Patent Description:
The disclosure relates to a display apparatus and a control method thereof, in which an image is displayed with image quality optimized according to frames even though brightness is suddenly varied within one scene of high dynamic range (HDR) content in terms of applying dynamic tone mapping (DTM) to the HDR content, thereby increasing an immersion level of a user.

To satisfy a user who wants an image with more realistic image quality, high dynamic range (HDR) technology has recently been in the limelight. A dynamic range of brightness a human perceives is about <NUM>,<NUM> nits, whereas the dynamic range of brightness the display apparatus can handle is narrower than <NUM>,<NUM> nits. Therefore, there is a limit to how realistic the display apparatus can achieve the image quality. The HDR technology refers to a technique for extending a brightness range of an input image to become closer to a brightness range a human's eye perceives, by adjusting a brightness range between the brightest part and the darkest part of the input image. With such HDR technology, an image with various authentic brightness levels from intense sunlight to starlight in a dark night sky is so realistically displayed that a user can become more immersed in the image.

To display an HDR image based on the HDR technology, there is a need of setting the image quality. For example, static tone mapping (STM) may be performed by equally applying tone mapping throughout the image, or dynamic tone mapping (DTM) may be performed by applying tone mapping in units of scenes of the image. In a case of the DTM, tone mapping curves set according to the scenes of the image are used to display the image with a tone optimized according to the scenes.

<CIT> discloses an image processing device comprising: a display panel; and a controller configured to acquire a peak luminance value of a high dynamic range (HDR) image, and adjust a luminance of the high dynamic range image to be within an available output luminance range of the display panel, based on the acquired peak luminance value.

<CIT> discloses a display device comprising a processor which receives image data and reference information indicating whether a sub content along with a main content is included in the image data, and enables the image to be displayed by means of any one image processing method selected, among a plurality of image processing methods, so as to correspond to whether the sub content is included in the image.

<CIT> discloses a method of producing at least one output image signal representing, at least, a plurality of output luminance values in an output range of luminance values is disclosed. The method involves: identifying a mapping function based at least in part on a perceptually scaled distribution of a plurality of input luminance values in an input range of luminance values different from the output range of luminance values; transforming the plurality of input luminance values into respective perceptually scaled output luminance values according to the mapping function; transforming the perceptually scaled output luminance values into respective ones of the plurality of output luminance values; and producing the at least one output signal representing, at least, the plurality of output luminance values. Computer-readable media and apparatuses are also disclosed.

According to an aspect, there is provided a display apparatus as set out in claim <NUM>. Optional features are set out in claim <NUM>.

According to another aspect, there is provided method as set out in claim <NUM>.

According to another aspect, there is provided a recording medium as set out in claim <NUM>.

The above and/or the aspects will become apparent and more readily appreciated from the following description of exemplary embodiments taken in conjunction with the accompanying drawings, in which:.

Below, embodiments of the disclosure will be described in detail with reference to accompanying drawings. In the description of the following embodiments, elements illustrated in the accompanying drawings will be referenced, and like numerals or symbols set forth in the drawings refer to like elements having substantially the same operations. In the disclosure, at least one among a plurality of elements refers to not only all the plurality of elements but also both each one of the plurality of elements excluding the other elements and a combination thereof.

<FIG> illustrates a display apparatus according to an embodiment of the disclosure. As shown in <FIG>, the display apparatus <NUM> according to this embodiment is configured to display an image on a display <NUM>. <FIG> shows that the display apparatus <NUM> is a television (TV), but the display apparatus <NUM> is not limited to the TV. Alternatively, the display apparatus <NUM> may be embodied by a smartphone, a tablet computer, a personal computer, a wearable device such as a smart watch, a multimedia player, an electronic frame, home appliances such as a refrigerator, or the like capable of displaying an image. However, for convenience of description, descriptions will be made on the assumption that the display apparatus <NUM> is the TV.

The display apparatus <NUM> is configured to display an image based on content. The content may include high dynamic range (HDR) content. The HDR content may be produced having brightness or the like suited for a reference display apparatus by a so-called mastering process on the assumption that it will be displayed on the reference display apparatus. The HDR content produced by such a mastering process may include HDR content data, and characteristic information for setting the image quality of the HDR content. For example, the characteristic information may include static metadata for setting a fixed image quality to the whole HDR content. In this case, the display apparatus <NUM> may obtain image-quality setting information fixed with regard to the whole HDR content based on the static metadata, performs batch image-quality setting with regard to the whole HDR content based on the obtained image-quality setting information, and display an image based on the HDR content with the set image quality.

Alternatively, the characteristic information may include dynamic metadata for setting image quality variable depending on each of a plurality of sections in the HDR content. Here, the sections refer to a series of image event units in which at least one action, behavior, event, etc. occurs in continuous time or space, and may for example include scenes. In this case, the display apparatus <NUM> may obtain section image-quality setting information corresponding to each section of the sections of the HDR content based on the dynamic metadata, perform image-quality setting according to the sections based on the obtained section image-quality setting information, and display an image <NUM> of each section of the sections of the HDR content based on the image quality set according to the sections.

Thus, the display apparatus <NUM> carries out the image-quality setting according to the sections based on the section image-quality setting information corresponding to each of the sections of the content, and displays the image <NUM> of each section of the sections with the set image quality, thereby displaying the image <NUM> of the section with the image quality optimized according to the sections.

In particular, with regard to content having a plurality of frames, the display apparatus <NUM> according to this embodiment may obtain frame image-quality setting information based on frame characteristic information of each frame of the frames and section image-quality setting information of a section of the sections, to which each frame belongs, set image quality according to the frames based on the obtained frame image-quality setting information, and display an image <NUM> of the corresponding frame with the set image quality. For example, the display apparatus <NUM> may obtain frame brightness-setting information for setting a brightness range of each frame of the frames by considering the frame characteristic information corresponding to each frame of the frames and section brightness-setting information of a section of the sections, to which each frame belongs, with regard to the HDR content. The display apparatus <NUM> may set the brightness range of each frame of the frames based on the obtained frame brightness-setting information, and display the image <NUM> of the corresponding frame with the set brightness range.

Thus, the display apparatus <NUM> according to this embodiment obtains the frame image-quality setting information based on the frame characteristic information corresponding to each frame of the frames and the section image-quality setting information of the section, to which each frame belongs, with regard to the frames in the content, and displays the image <NUM> of the corresponding frame with the image quality set based on the obtained frame image-quality setting information, thereby displaying the image <NUM> of the frame with the image quality optimized according to the frames as compared to the case where the image <NUM> of each frame is displayed with a batch-set image quality in the corresponding section based on only the section image-quality setting information corresponding to the section.

<FIG> is a block diagram showing an exemplary configuration of the display apparatus in <FIG>. As shown in <FIG>, the display apparatus <NUM> include a display <NUM>, a signal receiver <NUM>, and a processor <NUM>.

The signal receiver <NUM> is configured to receive a signal. The signal may include HDR content, and may be received from a content providing apparatus. The content providing apparatus may for example include a set-top box, a Blu-ray disc, etc. In this case, the signal receiver <NUM> may receive a signal from the set-top box, the Blu-ray disc, etc. according to high definition multimedia interface (HDMI) standards. Alternatively, the content providing apparatus may include a server of a content provider or the like connected through a network. In this case, the signal receiver <NUM> may receive a signal from the server of the content provider or the like by a streaming method. However, the content providing apparatus from which the signal receiver <NUM> receives the signal is not limited to the foregoing examples. Alternatively, the signal receiver <NUM> may receive a terrestrial signal, a cable signal, an Internet protocol (IP) signal, etc. from a server of an external terrestrial TV, a cable TV (CATV), an IPTV, etc. or may receive a signal through a portable storage medium such as a digital versatile disc (DVD), a smart phone, a tablet computer, etc..

The display <NUM> is configured to display an image based on a signal received in the signal receiver <NUM>. For example, the display <NUM> may display a broadcast image based on a broadcast signal of a tuned channel. For example, there are various types of the display <NUM>, such as liquid crystal, plasma, an organic light-emitting diode, a carbon nano-tube, nano-crystal, etc., and the display <NUM> is not limited to these types.

The processor <NUM> is configured to control general elements of the display apparatus <NUM>. The processor <NUM> is configured to obtain first characteristic information, which is provided according to a plurality of sections of content and corresponds to an image characteristic of a section to be displayed among the plurality of sections, from a signal received through the signal receiver <NUM>, and obtain first image-quality setting information for setting image quality of the section based on first characteristic information. Further, the processor <NUM> is configured to obtain second characteristic information corresponding to an image characteristic of a frame included in the section from the frame, and obtain second image-quality setting information for setting image quality of the frame based on the first image-quality setting information and the second characteristic information. Further, the processor <NUM> is configured to control the display <NUM> to display the image <NUM> of the frame with the image quality set based on the second image-quality setting information.

The processor <NUM> may include a control program (or instruction) for performing control with regard to general elements, a nonvolatile memory in which the control program is installed, a volatile memory in which at least a part of the installed control program is loaded, and at least one processor or central processing unit (CPU) for executing a loaded control program. Further, such a control program may be stored in an electronic apparatus other than the display apparatus <NUM>.

The control program may include a program(s) implemented in the form of at least one among a basis input/output system (BIOS), a device driver, an operating system, a firmware, a platform, and an application. According to an exemplary embodiment, the application may be previously installed or stored when the display apparatus <NUM> is manufactured, or may be installed based on application data received from the outside when it is used in the future. The application data may for example be downloaded from an application market and the like external server. Such a server is an example of a computer program product, but not limited to this example.

At least one element may be excluded from the foregoing configuration of the display apparatus <NUM> or the display apparatus <NUM> may include another element in addition to the foregoing configuration. For example, the display apparatus <NUM> may further include a signal processor, a storage, a power supply, etc..

The signal processor may perform predetermined signal processing with regard to a signal received in the signal receiver. In a case of an image signal, for example, the signal processor performs image processing with regard to the image signal received in the signal receiver <NUM>, and displays an image on the display <NUM>. There are no limits to the kinds of image processing, and the image processing may for example include tuning for the received image signal, decoding corresponding to the kind of image signal, scaling, noise reduction, detail enhancement, frame refresh rate conversion, etc..

Further, the signal processor may perform audio processing with regard to an audio signal so that a sound can be output through a sound output unit achieved by a loudspeaker or the like.

The signal processor may include a hardware processor achieved by a chipset, a circuit, a buffer, etc. mounted onto a printed circuit board, or may be designed as a system on chip (SoC).

The storage may be configured to store data for processing the elements of the display apparatus <NUM> and programs for controlling the elements. The storage may include a storage medium of at least one type among a flash memory type, a hard disk type, a multimedia card micro type, a card type memory, and a read only memory (ROM). Further, the storage may be achieved by a web storage configured to store data and programs on the Internet.

Meanwhile, the power supply may receive power from an external power source or an internal power source under control of the processor <NUM> and supply required power to the elements of the display apparatus <NUM>.

<FIG> is a block diagram showing another exemplary configuration of the display apparatus in <FIG>. As shown in <FIG>, the display apparatus <NUM> according to this embodiment may include a decoder <NUM>, an extractor <NUM>, a tone mapper <NUM>, and the display <NUM>, and the tone mapper <NUM> may further include an adjuster <NUM>. Below, details will be described avoiding repetitive descriptions and focusing on only difference between <FIG> and <FIG>.

The decoder <NUM> may receive a signal including HDR content from the content provider or the content providing apparatus, and decode the received signal. For example, the content provider may generate the HDR content based on raw data of an image or digital data digitally converted from an image scanned from an analog film by a scanner. The content provider may encode the HDR content and the characteristic information showing an image characteristic of the HDR content. As necessary, the encoded signal may be provided to the content providing apparatus such as a set-top box, a Blu-ray disc, etc..

The characteristic information refers to information about image characteristics of the HDR content, and may include section metadata about image characteristics of each of the plurality of sections of the HDR content. The section metadata may for example include information about a histogram, an average brightness value, a maximum brightness value, distribution of brightness values, etc. of each section of the plurality of sections of the HDR content.

In particular, the characteristic information according to this embodiment may include frame metadata about image characteristics of each frame of the HDR content. The frame metadata may be provided corresponding to the frames of each section of the plurality of sections, and may include characteristic information about image characteristics of each frame of the frames. For example, the frame metadata may include information about a histogram, an average brightness value, a maximum brightness value, distribution of brightness values, etc. of each frame of the frames.

The extractor <NUM> may extract the characteristic information from the decoded signal, and transmit the extracted characteristic information to the tone mapper <NUM>. For example, the extractor <NUM> may identify the kind of metadata to extract the metadata. The metadata includes a field of various information units, and a value of the corresponding field. The field refers to format data of the metadata showing items of the information, and the value of the field refers to content data or parameter showing a value of the item of the corresponding information. The extractor <NUM> may perform a search for the field showing the kind of metadata, identify the kind of metadata, e.g. identify whether the kind of metadata is the section metadata or the frame metadata based on the search results, and extract the identified section metadata or frame metadata from the signal.

The tone mapper <NUM> may obtain the image-quality setting information for setting image quality of an image about HDR content based on the characteristic information received from the extractor <NUM>. The image-quality setting information may include a tone mapping curve for setting a tone of the HDR content. For example, the tone mapper <NUM> may receive the section metadata from the extractor <NUM>, and obtain a section tone mapping curve for setting the tone corresponding to each section of the plurality of sections of the HDR content based on the received section metadata. Further, the display <NUM> may display the image <NUM> of each section of the plurality of sections of the HDR content, the tone of which is set based on the obtained section tone mapping curve.

In particular, the adjuster <NUM> according to this embodiment may receive the frame metadata from the extractor <NUM>, and adjust the section tone mapping curve obtained by the tone mapper <NUM> based on the received frame metadata. The adjuster <NUM> may obtain a frame tone mapping curve for setting the tone of each frame of the frames of the HDR content based on the adjusted section tone mapping curve. The display <NUM> may display the image <NUM> of each frame of the frames of the HDR content, the tone of which is set based on the obtained frame tone mapping curve.

Thus, the display apparatus <NUM> according to this embodiment obtains the frame tone mapping curve by adjusting the section tone mapping curve based on the frame metadata, sets the image quality of each frame of the frames of the HDR content based on the obtained frame tone mapping curve, and displays the image <NUM> of each frame of the frames based on the set image quality, thereby displaying the image <NUM> of the frame with the image quality optimized according to the frames as compared to the case where the image <NUM> of each frame of the frames is displayed with a batch-set image quality in the corresponding section based on only the section tone mapping curve.

<FIG> is a block diagram showing an exemplary configuration of the processor in <FIG>. Referring to <FIG>, the processor <NUM> may include a frame analyzer <NUM>, an image-quality setter <NUM>, and a post processor <NUM>, and the frame analyzer <NUM> may further include a histogram matcher <NUM>.

The frame analyzer <NUM> may identify a frame, image quality of which will be set based on the frame image-quality setting information, among a plurality of frames in content. The frame analyzer <NUM> may identify the frame, the image quality of which will be set, based on difference between the section characteristic information showing image characteristics of a section in the content and the frame characteristic information showing the image characteristics of the frame of the section. However, the identification is not limited to this example. Alternatively, the frame analyzer <NUM> may identify at least one frame, which is identified based on predetermined periodicity or aperiodicity, among the plurality of frames included in the section, as the frame of which the image quality needs to be set based on the frame image-quality setting information.

The histogram matcher <NUM> may identify a frame of which image quality needs to be set based on comparison between a histogram of a frame and a histogram of a section to which the frame belongs. The comparison between the histograms may include comparison between the section and at least one among an average brightness value, a maximum brightness value, and a brightness value distribution of a plurality of pixels obtained from the histogram of the frame. In a case of the average brightness value, the histogram matcher <NUM> may for example identify a frame as the frame of which the image quality needs to be set, when difference between the average brightness value of the section and the average brightness value of the frame is greater than or equal to a predetermined threshold. Here, the predetermined threshold may be set with various values according to design methods.

The image-quality setter <NUM> may obtain the frame image-quality setting information based on the section image-quality setting information of the section to which the frame belongs and the frame characteristic information of the frame with regard to the frame identified by the frame analyzer <NUM>, and set the image quality of the frame based on the obtained frame image-quality setting information.

For example, the image-quality setter <NUM> may adjust the section brightness-setting information of the section, to which the frame belongs, based on the frame characteristic information of the frame with regard to the frame identified by the frame analyzer <NUM>, and obtain the frame brightness-setting information to display the image <NUM> of the frame within the brightness range of the corresponding frame.

Alternatively, the image-quality setter <NUM> may obtain the frame brightness-setting information to display the image <NUM> of the frame with the brightness range corresponding to the frame based on the frame characteristic information of the frame with regard to the frame identified by the frame analyzer <NUM>. In other words, in an arrangement not covered by the claimed invention, the image-quality setter <NUM> may directly generate the frame brightness-setting information by taking the frame characteristic information into account, regardless of the section brightness-setting information of the section to which the frame belongs.

The post processor <NUM> may compensate for color distortion in the image <NUM> of the frame of which the image quality is set. For example, the post processor <NUM> may employ an infinite impulse response (IIR) filter to prevent a flicker phenomenon or the like that may occur while the image <NUM> of the frame, the image quality of which is set based on the frame image-quality setting information, is displayed.

<FIG> shows a control method of the display apparatus in <FIG>. In this embodiment, the control method may be carried out as the processor <NUM> of the display apparatus <NUM> executes the control program described above. Hereafter, for convenience of description, the operations of the processor <NUM> carried out by executing the control program may be simply regarded as the operations of the processor <NUM>.

Referring to <FIG>, the processor <NUM> is configured to obtain first characteristic information, which is provided according to the plurality of sections of the content and corresponds to an image characteristic of a section to be displayed among the plurality of sections, from the received signal (S51).

Further, the processor <NUM> is configured to obtain the first image-quality setting information for setting the image quality of the section based on the obtained first characteristic information (S52).

Further, the processor <NUM> is configured to obtain the second characteristic information, which corresponds to the image characteristic of the frame included in the section, from the frame (S53).

Further, the processor <NUM> is configured to obtain the second image-quality setting information for setting the image quality of the frame based on the obtained first image-quality setting information and the obtained second characteristic information (S54).

Further, the processor <NUM> is configured to display the image of the frame, the image quality of which is set based on the obtained second image-quality setting information (S55).

Thus, by the control method according to this embodiment, an image is displayed with optimum image quality even though image quality is suddenly varied within one section when the image-quality is set according to the section of the image, thereby increasing an immersion level of a user.

Meanwhile, the operations of the foregoing control method may be implemented by a computer program that includes instructions to make a computer carry out the operations, and such a computer program may be stored or recorded in a storage and the like recording medium.

<FIG> illustrates an example of displaying images of a section in which image quality is set based on section image-quality setting information, and images of frames in which image quality is set based on frame image-quality setting information, in connection with operation S55 in <FIG>. As shown in <FIG>, it will be assumed that content includes a plurality of sections <NUM> and <NUM> and the section <NUM> includes four frames, i.e., first to fourth frames <NUM>, <NUM>, <NUM> and <NUM>. However, the number of sections and the number of frames in the content shown in <FIG> are just given for convenience of description, and may be varied depending on design methods.

The processor <NUM> may obtain the section image-quality setting information for setting the image quality of the section <NUM> based on the section characteristic information of the section <NUM>, and display the image <NUM> corresponding to the frames <NUM>, <NUM>, <NUM> and <NUM> included in the section <NUM> based on the obtained section image-quality setting information. In other words, the processor <NUM> may display images <NUM>, <NUM>, <NUM> and <NUM> with the image quality based on one piece of the section image-quality setting information with regard to the frames <NUM>, <NUM>, <NUM> and <NUM>. For example, the processor <NUM> may display the images <NUM>, <NUM>, <NUM> and <NUM> within the brightness range set based on the section brightness-setting information of the section <NUM>, to which the frames <NUM>, <NUM>, <NUM> and <NUM> belong, with respect to the frames <NUM>, <NUM>, <NUM> and <NUM>.

In particular, the processor <NUM> according to this embodiment may obtain the frame image-quality setting information corresponding to each of the frames <NUM>, <NUM>, <NUM> and <NUM>, based on the section image-quality setting information of the section <NUM> to which the frames <NUM>, <NUM>, <NUM> and <NUM> belong and the frame characteristic information of each of the frames <NUM>, <NUM>, <NUM> and <NUM>. Further, the processor <NUM> may set the image quality of each of the frames <NUM>, <NUM>, <NUM> and <NUM> based on the obtained frame image-quality setting information, and display images <NUM>, <NUM>, <NUM> and <NUM> of the corresponding frames with the set image quality. For example, the processor <NUM> may obtain the frame brightness-setting information based on the section brightness-setting information of the section <NUM> to which the frames <NUM>, <NUM>, <NUM> and <NUM> belong and the frame characteristic information corresponding to each of the frames <NUM>, <NUM>, <NUM> and <NUM>, and display the images <NUM>, <NUM>, <NUM> and <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> within the brightness range set based on the obtained frame brightness-setting information.

Below, comparison between the image <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> displayed in the brightness range set based on only the section image-quality setting information and the image <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> displayed in the brightness range set based on the frame brightness-setting information will be described with reference to <FIG>, on the assumption that brightness suddenly increases between the first frame <NUM> and the fourth frame <NUM> in the section <NUM>.

As shown in <FIG>, scenes in which a person <NUM> is in the dark and a light <NUM> slowly moves toward the person <NUM> are respectively displayed on the frames <NUM>, <NUM>, <NUM> and <NUM>. When the first frame <NUM> and the fourth frame <NUM> are displayed in a set brightness range based on only the section brightness-setting information, the image <NUM> of the first frame <NUM> in which the light <NUM> is distant from the person <NUM> is displayed darkly, but the image <NUM> of the fourth frame <NUM> in which the light <NUM> is near to the person <NUM> is displayed brightly.

According to this embodiment, the processor <NUM> may set the brightness range of the first frame <NUM> according to first frame brightness-setting information obtained based on the section brightness-setting information of the section <NUM> and first frame characteristic information of the first frame <NUM>. Because the processor <NUM> displays the image <NUM> of the first frame <NUM> with the set brightness range, the image <NUM> of the first frame <NUM> in which the light <NUM> is distant from the person <NUM> is displayed more brightly than the image <NUM> of the first frame <NUM> based on only the section brightness-setting information.

Further, the processor <NUM> may set the brightness range of the fourth frame <NUM> according to fourth frame brightness-setting information obtained based on the section brightness-setting information of the section <NUM> and fourth frame characteristic information of the fourth frame <NUM>. Because the processor <NUM> displays the image <NUM> of the fourth frame <NUM> with the set brightness range, the image <NUM> of the fourth frame <NUM> in which the light <NUM> is near to the person <NUM> is displayed more darkly than the image <NUM> of the fourth frame <NUM> based on only the section brightness-setting information. Likewise, regarding the second frame <NUM> and the third frame <NUM>, the processor <NUM> may display each of the image <NUM> of the second frame <NUM> and the image <NUM> of the third frame <NUM> with the set brightness range based on each frame brightness-setting information.

Thus, the processor <NUM> according to this embodiment obtains the frame brightness-setting information based on the frame characteristic information of the frames <NUM>, <NUM>, <NUM> and <NUM> and the section brightness-setting information of the section <NUM> with regard to the frames <NUM>, <NUM>, <NUM> and <NUM> of the section <NUM>, displays the images <NUM>, <NUM>, <NUM> and <NUM> with the set brightness range based on the obtained frame brightness-setting information, thereby displaying the images <NUM>, <NUM>, <NUM> and <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> with the brightness ranges optimized according to the frames <NUM>, <NUM>, <NUM> and <NUM> as compared to the case where the images <NUM>, <NUM>, <NUM> and <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> are displayed with the set brightness range based on only the section brightness-setting information of the section <NUM>.

Alternatively, the processor <NUM> may set a brightness range based on frame setting information with regard to only some frames, without setting the brightness range based on the frame setting information of all the frames <NUM>, <NUM>, <NUM> and <NUM> in the section <NUM>. For example, the processor <NUM> may set the brightness range based on the frame setting information of only at least one frame selected among the frames <NUM>, <NUM>, <NUM> and <NUM> based on predetermined periodicity or aperiodicity. Thus, resources may be more efficiently used than those of when the image quality is set based on the frame image-quality setting information of all the frames.

<FIG> illustrates a histogram for obtaining characteristic values of characteristic information, in connection with operation S53 in <FIG>, and <FIG> is a graph showing weighted values in brightness value distribution obtained based on the histogram.

The processor <NUM> may obtain a histogram of the frames <NUM>, <NUM>, <NUM> and <NUM> which belong to the section <NUM> of the content. The histogram may be included in the section characteristic information of the section <NUM> or the frame characteristic information of the frames <NUM>, <NUM>, <NUM> and <NUM>.

The histogram refers to a graph showing how many pixels have a corresponding brightness value with respect to the brightness values of the frames <NUM>, <NUM>, <NUM> and <NUM>. Below, a process of obtaining a characteristic value of frame characteristic information from the histogram will be described in detail on the assumption that the processor <NUM> obtains the histogram as shown in <FIG> with respect to the first frame <NUM> of <FIG>. However, the histogram shown in <FIG> is merely given for convenience of description, and therefore, even when another histogram is obtained with regard to another frame, the characteristic value of the frame characteristic information may also be obtained from the histogram about the corresponding frame by the process set forth herein.

The processor <NUM> may obtain a characteristic value of the first frame <NUM>, for example, at least one among an average brightness value <NUM> of a plurality of pixels of the first frame <NUM>, a maximum brightness value <NUM> of the first frame <NUM>, and a distribution of brightness values of the first frame <NUM>, from the histogram.

The average brightness value <NUM> may be obtained by dividing the sum of brightness values of the whole pixels by a total number of pixels. Referring to <FIG>, the plurality of pixels of the first frame <NUM> has the average brightness value <NUM> of '<NUM>' in the whole brightness values from '<NUM>' to `<NUM>'.

Further, the maximum brightness value <NUM> refers to a bin in which the pixel having the maximum brightness value is distributed. Referring to <FIG>, when the whole brightness values from '<NUM>' to '<NUM>' are divided into sixteen bins, the maximum brightness value <NUM> may be identified as the ninth bin.

Meanwhile, the distribution of the brightness values may be identified by the following expression.

In this expression, T1 and T3 may indicate the bins of the histogram, which the brightness values of the plurality of pixels are distributed. Further, w(i) may indicate a weighted value of Histogram(i), and Histogram(i) may indicate the number of pixels in a histogram corresponding to a corresponding bin.

<FIG> is a graph <NUM> showing a weighted value w about the distribution of the brightness values obtained based on the histogram. Referring to <FIG>, the weighted value w about the distribution of the brightness values may be given in a function form of the bin of the histogram. In other words, the weighted value w may be set to slowly increase from a first bin T1 to a second bin T2, but be maintained constant from the second bin T2 to the third bin T3. Here, the first bin T1 to the third bin T3 may be set with various values based on the histograms of the frames according to design methods.

In this manner, the processor <NUM> may obtain the average brightness value <NUM> of the plurality of pixels of the frames <NUM>, <NUM>, <NUM> and <NUM>, the maximum brightness value <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM>, the distribution of the brightness values of the frames <NUM>, <NUM>, <NUM> and <NUM>, and the like characteristic values from the histograms of the frames <NUM>, <NUM>, <NUM> and <NUM> which belong to one section <NUM>.

<FIG> is a graph <NUM> showing gains assigned to the characteristic values of the characteristic information, in connection with operation S53 in <FIG>. As shown in <FIG>, the processor <NUM> may obtain the characteristic values about the plurality of pixels of the frames <NUM>, <NUM>, <NUM> and <NUM> in one section <NUM>. The characteristic values may for example include the average brightness value <NUM>, the maximum brightness value <NUM>, the distribution of the brightness values, etc. of the first frame <NUM>.

Below, a process of setting a gain to the average brightness value <NUM> of the first frame <NUM> will be described in detail with reference to the gain graph of <FIG>. However, the gain graph shown in <FIG> is given by way of example for convenience of description, and thus various graphs may be provided according to design methods.

Referring to the gain graph of <FIG>, a gain about the average brightness value <NUM> of the first frame <NUM> may be set as the highest gain Gah between `<NUM>' and a first average brightness value Tah, and may be set to gradually decrease from the highest gain Gah to the lowest gain Gal between the first average brightness value Tah and a second average brightness value Tal. Likewise, a gain about the maximum brightness value <NUM> of the first frame <NUM> may also be set as the highest gain between '<NUM>' and a first maximum brightness value, and may be set to gradually decrease from the highest gain to the lowest gain between the first maximum brightness value and a second maximum brightness value. In addition, a gain about the brightness value distribution may also be constantly set as the highest gain between '<NUM>' and a first maximum brightness value, and may be set to gradually decrease from the highest gain to the lowest gain between the first maximum brightness value and a second maximum brightness value.

The processor <NUM> may for example identify the first frame characteristic information of the first frame <NUM> based on a total gain obtained by adding up the gain about the average brightness value <NUM> of the first frame <NUM>, the gain about the maximum brightness value <NUM> of the first frame <NUM>, and the gain about the brightness value distribution of the first frame <NUM>. In this case, the processor <NUM> may obtain the first frame image-quality setting information by applying the identified first frame characteristic information to the section image-quality setting information of the section <NUM>, and set the image quality of the first frame <NUM> based on the obtained first frame image-quality setting information. Similarly, the processor <NUM> may identify the total gain about the fourth frame <NUM> as the fourth frame characteristic information of the fourth frame <NUM>, obtain the fourth frame image-quality setting information by applying the identified fourth frame characteristic information to the section image-quality setting information, and set the image quality of the fourth frame <NUM> based on the obtained fourth frame image-quality setting information.

Below, it will be described in more detail with reference to <FIG>, <FIG> and <FIG> that the image qualities about the first frame <NUM> and the fourth frame <NUM> are set when brightness is suddenly increased between the first frame <NUM> and the fourth frame <NUM> in one section <NUM>. When the first frame <NUM> and the fourth frame <NUM> are displayed in the brightness range set based on the section brightness-setting information of the section <NUM>, the image <NUM> of the first frame <NUM> may be too dark and the image <NUM> of the fourth frame <NUM> may be too bright.

When the total gain obtained by adding up the gain about the average brightness value <NUM> of the first frame <NUM>, the gain about the maximum brightness value <NUM> of the first frame <NUM>, and the gain about the brightness value distribution of the first frame <NUM>, which is greater than '<NUM>', is applied to the section brightness-setting information, the image <NUM> of the first frame <NUM> based on the first frame brightness-setting information may be displayed more brightly than the image <NUM> of the first frame <NUM> based on the section brightness-setting information.

Regarding the fourth frame <NUM>, when the total gain obtained by adding up the gain about the average brightness value <NUM> of the fourth frame <NUM>, the gain about the maximum brightness value <NUM> of the fourth frame <NUM>, and the gain about the brightness value distribution of the fourth frame <NUM>, which is greater than '<NUM>', is applied to the section brightness-setting information, the image <NUM> of the fourth frame <NUM> based on the fourth frame brightness-setting information may be displayed more darkly than the image <NUM> of the fourth frame <NUM> based on the section brightness-setting information.

Thus, the processor <NUM> according to this embodiment sets the gain to the characteristic values of the frames <NUM>, <NUM>, <NUM> and <NUM>, and displays the image <NUM> of the frames <NUM>, <NUM>, <NUM> and <NUM> in the brightness range set based on the set gain, thereby displaying the image <NUM> with the image quality optimized according to the frames <NUM>, <NUM>, <NUM> and <NUM>.

<FIG> is a graph <NUM> showing an example of obtaining a frame tone mapping curve by applying frame characteristic information to a section tone mapping curve, in connection with operation S54 in <FIG>. According to this embodiment, the processor <NUM> may obtain the section image-quality setting information for setting the image quality of the section, and the frame image-quality setting information for setting the image quality of the frame based on the frame characteristic information about the image characteristics of the frame which belongs to the section. Below, it will be described in detail with reference to <FIG> and <FIG> that the frame tone mapping curve is obtained based on the section tone mapping curve and the frame characteristic information when the section image-quality setting information includes the section tone mapping curve for setting the tone of the image in the section and the frame image-quality setting information includes the frame tone mapping curve for setting the tone of the image of the frame.

As described above with reference to <FIG>, the processor <NUM> may obtain a section tone mapping curve <NUM> of the section <NUM>, to which the first frame <NUM> belongs, based on the section characteristic information like that of <FIG>. When the processor <NUM> displays the image <NUM> of the first frame <NUM> in the set brightness range based on the section tone mapping curve <NUM>, the image <NUM> may be relatively darkly displayed.

The processor <NUM> may adjust the section tone mapping curve <NUM> to a first frame tone mapping curve <NUM> corresponding to the first frame <NUM> based on the first frame characteristic information of the first frame <NUM>. For example, as described above with reference to <FIG>, the first frame characteristic information may correspond to the total gain about the characteristic value of the first frame <NUM>. In other words, the processor <NUM> may obtain the first frame tone mapping curve <NUM> by adjusting the section tone mapping curve <NUM> to correspond to the total gain. Regarding the brightness value of one input image, a brightness value of a displayed image set based on the first frame tone mapping curve <NUM> may be higher than a brightness value of a displayed image set based on the section tone mapping curve <NUM>. Therefore, the image <NUM> with the brightness set based on the first frame tone mapping curve <NUM> may be displayed more brightly than the image <NUM> with the brightness set based on the section tone mapping curve <NUM>.

<FIG> is a graph <NUM> showing another example of obtaining a frame tone mapping curve by applying frame characteristic information to a section tone mapping curve, in connection with operation S54 in <FIG>. It is described with reference to <FIG> that the first frame tone mapping curve <NUM> of the first frame <NUM> of <FIG> is obtained, whereas it will be described below in detail that the fourth frame tone mapping curve of the fourth frame <NUM> of <FIG> is obtained.

As described above with reference to <FIG>, the processor <NUM> may obtain the section tone mapping curve <NUM> of the section <NUM>, to which the fourth frame <NUM> belongs. When the processor <NUM> displays the image <NUM> of the fourth frame <NUM> in the brightness range set based on the section tone mapping curve <NUM>, the image <NUM> may be too bright.

Therefore, the processor <NUM> may adjust the section tone mapping curve <NUM> to a fourth frame tone mapping curve <NUM> corresponding to the fourth frame <NUM> based on the fourth frame characteristic information of the fourth frame <NUM>. For example, the fourth frame characteristic information may include the total gain about the characteristic value of the fourth frame <NUM> as described above with reference to <FIG>. In this case, the processor <NUM> may obtain the fourth frame tone mapping curve <NUM> by adjusting the section tone mapping curve <NUM> to correspond to the total gain. Regarding the brightness value of one input image, a brightness value of a displayed image set based on the fourth frame tone mapping curve <NUM> may be lower than a brightness value of a displayed image set based on the section tone mapping curve <NUM>. Therefore, the image <NUM> with the brightness set based on the fourth frame tone mapping curve <NUM> may be displayed more darkly than the image <NUM> with the brightness set based on the section tone mapping curve <NUM>.

<FIG> is a flowchart showing another exemplary control method of the display apparatus in <FIG>. Operations S121 to S123 in <FIG> are equal to the operations S51 to S53 in <FIG>, and therefore descriptions will be made avoiding repetitive descriptions and focusing on only difference for convenience of description.

Referring to <FIG>, the processor <NUM> is configured to identify whether difference between the image characteristic of the frame and the image characteristic of the section is greater than or equal to a predetermined value (S124).

When it is identified in the operation S124 that the difference is greater than or equal to the predetermined value, the processor <NUM> is configured to obtain the second image-quality setting information for setting the image quality of the frame based on the obtained first image-quality setting information and the obtained second characteristic information (S125), and display the image of the frame, the image quality of which is set based on the second image-quality setting information (S126).

On the other hand, when it is identified in the operation S124 that the difference is lower than the predetermined value, the processor <NUM> displays the image of the section, the image quality of which is set based on the first image-quality setting information (S127).

Thus, by the control method according to this embodiment, the image quality is set for the identified frame based on the frame image-quality setting information, and thus resources are more efficiently used than those of when the image qualities are set for all the frames based on the frame image-quality setting information. The operations of the foregoing control method of this embodiment may be implemented by a computer program that includes instructions to make a computer carry out the operations, and such a computer program may be stored or recorded in a storage and the like recording medium. In this disclosure, the storage may be provided as a non-transitory storage medium. Here, the term "non-transitory" means that the storage medium does not include a signal and is tangible but does not indicate whether data is stored in the storage medium semi-permanently or temporarily.

According to the disclosure, there are provided a display apparatus and a control method thereof, in which an image is displayed with optimum image quality even though brightness is suddenly varied within one scene, by applying DTM based on an image analysis performed in units of frames when image quality is set according to the scenes of the image, thereby increasing an immersion level of a user.

Claim 1:
A display apparatus (<NUM>) comprising:
a signal receiver (<NUM>);
a display (<NUM>); and
a processor (<NUM>) configured to:
obtain first characteristic information, which is provided according to a plurality of sections (<NUM>, <NUM>) of content and corresponds to an image characteristic of a section (<NUM>) to be displayed among the plurality of sections (<NUM>, <NUM>), from a signal received in the signal receiver (<NUM>), each of the plurality of sections comprising a plurality of image frames,
obtain first image-quality setting information for setting image quality of the section (<NUM>) based on the obtained first characteristic information,
obtain second characteristic information corresponding to an image characteristic of a frame included in the section (<NUM>) from the frame, the image characteristic of the frame being the same characteristic as the image characteristic of the section,
based on a difference between a value of the first image characteristic information and a value of the second image characteristic information being greater than or equal to a predetermined value, obtain second image-quality setting information for setting image quality of the frame by adjusting the obtained first image-quality setting information based on the obtained second characteristic information, and
control the display (<NUM>) to display an image of the frame, the image quality of the frame being set based on the obtained second image-quality setting information.