Patent Description:
A dynamic range (DR) refers to a range from the brightest to the darkest. As the dynamic range is increased, a user is capable of feeling as he or she is actually seeing an environment in an image.

Recently, a standard dynamic range (SDR) has been mainly used for an image source input to a display device, and in this regard, has a limit in realizing realistic image quality in that a range of brightness is narrower than a range seen by the human eye.

To overcome the limit, a tone mapping algorithm for improving the color or contrast of an image is used. However, the tone mapping algorithm currently uses a static curve, and thus there is a problem in that a contrast ratio is lowered or saturated in some images.

Accordingly, there is a need for a method of improving color or contrast irrespective of the characteristics of an image.

Patent documents <CIT> and <CIT> disclose prior art processes for enhancing image contrast.

The present disclosure provides a display device and an operation method thereof for improving the color or contrast of all input images.

The present disclosure provides a display device and an operation method thereof for improving the color or contrast irrespective of the characteristics of an image.

A display device and an operation method thereof according to an embodiment of the present disclosure may perform tone mapping for applying a curve in various ways depending on the characteristics of an image.

A display device according to an embodiment of the present disclosure not forming part of the invention comprises a controller configured to perform tone mapping for converting RGB data of an input image through a look-up table (LUT) curve, and a display configured to display an image based on the RGB data converted by the tone mapping, wherein the controller corrects the LUT curve according to a histogram of the input image.

The controller acquires an offset gain based on the histogram of the input image and corrects the LUT curve by applying the offset gain.

The controller acquires a max bin with concentrated data in the histogram of the input image and acquires the offset gain based on the max bin.

The controller acquires a representative bin of a group with a high ratio of data based on the histogram of the input image and acquires the offset gain based on the max bin and the representative bin.

When the max bin belongs to the group with a high ratio of data, the controller acquires a gain value corresponding to the max bin as the offset gain.

When the max bin does not belong to the group with a high ratio of data, the controller acquires a gain value corresponding to an average of the max bin and the representative bin as the offset gain.

The controller acquires the group with a high ratio of data based on a bin with an amount of data equal to or greater than a predetermined ratio in the histogram of the input image.

The controller acquires an offset point based on at least one of the max bin or the representative bin and acquires a gain value mapped to the offset point as the offset gain, and wherein a higher gain value is mapped as the gain value is increased.

When data corresponding to <NUM>% or more in the histogram of the input image belongs to a range corresponding to an upper first setting ratio, the controller acquires the offset gain as <NUM>.

When data corresponding to the top <NUM>% or more in the histogram of the input image belongs to a range corresponding to an upper second setting ratio, the controller differently acquires the offset gain depending on an amount of data belonging to a range corresponding to the upper second setting ratio.

The controller acquires the offset gain by multiplying a gain value mapped to an offset point by a specified constant depending on an amount of data belonging to the range of the upper second setting ratio.

The controller acquires an LUT curve obtained by compensating for luminance based on a reduced value of max luminance when the offset gain is applied.

The controller selects any one of a plurality of predetermined LUT curves based on a peak luminance level or an average picture level (APL) of the input image and corrects the selected LUT curve according to the histogram of the input image.

The controller acquires an offset gain based on the histogram of the input image and corrects the LUT curve by applying the offset gain to the selected LUT curve.

An operation method of a display device according to an embodiment of present disclosure not forming part of the invention comprises storing a plurality of look-up table (LUT) curves, selecting any one of the plurality of LUT curves, correcting the LUT curve selected among the plurality of LUT curves according to a histogram of an input image, performing tone mapping for converting RGB data of an input image using an LUT curve corrected according to the histogram of the input image, and displaying an image on which the tone mapping is performed.

The invention is set out in the appended set of claims Advantageous Effects.

According to an embodiment of the present disclosure, the color or contrast may be enhanced for all input images by applying different look-up table (LUT) curves to tone mapping when the characteristics of an image are different.

Hereinafter, embodiments relating to the present disclosure will be described in detail with reference to the accompanying drawings. The suffixes "module" and "interface" for components used in the description below are assigned or mixed in consideration of easiness in writing the specification and do not have distinctive meanings or roles by themselves.

<FIG> is a block diagram illustrating a configuration of a display device according to an embodiment of the present disclosure.

Referring to <FIG>, a display device <NUM> can include a broadcast reception module <NUM>, an external device interface <NUM>, a storage <NUM>, a user input interface <NUM>, a controller <NUM>, a wireless communication interface <NUM>, a voice acquisition module <NUM>, a display <NUM>, an audio output interface <NUM>, and a power supply <NUM>.

The broadcast reception module <NUM> can include a tuner <NUM>, a demodulator <NUM>, and a network interface <NUM>.

The tuner <NUM> can select a specific broadcast channel according to a channel selection command. The tuner <NUM> can receive broadcast signals for the selected specific broadcast channel.

The demodulator <NUM> can divide the received broadcast signals into video signals, audio signals, and broadcast program related data signals and restore the divided video signals, audio signals, and data signals to an output available form.

The network interface <NUM> can provide an interface for connecting the display device <NUM> to a wired/wireless network including internet network. The network interface <NUM> can transmit or receive data to or from another user or another electronic device through an accessed network or another network linked to the accessed network.

The network interface <NUM> can access a predetermined webpage through an accessed network or another network linked to the accessed network. That is, it can transmit or receive data to or from a corresponding server by accessing a predetermined webpage through network.

Then, the network interface <NUM> can receive contents or data provided from a content provider or a network operator. That is, the network interface <NUM> can receive contents such as movies, advertisements, games, VODs, and broadcast signals, which are provided from a content provider or a network provider, through network and information relating thereto.

Additionally, the network interface <NUM> can receive firmware update information and update files provided from a network operator and transmit data to an internet or content provider or a network operator.

The network interface <NUM> can select and receive a desired application among applications open to the air, through network.

The external device interface <NUM> can receive an application or an application list in an adjacent external device and deliver it to the controller <NUM> or the storage <NUM>.

The external device interface <NUM> can provide a connection path between the display device <NUM> and an external device. The external device interface <NUM> can receive at least one of image and audio outputted from an external device that is wirelessly or wiredly connected to the display device <NUM> and deliver it to the controller. The external device interface <NUM> can include a plurality of external input terminals. The plurality of external input terminals can include an RGB terminal, at least one High Definition Multimedia Interface (HDMI) terminal, and a component terminal.

An image signal of an external device inputted through the external device interface <NUM> can be outputted through the display <NUM>. A sound signal of an external device inputted through the external device interface <NUM> can be outputted through the audio output interface <NUM>.

An external device connectable to the external device interface <NUM> can be one of a set-top box, a Blu-ray player, a DVD player, a game console, a sound bar, a smartphone, a PC, a USB Memory, and a home theater system but this is just exemplary.

Additionally, some content data stored in the display device <NUM> can be transmitted to a user or an electronic device, which is selected from other users or other electronic devices pre-registered in the display device <NUM>.

The storage <NUM> can store signal-processed image, voice, or data signals stored by a program in order for each signal processing and control in the controller <NUM>.

Additionally, the storage <NUM> can perform a function for temporarily store image, voice, or data signals outputted from the external device interface <NUM> or the network interface <NUM> and can store information on a predetermined image through a channel memory function.

The storage <NUM> can store an application or an application list inputted from the external device interface <NUM> or the network interface <NUM>.

The display device <NUM> can play content files (for example, video files, still image files, music files, document files, application files, and so on) stored in the storage <NUM> and provide them to a user.

The user input interface <NUM> can deliver signals inputted from a user to the controller <NUM> or deliver signals from the controller <NUM> to a user. For example, the user input interface <NUM> can receive or process control signals such as power on/off, channel selection, and screen setting from the remote control device <NUM> or transmit control signals from the controller <NUM> to the remote control device <NUM> according to various communication methods such as Bluetooth, Ultra Wideband (WB), ZigBee, Radio Frequency (RF), and IR.

Additionally, the user input interface <NUM> can deliver, to the controller <NUM>, control signals inputted from local keys (not shown) such as a power key, a channel key, a volume key, and a setting key.

Image signals that are image-processed in the controller <NUM> can be inputted to the display <NUM> and displayed as an image corresponding to corresponding image signals. Additionally, image signals that are image-processed in the controller <NUM> can be inputted to an external output device through the external device interface <NUM>.

Voice signals processed in the controller <NUM> can be outputted to the audio output interface <NUM>. Additionally, voice signals processed in the controller <NUM> can be inputted to an external output device through the external device interface <NUM>.

Besides that, the controller <NUM> can control overall operations in the display device <NUM>.

Additionally, the controller <NUM> can control the display device <NUM> by a user command or internal program inputted through the user input interface <NUM> and download a desired application or application list into the display device <NUM> in access to network.

The controller <NUM> can output channel information selected by a user together with processed image or voice signals through the display <NUM> or the audio output interface <NUM>.

Additionally, according to an external device image playback command received through the user input interface <NUM>, the controller <NUM> can output image signals or voice signals of an external device such as a camera or a camcorder, which are inputted through the external device interface <NUM>, through the display <NUM> or the audio output interface <NUM>.

Moreover, the controller <NUM> can control the display <NUM> to display images and control broadcast images inputted through the tuner <NUM>, external input images inputted through the external device interface <NUM>, images inputted through the network interface, or images stored in the storage <NUM> to be displayed on the display <NUM>. In this case, an image displayed on the display <NUM> can be a still image or video and also can be a 2D image or a 3D image.

Additionally, the controller <NUM> can play content stored in the display device <NUM>, received broadcast content, and external input content inputted from the outside, and the content can be in various formats such as broadcast images, external input images, audio files, still images, accessed web screens, and document files.

Moreover, the wireless communication interface <NUM> can perform a wired or wireless communication with an external electronic device. The wireless communication interface <NUM> can perform short-range communication with an external device. For this, the wireless communication interface <NUM> can support short-range communication by using at least one of Bluetooth™, Radio Frequency Identification (RFID), Infrared Data Association (IrDA), Ultra Wideband (UWB), ZigBee, Near Field Communication (NFC), Wireless-Fidelity (Wi-Fi), Wi-Fi Direct, and Wireless Universal Serial Bus (USB) technologies. The wireless communication interface <NUM> can support wireless communication between the display device <NUM> and a wireless communication system, between the display device <NUM> and another display device <NUM>, or between networks including the display device <NUM> and another display device <NUM> (or an external server) through wireless area networks. The wireless area networks can be wireless personal area networks.

Herein, the other display device <NUM> can be a mobile terminal such as a wearable device (for example, a smart watch, a smart glass, and a head mounted display (HMD)) or a smartphone, which is capable of exchanging data (or inter-working) with the display device <NUM>. The wireless communication interface <NUM> can detect (or recognize) a communicable wearable device around the display device <NUM>. Furthermore, if the detected wearable device is a device authenticated to communicate with the display device <NUM>, the controller <NUM> can transmit at least part of data processed in the display device <NUM> to the wearable device through the wireless communication interface <NUM>. Accordingly, a user of the wearable device can use the data processed in the display device <NUM> through the wearable device.

The voice acquisition module <NUM> can acquire audio. The voice acquisition module <NUM> may include at least one microphone (not shown), and can acquire audio around the display device <NUM> through the microphone (not shown).

The display <NUM> can convert image signals, data signals, or OSD signals, which are processed in the controller <NUM>, or images signals or data signals, which are received in the external device interface <NUM>, into R, G, and B signals to generate driving signals.

Furthermore, the display device <NUM> shown in <FIG> is just one embodiment of the present disclosure and thus, some of the components shown can be integrated, added, or omitted according to the specification of the actually implemented display device <NUM>.

That is, if necessary, two or more components can be integrated into one component or one component can be divided into two or more components and configured. Additionally, a function performed by each block is to describe an embodiment of the present disclosure and its specific operation or device does not limit the scope of the present disclosure.

According to another embodiment of the present disclosure, unlike <FIG>, the display device <NUM> can receive images through the network interface <NUM> or the external device interface <NUM> and play them without including the tuner <NUM> and the demodulator <NUM>.

For example, the display device <NUM> can be divided into an image processing device such as a set-top box for receiving broadcast signals or contents according to various network services and a content playback device for playing contents inputted from the image processing device.

In this case, an operating method of a display device according to an embodiment of the present disclosure described below can be performed by one of the display device described with reference to <FIG>, an image processing device such as the separated set-top box, and a content playback device including the display <NUM> and the audio output interface <NUM>.

The audio output interface <NUM> receives the audio processed signal from the controller <NUM> and outputs the sound.

The power supply <NUM> supplies the corresponding power throughout the display device <NUM>. In particular, the power supply <NUM> supplies power to the controller <NUM> that can be implemented in the form of a System On Chip (SOC), a display <NUM> for displaying an image, and the audio output interface <NUM> for outputting audio or the like.

Specifically, the power supply <NUM> may include a converter for converting an AC power source into a DC power source, and a DC/DC converter for converting a level of the DC source power.

Then, referring to <FIG> and <FIG>, a remote control device is described according to an embodiment of the present disclosure.

<FIG> is a block diagram illustrating a remote control device according to an embodiment of the present disclosure and <FIG> is a view illustrating an actual configuration of a remote control device according to an embodiment of the present disclosure.

First, referring to <FIG>, a remote control device <NUM> can include a fingerprint recognition module <NUM>, a wireless communication interface <NUM>, a user input interface <NUM>, a sensor <NUM>, an output interface <NUM>, a power supply <NUM>, a storage <NUM>, a controller <NUM>, and a voice acquisition module <NUM>.

Referring to <FIG>, the wireless communication interface <NUM> transmits/receives signals to/from an arbitrary any one of display devices according to the above-mentioned embodiments of the present disclosure.

The remote control device <NUM> can include an RF module <NUM> for transmitting/receiving signals to/from the display device <NUM> according to the RF communication standards and an IR module <NUM> for transmitting/receiving signals to/from the display device <NUM> according to the IR communication standards. Additionally, the remote control device <NUM> can include a Bluetooth module <NUM> for transmitting/receiving signals to/from the display device <NUM> according to the Bluetooth communication standards. Additionally, the remote control device <NUM> can include an NFC module <NUM> for transmitting/receiving signals to/from the display device <NUM> according to the Near Field Communication (NFC) communication standards and a WLAN module <NUM> for transmitting/receiving signals to/from the display device <NUM> according to the Wireless LAN (WLAN) communication standards.

Additionally, the remote control device <NUM> can transmit signals containing information on a movement of the remote control device <NUM> to the display device <NUM> through the wireless communication interface <NUM>.

Moreover, the remote control device <NUM> can receive signals transmitted from the display device <NUM> through the RF module <NUM> and if necessary, can transmit a command on power on/off, channel change, and volume change to the display device <NUM> through the IR module <NUM>.

The user input interface <NUM> can be configured with a keypad button, a touch pad, or a touch screen. A user can manipulate the user input interface <NUM> to input a command relating to the display device <NUM> to the remote control device <NUM>. If the user input interface <NUM> includes a hard key button, a user can input a command relating to the display device <NUM> to the remote control device <NUM> through the push operation of the hard key button. This will be described with reference to <FIG>.

Referring to <FIG>, the remote control device <NUM> can include a plurality of buttons. The plurality of buttons can include a fingerprint recognition button <NUM>, a power button <NUM>, a home button <NUM>, a live button <NUM>, an external input button <NUM>, a voice adjustment button <NUM>, a voice recognition button <NUM>, a channel change button <NUM>, a check button <NUM>, and a back button <NUM>.

The fingerprint recognition button <NUM> can be a button for recognizing a user's fingerprint. According to an embodiment of the present disclosure, the fingerprint recognition button <NUM> can perform a push operation and receive a push operation and a fingerprint recognition operation. The power button <NUM> can be button for turning on/off the power of the display device <NUM>. The power button <NUM> can be button for moving to the home screen of the display device <NUM>. The live button <NUM> can be a button for displaying live broadcast programs. The external input button <NUM> can be button for receiving an external input connected to the display device <NUM>. The voice adjustment button <NUM> can be button for adjusting the size of a volume outputted from the display device <NUM>. The voice recognition button <NUM> can be a button for receiving user's voice and recognizing the received voice. The channel change button <NUM> can be a button for receiving broadcast signals of a specific broadcast channel. The check button <NUM> can be a button for selecting a specific function and the back button <NUM> can be a button for returning to a previous screen.

If the user input interface <NUM> includes a touch screen, a user can touch a soft key of the touch screen to input a command relating to the display device <NUM> to the remote control device <NUM>. Additionally, the user input interface <NUM> can include various kinds of input means manipulated by a user, for example, a scroll key and a jog key, and this embodiment does not limit the scope of the present disclosure.

The sensor <NUM> can include a gyro sensor <NUM> or an acceleration sensor <NUM> and the gyro sensor <NUM> can sense information on a movement of the remote control device <NUM>.

For example, the gyro sensor <NUM> can sense information on an operation of the remote control device <NUM> on the basis of x, y, and z axes and the acceleration sensor <NUM> can sense information on a movement speed of the remote control device <NUM>. Moreover, the remote control device <NUM> can further include a distance measurement sensor and sense a distance with respect to the display <NUM> of the display device <NUM>.

The output interface <NUM> can output image or voice signals corresponding to a manipulation of the user input interface <NUM> or corresponding to signals transmitted from the display device <NUM>. A user can recognize whether the user input interface <NUM> is manipulated or the display device <NUM> is controlled through the output interface <NUM>.

For example, the output interface <NUM> can include an LED module <NUM> for flashing, a vibration module <NUM> for generating vibration, a sound output module <NUM> for outputting sound, or a display module <NUM> for outputting an image, if the user input interface <NUM> is manipulated or signals are transmitted/received to/from the display device <NUM> through the wireless communication interface <NUM>.

Additionally, the power supply <NUM> supplies power to the remote control device <NUM> and if the remote control device <NUM> does not move for a predetermined time, stops the power supply, so that power waste can be reduced. The power supply <NUM> can resume the power supply if a predetermined key provided at the remote control device <NUM> is manipulated.

The storage <NUM> can store various kinds of programs and application data necessary for a control or operation of the remote control device <NUM>. If the remote control device <NUM> transmits/receives signals wirelessly through the display device <NUM> and the RF module <NUM>, the remote control device <NUM> and the display device <NUM> transmits/receives signals through a predetermined frequency band.

The controller <NUM> of the remote control device <NUM> can store, in the storage <NUM>, information on a frequency band for transmitting/receiving signals to/from the display device <NUM> paired with the remote control device <NUM> and refer to it.

The controller <NUM> controls general matters relating to a control of the remote control device <NUM>. The controller <NUM> can transmit a signal corresponding to a predetermined key manipulation of the user input interface <NUM> or a signal corresponding to a movement of the remote control device <NUM> sensed by the sensor <NUM> to the display device <NUM> through the wireless communication interface <NUM>.

Additionally, the voice acquisition module <NUM> of the remote control device <NUM> can obtain voice.

The voice acquisition module <NUM> can include at least one microphone <NUM> and obtain voice through the microphone <NUM>.

<FIG> is a view of utilizing a remote control device according to an embodiment of the present disclosure.

<FIG> illustrates that a pointer <NUM> corresponding to the remote control device <NUM> is displayed on the display <NUM>.

A user can move or rotate the remote control device <NUM> vertically or horizontally. The pointer <NUM> displayed on the display <NUM> of the display device <NUM> corresponds to a movement of the remote control device <NUM>. Since the corresponding pointer <NUM> is moved and displayed according to a movement on a 3D space as show in the drawing, the remote control device <NUM> can be referred to as a spatial remote controller.

<FIG> illustrates that if a user moves the remote control device <NUM>, the pointer <NUM> displayed on the display <NUM> of the display device <NUM> is moved to the left in correspondence thereto.

Information on a movement of the remote control device <NUM> detected through a sensor of the remote control device <NUM> is transmitted to the display device <NUM>. The display device <NUM> can calculate the coordinates of the pointer <NUM> from the information on the movement of the remote control device <NUM>. The display device <NUM> can display the pointer <NUM> to match the calculated coordinates.

<FIG> illustrates that while a specific button in the remote control device <NUM> is pressed, a user moves the remote control device <NUM> away from the display <NUM>. Thus, a selection area in the display <NUM> corresponding to the pointer <NUM> can be zoomed in and displayed largely.

On the other hand, if a user moves the remote control device <NUM> close to the display <NUM>, a selection area in the display <NUM> corresponding to the pointer <NUM> can be zoomed out and displayed reduced.

On the other hand, if the remote control device <NUM> is away from the display <NUM>, a selection area can be zoomed out and if the remote control device <NUM> is close to the display <NUM>, a selection area can be zoomed in.

Additionally, if a specific button in the remote control device <NUM> is pressed, the recognition of a vertical or horizontal movement can be excluded. That is, if the remote control device <NUM> is moved away from or close to the display <NUM>, the up, down, left, or right movement can not be recognized and only the back and fourth movement can be recognized. While a specific button in the remote control device <NUM> is not pressed, only the pointer <NUM> is moved according to the up, down, left or right movement of the remote control device <NUM>.

Moreover, the moving speed or moving direction of the pointer <NUM> can correspond to the moving speed or moving direction of the remote control device <NUM>.

Furthermore, a pointer in this specification means an object displayed on the display <NUM> in correspondence to an operation of the remote control device <NUM>. Accordingly, besides an arrow form displayed as the pointer <NUM> in the drawing, various forms of objects are possible. For example, the above concept includes a point, a cursor, a prompt, and a thick outline. Then, the pointer <NUM> can be displayed in correspondence to one point of a horizontal axis and a vertical axis on the display <NUM> and also can be displayed in correspondence to a plurality of points such as a line and a surface.

<FIG> is a block diagram of a tone mapper according to an embodiment of the present disclosure.

A display device <NUM> according to an embodiment of the present disclosure may further include a tone mapper <NUM>. In particular, a controller <NUM> may include the tone mapper <NUM>. However, this is merely exemplary, and the tone mapper <NUM> may be provided at any position within the display device <NUM>.

The tone mapper <NUM> may convert RGB data by performing tone mapping for applying a look-up table (LUT) curve to an input image. The display <NUM> may display an image based on the RGB data converted by tone mapping.

In detail, upon receiving an image, the tone mapper <NUM> may convert the RGB data of the input image to output the converted data. The display <NUM> may receive converted RGB data output from the tone mapper <NUM>. The display <NUM> may display an image based on the converted RGB data.

The tone mapper <NUM> may include at least some or all of a tone curve determiner <NUM> and a tone curve corrector <NUM>.

The tone curve determiner <NUM> may acquire a LUT curve to be used in tone mapping.

The LUT curve may be a table for changing RGB of a captured original image to new RGB by adjusting hue, saturation, and brightness.

In detail, the storage <NUM> may store a plurality of LUT curves, and the tone curve determiner <NUM> may recognize at least one of a plurality of LUT curves stored in the storage <NUM> as an LUT curve to be used in tone mapping.

The tone curve determiner <NUM> may select any one of a plurality of predetermined LUT curves based on at least one of a peak luminance level or an average picture level (APL) of the input image. A method of selecting any one of a plurality of LUT curves will be described with reference to <FIG>.

The tone curve corrector <NUM> may correct the LUT curve determined by the tone curve determiner <NUM>. The tone curve corrector <NUM> may correct the LUT curve selected from the plurality of LUT curves based on a histogram of the input image.

The tone curve corrector <NUM> may perform tone mapping for converting RGB data of the input image using the corrected LUT curve. The tone curve corrector <NUM> may output the RGB data converted using the tone mapping.

<FIG> is a flowchart of an operation method of a display device according to an embodiment of the present disclosure.

The controller <NUM> may receive an image (S11).

The controller <NUM> may receive the received image through the broadcast reception module <NUM>, the external device interface <NUM>, the user input interface <NUM>, the wireless communication interface <NUM>, etc..

The controller <NUM> may acquire RGB data of the input image.

The controller <NUM> may select any one of the plurality of predetermined LUT curves (S13).

The controller <NUM> may select any one of the plurality of predetermined LUT curves based on the peak luminance level or the average picture level (APL) of the input image.

<FIG> is an example diagram of a method of selecting any one from a plurality of LUT curves by a display device according to an embodiment of the present disclosure.

As shown in <FIG>, the storage <NUM> may store the plurality of LUT curves. Referring to <FIG>, the plurality of LUT curves may have different respective gains for improving color or contrast, and in this regard, the closer the LUT curve to a side "a", the higher an improvement gain of color or contrast, and the closer the LUT curve to a side "b", the lower an improvement gain of color or contrast.

The controller <NUM> may select any one of the plurality of LUT curves based on image information. For example, the controller <NUM> may select an LUT curve closer to the side "b" for an image with a higher peak luminance level and APL and may select an LUT curve closer to the side "a" for an image with a lower peak luminance level and APL.

To this end, the controller <NUM> may pre-store a table to which LUT curves corresponding to peak luminance levels and APLs and may acquire an LUT curve from the table based on the peak luminance level and APL of the input image. However, this is merely exemplary, and the controller <NUM> may acquire any one of a plurality of LUT curves using various methods.

The controller <NUM> may correct the selected LUT curve based on a histogram of the input image (S15).

The controller <NUM> may acquire the histogram of the input image based on RGB data of the input image and may correct the selected LUT curve based on the histogram of the input image.

In the case of an image, distribution of luminance levels of which is not uniform, a contrast ratio may be rather lowered or saturated during tone mapping for improving the color or contrast of the image. Thus, according to the present disclosure, for data with concentrated luminance levels, the LUT curve may be further corrected to perform tone mapping by reduce a gain of the LUT curve.

Hereinafter, a method of correcting an LUT curve by a display device according to an embodiment of the present disclosure will be described with reference to <FIG>.

The controller <NUM> may adjust an LUT curve according to the histogram of the input image.

<FIG> is a flowchart of a method of correcting an LUT curve by a display device according to an embodiment of the present disclosure.

<FIG> is a flowchart for specifying operation S15 of <FIG>.

The controller <NUM> may acquire a histogram of an input image (S107).

The histogram of the input image may be a graph showing distribution of a luminance level of an input image and shows a frequency for each luminance level of the input image.

For example, the controller <NUM> may group luminance levels of the input image in units of <NUM> bins. When the luminance levels are grouped in units of <NUM> bins, an image processing speed may be advantageously improved.

The controller <NUM> may extract a group with a high ratio of data from the histogram of the input image (S104).

The controller <NUM> may extract a group with concentrated data from a histogram indicated in units of bins. The controller <NUM> may recognize six consecutive bins as one group and may extract a group with the highest data frequency among the recognized groups as a group with a higher data ratio.

That is, the controller <NUM> may obtain a group with a high data ratio based on a bin with the amount of data equal to or greater than a predetermined ratio in the histogram of the input image.

In some embodiments, when recognizing six consecutive bins as one group, the controller <NUM> may recognize corresponding bins as one group only when a ratio of data occupied by each of six bins is equal to or greater than <NUM>%. In this case, a ratio of data may not be extracted for a group having bins less than <NUM>%, and thus unnecessary calculation may be advantageously minimized.

The controller <NUM> may acquire the max bin and a representative bin belonging to a group with a high ratio of data (S106).

The max bin may refer to a bin with the highest frequency among <NUM> bins. That is, the max bin may be a bin with concentrated data in the histogram of the input image.

For example, the controller <NUM> may acquire a bin with the highest frequency as the max bin in the histogram.

The representative bin may be any one bin belonging to a group with a high ratio of data. For example, the representative bin may be the first bin of the group with a high data ratio.

The controller <NUM> may acquire an offset point based on at least one of the max bin or the representative bin (S108).

The offset point may refer to a bin having data corresponding to a region, a contrast ratio of which is supposed to be further lowered via tone mapping.

A region in which data is concentrated is different for each image, and thus the controller <NUM> may obtain an offset point in order to differently apply the offset gain depending on a region in which data is concentrated.

Hereinafter, a method of acquiring an offset point by a display device according to an embodiment of the present disclosure will be described with reference to <FIG>.

<FIG> is an example diagram for explaining a method of acquiring an offset point based on a histogram of an input image by a display device according to an embodiment of the present disclosure.

Referring to an example of <FIG>, the controller <NUM> may acquire groups G1 to G12 with six consecutive bins having the amount of data of at least <NUM>% of the total. The controller <NUM> may extract a group with a high data ratio by calculating a ratio of data belonging to each group based on the total for each of the plurality of groups G1 to G12. In the example of <FIG>, a sixth group G6 of the plurality of groups G1 to G12 may be a group with a high data ratio.

The controller <NUM> may acquire a representative bin in the group with a high data ratio. For example, when the representative bin is a first bin of the group with a high data ratio, the representative bin may be a bin #<NUM> in the example of <FIG>.

The controller <NUM> may acquire the max bin, and in the example of <FIG>, the max bin may be a bin #<NUM>.

Upon acquiring the representative bin and the max bin, the controller <NUM> may acquire an offset point based on the representative bin and the max bin.

To acquire the offset point, the controller <NUM> may determine whether the max bin belongs to the group with a high data ratio. In the example of <FIG>, the controller <NUM> may determine whether a bin #<NUM> as the max bin corresponds to any one of bins #<NUM> to #<NUM> as the group G6 with a high data ratio.

When the max bin belongs to the group with a high data ratio, the controller <NUM> may acquire the max bin as an offset point. In the example of <FIG>, the controller <NUM> may acquire a bin #<NUM> as an offset point.

When the max bin does not belong to the group with a high data ratio, the controller <NUM> may acquire a bin corresponding to an average of the max bin and the representative bin as an offset point. Differently from the example of <FIG>, when the max bin is a bin #<NUM> and the representative bin is a bin #<NUM>, a bin #<NUM> as an average of bins #<NUM> and #<NUM> as an offset point. That is, when the max bin does not belong to the group with a high ratio, the controller <NUM> may acquire the average of the max bin and the representative bin as an offset point.

The controller <NUM> may acquire an offset gain based on the offset point (S110).

The controller <NUM> may map a gain value to each bin as an offset point. Thus, upon acquiring the offset point, the controller <NUM> may extract the gain value mapped to the offset point and may acquire the extracted gain value as an offset gain. That is, the controller <NUM> may acquire the gain value mapped to the offset point as the offset gain. In this case, a higher gain value may be mapped as the offset point is increased.

According to an embodiment of the present disclosure, the controller <NUM> may acquire the max bin with concentrated data in the histogram of the input image and may acquire the offset gain based on the max bin.

According to another embodiment, the controller <NUM> may acquire the offset gain based on the max bin and the representative bin.

For example, when the max bin belongs to the group with a high data ratio, the controller <NUM> may acquire a gain value corresponding to the max bin as the offset gain. In another example, when the max bin does not belong to the group with a high data ratio, the controller <NUM> may acquire a gain value corresponding to an average of the max bin and the representative bin as the offset gain.

For example, when the input image is a <NUM>-bit image, the offset gain may be any one of <NUM> to <NUM>.

When acquiring the offset gain, the controller <NUM> may adjust the offset gain depending on distribution and amount of data corresponding to the top <NUM>% or more in the histogram of the input image.

Hereinafter, a method of adjusting an offset gain according to distribution of data corresponding to the top <NUM>% or more in the histogram of the input image by the controller <NUM> will be described.

According to an embodiment, when data corresponding to <NUM>% or more in the histogram of the input image belongs to a range corresponding to an upper first setting ratio, the controller <NUM> may acquire an offset gain as <NUM>. For example, the first setting ratio may be <NUM>%. That is, when more than half of the data of the input image belongs to the top <NUM>%, the controller <NUM> may recognize that the image corresponds to an overall bright image, and in this case, data may not be concentrated at a specific luminance level, and thus the controller <NUM> may acquire the offset gain as <NUM>.

Hereinafter, a method of adjusting an offset gain depending on the amount of data corresponding to the top <NUM>% or more in a histogram of an input image by the controller <NUM> will be described.

According to an embodiment, when data corresponding to the top <NUM>% or more in the histogram of the input image belongs to a range corresponding to an upper second setting ratio, the controller <NUM> may differently acquire an offset gain depending on the amount of data belonging to the range corresponding to the upper second setting ratio. For example, the second setting ratio may be <NUM>%.

<FIG> is an example diagram for explaining a method of setting an offset gain depending on the amount of data by a display device according to an embodiment of the present disclosure.

When data corresponding to the top <NUM>% or more in the histogram of the input image is concentrated in the top <NUM>%, the controller <NUM> may acquire a gain obtained by multiplying a gain value by a specified constant as an offset gain.

Referring to <FIG>, when the amount of data of the top <NUM>% in the histogram of the input image, the controller <NUM> may set the specified constant to <NUM>, and in this case, the offset gain may be a gain value corresponding to the offset point.

When the amount of data of the top <NUM>% in the histogram of the input image is <NUM>%, the controller <NUM> may set the specified constant to <NUM>. That is, when the amount of data belonging to a range corresponding to the top <NUM>% is <NUM>% of the total data, the controller <NUM> may set the specified constant to <NUM>. In this case, the controller <NUM> may acquire a value obtained by multiplying a gain value corresponding to an offset point by <NUM> as the offset gain.

When the amount of data of the top <NUM>% in the histogram of the input image is <NUM>%, the controller <NUM> may set the specified constant to <NUM>. That is, when the amount of data belonging to a range corresponding to the top <NUM>% is <NUM>% of the total data, the controller <NUM> may set the specified constant to <NUM>. In this case, a value obtained by multiplying a gain value corresponding to the offset point by <NUM> may be acquired as an offset gain.

That is, the controller <NUM> may adjust a gain value to be increased as the amount of data belonging to the top <NUM>% of data of the input image is increased.

When the amount of data of the top <NUM>% is greater than <NUM>% and less than <NUM>% and is greater than <NUM>% and less than <NUM>%, the controller <NUM> may acquire a specified constant and may adjust an offset gain according to a graph shown in <FIG>, similarly to the above description.

When any one of <NUM> to <NUM> is set to an offset gain depending on an offset point, the controller <NUM> may adjust the offset gain to any one of <NUM> to <NUM> depending on the amount of data of the top <NUM>%.

The controller <NUM> may apply the offset gain to an LUT curve (S112).

The controller <NUM> may apply the offset gain to an LUT curve via calculation of subtracting the offset gain from the LUT curve selected from a plurality of LUT curves. That is, when the offset gain is applied to the LUT curve, this may mean that a curve obtained by subtracting the offset gain from the LUT curve is acquired.

In short, the controller <NUM> may acquire the offset gain based on the histogram of the input image and may correct the LUT curve by applying the offset gain.

The controller <NUM> may perform luminance compensation according to the result of applying the offset gain (S114).

The controller <NUM> may or may not perform luminance compensation according to the result of applying the offset gain. That is, the controller <NUM> may analyze the result of applying the offset gain and may perform luminance compensation only when luminance compensation is required.

As such, the controller <NUM> may acquire the LUT curve corrected by applying the offset gain to the LUT curve or may apply the offset gain to the LUT curve and may then acquire the corrected LUT curve through luminance compensation.

<FIG> is an example diagram for explaining a method of correcting an LUT curve by applying an offset gain by a display device according to an embodiment of the present disclosure.

Referring to <FIG>, "input data" indicates an LUT curve based on RGB data of an input image and "offset applied" indicates an LUT curve when the offset gain is applied.

In some cases, as seen from <FIG>, luminance may decrease as the offset gain is applied. In particular, max luminance (Max input data) may be dark in a section in which a signal is present, and thus luminance compensation may be performed to compensate for this, and "output data" indicates an LUT curve when luminance compensation is performed. In particular, the controller <NUM> may perform luminance compensation using the following expression.

That is, as shown in <FIG>, when the max luminance decreases when the offset gain is applied, the controller <NUM> may acquire an LUT curve obtained by compensating for luminance based on the reduced value of the max luminance.

The controller <NUM> may perform tone mapping using the corrected LUT curve (S17).

The controller <NUM> may perform tone mapping for converting RGB data of an input image according to the corrected LUT curve.

The controller <NUM> may output an image according to tone mapping (S19).

The controller <NUM> may control the display <NUM> to output an image based on the RGB data converted according to tone mapping.

12A to 12bB are example diagrams for explaining a method of differently outputting an LUT curve according to a peak of an input image by a display device according to an embodiment of the present disclosure.

In a histogram when an image is input as shown in an upper part of <FIG>, the controller <NUM> may detect data of an image output from the display <NUM> to acquire an LUT curve, which may be a curve C1 of <FIG>. When an image in which data of a bin corresponding to a peak of the histogram shown in the upper part of <FIG> is input, the controller <NUM> may detect data of the image output from the display <NUM> to acquire an LUT curve, which may be curves C1 and C2 of <FIG>. That is, as seen from the curves C1 and C2 shown in <FIG>, as data of a bin corresponding to a peak is changed, the LUT curve may be changed.

<FIG> and <FIG> are example diagrams for explaining a method of differently outputting an LUT curve according to distribution of a histogram of an input image by a display device according to an embodiment of the present disclosure.

In a histogram when an image is input as shown in an upper part of <FIG>, the controller <NUM> may detect data of an image output from the display <NUM> to acquire an LUT curve, which may be a curve C3 of <FIG>. When an image in which distribution of the histogram shown in the upper part of <FIG> is input, the controller <NUM> may detect data of the image output from the display <NUM> to acquire an LUT curve, which may be a curve C4 of <FIG>. That is, as seen from the curves C1 and C2 shown in <FIG>, as distribution of the histogram is changed, the LUT curve may be changed.

<FIG> is an example diagram of an output image based on RGB data of an input image by a display device according to an embodiment of the present disclosure. <FIG> is an example diagram of an output image when a static curve is applied to RGB data of an input image by a display device according to an embodiment of the present disclosure. <FIG> is an example diagram of an output image by performing tone mapping on RGB data of an input image using a corrected LUT curve by a display device according to an embodiment of the present disclosure.

As seen from <FIG> and <FIG>, a static curve may be applied irrespective of image information, and thus the image may brighten only and a contrast ratio may decrease. However, as seen from <FIG> and <FIG>, when any one of a plurality of LUT curves is selected and an LUT curve is corrected based on a histogram, a contrast ratio, expressiveness, three-dimensional effect, etc. may be improved.

That is, according to an embodiment of the present disclosure, an LUT curve is changed based on image information, and thus an image based on an LUT curve optimized for the current scene may be output, and accordingly, a contrast ratio may be maximized, and a subtle differences in color may be greatly expanded, thereby advantageously improving expressiveness.

The above description is merely illustrative of the technical idea of the present disclosure, and various modifications and changes may be made thereto by those skilled in the art without departing from the scope as disclosed in the accompanying claims.

Claim 1:
A display device comprising:
a storage (<NUM>) configured to store a plurality of look-up table, LUT, curves, wherein the plurality of LUT curves have different respective gains for improving color or contrast;
a controller (<NUM>) configured to:
receive an input image;
select one of the plurality of LUT curves based on a peak luminance level or an average picture level, APL, of the input image;
extract a group of consecutive bins from a histogram showing distribution of the luminance levels of the input image, the extracted group having a high data ratio;
acquire the max bin in the histogram of the input image, the max bin being the bin with the highest frequency, and a representative bin belonging to the group with the high data ratio;
acquire an offset point being a bin from the histogram based on the max bin and the representative bin;
extract a gain value mapped to the offset point, the gain value being an offset gain;
correct the LUT curve by applying the offset gain to the LUT curve;
perform tone mapping for converting RGB data of the input image according to the corrected LUT curve; and
a display (<NUM>) configured to display an image based on the RGB data converted by the tone mapping.