Signal processing device and display device

Abstract

To display an image without changing grayscale characteristics when displaying the image on a display unit which is constituted so as to limit luminous intensity in accordance with the luminance of the image signal.SOLUTION: An image signal processing unit 13 generates an image signal in which a fixed luminance pattern having a white level is superimposed on the luminance pattern of a prescribed first region in each frame of image data. A luminance detection unit 14 detects the luminous intensity of a second region 24 of a display unit 20 that corresponds to the first region while the display unit 20 is displaying an image based on the image signal. A determination unit 15 determines that the display unit 20 is displaying an image signal applying a limiter to luminance when the luminance intensity in the second region 24 is lower than a prescribed value. A luminance adjustment indication unit 16 indicates to the image signal processing unit 13 so as to lower luminance in a prescribed third region, except the first region, in each frame of the image signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a signal processing device and a display device. [Background technology]

[0002] Display devices equipped with a self-luminous display unit such as an organic EL (Electro Luminescence) panel are generally configured to limit the luminance of the input image signal by applying a limiter to the luminance of the input image signal when the average luminance of the input image signal is equal to or greater than a predetermined value, in order to prevent overcurrent and extend the life of the display unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-219034 A Summary of the Invention [Problem to be solved by the invention]

[0004] A display device having a self-luminous display unit may be used as, for example, a medical monitor. In a medical monitor, the gradation characteristics of a display image for an input image signal are strictly specified so that a correct diagnosis can be made based on a displayed medical image. If the emission luminance of an area displaying an image to be confirmed while a medical image is displayed on the medical monitor is limited, the gradation characteristics of the image to be confirmed may change and the image may not be displayed with the specified gradation characteristics, which may prevent a proper diagnosis based on the medical image. For this reason, even when the emission luminance of the display device is limited, it is necessary to display an image for confirmation without changing the gradation characteristics. In monitors other than medical monitors, there are also cases where an image needs to be displayed with the specified gradation characteristics based on an input image signal.

[0005] The present invention aims to provide a signal processing device and a display device that can display an image without changing the gradation characteristics when displaying an image on a display unit that is configured to limit the emission brightness in accordance with the brightness of an image signal. [Means for solving the problem]

[0006] The present invention provides a signal processing device comprising: an image signal processing unit that generates an image signal in which a fixed luminance pattern having a white level is superimposed on the luminance pattern of a predetermined first region in each frame of image data, and supplies the image signal to a display unit; a luminance detection unit that detects the emission luminance in a second region of the display unit corresponding to the first region while the display unit is displaying an image based on the image signal; a judgment unit that judges that the display unit is applying a limiter to the luminance at which the image signal is displayed when the emission luminance in the second region detected by the luminance detection unit is lower than a predetermined value; and a luminance adjustment instruction unit that instructs the image signal processing unit to reduce the luminance in a predetermined third region excluding the first region in each frame of the image data when the judgment unit determines that the display unit is applying a limiter to the luminance at which the image signal is displayed.

[0007] The present invention provides a display device comprising: an image signal processing unit that generates an image signal in which a fixed luminance pattern having a white level is superimposed on a luminance pattern of a predetermined first region in each frame of image data, and supplies the image signal to a display unit; a display unit that, when an average luminance of the image signal supplied from the image signal processing unit exceeds an upper limit value, applies a limiter to the luminance and displays an image based on the image signal; a luminance detection unit that detects the emission luminance in a second region of the display unit corresponding to the first region while the display unit is displaying an image based on the image signal; a judgment unit that judges that the display unit is limiting the luminance at which the image signal is displayed when the emission luminance in the second region detected by the luminance detection unit is lower than a predetermined value; and a luminance adjustment instruction unit that instructs the image signal processing unit to reduce the luminance in a predetermined third region excluding the first region in each frame of the image data when the judgment unit determines that the display unit is limiting the luminance at which the image signal is displayed. Effect of the Invention

[0008] According to the signal processing device and display device of the present invention, when an image is displayed on a display unit configured to limit the emission brightness in accordance with the brightness of an image signal, the image can be displayed without changing the gradation characteristics. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a display device according to an embodiment of the present invention; [Diagram 2] 4 is a partial cross-sectional view showing the positional relationship between a light-emitting section and a brightness detection section of the display device. FIG. [Diagram 3] FIG. 4 is a characteristic diagram showing gradation characteristics in the first mode. [Figure 4] FIG. 11 is a characteristic diagram showing gradation characteristics in a second mode. [Figure 5A] FIG. 13 is a diagram showing a first example of brightness adjustment in an end region of a frame in the second mode. [Figure 5B] FIG. 13 is a diagram showing a second example of brightness adjustment in an end region of a frame in the second mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A signal processing device and a display device according to an embodiment will be described below with reference to the accompanying drawings. The signal processing device and the display device according to an embodiment are exemplified by a signal processing device for a display device that displays medical images and a display device that displays medical images, but are not limited to display devices that display medical images. In addition, in this embodiment, a display device having an organic EL panel as a display unit is exemplified, but are not limited thereto. That is, this embodiment is applicable to a display device having a display unit that may limit the emission brightness.

[0011] FIG. 1 is a block diagram showing an example of the configuration of a display device according to an embodiment. In FIG. 1, the display device is connected to an image data generating device (not shown), and image data supplied from the image data generating device is input to the display device. Various image data used for diagnosis in medical practice, such as chest X-ray images or mammography images, is input to the display device. The image data is 8-bit or 10-bit digital data. The display device may be connected to a PACS (Picture Archiving and Communication System) server in which various medical images are stored, and image data supplied from the PACS server may be input to the display device. There is no particular limitation on the image data input to the display device.

[0012] 1, the display device includes an image input unit 11, a gradation characteristic lookup table (hereinafter, gradation characteristic LUT) 12, an image signal processing unit 13, a luminance detection unit 14, a limiter determination unit 15, a luminance adjustment instruction unit 16, and a display unit 20. The image input unit 11, the gradation characteristic LUT 12, the image signal processing unit 13, the luminance detection unit 14, the limiter determination unit 15, and the luminance adjustment instruction unit 16 function as a signal processing device.

[0013] Image data is input to an image input unit 11. The image input unit 11 supplies the input image data to an image signal processing unit 13.

[0014] The gradation characteristic LUT12 is a lookup table for setting the gradation characteristic of image data. The gradation characteristic LUT12 is stored in a non-volatile memory such as a ROM (Read Only Memory). The gradation characteristic is, for example, a so-called DICOM GSDF gradation characteristic that uses a Grayscale Standard Display Function (GSDF) conforming to the DICOM (Digital Imaging and Communications in Medicine) standard. FIG. 3, which will be described later, corresponds to the DICOM GSDF gradation characteristic set in the gradation characteristic LUT12.

[0015] The image signal processing unit 13 performs gamma correction on the image data using the gradation characteristics read out from the gradation characteristic LUT 12. The image signal processing unit 13 generates an image signal in which a fixed luminance pattern having a white level is superimposed on the luminance pattern of a predetermined first region in each frame of the gamma-corrected image data, and supplies the image signal to the display unit 20. The image signal processing unit 13 may adjust the luminance of the image signal according to an instruction from the luminance adjustment instruction unit 16, and supply the image signal to the display unit 20. How the luminance adjustment instruction unit 16 instructs the adjustment of the luminance of the image signal will be described later.

[0016] The display unit 20 includes an image input unit 21, a brightness control unit 22, and a light-emitting unit 23. The light-emitting unit 23 is an area in which organic EL elements are arranged in a matrix. The display unit 20 may limit the emission brightness of the light-emitting unit 23 (the brightness on the screen of the display unit 20) in order to extend the life of the light-emitting unit 23. The display unit 20 may limit the emission brightness in order to reduce power consumption. When the average brightness of each frame of the image signal supplied from the image signal processing unit 13 exceeds a preset upper limit value, the display unit 20 applies a limiter to the brightness and displays the image signal.

[0017] The image input unit 21 receives the image signal supplied from the image signal processing unit 13. The image input unit 21 supplies the input image signal to a luminance control unit 22.

[0018] The luminance control unit 22 controls the emission luminance of each pixel of the light-emitting unit 23 according to the gradation value of each pixel of the image signal. The luminance control unit 22 controls the emission luminance, for example, by the amount of current that drives the organic EL element in each pixel of the light-emitting unit 23. The gradation value is expressed by the amount of current flowing through each organic EL element of the light-emitting unit 23.

[0019] The luminance control unit 22 calculates the average luminance of each frame of the image signal. An upper limit value for the average luminance of the image signal is set in the luminance control unit 22. When the average luminance of each frame of the image signal exceeds a preset upper limit value, the luminance control unit 22 applies a limiter to the luminance of the image signal to limit the luminance of the light emitted by the light-emitting unit 23. When the average luminance of each frame is equal to or lower than the upper limit value, the luminance control unit 22 does not apply a limiter to the luminance of the image signal and does not limit the luminance of the light emitted by the light-emitting unit 23.

[0020] The region of the light-emitting unit 23 corresponding to the first region in each frame of the image signal is defined as the second region. As shown in the partial cross-sectional view of FIG. 2, if the first region in each frame of the image signal is located at the upper end of the frame, the second region 24 of the light-emitting unit 23 is a region adjacent to the bezel 201 of the display unit 20. As shown in FIG. 5A described later, the second region 24 is located, for example, near the right end in the horizontal direction. The second region 24 may be located in the center in the horizontal direction or at the lower end of the frame and the light-emitting unit 23, and the position is not limited.

[0021] 2, the luminance detection unit 14 is attached to the bezel 201 by any fixing method so as to face the second region 24. The luminance detection unit 14 can be composed of a luminance sensor. The luminance detection unit 14 detects the emission luminance of the second region 24 of the light-emitting unit 23 in a state in which the light-emitting unit 23 displays an image based on an image signal.

[0022] The emission luminance in the second region 24 detected by the luminance detection unit 14 is input to the limiter determination unit 15. The limiter determination unit 15 determines whether or not the emission luminance in the second region 24 detected by the luminance detection unit 14 is lower than a predetermined value of the emission luminance set in advance. If the image data is, for example, 8 bits and the fixed luminance pattern is a white level with a gradation value of 255, the limiter determination unit 15 holds in advance a predetermined value corresponding to the emission luminance when the display unit 20 displays an image of a white level without applying a limiter. If the emission luminance in the second region 24 detected by the luminance detection unit 14 is lower than the predetermined value, the limiter determination unit 15 determines that the display unit 20 displays an image signal by applying a limiter to the luminance.

[0023] When limiter determination unit 15 determines that display unit 20 is displaying an image signal with a luminance limiter applied, luminance adjustment instruction unit 16 instructs image signal processing unit 13 to reduce the luminance of the image signal.

[0024] Specifically, when the limiter determination unit 15 determines that the display unit 20 displays the image signal with a limiter applied to the luminance, the luminance adjustment instruction unit 16 selects between a first mode instructing the image signal processing unit 13 to uniformly reduce the luminance of the entire frame of the image signal and a second mode instructing the image signal processing unit 13 to reduce the luminance in a predetermined third region excluding the first region in each frame of the image signal. The third region is a partial region in each frame. The image signal processing unit 13 reduces the luminance of the image signal according to the mode instructed by the luminance adjustment instruction unit 16. The luminance adjustment instruction unit 16 may instruct the image signal processing unit 13 to adjust the luminance of the image signal by adopting only the second mode.

[0025] Fig. 3 shows the gradation characteristic used in the first mode. In Fig. 3, the horizontal axis indicates the signal level of the image signal, and the vertical axis indicates the light emission luminance by the display unit 20. The gradation characteristic used in the first mode is a characteristic that uniformly reduces the luminance of the entire each frame of the image signal to express gradation from 0 to the maximum signal level within a range below the limiter level of the display unit 20. The gradation characteristic shown in Fig. 3 may be a characteristic obtained by compressing the gradation characteristic of the DICOMGSDF shown in Fig. 4.

[0026] When the first mode is used, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to uniformly reduce the luminance of the entire frame except the first region in each frame of the image signal. If the limiter determination unit 15 determines that the display unit 20 applies a limiter to the luminance, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to uniformly further reduce the luminance of the entire frame except the first region in each frame of the image signal. The limiter determination unit 15 and the luminance adjustment instruction unit 16 repeat this operation, so that the luminance adjustment instruction unit 16 can obtain the limiter level in the display unit 20. The limiter level is a variable value that varies depending on the image displayed on the display unit 20. The luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to set the gradation characteristics of the entire frame except the first region to gradation characteristics that use the emission luminance of 0 in the display unit 20 to the limiter level in the display unit 20.

[0027] 3, the average luminance of each frame of the image signal does not exceed the upper limit, and the display unit 20 releases the limiter. According to the first mode, the image signal is not displayed at the maximum emission luminance on the display unit 20 even if it is at the maximum signal level, but a gradation according to the signal level from 0 to the maximum signal level is expressed.

[0028] Fig. 4 shows the gradation characteristic used in the second mode. The horizontal axis in Fig. 4 indicates the signal level of the image signal, and the vertical axis indicates the emission luminance of the display unit 20. The gradation characteristic used in the second mode is a characteristic that expresses a gradation from a signal level of 0 to a maximum signal level, using the entire range from emission luminance of 0 to maximum emission luminance in the display unit 20. The gradation characteristic shown in Fig. 4 is preferably the gradation characteristic of the DICOM GSDF, but is not limited to the gradation characteristic of the DICOM GSDF.

[0029] The gradation characteristic used in the second mode uses a light emission luminance exceeding a limiter level in the display unit 20. The luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to reduce the luminance of a part of an area of ​​each frame, as shown in Fig. 5A or 5B.

[0030] When the second mode is used, the luminance adjustment instruction unit 16 sets the end 25, which is a predetermined range in the up / down and left / right directions from the top / bottom and left / right ends of each frame, as the third region, excluding the first region in each frame of the image signal, as shown in FIG. 5A. The luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to reduce the luminance at the end 25. In addition, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to set the gradation characteristic of the center part 26 (fourth region) inside the end 25 to the gradation characteristic shown in FIG. 4. The fourth region is a region excluding the first and third regions in each frame of the image signal. In other words, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to set the gradation characteristic of the fourth region excluding the first and third regions in each frame of the image signal to the gradation characteristic using the entire luminance from 0 to the maximum luminance in the display unit 20.

[0031] When limiter determination unit 15 determines that display unit 20 is displaying the image signal with a luminance limiter applied, luminance adjustment instruction unit 16 adjusts the range of end portion 25 or adjusts the luminance at end portion 25. When image signal processing unit 13 reduces the luminance at end portion 25 and the average luminance of each frame of the image signal does not exceed the upper limit value, display unit 20 releases the limiter. When display unit 20 releases the limiter, the image is displayed at low luminance at end portion 25, but in center portion 26, the image is displayed in all gradations from luminance 0 to maximum luminance as shown in FIG.

[0032] The luminance adjustment instruction unit 16 may adjust the range of the third region in each frame so that the range of the third region in each frame becomes wider as the average luminance of the image signal increases and the difference between the average luminance and the upper limit value preset in the display unit 20 increases. When the range of the third region is fixed, the luminance adjustment instruction unit 16 may instruct the image signal processing unit 13 to reduce the luminance of the third region as the difference between the average luminance of the image data and the upper limit value increases. The luminance adjustment instruction unit 16 may instruct the image signal processing unit 13 to reduce the luminance of the third region to 0. The luminance adjustment instruction unit 16 may adjust each of the range of the third region and the luminance of the third region.

[0033] When using the second mode, brightness adjustment instruction unit 16 may adjust at least one of the range of the third region in each frame of the image signal and the brightness in the third region. End portion 25 may be an upper or lower region of light-emitting unit 23, or may be an area on the left or right side of light-emitting unit 23. The shape of end portion 25 is not particularly limited.

[0034] Fig. 5B shows an example of the range of end 25 when an image signal having a lower average luminance than that in Fig. 5A is displayed. In the second example of Fig. 5B, the average luminance of the image signal is lower than that in the first example of Fig. 5A, so that when adjusting the range of the third region, the range of end 25 may be narrower than that in Fig. 5A.

[0035] As shown in Fig. 5A or 5B, by lowering the luminance of the end portion 25 and displaying an image in the central portion 26 with the gradation characteristics of the second mode shown in Fig. 4, an image can be displayed in the central portion 26 in a state in which the display unit 20 can emit light up to the maximum luminance that it can display. That is, an image can be displayed in the central portion 26 of the display unit 20 without changing the gradation characteristics. In the central portion 26 of the display unit 20, the original gradation according to the signal level from 0 to the maximum signal level is expressed.

[0036] For example, when the input image data is a mammography image in which most of the frame is black, the second mode can be used to display the high-luminance image of the mammography image in the central portion 26 at its original luminance without changing the gradation characteristics. The second mode is preferably used when displaying medical images of this type in which most of the frame is black. The second mode is also preferably used when displaying images that do not contain important image information at the top and bottom or left and right ends of the frame. It is preferable that the display is configured to allow the user to select between the first mode and the second mode.

[0037] As described above, the signal processing device and the display device according to the present invention include the image signal processing unit 13, the luminance detection unit 14, the judgment unit (limiter judgment unit 15), and the luminance adjustment instruction unit 16. The image signal processing unit 13 generates an image signal in which a fixed luminance pattern having a white level is superimposed on the luminance pattern of a predetermined first region in each frame of image data, and supplies the image signal to the display unit 20. The luminance detection unit 14 detects the emission luminance of a second region of the display unit 20 corresponding to the first region while the display unit 20 is displaying an image based on the image signal. When the emission luminance of the second region 24 detected by the luminance detection unit 14 is lower than a predetermined value, the judgment unit judges that the display unit 20 is displaying the image signal by applying a limiter to the luminance. When the judgment unit judges that the display unit 20 is displaying the image signal by applying a limiter to the luminance, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to reduce the luminance of a predetermined third region, which is a part of a region in each frame of the image signal and is excluding the first region.

[0038] When the display unit 20 displays the image signal with a luminance limiter applied, the luminance adjustment instruction unit 16 instructs the image signal processing unit 13 to reduce the luminance of the third region excluding the first region in each frame of the image signal. That is, the luminance adjustment instruction unit 16 reduces the luminance of the third region excluding the first region in each frame of the image data so that the average luminance of the image data is equal to or lower than the upper limit value. This makes it possible to reduce the average luminance in each frame of the image signal, and to release the luminance limiter of the display unit 20. The gradation characteristic of the fourth region excluding the first and third regions in each frame of the image signal can be set to a gradation characteristic that uses the entire luminance from 0 to the maximum luminance in the display unit 20, and the luminance performance of the display unit 20 can be utilized to the maximum. When an image is displayed on the display unit 20 that is configured to limit the luminance according to the luminance of the image signal, the image can be displayed without changing the gradation characteristic.

[0039] Furthermore, the luminance adjustment instruction unit 16 of the signal processing device and display device according to the present invention adjusts at least one of the range of the third region and the luminance in the third region when the determination unit determines that the display unit 20 displays the image signal with a luminance limiter applied. This makes it possible to prevent the range of the third region from becoming excessively wide and to prevent the luminance in the third region from becoming excessively low. This makes it possible to prevent a decrease in the visibility of the image on the display unit 20.

[0040] Furthermore, when the judgment unit judges that the display unit 20 is displaying the image signal by applying a limiter to the brightness, the brightness adjustment instruction unit 16 of the information processing device and display device according to the present invention selects between a first mode instructing the image signal processing unit 13 to uniformly reduce the brightness of the entire frame except for a first region in each frame of the image signal, and a second mode instructing the image signal processing unit 13 to reduce the brightness in a third region.

[0041] In the first mode, the luminance of the entire frame excluding the first region in each frame of the image signal is uniformly reduced, and the gradation characteristics of the entire frame excluding the first region can be set to gradation characteristics using the emission luminance of 0 in the display unit 20 to the limiter level in the display unit 20. This makes it possible to reduce the average luminance of the image signal in a manner suitable for the type of image data. When it is not necessary to display an image in the display unit 20 without changing the gradation characteristics, the first mode can be selected, and the life of the display unit 20 can be extended.

[0042] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0043] 13 Image signal processing section 14 Luminance detection section 15 Limiter judgment unit (judgment unit) 16 Brightness adjustment indicator 20 Display section 24 The Second Region

Claims

1. an image signal processing unit that generates an image signal in which a fixed luminance pattern having a white level is superimposed on a luminance pattern of a predetermined first region in each frame of image data, and supplies the image signal to a display unit; a brightness detection unit that detects a light emission brightness in a second region, which is a display region of the display unit corresponding to the first region, while the display unit is displaying an image based on the image signal; a determination unit that determines that the display unit is displaying the image signal while limiting the luminance when the emission luminance in the second region detected by the luminance detection unit is lower than a predetermined value; a luminance adjustment instruction unit for decreasing luminance in a predetermined third region, which is a part of each frame of the image signal and excludes the first region; Equipped with the luminance adjustment instruction unit adjusts the range of the third region to be wider when the determination unit determines that the display unit is displaying the image signal while applying a luminance limiter. Signal processing device.

2. 2 . The signal processing device according to claim 1 , wherein the brightness adjustment instruction unit adjusts the brightness in the range of the third region so as to decrease the brightness when the determination unit determines that the display unit is displaying the image signal by applying a limiter to the brightness.

3. When the determination unit determines that the display unit is displaying the image signal while applying a limiter to the luminance, the luminance adjustment instruction unit: a first mode instructing the image signal processor to uniformly reduce the luminance of an entire frame excluding the first region in each frame of the image signal; a second mode instructing the image signal processor to reduce the luminance in the third region; Select 3. A signal processing device according to claim 1 or 2.

4. an image signal processing unit that generates an image signal in which a fixed luminance pattern having a white level is superimposed on a luminance pattern of a predetermined first region in each frame of image data, and supplies the image signal to a display unit; a display unit that displays the image signal by applying a limiter to the luminance when the average luminance of the image signal supplied from the image signal processing unit exceeds an upper limit value; a brightness detection unit that detects a light emission brightness in a second region, which is a display region of the display unit corresponding to the first region, while the display unit is displaying an image based on the image signal; a determination unit that determines that the display unit is limiting the luminance at which the image signal is displayed when the emission luminance in the second region detected by the luminance detection unit is lower than a predetermined value; a luminance adjustment instruction unit for decreasing luminance in a predetermined third region, which is a part of each frame of the image signal and excludes the first region; Equipped with the luminance adjustment instruction unit adjusts the range of the third region to be wider when the determination unit determines that the display unit is displaying the image signal while applying a luminance limiter. Display device.

Images