JP5261607B2 - Image processing apparatus, image processing method, and display system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation in the display quality of a display device whose dynamic range changes depending on video. <P>SOLUTION: For an LCD whose dynamic range, which is the width of outputtable luminance, changes depending on video to be displayed, a video processing circuit 108 processes video to create the video to be displayed. The video processing circuit 108 acquires the dynamic range of the LCD from an LCD controller 109, and depending on the acquired dynamic range, a noise removal circuit 22 changes a degree of noise removal and performs noise removal of the video, and an edge enhancement circuit 23 changes a degree of edge enhancement and performs edge enhancement of the video. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to an image processing apparatus, an image processing method, and a display system for processing an image and generating the image to be displayed for a display apparatus whose dynamic range changes according to the image to be displayed. is there.

  As a recent display device, an FPD (Flat Panel Display) that can be made thinner and lighter than a CRT (Cathode Ray Tube) is used. Examples of the FPD include an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel), an EL (Electroluminescence) display, and an FED (Field Emission Display). Of these FPDs, LCDs are particularly popular. In recent LCDs (liquid crystal display devices), those using LEDs (light emitting diodes) as backlights are increasing. Such a backlight is called an “LED backlight”.

  In general, an LCD has a lower contrast ratio, which is the ratio of the darkest color that can be displayed to the brightest color, as compared to an FPD such as a PDP that includes a light emitting element for each pixel. Thus, recently, LCDs having a so-called local dimming function that improves the contrast ratio by controlling the brightness of individual LEDs in the LED backlight are commercially available (for example, manufactured by Sharp Corporation). Model number XS1, etc.). In addition, recently, LCDs that further improve the contrast ratio by additionally supplying the power saved by the darkly controlled LEDs to the brightly controlled LEDs are also commercially available (for example, Sharp Corporation). Manufactured model number 60X50A, etc.).

Special table 2005-523655 (released on August 04, 2005)

  In a normal LCD, the dynamic range, which is the width of brightness that can be output, corresponds to the contrast ratio. On the other hand, in the LCD with an improved contrast ratio, the dynamic range changes according to the ratio of dark areas and the ratio of bright areas in the image.

  When the dynamic range is increased, the amount of noise included in the image is also increased, so that an image in which noise is conspicuous is displayed. In addition, when the dynamic range changes for each image, the noise feeling, fineness, sharpness, and the like of the displayed image are different for each image, and the display quality is deteriorated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image processing apparatus that can suppress deterioration in display quality of a display apparatus in which a dynamic range changes according to an image. .

  An image processing apparatus according to the present invention generates an image to be displayed by processing an image for a display device in which a dynamic range, which is a width of outputable brightness, changes according to an image to be displayed. In order to solve the above-described problem, the image processing apparatus is configured to acquire an acquisition unit that acquires a dynamic range of the display device, and to change a degree of processing of the image according to the dynamic range acquired by the acquisition unit. And image processing means for processing the image.

  In addition, the image processing method according to the present invention performs processing of an image and displays the image to be displayed for a display device in which a dynamic range that is a width of output brightness varies depending on the image to be displayed. An image processing method to be created, in order to solve the above problem, an acquisition step of acquiring a dynamic range of the display device, and a degree of processing of the image according to the dynamic range acquired in the acquisition step And an image processing step for processing the image by changing.

  According to the above configuration and method, the dynamic range of the display device whose dynamic range changes according to the image to be displayed is acquired, and the degree of image processing is changed according to the acquired dynamic range. Then, the image to be displayed is created by processing the image with the degree of change.

  Accordingly, for example, by removing noise by increasing the degree of noise removal for an image with a large dynamic range, an image with no noticeable noise can be displayed on the display device. In addition, even if the dynamic range changes according to the image to be displayed, the image to be displayed is the image processed to the extent corresponding to the dynamic range. It is possible to provide a sense of noise, fineness, sharpness and the like of the image to be displayed. Therefore, deterioration of display quality of the display device can be suppressed.

  The image processing apparatus according to the present invention is characterized in that the acquisition unit estimates and acquires the dynamic range from an image to be processed by the image processing unit. In the image processing method according to the present invention, the obtaining step is characterized in that the dynamic range is estimated and obtained from an image to be processed by the image processing step. In this case, the dynamic range is estimated from the image to be processed, and the image is processed in a degree corresponding to the estimated dynamic range, so that the display quality is deteriorated with good followability. Can be suppressed.

  In the image processing apparatus according to the present invention, the acquisition unit may acquire an actual dynamic range in the display device from the display device. In this case, it becomes a feedback type in which image processing is performed to the extent corresponding to the actual dynamic range in the display device, and deterioration of the display quality can be accurately suppressed.

  Further, a feedback type may be used for certain image processing, while a feed-forward type may be used for other image processing. For other processing of the image, both a feedback type and a feed forward type may be used. In this case, the acquisition source of the dynamic range can be changed according to the characteristics of the image processing, and the deterioration of the display quality can be satisfactorily suppressed.

  Examples of the image processing include noise removal and edge enhancement.

  In the image processing apparatus according to the present invention, the image processing unit includes a noise removing unit that removes noise included in the image, and the noise removing unit increases as the dynamic range acquired by the acquiring unit increases. The strength of noise removal is increased. In the image processing method according to the present invention, the image processing step includes a noise removal step of removing noise included in the image, and the noise removal step includes the dynamic range acquired in the acquisition step. As the value increases, the noise removal strength increases.

  Since the rate of change of the noise removal strength with respect to the dynamic range is large, it is preferable to change the noise removal strength with good followability with respect to the change of the dynamic range. Therefore, the noise removal unit uses the dynamic range estimated by the acquisition unit from the image to be processed, or both the dynamic range and the actual dynamic range acquired by the acquisition unit from the display device. Is preferably used.

  In the image processing apparatus according to the present invention, the image processing unit includes an edge enhancement unit that performs edge enhancement of the image, and the edge enhancement unit increases the dynamic range acquired by the acquisition unit. It is characterized by reducing the strength of edge enhancement. In the image processing method according to the present invention, the image processing step includes an edge enhancement step for performing edge enhancement of the image, and the edge enhancement step has a large dynamic range acquired in the acquisition step. As a result, the strength of the edge emphasis is reduced.

  Note that since the rate of change of the edge emphasis strength with respect to the dynamic range is small, it is preferable to accurately change the noise removal strength with respect to the dynamic range change. Therefore, it is preferable that the edge enhancement unit uses an actual dynamic range acquired by the acquisition unit from the display device.

  Note that a display device in which a dynamic range, which is the width of outputable luminance, changes according to an image to be displayed, and the above-described configuration for processing the image and creating the image to be displayed for the display device If it is a display system provided with this image processing apparatus, there can exist an effect similar to the above-mentioned effect.

  Examples of a display device whose dynamic range changes according to an image to be displayed include an LCD (liquid crystal display device) using a plurality of light emitting diodes as a backlight, a PDP having a light emitting element for each pixel, and the like. Can be mentioned.

  Among them, the present invention is suitable for a display device that includes a plurality of light emitting elements for displaying the image to be displayed and stops the light emission of the light emitting elements corresponding to the black region of the image to be displayed. . Furthermore, the present invention is more suitable for a display device that additionally supplies surplus power due to the stop of light emission of the light emitting element to the light emitting element corresponding to the white region of the image to be displayed.

  The display system according to the present invention has a display device in which a dynamic range, which is a range of luminance that can be output, changes according to an image to be displayed, and the display device performs processing of the image to display the image. An image processing apparatus that creates an image, and in order to solve the above-described problem, an acquisition unit that acquires a dynamic range of the display device, and according to the dynamic range acquired by the acquisition unit, Image processing means for processing the image by changing the degree of image processing, and the display device includes a plurality of light emitting elements for displaying the image to be displayed. The light emission of the light emitting element corresponding to the black area of the image is stopped, and the display device corresponds to the white area of the image to be displayed with the surplus power due to the stop of light emission of the light emitting element It is characterized by additionally supplying to that the light emitting element.

  The present invention is suitable for a display system that is a television receiver that receives an image signal from the outside and displays an image based on the received image signal.

  As described above, even if the dynamic range of the display device changes according to the image to be displayed, the image processing device according to the present invention can process the image to be displayed to the extent corresponding to the dynamic range. Therefore, the noise, fineness, sharpness, etc. of the image displayed on the display device can be made uniform, and the display quality of the display device can be prevented from deteriorating. Play.

1 is a block diagram illustrating a schematic configuration of a video processing circuit in a television which is an embodiment of the present invention. It is a block diagram which shows schematic structure of the said television. It is a block diagram which shows schematic structure of LCD controller and LCD in the said television. It is a figure which shows the relationship between control of the LED backlight in the said LCD, and the change of the dynamic range of the said LCD. It is a figure which shows an example of the luminance information of the said LED backlight in a table format. It is a graph which shows the method of performing edge emphasis of a picture using secondary differentiation. It is a graph which shows how the coefficient of noise removal of an image | video, and the coefficient of edge enhancement of an image | video change with respect to a dynamic range. It is a block diagram which shows schematic structure of the video processing circuit in the television which is another embodiment of this invention. It is a graph which shows an example of the histogram of the luminance signal in a certain image | video. It is a block diagram which shows schematic structure of the video processing circuit in the television which is other embodiment of this invention.

[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram showing a schematic configuration of a television receiver (hereinafter abbreviated as “TV (TV)”) 1 according to the present embodiment.

  As shown in FIG. 2, a television (display system) 1 includes a high-definition multimedia interface (HDMI) (registered trademark) receiver 100, a video input terminal 101a, an audio input terminal 101b, a BD drive 102, a tuner 103, and an IP broadcast tuner. 104, satellite broadcast tuner 105, OSD generation unit 106, video selector 107, video processing circuit (image processing device) 108, LCD controller (display device) 109, LCD (display device) 110, audio selector 111, audio processing circuit 112, Digital amplifier 113, speaker 114, Ethernet (registered trademark) I / F 115, ROM (Read-Only Memory) 116, RAM (Random Access Memory) 117, CPU (Central Processing Unit) 118, infrared light receiving unit 119, camera 120, and The human sensor 121 is provided. In FIG. 2, the video signal path is indicated by a solid line, the audio signal path is indicated by a one-dot chain line, and the data (control) path (bus) is indicated by a bold line.

  (1) Video received by the HDMI receiver 100, (2) Video input from the video input terminal 101a, (3) Video read out from the BD (Blu-ray Disc) by the BD drive 102, (4) (Terrestrial digital The video received by the tuner 103 for broadcasting, the video received by the IP broadcast tuner 104, and the video received by the satellite broadcast tuner 105 are supplied to the video selector 107, respectively. Also, (1) audio received by the HDMI receiver 100, (2) audio input from the audio input terminal 101b, (3) audio read by the BD drive 102 from the BD, (4) audio received by the tuner 103, ( 5) The audio received by the IP broadcast tuner 104 and (6) the audio received by the satellite broadcast tuner 105 are supplied to the audio selector 111, respectively.

  Note that (a) the tuner 103 receives the content transmitted through which channel, (b) the server from which the IP broadcast tuner 104 receives the distributed content, (c) the satellite broadcast tuner. Selection control for determining which channel 105 receives the content transmitted through is performed by the CPU 118. The CPU 118 also performs playback control such as (d) playback, stop, fast forward, rewind, and chapter transition in the BD drive 102.

  The video selector 107 is (1) video supplied from the HDMI receiver 100, (2) video supplied from the video input terminal 101a, (3) video supplied from the BD drive 102, and (4) video supplied from the tuner 103. 1, (5) an image supplied from the IP broadcast tuner 104, and (6) an image supplied from the satellite broadcast tuner 105. The video selected by the video selector 107 is supplied to the video processing circuit 108. Note that the CPU 118 controls which video the video selector 107 selects.

  The video processing circuit 108 performs video processing such as image quality adjustment, scaling, and image enhancement on the video supplied from the video selector 107. The video processed by the video processing circuit 108 is supplied to the LCD controller 109.

  Here, adjustment of image quality refers to changing at least one of brightness, sharpness, and contrast, for example. Scaling refers to reducing the size while maintaining the original aspect ratio of the video to be displayed. Image enhancement refers to conversion into an easy-to-see image by sharpening the image, enhancing lines and edges of the image, removing noise from the image, and the like. Note that the CPU 118 controls how the image processing circuit 108 changes the image quality, how much the image is reduced, and how much image enhancement is performed. Details of the video processing circuit 108 will be described later.

  The LCD controller 109 drives the LCD 110 so that the video supplied from the video processing circuit 108 is displayed. As a result, the image selected by the image selector 107 is output from the LCD 110. When an OSD image is supplied from the OSD generation unit 106, the LCD controller 109 displays the OSD image supplied from the OSD generation unit 106 on the video supplied from the video processing circuit 108. Details of the LCD controller 109 and the LCD 110 will be described later.

The audio selector 111 is an audio supplied from the HDMI receiver 100, an audio supplied from the video input terminal 101a, an audio supplied from the BD drive 102, an audio supplied from the tuner 103, and an audio supplied from the IP broadcast tuner 104. And any one of the voices supplied from the satellite broadcast tuner 105 is selected. The sound selected by the sound selector 111 is supplied to the sound processing circuit 112. Note that the CPU 118 controls which sound the sound selector 111 selects. However, the selection of the video by the video selector 107 and the selection of the audio by the audio selector 111 are linked. For example, when the video selector 107 selects the video supplied from the HDMI receiver 100, the audio selector 111 is also selected. The audio supplied from the HDMI receiver 100 is selected.

  The audio processing circuit 112 adjusts the volume and quality of the audio supplied from the audio selector 111. Here, the adjustment of the sound quality refers to changing the frequency characteristics of the sound supplied from the sound selector 111 (for example, emphasizing a low frequency or emphasizing a high frequency). The sound whose volume and sound quality are adjusted by the sound processing circuit 112 is supplied to the digital amplifier 113. Note that the CPU 118 controls how the sound processing circuit 112 changes the sound volume and sound quality.

  The digital amplifier 113 drives the speaker 114 so that the sound supplied from the sound processing circuit 112 is output. Thereby, the sound selected by the sound selector 111 is output from the speaker 114.

  The CPU 118 controls each of the above units according to the remote control signal received by the infrared light receiving unit 119, the image captured by the camera 120, and the output signal output from the human sensor 121. The output signal of the human sensor 121 is a binary signal indicating whether or not a viewer exists within the sensing range. Control using the infrared light receiving unit 119 includes, for example, control for switching a channel selected by the tuner 103 according to a remote control signal, and video and audio selected by the video selector 107 and the audio selector 111 according to a remote control signal. Examples include switching control. The control using the camera 120 includes, for example, control for switching how the image quality is adjusted in the video processing circuit 108 according to the viewer specified based on the captured image. In addition, examples of the control using the human sensor 121 include control for switching whether the backlight of the LCD 110 is turned on or off according to the detection result.

  Further, the CPU 118 executes a CEC (Consumer Electronics Control) command received by the HDMI receiver 100 from an external device (not shown), or generates a CEC command that the HDMI receiver 100 transmits to the external device. Realizes cooperative operation with the external device. Examples of the external device include a mobile phone terminal and an HDD (Hard Disk Drive) recorder.

  The ROM 116 is a readable and non-writable memory in which fixed data such as a program executed by the CPU 118 is stored. The ROM 116 also stores JPEG data, SVG (Scalable Vector Graphics) data, and the like referred to by the OSD generation unit 106 to generate an OSD image. On the other hand, the RAM 117 is a readable and writable memory in which variable data such as data referred to by the CPU 118 for calculation and data generated by the CPU 118 by calculation is stored.

  The Ethernet (registered trademark) I / F 115 is an interface for connecting the television 1 to a network. The IP broadcast tuner 104 described above accesses a server on the Internet via the Ethernet (registered trademark) I / F 115.

  Note that the television 1 has a communication function. That is, it has a function of executing communication applications such as an e-mail client, a web browser, and a call application. Such a function is realized by the CPU 118 executing a program stored in the ROM 116. When the television 1 is provided with a call function, it is desirable to incorporate a microphone for picking up the user's voice during a call in the television 1 (or a remote controller for operating the television 1).

  Next, details of the LCD controller 109 and the LCD 110 will be described. FIG. 3 is a block diagram showing a schematic configuration of the LCD controller 109 and the LCD 110.

  As shown in FIG. 3, in the present embodiment, the LCD 110 has a configuration in which a plurality of LEDs are provided as the LED backlight 11 on the back side of the liquid crystal module 10. The LCD controller 109 includes a display control unit 12 that controls the liquid crystal module 10 to display the supplied video, and a backlight control unit 13 that controls the LED backlight 11.

  In the present embodiment, the backlight control unit 13 controls the luminance of each LED of the LED backlight 11 based on the supplied video. Thereby, the dynamic range of the LCD 110 can be changed. This point will be described in detail with reference to FIG. 4 and FIG.

  FIG. 4 is a diagram illustrating the relationship between the control of the LED backlight 11 and the change in the dynamic range of the LCD 110. In the upper and lower stages of the figure, three liquid crystal modules 10 and LED backlights 11 and three dynamic ranges are shown in association with each other.

  The left side of FIG. 4 shows a case where the backlight control unit 13 does not individually control the LEDs in the LED backlight 11. In this case, light with uniform luminance is emitted from the LED backlight 11 through the liquid crystal module 10. In this case, the dynamic range of the LCD 110 corresponds to the contrast ratio of the liquid crystal module 10.

  In the center of FIG. 4, a case where the backlight control unit 13 controls the LEDs of the LED backlight 11 corresponding to the black area in the supplied video to be non-lighted (light emission stop), that is, a case where local dimming is performed. Has been. In this case, when the LED corresponding to the black region is not lit, the luminance of light emitted from the LED through the liquid crystal module 10 is lowered. As a result, the dynamic range of the LCD 110 is expanded.

  On the right side of FIG. 4, there is a case where the backlight control unit 13 performs control to additionally supply surplus power from the non-lighted LED to the LED of the LED backlight 11 corresponding to the white area in the supplied video. It is shown. In this case, since the brightness of the LED corresponding to the white region increases, the brightness of light emitted from the LED through the liquid crystal module 10 increases. As a result, the dynamic range of the LCD 110 is further expanded.

  As illustrated in FIG. 4, the backlight control unit 13 divides one screen into a plurality of areas, and calculates luminance information of the LED backlight 11 in each area based on the supplied video. The backlight control unit 13 controls the luminance of the LED of the LED backlight 11 based on the calculated luminance information.

  FIG. 5 is a diagram illustrating an example of luminance information of the LED backlight 11 in a table format. In the illustrated example, the area is divided into 16 × 9 = 144 areas, and the luminance information is calculated based on the video shown in FIG. In the example of FIG. 5, no power is supplied to the LEDs in the area where the luminance information is 0, and additional power is supplied to the LEDs in the area where the luminance information exceeds 100.

  It is desirable that the LEDs of the LED backlight 11 are arranged for each area. In this case, the luminance control of the LED by the backlight control unit 13 becomes easy. Further, it is desirable that display control of the display control unit 12 and luminance control of the backlight control unit 13 are interlocked. For example, when the backlight control unit 13 turns off the LED or increases the luminance, display unevenness may occur. For this reason, it is desirable that the display control unit 12 controls the liquid crystal module 10 so as to suppress the display unevenness.

  Next, details of the video processing circuit 108 of the present embodiment will be described. FIG. 1 is a block diagram showing a schematic configuration related to the image enhancement of the video processing circuit 108. As shown, the video processing circuit 108 includes a video detection circuit 20, a noise detection circuit 21, a noise removal circuit (acquisition means, image processing means, noise removal means) 22, an edge enhancement circuit (acquisition means, image processing means, edge). Emphasis means) 23 and a synthesis circuit 24.

  The video detection circuit 20 detects various types of information related to the video, such as a histogram of luminance signals and APL (Average Picture Level) in the video supplied from the video selector 107. Information detected by the video detection circuit 20 is used for various types of video processing in the video processing circuit 108.

  The noise detection circuit 21 detects noise included in the video supplied from the video selector 107. The noise component of the video detected by the noise detection circuit 21 is supplied to the noise removal circuit 22, and the components other than the video noise are supplied to the edge enhancement circuit 23.

  The noise removal circuit 22 removes the noise component of the video supplied from the noise detection circuit 21. The processed component of the video from which the noise component has been removed by the noise removal circuit 22 is supplied to the synthesis circuit 24.

  As an example of the method for removing the noise component, there is a method using a time-axis IIR (infinite pulse response) filter. In this method, the following equation is calculated.

_{Y N = Y N-1 ×} α + Y CUR × (1-α) ··· (1)
Here, _{Y N} is the luminance signal of the N _{frame, Y N-1} represents the original luminance signal of the luminance signal of the (N-1) th _{frame, Y CUR} is the processing target frame (N-th frame). Moreover, (alpha) is a coefficient regarding a noise removal effect, and is a value of 0-1. As the coefficient α is increased, the influence of the previous frame ((N−1) th frame) is increased, and the noise removal effect is increased. Note that other methods for removing the noise component may be used.

  The edge emphasis circuit 23 performs edge emphasis on components other than video noise supplied from the noise detection circuit 21. The processed component of the video whose edge is enhanced by the edge enhancement circuit 23 is supplied to the synthesis circuit 24.

  As an example of the method for enhancing the edge, there is a method using second order differentiation. FIG. 6 is a graph showing a method of enhancing the edge using second order differentiation. First, when second-order differentiation is performed on the luminance signal (original signal) as shown in (a) of the figure, it becomes as shown in (b) of the figure, and when further multiplied by the coefficient β, (c) of the figure is obtained. )become that way. When the original signal− (secondary derivative of the original signal) × β is calculated, the signal is as shown in (d) of FIG. The greater the coefficient β, the greater the degree of edge enhancement. Note that other methods for enhancing the edge may be used.

  The synthesis circuit 24 synthesizes the processed component of the video from the noise removal circuit 22 and the processed component of the video from the edge enhancement circuit 23 to create a video after image enhancement. The image after image enhancement synthesized by the synthesis circuit 24 is supplied to the LCD controller 109.

  In the present embodiment, the noise removal circuit 22 acquires the dynamic range of the LCD 110 from the LCD controller 109, and changes the noise removal intensity according to the acquired dynamic range. The edge enhancement circuit 23 acquires the dynamic range of the LCD 110 from the LCD controller 109, and changes the edge enhancement strength according to the acquired dynamic range.

  Specifically, the backlight control unit 13 of the LCD controller 109 extracts the maximum value and the minimum value from the luminance information (FIG. 5) of the LED backlight 11 in each area calculated as described above. Next, the backlight control unit 13 transmits the difference between the extracted maximum value and minimum value as the dynamic range of the LCD 110 to the noise removal circuit 22 and the edge enhancement circuit 23. Thereby, the noise removal circuit 22 and the edge enhancement circuit 23 can acquire the dynamic range of the LCD 110.

  Next, the noise removal circuit 22 and the edge enhancement circuit 23 change the coefficient α and the coefficient β, respectively, according to the acquired dynamic range. 7A and 7B are graphs showing how the coefficient α and the coefficient β change with respect to the dynamic range, respectively.

  As shown in FIG. 7A, the noise removal circuit 22 increases the coefficient α to increase the noise removal effect as the dynamic range increases. As a result, even if the dynamic range is increased, it is possible to display an image in which noise is not noticeable.

  Further, as shown in FIG. 7B, in the edge enhancement circuit 23, the coefficient β is decreased and the degree of edge enhancement is reduced as the dynamic range is increased. Thereby, even if the dynamic range becomes large, an image in which the edge is not conspicuous can be displayed.

  Even if the dynamic range changes according to the video to be displayed, the video to be displayed has been subjected to noise removal and edge enhancement to the extent corresponding to the dynamic range, and is therefore displayed on the LCD 110. The image can have a sense of noise, fineness, sharpness, and so on. Therefore, deterioration of the display quality of the LCD 110 can be suppressed.

  In this embodiment, as shown in FIG. 7, the coefficients α and β corresponding to the acquired dynamic range are determined. However, the dynamic range may change frequently depending on the video, and in this case, the coefficients α and β may be changed frequently, and the displayed video may feel uncomfortable. Therefore, as shown in the following equation, LPF (Low Pass Filter) may be applied to the coefficients α and β to smoothly change the coefficients α and β.

α (Nth frame) = (α ((N−3) frame) × 1 + α ((N−2) frame) × 2 + α ((N−1) frame) × 3 + α (Nth frame before LPF) × 4) / 10 (2)
β (Nth frame) = (β ((N−3) frame) × 1 + β ((N−2) frame) × 2 + β ((N−1) frame) × 3 + β (Nth frame before LPF) × 4) / 10 (3)
In this case, even if the dynamic range changes frequently according to the video, the coefficients α and β are smoothly changed, so that it is possible to prevent the displayed video from feeling uncomfortable.

  The dynamic range may be acquired every frame, or may be acquired every predetermined frame or every predetermined time. Further, a plurality of dynamic ranges may be acquired every predetermined frame or every predetermined time, or an average value of the plurality of dynamic ranges may be acquired. Thus, the timing for acquiring the dynamic range can be arbitrarily set.

[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIGS. The television 1 of the present embodiment is different from the television 1 shown in FIGS. 1 to 7 in the configuration of the video processing circuit 108 and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure and process similar to the structure and process demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 8 is a block diagram showing a schematic configuration related to the image enhancement of the video processing circuit 108 in the present embodiment. As shown in the figure, the control of the video processing circuit 108 based on the dynamic range of the LCD 110 is a feedback type in FIG. 1, but is a feedforward type in this embodiment.

  The video processing circuit 108 of the present embodiment is different from the video processing circuit 108 shown in FIG. 1 in the configuration of the video detection circuit 30, and the other configurations are the same. The video detection circuit 30 adds a function for estimating the dynamic range of the LCD 110 from the video supplied from the video selector 107 to the function of the video detection circuit 20 shown in FIG.

  As an example of the method for estimating the dynamic range, there is a method using a histogram of luminance signals (shading information) in video. Referring to FIG. 4, it can be understood that the minimum value of the dynamic range of the LCD 110 decreases due to the presence of a black region in the image, and further increases due to the presence of a white region in the image. In particular, when there are many black areas and a few white areas, the dynamic range is most widened. Therefore, it can be estimated how much the dynamic range of the LCD 110 is expanded from the black region and the white region of the video.

  First, the video detection circuit 30 of the present embodiment calculates a histogram of luminance signals from the video supplied from the video selector 107, and from the calculated histogram, the number of pixels in the black region and the number of pixels in the white region in the video. Is calculated. FIG. 9 is a graph showing an example of a histogram of luminance signals in the video shown in FIG. In the illustrated graph, the horizontal axis indicates the quantization unit (LSB) of the luminance signal, and the vertical axis indicates the frequency of the pixel. The minimum part of the luminance signal corresponds to the black area, and the maximum part corresponds to the white area.

  Next, the video detection circuit 30 estimates the dynamic range of the LCD 110 from the calculated number of pixels in the black area and the number of pixels in the white area by the following equation.

(Dynamic range) = ((number of pixels in black region) × δ + (number of pixels in white region) × (1−δ)) / total number of pixels (4)
Here, the coefficient δ is a real number greater than 0 and equal to or less than 1.

  Then, the video detection circuit 30 transmits the estimated dynamic range to the noise removal circuit 22 and the edge enhancement circuit 23. As a result, in the noise removal circuit 22 and the edge enhancement circuit 23, the coefficient α and the coefficient β are changed according to the acquired dynamic range.

[Embodiment 3]
Next, another embodiment of the present invention will be described with reference to FIG. The television 1 of the present embodiment is different from the television 1 shown in FIGS. 1 to 7 in the configuration of the video processing circuit 108 and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure and process similar to the structure and process demonstrated in the said embodiment, and the description is abbreviate | omitted.

  FIG. 10 is a block diagram showing a schematic configuration related to the image enhancement of the video processing circuit 108 in the present embodiment. As shown in the figure, in this embodiment, the noise removal circuit 22 is a feed forward type that acquires the estimated dynamic range from the video detection circuit 30. On the other hand, the edge enhancement circuit 23 is a feedback type that acquires the actual dynamic range from the LCD controller 109.

  In the case of the feedback type, since the actual dynamic range is used, the accuracy of the control is good. However, since the dynamic range is that of the previous image, there is a difficulty in followability. On the other hand, in the case of the feedforward type, since the estimated dynamic range is used, there is a difficulty in control accuracy. However, since the dynamic range is that of the video to be processed, followability is good.

  In the noise removal circuit 22, the rate of change of the coefficient α with respect to the dynamic range is large as shown in FIG. For this reason, when the noise removal circuit 22 is a feedback type, the followability is deteriorated, and there is a possibility that the displayed image becomes noise-like for a moment. Therefore, in the present embodiment, the noise removal circuit 22 is a feed-forward type with good followability.

  On the other hand, in the edge enhancement circuit 23, as shown in FIG. 7B, since the rate of change of the coefficient α with respect to the dynamic range is small, the followability does not deteriorate so much even in the feedback type. Therefore, in the present embodiment, the edge enhancement circuit 23 is a feedback type with high control accuracy. As described above, the feedback type and the feedforward type can be selectively used according to the contents of the video processing.

  The noise removal circuit 22 may use both the estimated dynamic range from the video detection circuit 30 and the actual dynamic range from the LCD controller 109. In this case, the noise removal circuit 22 uses both a feedforward type with good followability and a feedback type with good control accuracy, and can effectively suppress display quality deterioration of the LCD 110.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  For example, in the above embodiment, the LCD 110 is used as the display device. However, even an FPD including a light emitting element for each pixel, such as a PDP or an EL display, can expand the dynamic range of the display device as shown in FIG. 4, and thus the FPD may be used as the display device. .

  In the above embodiment, the change based on the dynamic range of the LCD 110 is applied to image enhancement such as noise removal and edge enhancement. However, the change can be applied to arbitrary video processing such as image quality adjustment.

  As described above, even if the dynamic range of the display device changes according to the image to be displayed, the image processing device according to the present invention can process the image to be displayed to the extent corresponding to the dynamic range. Therefore, it is possible to align the noise, fineness, sharpness, etc. of the image displayed on the display device, and to suppress the deterioration of the display quality of the display device. The present invention can be applied to an image processing device for an arbitrary display device whose dynamic range changes according to an image to be processed.

1 TV (display system)
DESCRIPTION OF SYMBOLS 10 Liquid crystal module 11 LED backlight 12 Display control part 13 Backlight control part 20 Image | video detection circuit 21 Noise detection circuit 22 Noise removal circuit (acquisition means, image processing means, noise removal means)
23 Edge enhancement circuit (acquisition means, image processing means, edge enhancement means)
24 Synthesis Circuit 30 Video Detection Circuit 108 Video Processing Circuit (Image Processing Device)
109 LCD controller (display device)
110 LCD (display device)

Claims (15)

An image processing apparatus that processes an image and creates the image to be displayed for a display apparatus in which a dynamic range that is an outputable luminance range changes according to the image to be displayed,
Obtaining means for obtaining a dynamic range of the display device;
Image processing means for processing the image by changing the degree of processing of the image according to the dynamic range acquired by the acquisition means,
The image processing apparatus, wherein the acquisition unit estimates and acquires the dynamic range from an image to be processed by the image processing unit. The acquisition unit acquires an actual dynamic range in the display device from the display device in addition to estimating and acquiring the dynamic range from an image to be processed by the image processing unit. Item 8. The image processing apparatus according to Item 1. An image processing apparatus that processes an image and creates the image to be displayed for a display apparatus in which a dynamic range that is an outputable luminance range changes according to the image to be displayed,
Obtaining means for obtaining a dynamic range of the display device;
Image processing means for processing the image by changing the degree of processing of the image according to the dynamic range acquired by the acquisition means,
The image processing means includes noise removing means for removing noise included in the image,
The image processing apparatus according to claim 1, wherein the noise removal unit increases the noise removal strength as the dynamic range acquired by the acquisition unit increases.   The noise removing unit uses the dynamic range estimated by the acquiring unit from an image to be processed, or uses both the dynamic range and the actual dynamic range acquired by the acquiring unit from the display device. The image processing apparatus according to claim 3, wherein: An image processing apparatus that processes an image and creates the image to be displayed for a display apparatus in which a dynamic range that is an outputable luminance range changes according to the image to be displayed,
Obtaining means for obtaining a dynamic range of the display device;
Image processing means for processing the image by changing the degree of processing of the image according to the dynamic range acquired by the acquisition means,
The image processing means includes edge enhancement means for performing edge enhancement of the image,
The edge enhancement unit reduces the edge enhancement intensity as the dynamic range acquired by the acquisition unit increases.   The image processing apparatus according to claim 5, wherein the edge enhancement unit uses an actual dynamic range acquired by the acquisition unit from the display device. A display device in which a dynamic range, which is a range of luminance that can be output, changes according to an image to be displayed;
A display system comprising: the image processing apparatus according to claim 1, wherein the display apparatus creates an image to be displayed by performing image processing for the display apparatus.   The display device includes a plurality of light emitting elements for displaying the image to be displayed, and stops light emission of the light emitting elements corresponding to a black region of the image to be displayed. 8. The display system according to 7.   The display system according to claim 8, wherein the display device additionally supplies surplus power due to the stop of light emission of the light emitting element to the light emitting element corresponding to a white region of the image to be displayed. A display device in which a dynamic range, which is a width of outputable brightness, changes according to an image to be displayed; and an image processing device for processing the image to create the image to be displayed for the display device; A display system comprising:
Obtaining means for obtaining a dynamic range of the display device;
Image processing means for processing the image by changing the degree of processing of the image according to the dynamic range acquired by the acquisition means,
The display device includes a plurality of light emitting elements for displaying the image to be displayed, and stops the light emission of the light emitting elements corresponding to the black region of the image to be displayed,
The display device additionally supplies surplus power due to the stop of light emission of the light emitting element to the light emitting element corresponding to a white region of the image to be displayed.   The display system according to any one of claims 7 to 10, wherein the display device is a liquid crystal display device using a plurality of light emitting diodes as a backlight.   12. The display system according to claim 7, wherein the display system is a television receiver that receives an image signal from the outside and displays an image based on the received image signal. An image processing method for generating an image to be displayed by processing an image for a display device in which a dynamic range that is a brightness width that can be output varies depending on the image to be displayed,
An acquisition step of acquiring a dynamic range of the display device;
An image processing step of changing the degree of processing of the image and processing the image according to the dynamic range acquired in the acquiring step,
The image processing method according to claim 1, wherein the acquiring step estimates and acquires the dynamic range from an image to be processed by the image processing step. An image processing method for generating an image to be displayed by processing an image for a display device in which a dynamic range that is a brightness width that can be output varies depending on the image to be displayed,
An acquisition step of acquiring a dynamic range of the display device;
An image processing step of changing the degree of processing of the image and processing the image according to the dynamic range acquired in the acquiring step,
The image processing step includes a noise removal step of removing noise included in the image,
The noise removing step increases the intensity of noise removal as the dynamic range acquired in the acquiring step increases. An image processing method for generating an image to be displayed by processing an image for a display device in which a dynamic range that is a brightness width that can be output varies depending on the image to be displayed,
An acquisition step of acquiring a dynamic range of the display device;
An image processing step of changing the degree of processing of the image and processing the image according to the dynamic range acquired in the acquiring step,
The image processing step includes an edge enhancement step for performing edge enhancement of the image,
The edge enhancement step reduces the edge enhancement intensity as the dynamic range acquired in the acquisition step increases.