KR20180071810A - Transparent display device and method for driving the same - Google Patents

Abstract

The present invention relates to a transparent display device and a driving method thereof, capable of improving image quality by adaptively correcting the sharpness of an image according to the characteristics of the image and a background of the transparent display device. The transparent display device according to an embodiment of the present invention determines a sharpness enhancement strength according to the brightness and color of an original image and the background image, and correct the sharpness of the original image by applying the sharpness enhancement strength, thereby improving the image quality.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent display device and a method of driving the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent display device and a driving method thereof that can improve image quality by adaptively adjusting the sharpness of an image according to characteristics of an image characteristic and a background background of a transparent display device.

BACKGROUND ART In recent years, a transparent display device using a liquid crystal display (LCD) device or an organic light emitting diode (OLED) display device has been developed as a display device.

Since the transparent display device transmits light in both forward and backward directions, information can be displayed in both directions of the display device, and each user facing the display device can see beyond the transparent display device. Transparent display devices can be applied to various applications such as automobile glass, building glass, advertisement display board, cooler door, screen door, and the like.

Since the transparent display device recognizes the image together with the background of the background due to the transmission characteristics, the sharpness of the image is deteriorated according to the characteristic of the image such as the brightness of the image and the background of the background such as the brightness of the background, There is a problem.

For example, as the brightness of the image displayed on the transparent display device decreases, that is, in the case of a dark image, the background is recognized together with the image, and the edge expressing power of the image is lowered. Further, as the background luminance of the transparent display device increases, the more the image and the background color are different, the lower the edge expressive power of the image, and the visibility of the image is lowered.

The present invention provides a transparent display device and a method of driving the same that can improve the image quality by adaptively adjusting the sharpness of an image according to characteristics of a transparent display device and a background of the backlight.

According to an embodiment of the present invention, there is provided a transparent display device including a transparent display unit, a camera that captures a background image, a display drive unit, and a display unit that determines sharpness enhancement strength according to luminance and color of the original image and background image, And an image processor for correcting the sharpness of the original image and outputting the corrected image to the display driver.

The image processing unit includes a low pass filter, a mask generating unit, a sharpness improving strength determining unit, a sharpness improving mask determining unit, and an image correcting unit. The low-pass filter low-pass filters the original image to generate and output a blurred image. The mask generation unit generates an edge mask image by subtracting the blurred image supplied from the low pass filter from the original image and outputs the generated edge mask image. The sharpness improvement mask determination unit generates and outputs a sharpness improvement mask image by applying the sharpness enhancement strength for each block supplied from the sharpness improvement strength determination unit to the edge mask image supplied from the mask generation unit. The image correction unit synthesizes the sharpness enhancement mask image supplied from the sharpness enhancement mask determination unit with the original image, and outputs the corrected image to the panel driver.

According to another aspect of the present invention, there is provided a method of driving a transparent display device including: generating a blurred image by low-pass filtering an original image; generating an edge mask image by subtracting a blurred image from an original image; The method of claim 1, further comprising the steps of: determining a sharpness enhancement strength according to a luminance and a color of a background image; generating a sharpness enhancement mask image by applying a sharpness enhancement strength to an edge mask image; And displaying the image on the transparent display unit.

The sharpness enhancement strength determination unit according to an exemplary embodiment synthesizes the average luminance of each area obtained by dividing the original image and the average luminance of each area obtained by dividing the background image, And derives the average brightness for The sharpness enhancement strength determination unit compares the average brightness of each area of the original image with the average brightness of each area of the perceived image to determine a sharpness improvement intensity of each area of the original image and a brightness degree of each area of the perceived image Thereby deriving the degree of brightness change perception (JND). The sharpness improving strength determining unit determines the first sharpness improving strength for each region according to the degree of perception (JND) of luminance change per region.

The sharpness enhancement strength determination unit according to an exemplary embodiment compares the average color of each area of the original image with the average color of each area of the perceived image to determine the sharpness of the area of the original image and the area of the perceived image (? U'v ') for each region indicating the extent of color change and determines the second sharpness enhancement intensity for each region according to the perceived color change per region (? U'v'). The sharpness improvement strength determination unit determines the sharpness improvement strength for each area of the original image by applying the first sharpness improvement strength for each area and the second sharpness improvement strength for each area.

The sharpness enhancement strength determination unit according to an exemplary embodiment converts RGB data of the original image and the background image into XYZ data using the RGB-to-XYZ conversion function, And the average brightness for each region of the perceived image is calculated.

The sharpness enhancement strength determining unit according to an embodiment converts the average XYZ data for each region of the original image and the perceived image into the average Lu'v 'data for each region using the XYZ-to-Lu'v' conversion function, The average color (u'v ') of each image and perceived image is calculated.

A transparent display device and a driving method thereof according to an exemplary embodiment of the present invention adaptively adjust sharpness enhancement intensity in consideration of brightness of a background and background, The visibility of both the image and the background can be improved by enhancing the sharpness and emphasizing the boundary between the background and the image when both the background and the background convey meaningful information.

FIG. 1 is a block diagram schematically showing a configuration of a transparent display device according to an embodiment of the present invention. Referring to FIG.
2 is an equivalent circuit diagram illustrating one pixel configuration applied to the transparent display unit shown in FIG.
3 is a block diagram illustrating a configuration of an image processing unit according to an embodiment of the present invention.
4 is a flowchart illustrating an image processing method according to an exemplary embodiment of the present invention.
FIG. 5 is a diagram for explaining brightness perception degree and a sharpness improvement strength determination method according to an embodiment of the present invention. Referring to FIG.
FIG. 6 is a diagram for explaining a color change perception degree and a sharpness improvement strength determination method according to an embodiment of the present invention.
FIG. 7 is a view illustrating an image obtained when the sharpness enhancement intensity is adjusted in a transparent display device according to an embodiment of the present invention, in contrast to a prior art image.

FIG. 1 is a block diagram schematically showing a configuration of a transparent display device according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram illustrating one pixel configuration applied to the transparent display part shown in FIG.

1, a transparent display device according to an exemplary embodiment of the present invention includes an image processing unit 500, a timing controller 400, a data driver 300 and a gate driver 200, a transparent display unit 100, a camera 600) and the like. Here, the timing controller 400, the data driver 300, and the gate driver 200 may be represented as a display driver for driving the transparent display unit 100.

The transparent display unit 100 displays an image through a pixel array in which pixels are arranged in a matrix form. The basic pixel of the pixel array includes at least three or more pixels (W / R / G) capable of white representation by color mixing among white (W), red (R), green (G) , B / W / R, G / B / W, R / G / B, or W / R / G / B).

As the transparent display unit 100, a liquid crystal panel, an organic light emitting diode (OLED) panel, or the like can be used. Hereinafter, an OLED panel will be described as an example.

2, each pixel PXL includes a light emitting region EA in which the OLED element is located, a transmissive region TA for transmitting light from the front / rear side, . The light emitting region EA of the OLED element may overlap or not overlap with the pixel circuit.

2, the pixel circuit includes an OLED element connected between a high potential power supply (EVDD) line and a low potential power supply (EVSS) line, a first and a second switching TFTs ST1 and ST2 for independently driving the OLED element, ST2, a driving TFT DT and a storage capacitor Cst, and the configuration of the pixel circuit is not limited to the configuration of FIG.

The OLED element includes an anode connected to the driving TFT DT, a cathode connected to the low potential voltage EVSS, and a light emitting layer between the anode and the cathode to emit light proportional to the amount of current supplied from the driving TFT DT Occurs.

The first switching TFT ST1 is driven by the gate signal of one gate line GLn1 to supply the data voltage from the corresponding data line DL to the gate node of the driving TFT DT and the second switching TFT ST2 Is driven by the gate signal of the other gate line GLn2 to supply a reference voltage from the reference line REF to the source node of the driving TFT DT. The second switching TFT ST2 is further used as a path for outputting the current from the driving TFT DT to the reference line REF in the sensing mode.

The storage capacitor Cst connected between the gate node and the source node of the driving TFT DT is connected between the data voltage supplied to the gate node through the first switching TFT ST1 and the data voltage supplied to the source node through the second switching TFT ST2. And supplies the difference voltage to the driving voltage of the driving TFT DT.

The driving TFT DT controls the current supplied from the high potential power supply EVDD according to the driving voltage supplied from the storage capacitor Cst to supply a current proportional to the driving voltage to the OLED element to emit the OLED element.

The camera 600 is mounted on the rear surface of the transparent display device, captures the background of the transparent display device, and supplies the captured background image to the image processing unit 500.

The image processor 500 generates a mask image by extracting an edge component from an input original image, and adds a mask image to an original image to enhance sharpness based on an unsharp masking method of increasing edge strength Processing is performed.

In particular, in order to improve the sharpness of the image reduced due to the background transmission characteristic of the transparent display device, the image processing unit 500 determines an appropriate sharpness enhancement strength according to the degree of background recognition and applies the weight to the edge strength of the image, Adjust the sharpness.

The degree of background recognition of the transparent display device changes according to the brightness and color of the image and the background. For example, the greater the difference in the brightness of the image due to the background, the greater the background perception increases as the color difference between the image and the background increases, and as the background perception increases, the image clarity decreases.

In order to improve this, the image processing unit 500 can increase the sharpness enhancement intensity as the degree of background recognition increases. In other words, the image processing unit 500 increases the sharpness enhancement intensity because the image portion having a large background influence is large, and the sharpness improvement strength is low because the image portion having a small background effect has a small background extent .

Since the degree of background perception varies according to the brightness and color of the image and the background, the image processor 500 derives the brightness enhancement strength considering at least one of the brightness change and the color change due to the background.

For example, the image processing unit 500 compares the brightness of the original image, the brightness of the perceived image synthesized with the original image and the background image on a divided area basis, and calculates a brightness change indicating the degree of brightness change between the original image and the perceived image Just Noticeable Difference (JND) is calculated for each region. Also, the image processing unit compares the colors of the original image and the perceived image with respect to each divided region, and calculates the degree of color change perception ([Delta] u'v ') indicating the degree of color change between the original image and the perceived image due to the background. Then, the image processing unit 500 determines the sharpness enhancement intensity for each area according to the brightness change perceived area (JND) and the perceived color change per area (? U'v '). Then, the image processing unit 500 applies the sharpness enhancement strength for each region as a weight to the edge strength to correct the image. A detailed description of the image processing unit 500 will be described later.

The image processing unit 500 converts the three-color data R, G, and B into four-color data W, R, G, and B using a normal RGB-to-WRGB conversion method before or after the above- Can be converted. The image processor 500 may further perform necessary image processing such as power consumption reduction, image quality compensation, degradation compensation, etc. after the above-described image processing. The image processing unit 500 supplies the image data and the timing control signals to the timing controller 400.

The image processing unit 500 may embody hardware in the timing controller 100 or an image processing module of software stored in the memory.

The timing controller 400 generates a data control signal for controlling the driving timing of the data driver 300 and a gate control signal for controlling the driving timing of the gate driver 200 using the timing control signals supplied from the image processor 500 And outputs the data to the data driver 300 and the gate driver 200, respectively. The timing control signals include a dot clock, a data enable signal, a vertical synchronizing signal, and a horizontal synchronizing signal. The vertical synchronizing signal and the horizontal synchronizing signal can be omitted because they can be generated by counting the data enabling signal.

The timing controller 400 controls the pixel driving characteristics (threshold voltage, mobility, OLED threshold voltage, etc.) of each pixel of the transparent display unit 100 to a deviation of the image data supplied from the image processing unit 500, ), And then outputs the resultant image data to the data driver 300. The data driver 300 may further perform image processing such as external compensation or deterioration compensation.

The data driver 300 receives the data control signal and the video data from the timing controller 400. The data driver 300 is driven in accordance with the data control signal, subdivides the set of reference gamma voltages supplied from the gamma voltage generator into gray voltages corresponding to the gray scale values of the data, Converts the image data into analog data signals, and supplies analog data signals to the data lines of the transparent display unit 100, respectively.

The data driver 300 includes a plurality of data driver ICs for dividing and driving the data lines of the transparent display unit 100. Each data driver IC includes a Tape Carrier Package (TCP), a Chip On Film (COF) Circuit or the like and may be mounted on the transparent display unit 100 by TAB (Tape Automatic Bonding) or on a transparent display unit 100 by a COG (Chip On Glass) method.

The gate driver 200 drives the plurality of gate lines of the transparent display unit 100 using the gate control signal supplied from the timing controller 400. The gate driver 200 supplies a gate-on voltage to the respective gate lines in response to the gate control signal, and supplies a gate-off voltage in the remaining periods.

The gate driver 200 includes at least one gate IC and is mounted on a circuit film such as TCP, COF, or FPC to be attached to the transparent display unit 100 in a TAB manner or mounted on the transparent display unit 100 in a COG manner . Alternatively, the gate driver 200 may be formed on the thin film transistor substrate together with the thin film transistor array constituting the pixel array of the transparent display unit 100, thereby forming a GIP (Gate In Panel) type built in the non-display region of the transparent display unit 100 As shown in FIG.

FIG. 3 is a block diagram illustrating a configuration of an image processing unit 500 according to an exemplary embodiment. FIG. 4 is a flowchart illustrating an image processing method of the image processing unit 500 according to an embodiment. 6 is a diagram for explaining a degree of perceived color change according to an exemplary embodiment and a method for determining sharpness improvement strength according to an embodiment of the present invention. Hereinafter, an image processing unit 500 and an image processing method thereof according to an embodiment will be described with reference to FIG. 3 to FIG.

3, the image processing unit 500 includes an unsharp masking filter (unsharp masking filter) 540 including a low-pass filter 510, a mask generating unit 520, a sharpness improving mask determining unit 530, masking filter, and further includes a sharpness improving strength determining unit 550. [

3 and 4, the image processing method of the image processing unit 500 determines the sharpness improving strength K according to the luminance and color of the original image and the background image using the sharpness improving strength determining unit 550 (Step S10). The image processing method of the image processing unit 500 uses an unsharp masking filter including a low-pass filter 510, a mask generating unit 520, a sharpness improving mask determining unit 530, and an image correcting unit 540, And an unsharp masking processing step S20 for improving the sharpness of the image in proportion to the edge strength of the original image FD and the sharpness improving strength K and outputting the image FD 'with improved sharpness.

The image processing unit 500 receives the original image FD from the external system and receives the background image RD photographed from the camera 600.

The low-pass filter 510 low-pass-filters the original image FD on a frame-by-frame basis to generate a blurred image with a reduced luminance difference between pixels and outputs a blurred image. The mask generation unit 520 generates an edge mask image MD representing the edge component of the original image FD by subtracting the blurred image supplied from the low pass filter 510 from the original image FD, (MD) is output (S21).

The sharpness enhancement mask determination unit 530 adds the sharpness enhancement intensity determination unit 550 to the edge mask image MD supplied from the mask generation unit 520 with the sharpness enhancement intensity determined by the brightness and color of the original image and background image (K ') to determine a sharpness improving mask image MD' and output a sharpness improving mask image MD '(S22). The sharpness improvement mask determination unit 530 multiplies the sharpness improvement intensity K by the weight by multiplying the edge mask image MD by the weight so that the intensity of the edge component in the edge mask image MD becomes the sharpness degree K Thereby generating an enhancement mask image MD '. The sharpness improving strength determining unit 550 outputs the sharpness improving intensity K determined according to the luminance and color of each divided area of the original image and the background image for each divided area. Therefore, the sharpness improvement mask determination unit 530 generates the sharpness improvement mask image MD 'by applying the sharpness enhancement strength K to each of the edge regions in the edge mask image MD.

The image correcting unit 540 generates an output image FD 'having improved sharpness by combining the input image FD and the sharpness improving mask image MD' supplied from the sharpness improving mask determining unit 1300, And outputs the output image FD '(S23).

The sharpness enhancement strength determination unit 550 compares the average brightness of the original image and the average brightness of the perceived image obtained by combining the original image and the background image, and calculates the sharpness improvement strength of each of the regions of the original image and the perceived image (JND) indicating the degree of luminance change is calculated for each region, and the average color of the original image and the perceived image is compared and calculated for each divided region to determine a color change between each region of the original image and each region of the perceived image due to the background (K) is calculated according to the degree of change in brightness per area (JND) and the degree of color change perception (? U'v '), and the degree of sharpness improvement And outputs it. (S10)

Referring to FIG. 4, the sharpness enhancement strength determining unit 550 converts the RGB data of each of the original image and the background image into XYZ data indicating a tristimulus value using a known RGB-to-XYZ color space conversion function. (S11, S12) Y of the XYZ data for the original image is the absolute luminance value reflecting the display characteristic, Y of the XYZ data for the background image is the absolute luminance value reflecting the camera characteristic, The absolute luminance value of each of the original image and the background image is used to calculate the JND.

The sharpness improving strength determining unit 550 divides the original image into a plurality of regions and calculates an average value of each of the X, Y, and Z data for each region having n1 * n1 size (n1 is the number of pixels) (S13) . The sharpness improving strength determining unit 550 calculates the average value of each of the X, Y, and Z data for the region having the size of n2 * n2 (n2 is the number of pixels) corresponding to each region of the original image in the background image (S12) . At this time, since the area of the background image that affects each area of the original image is wider, it is preferable that the size (n2 * n2) of each area of the background image is larger than the size (n1 * n1) of each area of the original image Do. Accordingly, adjacent pixels of the background image corresponding to the adjacent areas of the original image overlap with each other.

The sharpness improving strength determining unit 550 combines the average XYZ data for each region of the original image and the average XYZ data for each region of the background image on a data basis to determine whether the corresponding region of the original image and the corresponding region of the background image are combined The average XYZ data for each region of the image is derived. (S15)

5, the sharpness improving strength determining unit 550 compares the average brightness (average Y data) of each region of the original image with the average brightness (average Y data) of each region of the perceived image, (JND) of brightness change in each region indicating the degree of luminance change between each region of the original image and the respective regions of the perceived image due to the luminance change. (S16)

The sharpness enhancement strength determining unit 550 determines the sharpness enhancement strength determining unit 550 based on the average XYZ data of the original image and the average XYZ data of the perceived image by using the known XYZ-to-Lu'v ' And Lu'v 'data indicating the chromaticity (u', v '), that is, average Lu'v' data. The sharpness improving strength determining unit 550 compares the average color (average u'v 'data) of the original image with the average color (average u'v' data) (? U'v ') of each region indicating the degree of color change between each region of the original image and each region of the perceived image due to the background for each region as shown in Fig. (S17)

5, the sharpness improving strength determiner 550 corresponds to the degree of brightness change perceived (JND) of each area by using the brightness enhancement strength (K_JND) function for the degree of brightness change recognition (JND) The first sharpness improving strength (K_JND) is calculated. Referring to FIG. 5, as the luminance change perception (JND) increases, the first sharpness enhancement intensity (K_JND) gradually increases. When the degree of brightness change recognition (JND) is smaller than the threshold value (1), the first sharpness improving strength (K_JND) is determined as a preset minimum value.

6, the sharpness improving strength determining unit 550 uses the sharpness improving strength (K_uv) function for the degree of perception of color change (? U'v ') as shown in FIG. 6, (V_uv) corresponding to the second sharpness improving intensity (K_uv). Referring to FIG. 6, as the degree of color change perception (? U'v ') increases, the second sharpening enhancement intensity (K_uv) gradually increases. And the second sharpness improving strength (K_uv) is determined as a preset minimum value when the degree of color change perception (DELTA u'v ') is smaller than the threshold value (0.02).

The sharpness improving strength determiner 550 determines the sharpness improving strength K (K = f (K_JND, K_uv)) of each area by applying the first sharpness improving strength K_JND and the second sharpening improving strength K_uv of each area (S17)

The sharpness improvement mask determination unit 530 receives the edge mask image MD supplied from the mask generation unit 520 from the sharpness enhancement strength determination unit 550 in accordance with the luminance and color of the original image and the background image, And the sharpness improving intensity (K) is applied to generate the sharpness improving mask image MD '. (S22)

The image correcting unit 540 synthesizes the original image FD and the sharpness improving mask image MD 'supplied from the sharpness improving mask determining unit 530 to output an output image FD' do. (S23)

As described above, the transparent display device and the driving method thereof according to an embodiment of the present invention adaptively adjust the sharpness enhancement intensity in consideration of the brightness of the image and the background, The visibility of both the image and the background can be improved by emphasizing the boundary between the background and the image when both the image and the background support the meaningful information.

FIG. 7 is a view illustrating an image obtained by adjusting sharpness enhancement intensity in a transparent display device according to an embodiment of the present invention.

Referring to FIG. 7, it can be seen that sharpness improvement of the cognitive image is improved by increasing the degree of brightness change due to the background due to darkness of the image and increasing the sharpness enhancement intensity. When the influence of the background is brighter and the influence of the background is small, the luminance perception of the image due to the background is reduced, and the sharpness improvement strength is reduced, thereby preventing degradation in image quality such as oversharpening in the perceived image. When the color difference between the image and the background is large, the recognition degree of the color change is increased, and the sharpness improvement strength is increased, which shows that the sharpness of the cognitive image is improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: transparent display part 200: gate driver
300: Data driver 400: Timing controller
500: image processor 600: camera
510: Low-pass filter 520:
530: sharpness improvement mask determination unit 540: image correction unit
550: sharpness improving strength determining section

Claims (9)

A transparent display portion including a transmissive region, a light emitting region,
A camera for photographing a background on the rear surface of the transparent display device and outputting a background image;
A display driver for supplying an output image to the transparent display unit,
And an image processing unit for determining the sharpness enhancement strength according to the luminance and color of the original image and the background image and correcting the sharpness of the original image by applying the sharpness enhancement strength and outputting the corrected image to the display driver. Device. The method according to claim 1,
The image processing unit
A low pass filter for low pass filtering the original image to generate and output a blur image;
A mask generator for generating an edge mask image by subtracting the blurred image supplied from the low-pass filter from the original image,
A sharpness improving strength determining unit for determining the sharpness improving strength,
A sharpness enhancement mask determination unit for generating and outputting a sharpness enhancement mask image by applying the sharpness enhancement strength supplied from the sharpness enhancement strength determination unit to the edge mask image supplied from the mask generation unit;
And an image correction unit for correcting the sharpness of the original image by combining the sharpness improving mask image supplied from the sharpness improving mask determining unit and the original image. The method according to claim 1,
The sharpness improving strength determining unit
The average luminance of each area of the original image and the background image is calculated by synthesizing the average luminance of each area obtained by dividing the original image and the average luminance of each area obtained by dividing the background image,
And comparing the average brightness of each region of the original image with the average brightness of each region of the perceived image to determine a brightness change degree between each region of the original image and each region of the perceived image due to the background The degree of brightness change perceived (JND) is derived,
Determines a first sharpness enhancement strength for each area according to the brightness change perceived area (JND)
Wherein a size of each area of the background image is larger than a size of each area of the original image. The method of claim 3,
The sharpness improving strength determining unit
And comparing the average color of each region of the original image with the average color of each region of the perceived image to determine a degree of color change between each region of the original image and each region of the perceived image due to the background (? U'v ') of color change per region,
Determines a second sharpness enhancement strength for each area according to the perceived color change per area (? U'v '),
Wherein the sharpness improving strength for each region of the original image is determined by applying the first sharpness improving strength for each region and the second sharpening improving strength for each region. The method of claim 4,
The sharpness improving strength determining unit
The RGB data of the original image and the background image are converted into the XYZ data using the RGB-to-XYZ conversion function, and then the average luminance for each region of the original image and the average luminance Calculating an average luminance for each region of the perceived image,
XYZ-to-Lu'v 'conversion function to convert the average XYZ data for each of the original image and the perceived image into the average Lu'v' data for each region, A transparent display device that calculates an average color per area (u'v '). Generating a blur image by low-pass filtering an original image;
Generating an edge mask image by subtracting the blurred image from the original image;
Determining a sharpness enhancement strength according to a luminance and a color of the original image and the background image;
Generating a sharpness enhancement mask image by applying the sharpness enhancement strength to the edge mask image;
And combining the sharpness improving mask image and the original image to display an image having a corrected sharpness on a transparent display unit. The method of claim 6,
The step of determining the sharpness improving strength
Deriving an average luminance for each area of the perceived image in which the original image and the background image are synthesized by synthesizing the average luminance of each area obtained by dividing the original image and the average luminance of each area obtained by dividing the background image, Wow,
And comparing the average brightness of each region of the original image with the average brightness of each region of the perceived image to determine a brightness change degree between each region of the original image and each region of the perceived image due to the background Deriving a degree of brightness change perception (JND)
And determining a first sharpness enhancement strength for each region according to the degree of brightness change perceived by each region (JND)
Wherein a size of each area of the background image is larger than a size of each area of the original image. The method of claim 7,
The step of determining the sharpness improving strength
And comparing the average color of each region of the original image with the average color of each region of the perceived image to determine a degree of color change between each region of the original image and each region of the perceived image due to the background Deriving a perceived color change per area (? U'v ');
Determining a second sharpness enhancement strength for each area according to the perceived color change per area (? U'v ');
Further comprising the step of determining a sharpness improving strength for each region of the original image by applying the first sharpness improving strength for each region and the second sharpening improving strength for each region. The method of claim 8,
Wherein deriving the average brightness comprises:
The RGB data of the original image and the background image are converted into the XYZ data using the RGB-to-XYZ conversion function, and then the average luminance for each region of the original image and the average luminance And calculating an average luminance for each region of the perceived image,
The step of comparing the average color
XYZ-to-Lu'v 'conversion function to convert the average XYZ data for each of the original image and the perceived image into the average Lu'v' data for each region, And calculating an average color per area (u'v ').

Images