TWI841326B - Display image optimization method, display driver chip, display device, and information processing device - Google Patents

Abstract

The present invention mainly discloses a display image optimization method, which is applied to a display driver chip, so that the display driver chip can adaptively perform a data optimization operation on an input image data transmitted by a host computer according to the DBV value currently set by the user by executing the display driver method of the present invention, and generate an output image data. Finally, the display driver chip drives a display panel according to the output image data, so that the display panel can still clearly display the grayscale gradient details in the image in terms of visual effect when displaying a low-brightness and low-grayscale image.

Description

Display image optimization method, display driver chip, display device, and information processing device

The present invention relates to the technical field of OLED displays, and more particularly to a display image optimization method for optimizing the display image when the OLED display displays a low-brightness, low-grayscale image.

As is known, organic light-emitting diodes (OLED) have advantages such as self-luminous properties, high brightness, high contrast, wide viewing angle, low power consumption, and high response rate. Therefore, they are currently widely used in the production of self-luminous display panels, including active OLED (i.e., AMOLED) display panels and passive OLED (i.e., PMOLED) display panels. FIG1 is a block diagram of a known OLED display device. As shown in FIG1, the OLED display device 1a is applied to an electronic device (e.g., a smart watch), and mainly includes an OLED panel 11a and at least one display driver chip 12a.

Taking a smart watch as an example, a user can manually set the brightness control (BC) of the OLED display device 1a, and this brightness control belongs to DC dimming. To be more specific, the application processor of the smart watch uses the display brightness value (DBV) to represent the brightness adjustment. For example, DBV=255 represents the maximum brightness setting, and DBV=0 represents the minimum brightness setting. In this way, according to the current DBV value, the display driver chip 12a will adjust an input display data transmitted by the host computer 2a (i.e., the application processor) to an output display data. For example, Data_in represents the input display data, and the display driver chip 12a uses Data_out=Data_in*(DBV/255) to adjust the input display data to the corresponding output display data, namely, Data_out.

It should be known that the OLED panel 11a includes M×N pixel circuits and M×N OLED elements, wherein the M×N OLED elements include (M×N)/3 red OLED elements, (M×N)/3 green OLED elements, and (M×N)/3 blue OLED elements, that is, a single pixel includes a red OLED element (i.e., R sub-pixel), a green OLED element (i.e., G sub-pixel), and a blue OLED element (i.e., B sub-pixel). In order to extend the usage time, the application processor of the smart watch controls the OLED display device 1a to display images in a low brightness and low grayscale manner. However, due to the mismatch in luminous efficiency among the red OLED element, the green OLED element, and the blue OLED element, the OLED display device 1a cannot clearly display the grayscale gradient details in the image when displaying low-brightness and low-grayscale images. Therefore, it is necessary to optimize the displayed image when the OLED display displays low-brightness and low-grayscale images.

From the above description, it can be seen that there is an urgent need in the art for a display image optimization method integrated into a display driver chip.

The main purpose of the present invention is to provide a display image optimization method, which is applied to a display driver chip, so that the display driver chip can adaptively perform a data optimization operation on an input image data transmitted by a host computer according to the DBV value currently set by the user through the display driver method of the present invention, and generate an output image data. Finally, the display driver chip drives the OLED panel according to the output image data, so that the OLED panel can clearly display the grayscale gradient details in the image in terms of visual effect when displaying a low-brightness and low-grayscale image.

To achieve the above-mentioned purpose, the present invention proposes an embodiment of the display image optimization method, comprising: Receiving a display brightness value (DBV) and a display data including a plurality of pixel data; When the display brightness value is greater than a DBV threshold value and/or each of the pixel data is greater than a grayscale threshold value, directly using the display data as a first output display data; and When the display brightness value is less than or equal to the DBV threshold value and there is at least one of the pixel data less than or equal to the grayscale threshold value, performing a data optimization operation on the display data, thereby generating a second output display data.

In one embodiment, the data optimization operation includes the following steps: Performing a first color space conversion operation to convert the display data in the RGB color space into a first display data in the YUV color space; Using a pre-made optimization curve, performing a brightness component adjustment operation on the first display data to generate a second display data; and Performing a second color space conversion operation to convert the second display data in the YUV color space into the second output display data in the RGB color space.

In one embodiment, the display driver chip executes the following mathematical formulas (1), (2) and (3) to complete the second color space conversion operation: ················ (1); ················ (2); ··············· (3); Among them, , and The red sub-pixel data, the green sub-pixel gray-scale data and the blue sub-pixel gray-scale data contained in one pixel data in the second output display data, , and is the luminance data, chrominance data and chroma data contained in one pixel data in the second display data, and , and They are a red sub-pixel offset compensation amount, a green sub-pixel offset compensation amount, and a blue sub-pixel offset compensation amount.

In one embodiment, when the DBV threshold value falls between 0 and a first DBV value, the display driver chip uses a pre-fabricated first luminance mapping curve as the optimization curve.

In one embodiment, when the DBV threshold value falls between the first DBV value and a second DBV value, the display driver chip uses a pre-fabricated second brightness mapping curve as the optimization curve.

In one embodiment, when the DBV threshold value falls between the second DBV value and a third DBV value, the display driver chip uses a pre-fabricated third brightness mapping curve as the optimization curve.

In one embodiment, the first brightness mapping curve, the second brightness mapping curve and the third brightness mapping curve all contain a plurality of nodes, so that the display driver chip can use linear difference operation in combination to perform the brightness component adjustment operation on one or more pixel data of the first display data.

The present invention also proposes an embodiment of a display driver chip, which is characterized in that the display image optimization method of the present invention as described above is executed to process an input display data into an output display data, thereby driving a display panel according to the output display data, thereby realizing display optimization for a low-brightness and low-grayscale image.

Furthermore, the present invention also proposes an embodiment of a display device, which includes a display panel and at least one display driver chip; its characteristic is that the display driver chip executes the display image optimization method of the present invention as described to process an input display data into an output display data, thereby driving the display panel according to the output display data, thereby realizing display optimization for a low-brightness and low-grayscale image.

In addition, the present invention also proposes an information processing device, which is characterized by comprising the display device of the present invention as described above. In a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a smart TV, a smart phone, a smart watch, a smart bracelet, a head-mounted display device, a tablet computer, a laptop computer, an all-in-one computer, a financial transaction device, an ATM, an interactive information service station (KIOSK), an electronic device as a point of sales (POS), an in-vehicle entertainment system, and an access control device.

In order to enable the Review Committee to further understand the structure, features, purpose, and advantages of the present invention, the following are attached with drawings and detailed descriptions of preferred specific embodiments.

Please refer to FIG. 2, which is a block diagram of a display device to which a display image optimization method of the present invention is applied. As shown in FIG. 2, the display device 1 includes a display panel 11 and at least one display driver chip 12, and the display driver chip 12 includes an image optimization unit 121. In actual application, a display image optimization method of the present invention can be compiled into an algorithm file using a programming language and then stored in a memory of the display driver chip 12, thereby forming the image optimization unit 121 embedded in the display driver chip 12. Furthermore, in a feasible embodiment, the display device 1 can be an independent electronic device or integrated into an electronic device in the form of a module, and the electronic device can be but is not limited to: a smart TV, a smart phone, a smart watch, a smart bracelet, a head-mounted display device, a tablet computer, a laptop computer, an all-in-one computer, a financial transaction device, an ATM, an interactive information service station (KIOSK), a point of sales (POS) device, a car entertainment system, or an access control device.

Specifically, the display driver chip 12 can execute the display driving method of the present invention by activating the image optimization unit 121, so as to adaptively perform a data optimization operation on an input image data transmitted by a host computer 2 (e.g., an application processor of a smart watch) according to the display brightness value (DBV) currently set by the user, and generate an output image data. Finally, the display driver chip 12 drives the display panel 11 according to the output image data, so that the display panel 11 can still clearly display the grayscale gradient details in the image in terms of visual effect when displaying a low-brightness and low-grayscale image.

FIG3 is a flow chart of a display image optimization method of the present invention. As shown in FIG3, after the display image optimization method of the present invention is activated, the method flow first executes step S1: receiving a display brightness value and a display data including a plurality of pixel data from a host computer 2, wherein each pixel data includes a red sub-pixel data, a green sub-pixel data, and a blue sub-pixel data. Then, the method flow executes step S2: when the display brightness value is greater than a DBV threshold value and/or each of the pixel data is greater than a grayscale threshold value, directly using the display data as a first output display data. Further, FIG4 is a schematic diagram of four DBV intervals. As shown in FIG. 4 , a plurality of control ranges can be distinguished between a maximum brightness setting value (eg, 255) and a minimum brightness setting value (eg, 0) of a display brightness value (DBV) of an electronic device in actual application (eg, a smart phone, a smart watch).

According to the design of the present invention, 0 and a first DBV value (i.e., TH1) are used to define the first interval, the first DBV value and a second DBV value (i.e., TH2) are used to define the second interval, the second DBV value and a third DBV value (i.e., TH3) are used to define the third interval, and the third DBV value and 255 are used to define the fourth interval. Thus, when a display brightness value (i.e., DBV value) set by a user is greater than the third DBV value, it means that the display brightness value falls within the fourth interval defined by TH3 and 255. At this time, the display driver chip 12 directly uses the display data as a first output display data.

As shown in FIG3 , in step S3 , the display driver chip 12 is configured so that when the display brightness value is less than or equal to the DBV threshold value and there is at least one pixel data less than or equal to the grayscale threshold value, a data optimization operation is performed on the display data to generate a second output display data. Specifically, TH1, TH2 and TH3 can be set to 20, 32 and 64 respectively. With such setting, as shown in FIG4 , when the DBV value set by the user falls within the first interval between 0 and 20, it indicates that the display device 1 is operating in a low brightness mode. At this time, when the display panel 11 displays a low brightness and low grayscale image, the grayscale gradient details in the image cannot be clearly displayed in terms of visual effect. Therefore, a data optimization operation must be performed on the display data. According to the design of the present invention, the data optimization operation includes the following steps: Performing a first color space conversion operation to convert the display data in the RGB color space into a first display data in the YUV color space; Using a pre-made optimization curve, performing a brightness component adjustment operation on the first display data to generate a second display data; and Performing a second color space conversion operation to convert the second display data in the YUV color space into the second output display data in the RGB color space.

Specifically, the following mathematical formulas (a), (b) and (c) may be used to complete the first color space conversion operation: ·················· (a) ················· (b) ·················· (c)

In the above formulas (a), (b) and (c), , and is the brightness (Luminance) data, chrominance (Chrominance) data and concentration (Chroma) data contained in a pixel data in the first display data, and, , and The red sub-pixel data, the green sub-pixel gray-scale data and the blue sub-pixel gray-scale data contained in one pixel data in the display data (ie, the original data).

Please also see the curve diagram of input display data Y_in relative to output display data Y_out shown in FIG5 . In FIG5 , curve C1 represents a first luminance mapping curve, curve C2 represents a second luminance mapping curve, and curve C3 represents a third luminance mapping curve. According to the design of the present invention, when the DBV valve value falls within the first interval defined by 0 and TH1 (i.e., the first DBV value), the display driver chip 12 uses a pre-made first luminance mapping curve (i.e., curve C1 shown in FIG5 ) as the optimization curve, thereby using the optimization curve to map Y_in (i.e., the first display data) to Y_out (i.e., the second display data).

On the other hand, if the DBV value set by the user falls within the second interval between 21 and 32, it means that the DBV value falls within the second interval defined by TH1 and TH2 (i.e., the second DBV value). At this time, the grayscale gradient details in the low grayscale image can be slightly distinguished in terms of visual effects, so only a moderate degree of data optimization is required for the display data. In this case, the display driver chip 12 uses a pre-made second brightness mapping curve (i.e., curve C2 shown in FIG. 5 ) as the optimization curve, thereby using the optimization curve to map Y_in to Y_out. Furthermore, when the DBV valve value falls within the third interval defined by TH2 and TH3 (i.e., the third DBV value), the display driver chip 12 uses a pre-made third brightness mapping curve (i.e., curve C3 shown in Figure 5) as the optimization curve, thereby using the optimization curve to map Y_in to Y_out.

Furthermore, if the DBV value set by the user falls within the third interval between 33 and 64, it means that the DBV value falls within the third interval defined by TH2 and TH3 (i.e., the third DBV value). At this time, most of the grayscale gradient details in the low grayscale image can be clearly displayed, so only a low level of data optimization is required for the display data. Therefore, the display driver chip 12 uses a pre-made third brightness mapping curve (i.e., curve C3 shown in FIG. 5) as the optimization curve, thereby using the optimization curve to map Y_in to Y_out. In contrast, if the DBV value set by the user falls within the fourth interval between 65 and 255, it means that all grayscale gradient details in the low grayscale image can be displayed clearly and completely. At this time, there is no need to perform any data optimization on the display data, and the display data can be directly used as the first output display data (i.e., step S2).

It should be known that converting display data from YUV color space to RGB color space (i.e., the aforementioned second color space conversion operation) is also a commonly used technical means. However, in order to ensure that the optimized display image is not distorted, in the present invention, the display driver chip 12 is configured to use the following mathematical formulas (1), (2) and (3) to complete the second color space conversion operation: ··················· (1) ·················· (2) ················· (3)

In the above formulas (1), (2) and (3), , and The red sub-pixel data, the green sub-pixel gray-scale data and the blue sub-pixel gray-scale data contained in one pixel data in the second output display data, , and is the luminance data, chrominance data and chroma data contained in one pixel data in the second display data, and , and They are a red sub-pixel offset compensation, a green sub-pixel offset compensation, and a blue sub-pixel offset compensation. In simple terms, , and The parameters are used to perform offset compensation on the optimized RGB data (ie, the second display data) to compensate for the color deviation of the RGB data after the brightness component is adjusted, thereby ensuring that the optimized screen display color is not distorted.

As shown in FIG5 , when the brightness component adjustment operation is performed, Y_in is mapped to Y_out through curves C1, C2 or C3, so that the first display data located in the YUV color space can be converted into the second display data. Finally, the second display data can be converted into the second output display data located in the RGB color space using the above formulas (1), (2) and (3). It is worth noting that when the DBV value set by the user is less than TH3, TH2 or TH1, the method of the present invention is to perform a grayscale threshold value judgment on each pixel data contained in the display data received from the host computer 2. Once the grayscale value of the pixel data is lower than the predetermined grayscale threshold value, the brightness component of the pixel data is adjusted to achieve data optimization.

In order to speed up the calculation speed, the first brightness mapping curve, the second brightness mapping curve and the third brightness mapping curve can be made to contain a plurality of nodes in advance, so that the display driver chip 12 can use linear difference calculation to perform the brightness component adjustment operation on one or more pixel data of the first display data. For example, according to the data measured in advance, 16 nodes can be set in each brightness mapping curve, and each node corresponds to one Y_in and one Y_out. In this way, when mapping a Y_in to Y_out through the brightness mapping curve, if the target Y_out has no corresponding node, the Y_out of the front and rear adjacent nodes can be used to perform linear interpolation calculation to obtain the target Y_out. With such a design, the brightness component of low grayscale pixel data can be adjusted to avoid excessive brightness compensation for high grayscale pixel data that does not need to be optimized. In an exemplary embodiment, 16 low grayscale nodes 2, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 50, 56, and 64 can be preset on the first brightness mapping curve C1 as shown in FIG. 5, and then the curve fitting is implemented using the following formula (4) to obtain a fitting curve: ································· (4)

In actual application, the fitting curve can be adjusted by setting the values of coefficients a, b, and c to meet different brightness adjustment requirements between high and low grayscale ranges. Finally, by using the fitting curve and the 16 low grayscale nodes, the display driver chip 12 can speed up the entire calculation process of mapping the first display data into the second display data using the first brightness mapping curve C1 as the optimization curve.

Thus, the above description has completely and clearly explained the display image optimization method of the present invention; and, from the above description, it can be known that the present invention has the following advantages:

(1) The present invention discloses a display image optimization method, which is applied to a display driver chip, so that the display driver chip can adaptively perform a data optimization operation on an input image data transmitted by a host computer according to the DBV value currently set by the user by executing the display driver method of the present invention, and generate an output image data. Finally, the display driver chip drives the OLED panel according to the output image data, so that the OLED panel can clearly display the grayscale gradient details in the image in terms of visual effect when displaying a low-brightness and low-grayscale image.

(2) The present invention also provides an embodiment of a display device, which includes a display panel and at least one display driver chip; its characteristic is that the display driver chip executes the display image optimization method of the present invention as described to process an input display data into an output display data, thereby driving the display panel according to the output display data, thereby realizing the display optimization of a low-brightness and low-grayscale image.

(3) The present invention further provides an information processing device, characterized in that it includes the display device of the present invention as described above. In a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a smart TV, a smart phone, a smart watch, a smart bracelet, a head-mounted display device, a tablet computer, a laptop computer, an all-in-one computer, a financial transaction device, an ATM, an interactive information service station (KIOSK), an electronic device as a point of sales (POS), an in-vehicle entertainment system, and an access control device.

It must be emphasized that what is disclosed in the above-mentioned case is a preferred embodiment. Any partial changes or modifications that are derived from the technical ideas of this case and are easily inferred by people familiar with the art do not deviate from the scope of the patent rights of this case.

In summary, this case shows that its purpose, means and effects are very different from the known technology, and it is the first invention that is practical and indeed meets the patent requirements for invention. We sincerely request the review committee to examine this carefully and grant a patent as soon as possible to benefit the society. This is our utmost prayer.

1a: OLED display device 11a: OLED panel 12a: display driver chip 2a: host computer 1: display device 11: display panel 12: display driver chip 121: image optimization unit 2: host computer S1: receiving a display brightness value and a display data including a plurality of pixel data S2: when the display brightness value is greater than a DBV threshold value and/or each of the pixel data is greater than a grayscale threshold value, directly using the display data as a first output display data S3: When the display brightness value is less than or equal to the DBV threshold value and there is at least one pixel data that is less than or equal to the grayscale threshold value, a data optimization operation is performed on the display data to generate a second output display data

FIG. 1 is a block diagram of a known OLED display device; FIG. 2 is a block diagram of a display device to which a display image optimization method of the present invention is applied; FIG. 3 is a flow chart of a display image optimization method of the present invention; FIG. 4 is a schematic diagram of four DBV intervals; and FIG. 5 is a curve diagram of input display data Y_in relative to output display data Y_out.

S1: Receive a display brightness value and a display data containing multiple pixel data

S2: When the display brightness value is greater than a DBV threshold value and/or each of the pixel data is greater than a grayscale threshold value, the display data is directly used as the first output display data

S3: When the display brightness value is less than or equal to the DBV threshold value and there is at least one pixel data that is less than or equal to the grayscale threshold value, a data optimization operation is performed on the display data to generate a second output display data

Claims (10)

A display image optimization method is executed by a display driver chip and includes: receiving a display brightness value (DBV) and a display data including a plurality of pixel data; when the display brightness value is greater than a DBV threshold value and/or each of the pixel data is greater than a grayscale threshold value, directly using the display data as a first output display data; and when the display brightness value is less than or equal to the DBV threshold value and there is at least one of the pixel data less than or equal to the grayscale threshold value, performing a data optimization operation on the display data to generate a second output display data. The display image optimization method as described in claim 1, wherein the data optimization operation includes the following steps: performing a first color space conversion operation to convert the display data in the RGB color space into a first display data in the YUV color space; performing a brightness component adjustment operation on the first display data using a pre-made optimization curve to generate a second display data; and performing a second color space conversion operation to convert the second display data in the YUV color space into the second output display data in the RGB color space. The display image optimization method as described in claim 2, wherein the display driver chip executes the following mathematical formulas (1), (2) and (3) to complete the second color space conversion operation:

in,

,

and

is red sub-pixel data, green sub-pixel grayscale data and blue sub-pixel grayscale data included in a pixel data in the second output display data, Y' , U and V are luminance data, chrominance data and chroma data included in a pixel data in the second display data, and r _offset , g _offset and b _offset are a red sub-pixel offset compensation amount, a green sub-pixel offset compensation amount and a blue sub-pixel offset compensation amount respectively. The display image optimization method as described in claim 2, wherein, when the DBV valve value falls between 0 and a first DBV value, the display driver chip uses a pre-made first luminance mapping curve as the optimization curve. The display image optimization method as described in claim 4, wherein, when the DBV valve value falls between the first DBV value and a second DBV value, the display driver chip uses a pre-made second brightness mapping curve as the optimization curve. The display image optimization method as described in claim 5, wherein, when the DBV valve value falls between the second DBV value and a third DBV value, the display driver chip uses a pre-made third brightness mapping curve as the optimization curve. The display image optimization method as described in claim 6, wherein the first brightness mapping curve, the second brightness mapping curve and the third brightness mapping curve all contain a plurality of nodes, so that the display driver chip can use linear difference calculation to perform the brightness component adjustment operation on one or more pixel data of the first display data. A display driver chip is characterized in that it executes a display image optimization method as described in any one of claim 1 to claim 7 to process an input display data into an output display data, thereby driving a display panel according to the output display data, thereby achieving display optimization for a low-brightness and low-grayscale image. A display device includes a display panel and at least one display driver chip; the characteristic is that the display driver chip executes the display image optimization method described in any one of claim 1 to claim 7 to process an input display data into an output display data, thereby driving the display panel according to the output display data, thereby realizing display optimization for a low-brightness and low-grayscale image. An information processing device, characterized in that it includes a display device as described in claim 9.

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