayed as a visible image having a gradation suitable for observation reading on the image display device 100 in accordance with the part of the radiation image. The storage unit 230 stores a plurality of gradation conversion tables 231, 232,... Set corresponding to each unit that converts and outputs an image signal, and according to information specifying the unit input from the information input unit 220. The plurality of gradation conversion tables stored in the storage unit 230
One of the gradation conversion tables suitable for displaying the relevant portion at the optimum gradation is selected from among the image data stored in the temporary storage unit 210 according to the selected gradation conversion table. And a gradation processing unit 240 for converting the signal S0.

The image processing apparatus 200 includes a frequency processing unit,
It may be configured to further include another processing unit such as a scaling processing unit.

On the other hand, the image display device 100 has a plurality of tone correction tables 111 and 112 for respectively correcting the tone characteristics so as to match desired tone characteristics such as substantially linear, for example, corresponding to a plurality of types of tone characteristics. ,... And a desired gradation characteristic for the image display device 100, and among the plurality of gradation correction tables 111, 112,. The selection unit 120 selects one suitable for correcting the 100 gradation characteristics C to the selected gradation characteristic and reads it out from the storage unit 110, and the rotation amount and rotation of the correction curve representing the selected gradation correction table. Adjuster 13 for adjusting the center and parallel shift amounts separately
0 and a correction unit 140 that converts the input image signal in accordance with the gradation correction table adjusted by the adjustment unit 130.
And a display unit 150 for displaying the converted image signal as a visible image corresponding to the gradation characteristic C. The adjusted gradation correction table is configured to be resident in the correction unit 140. .

Next, the operation of the illustrated image processing and display system will be described.

First, as described above, the image signal S0 indicating the radiation image obtained by reading from the stimulable phosphor sheet is provided.
Is input to the temporary storage unit 210 of the image processing apparatus 200, and the temporary storage unit 210 temporarily stores the image signal S0.

Here, an operator of the present system, such as a doctor or a radiological technologist, inputs information relating to the input image signal (such as information for specifying a portion represented by the image signal S0) to the information input section 220. The information input unit 220 outputs the input information to the gradation processing unit 240, and the gradation processing unit 240 generates one gradation conversion table suitable for displaying the input portion at the optimum gradation. , Stored in the storage unit 230, and converts the image signal S0 stored in the temporary storage unit 210 into the image signal S1 according to the selected conversion table.

The image signal S 1 obtained by processing by the gradation processing section 240 is output from the image processing apparatus 200 and is input to the correction section 140 of the image display apparatus 100.

Here, the correction unit 140 includes the image display device 100
An already adjusted gradation correction table for correcting the gradation characteristic C of the image data to a desired gradation is resident.

In this resident gradation correction table, a case where the desired gradation characteristic is linear in the relationship between the input (pixel value) and the output (the value obtained by taking the logarithm of the luminance value) will be described as an example. This will be described below.

Originally, the gradation characteristic of the display unit 150 of the image display device 100 should be perfectly linear.
As shown in FIG. 2A, the gradation characteristic C deviates from linear (indicated by a broken line) due to variations in accuracy of the individual components constituting 0, deterioration over time, and the like.

First, a desired gradation (linear) is selected by the selection unit 120, and a plurality of gradation correction tables 111 and 112 stored in the storage unit 110 prepared for each apparatus or deterioration state in accordance with the selection. , One gradation correction table suitable for correcting the gradation characteristic C of the display unit 150 substantially linearly is selected and read out from the storage unit 110. For example, it is assumed that the gradation characteristic C of the display unit 150 is as shown in FIG. 2A and the selected gradation correction table is as shown in FIG.

In this case, the gradation characteristics C 'after being corrected by the gradation correction table are as shown in FIG.
Although the corrected gradation characteristic C ′ has a gradation characteristic close to linearity, for example, when two different image display devices are arranged to display the same visible image,
If there is slight nonlinearity in both image display devices as shown in FIG. 3C, the two images displayed on both image display devices may give different impressions.

Therefore, in the image display apparatus 100 of the present embodiment, in order to correct the gradation characteristic C linearly with higher accuracy, the curve representing the selected gradation correction table (FIG. 2 (2)) is adjusted. It is configured to be able to.

That is, as shown in FIG. 3, the curve representing the gradation correction table is rotated by an arbitrary rotation amount (GA) around an arbitrary rotation center (GC) and / or an arbitrary parallel shift amount. The operator inputs these adjustment parameters GC, GA, and GS to the adjustment unit 130 so as to translate by (GS). The adjusting unit 130 is controlled in accordance with the adjustment parameters GC, GA, and GS input to the adjusting unit 130.
130 rotates the curve representing the gradation correction table selected by the selection unit 120 around the rotation center GC by the rotation amount GA and / or translates the curve by the parallel shift amount GS.

As described above, the adjustment parameters GC, GA, G
The gradation correction table adjusted by S (see FIG. 4A) is resident in the correction unit 140. The corrected gradation characteristic C ″, which is obtained by multiplying the adjusted gradation correction table resident in the correction unit 140 and the original gradation characteristic C of the display unit 150 (FIG. 2A), is shown in FIG. As shown in FIG. 4 (2), it is completely linear.

The image signal S1 input to the correction unit 140 is
The image signal S2 according to the adjusted gradation correction table
Is output to the display unit 150.

The display unit 150 converts the input image signal S2 into an image having a luminance corresponding to the gradation characteristic C. The image signal S2 is converted by the correction unit 140 into an adjusted gradation correction table. Therefore, the luminance of the visible image finally displayed on the display unit 150 retains the characteristics of the image signal S1 when input to the correction unit 140.

As described above, the image display device 100 of this embodiment
According to the above, even if any of the plurality of gradation correction tables prepared in advance cannot correct the gradation characteristics of the image display device to the desired gradation characteristics, the prepared gradation correction tables are prepared. One of the plurality of tables can be converted into a gradation correction table capable of correcting the gradation characteristics of the image display device to a desired gradation characteristic with higher accuracy than before. By making the adjusted gradation correction table resident in the correction unit, the trouble of adjusting the gradation correction table every time an image signal is input can be saved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an image processing and display system including an embodiment of an image display device of the present invention.

2A is a diagram showing a gradation characteristic of a display unit of the image display device. FIG. 2B is a diagram showing a curve of a gradation correction table stored in advance. Showing the gradation characteristics

FIG. 3 shows curves GA, GC, and G representing a gradation correction table.
Diagram showing how S is adjusted

FIG. 4 is a diagram (1) showing a curve of an adjusted tone correction table; and (2) a diagram showing a tone characteristic corrected by the adjusted tone correction table.

[Explanation of symbols]

 100 Image display device 110,230 Storage unit 120 Selection unit 130 Adjustment unit 140 Correction unit 150 Display unit 111,112, ... Tone correction table 200 Image processing device 210 Temporary storage unit 220 Information input unit 231,232, ... Tone conversion table 240 Tone processing unit C Gradation characteristics S1, S2 Image signal

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/407 H04N 1/40 101E

Claims (2)

[Claims] 1. A plurality of different tone correction tables prepared in advance for respectively correcting a plurality of different tone characteristics to predetermined tone characteristics corresponding to a plurality of different tone characteristics, respectively. Selecting means for setting tone characteristics and selecting a tone correction table suitable for correcting a unique tone characteristic among the plurality of tone correction tables to the desired tone characteristic. On the other hand, the amount of rotation of a correction curve representing the gradation correction table selected by the selection means, such that the gradation characteristic corrected by the gradation correction table matches the desired gradation characteristic, Adjusting the rotation center and the parallel shift amount separately, and displaying an input image signal as a visible image in accordance with the tone correction table and the unique tone characteristics obtained by the adjustment. Image display method and butterflies. 2. A plurality of different tone correction tables prepared in advance for respectively correcting a plurality of different tone characteristics to predetermined tone characteristics corresponding to the plurality of different tone characteristics, respectively, Selecting means for setting tone characteristics and selecting a tone correction table suitable for correcting a unique tone characteristic among the plurality of tone correction tables to the desired tone characteristic. A rotation amount of a correction curve representing the gradation correction table selected by the selection means, such that the gradation characteristics corrected by the gradation correction table match the desired gradation characteristics; Adjusting means for individually adjusting the rotation center and the parallel shift amount; and correcting means for correcting the unique tone characteristics using a tone correction table obtained by the adjustment. An image display apparatus, wherein an input image signal is displayed as a visible image according to the corrected tone characteristics.