Image display quality improvement method and system

Abstract

The invention provides an image display quality improvement method and system. The image display quality improvement method comprises the following steps: acquiring an input gray scale of an image; under the condition that the input gray scale is not zero, performing despeckle compensation on the input gray scale, and generating a corresponding despeckle compensation gray scale; judging whether the despeckle compensation gray scale is smaller than a preset over-compensation protection gray scale or not, and generating a corresponding judgment result; and when the judgment result is that the despeckle compensation gray scale is smaller than the over-compensation protection gray scale, generating and outputting an improved input gray scale which is the over-compensation protection gray scale. According to the invention, on the basis of the speckle-removing compensation technology, the scene with excessive compensation is identified, and then compensation protection is carried out on the black spot area with excessive compensation, so that the downward-compensated gray scale is effectively cut off and is not compensated to the gray scale in a black display state of the pixel; the uniformity effect of despeckle compensation is ensured, the occurrence of compensation black spots is prevented, and the image display quality is improved.

Description

Technical Field

[0001] This disclosure relates to the field of image display technology, and more specifically, to a method and system for improving image display quality. Background Technology

[0002] As OLED display panels become larger, the uneven brightness display caused by the non-uniformity of thin-film transistors (TFTs) is becoming increasingly serious, especially at extremely low brightness and grayscale levels, where the unevenness is even more pronounced. To overcome this technical problem, existing technologies have proposed De-mura (DMR) technology, which can effectively improve the uniformity of the panel at low brightness.

[0003] However, in practical applications, the aforementioned spot-reduction compensation technology is prone to producing compensation black spots at extremely low gray levels, thus deteriorating the spot-reduction compensation effect. To overcome this problem, the compensation intensity is usually reduced during the spot-reduction compensation process, which in turn can weaken the compensation effect of the panel in low-brightness conditions. Summary of the Invention

[0004] To address the problems in the prior art, the purpose of this disclosure is to provide a method and system for improving image display quality, capable of improving overcompensation that occurs in speckle removal compensation technology at extremely low grayscale levels. Specifically, the first aspect of this disclosure provides a method for improving image display quality, which may include the following steps:

[0005] Obtain the input grayscale of the image;

[0006] If the input gray level is not zero, perform speckle compensation on the input gray level and generate the corresponding speckle compensation gray level.

[0007] Determine whether the grayscale for spot removal compensation is less than the preset over-compensation protection grayscale, and generate the corresponding judgment result;

[0008] If the determination result is that the gray level for despot compensation is less than the gray level for overcompensation protection, an improved input gray level is generated and output, which is the gray level for overcompensation protection.

[0009] In one possible implementation of the first aspect above, if the determination result is that the speckle compensation grayscale is greater than or equal to the overcompensation protection grayscale, the speckle compensation grayscale is used as the improved input grayscale and output.

[0010] In one possible implementation of the first aspect above, when the input gray level is zero, the input gray level is used as an improved input gray level and output.

[0011] In one possible implementation of the first aspect above, speckle compensation is performed on the input grayscale, and a corresponding speckle-compensated grayscale is generated, including the following steps:

[0012] Based on the preset minimum binding point gray level, set the first compensation amount, which is the spot removal compensation amount when the input gray level is equal to the minimum binding point gray level.

[0013] When the input grayscale is within the range from zero to the lowest binding point grayscale, linear interpolation is used to perform speckle compensation on the input grayscale.

[0014] In one possible implementation of the first aspect described above, the image quality improvement method provided in this disclosure further includes the following steps:

[0015] Several overcompensation protection intervals are defined, and each endpoint of an overcompensation protection grayscale level corresponds to an overcompensation protection grayscale.

[0016] Obtain the overcompensation protection interval of the despot compensation grayscale, and within the overcompensation protection interval, use the overcompensation protection value corresponding to the endpoint of the overcompensation protection interval to perform interval linear interpolation to obtain the overcompensation protection value corresponding to the despot compensation grayscale, so as to generate and output the improved input grayscale.

[0017] In one possible implementation of the first aspect described above, the image quality improvement method provided in this disclosure further includes the following steps:

[0018] Several overcompensation protection intervals are set, and each overcompensation protection interval corresponds to an overcompensation protection value;

[0019] Obtain the over-compensation protection range where the spot removal compensation grayscale is located, and determine whether the spot removal compensation grayscale is less than the corresponding over-compensation protection value;

[0020] If so, generate and output an improved input grayscale, which is an overcompensated protective grayscale.

[0021] In one possible implementation of the first aspect above, there is no intersection between any two overcomplementary protection intervals; and

[0022] The entire overcompensation protection zone covers all input grayscale levels.

[0023] In one possible implementation of the first aspect above, the overcompensation protection interval is associated with the refresh rate of the display device of the image and / or the display color of the image;

[0024] The overcompensation protection value is related to the refresh rate of the display device and / or the display color of the image.

[0025] A second aspect of this disclosure provides an image display quality improvement system, which may specifically include:

[0026] The acquisition unit is used to acquire the input grayscale of the image;

[0027] The speckle compensation unit is used to perform speckle compensation on the input gray level when the input gray level is not zero, and to generate the corresponding speckle compensation gray level.

[0028] The overcompensation identification unit is used to determine whether the speckle removal compensation grayscale is greater than the preset overcompensation protection grayscale, and generates the corresponding judgment result;

[0029] The overcompensation unit is used to generate and output an improved input grayscale when the determination result is that the despot compensation grayscale is less than the overcompensation protection grayscale. The improved input grayscale is the overcompensation protection grayscale.

[0030] In one possible implementation of the second aspect described above, the image display quality improvement system provided by this disclosure further includes:

[0031] Overcompensation interval division unit is used to set several overcompensation protection intervals, and each overcompensation protection interval corresponds to an overcompensation protection value;

[0032] The overcompensation identification unit is also used to obtain the overcompensation protection range in which the speckle compensation grayscale is located, determine whether the speckle compensation grayscale is less than the corresponding overcompensation protection value, and generate the corresponding judgment result.

[0033] The overcompensation unit is also used to generate and output an improved input grayscale when the determination result is that the speckle compensation grayscale is less than the corresponding overcompensation protection value. The improved input grayscale is the overcompensation protection grayscale.

[0034] Compared with the prior art, this disclosure has the following beneficial effects:

[0035] The technical solution provided in this disclosure, based on speckle reduction compensation technology, identifies scenes where overcompensation occurs and then protects the overcompensated black spot areas, effectively cutting off downward compensation of gray levels and preventing compensation to the point where pixels display black. This ensures the uniformity of speckle reduction compensation while preventing the appearance of compensation black spots, thus improving image display quality. Similarly, if excessive compensation occurs in high brightness / high gray levels, a similar method can be used for cutoff protection. Attached Figure Description

[0036] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0037] Figure 1a Based on existing technology, a flowchart illustrating a method for improving image display quality is provided.

[0038] Figure 1b Based on existing technology, a schematic diagram of low grayscale brightness variation curves for different display areas is provided.

[0039] Figure 2 According to an embodiment of this disclosure, a flowchart of a method for improving image display quality is provided.

[0040] Figure 3 According to an embodiment of this disclosure, a schematic flowchart is provided for performing speckle compensation on an input grayscale and generating a corresponding speckle compensation grayscale.

[0041] Figure 4a According to an embodiment of this disclosure, a flowchart illustrating another method for improving image display quality is provided.

[0042] Figure 4b According to an embodiment of this disclosure, a flowchart illustrating another method for improving image display quality is provided.

[0043] Figure 5 According to an embodiment of this disclosure, a schematic diagram of an image display quality improvement system is provided. Detailed Implementation

[0044] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed herein. This disclosure can also be implemented or applied to systems through other different specific embodiments, and various details in this disclosure can also be modified or changed according to different viewpoints and application systems without departing from the spirit of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be combined with each other.

[0045] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, so that those skilled in the art to which this disclosure pertains can readily implement it. This disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0046] In this disclosure, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic represented in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples represented in this disclosure, as well as the features of those different embodiments or examples.

[0047] Furthermore, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the representation of this disclosure, "a plurality of" means two or more, unless otherwise expressly and specifically defined.

[0048] For the purpose of clarity, devices unrelated to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0049] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Furthermore, when it is said that a device "comprises" a certain constituent element, unless otherwise stated otherwise, this does not exclude other constituent elements, but rather implies that other constituent elements may be included.

[0050] When we say that a device is "above" another device, this can mean that it is directly above the other device, or it can mean that other devices are present in between. Conversely, when we say that a device is "directly" "above" another device, there are no other devices present in between.

[0051] Although the terms first, second, etc., are used in some instances herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of features, steps, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0052] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the scope of this disclosure. The singular form used herein includes the plural form unless the statement explicitly indicates otherwise. The word "comprising" as used in this specification means to specify a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0053] Although not explicitly defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with the relevant technical literature and the content of this present disclosure, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0054] Based on the relevant explanations in the background technology section, Figure 1a This diagram illustrates a comparison of the application of a speckle removal compensation technology, using a 4nit12 grayscale as an example. Figure 1a The left side of the display panel shows the effect without speckle compensation, while the right side shows the effect with speckle compensation. It can be seen that before speckle compensation, the display interface has three areas, A, B, and C, with brightness decreasing sequentially, resulting in severe uneven brightness. After speckle compensation, the overall display area becomes more uniform, but overcompensated black spots appear in area D. This is due to excessively high pixel compensation values ​​for the brighter area A. Correspondingly, Figure 1b It shows Figure 1a The diagram illustrates the low grayscale brightness variation curves of different display areas. The brightness-grayscale curve for area A is A', for area B is B', and for area C is C'. The dashed line represents the DMR brightness adjustment baseline. During speckle reduction compensation, the brightness of area A is lowered and the brightness of area C is increased, using the brightness of area B as the target value. As shown in the brightness-grayscale curves, the grayscale of area C changes from Gray12 to Gray18, while the grayscale of area A changes from Gray12 to Gray0. This is represented by a grayscale where the adjusted brightness is black, resulting in black spots and causing uncontrollable display abnormalities.

[0055] To overcome the problems encountered in practical applications, the brightness adjustment reference can be adjusted to reduce the compensation intensity. However, this weakens the compensation effect of the panel under low brightness conditions. To overcome these problems, this disclosure provides an image display quality improvement method and display panel. By detecting and compensating for potential overcompensation scenarios, it can avoid the occurrence of compensation black spots while maintaining the existing speckle removal compensation effect. The technical solutions involved in this disclosure will be explained and described in detail below:

[0056] Specifically, in some embodiments of this disclosure, Figure 2 A flowchart illustrating a method for improving image display quality is provided, such as... Figure 2 As shown, the specific steps may include the following:

[0057] Step 101: Obtain the input grayscale of the image.

[0058] Step 102: If the input grayscale is not zero, perform speckle compensation on the input grayscale and generate the corresponding speckle-compensated grayscale. The implementation of speckle compensation will be explained in detail below and will not be repeated here.

[0059] Step 103: Determine whether the spot removal compensation grayscale is less than the preset overcompensation protection grayscale, and generate the corresponding judgment result.

[0060] Step 104: If the determination result is that the speckle compensation grayscale is less than the overcompensation protection grayscale, generate and output the improved input grayscale, which is the overcompensation protection grayscale. It can be understood that when the obtained speckle compensation grayscale is less than the overcompensation protection grayscale, it indicates that compensation black spots have appeared in the area after speckle compensation processing, and corresponding improvement is needed using the overcompensation protection scheme provided in this disclosure.

[0061] It is understandable that through the above steps 101 to 104, the uniformity of image display can be achieved. Based on the spot removal compensation technology, the scene of over-compensation can be identified, and the black spot area with over-compensation can be compensated and protected without affecting the compensation strength of spot removal compensation. The specific implementation of the above steps 101 to 104 will be further explained and interpreted below.

[0062] In the above embodiments, further, if the determination result is that the speckle compensation grayscale is greater than or equal to the overcompensation protection grayscale, the speckle compensation grayscale is used as the improved input grayscale and output. It can be understood that when the speckle compensation grayscale is greater than or equal to the overcompensation protection grayscale, it indicates that there is no overcompensation, and naturally there is no need to perform the corresponding overcompensation protection, and the pixel processing grayscale of speckle compensation can be directly output.

[0063] In the above embodiments, further, when the input gray level is zero, the input gray level is used as the improved input gray level and output.

[0064] In the above embodiments, further, in the specific implementation of step 102 above, Figure 3 A schematic diagram of a process for performing speckle compensation on an input grayscale and generating a corresponding speckle-compensated grayscale is shown, such as... Figure 3 Specifically, this may include the following steps:

[0065] Step 1021: Set the first compensation amount according to the preset minimum binding point grayscale. The first compensation amount is the spot removal compensation amount when the input grayscale equals the minimum binding point grayscale.

[0066] Step 1022: When the input grayscale is within the range from zero to the lowest binding point grayscale, linear interpolation is used to perform speckle compensation on the input grayscale. It can be understood that in the speckle compensation design, the compensation amount corresponding to grayscale 0 can be set to 0, the speckle compensation amount from grayscale above 0 to the lowest binding point grayscale can be set to offset, and the compensation for the input grayscale within the range from 0 to the lowest binding point grayscale is linear interpolation.

[0067] In the above embodiments, further, Figure 4a A flowchart illustrating another method for improving image display quality is shown, such as... Figure 4a Specifically, this may include the following steps:

[0068] Step 103A: Set several overcompensation protection intervals, with each endpoint of an overcompensation protection interval corresponding to an overcompensation protection grayscale.

[0069] Step 103B: Obtain the overcompensation protection interval of the despot compensation grayscale, and within the overcompensation protection interval, use the overcompensation protection value corresponding to the endpoint of the overcompensation protection interval to perform interval linear interpolation to obtain the overcompensation protection value corresponding to the despot compensation grayscale, so as to generate and output the improved input grayscale.

[0070] Understandably, in the case of a complex gamma structure, overcompensation protection under full brightness display can be achieved by decoupling the gamma frequency of the display device from the display color. By setting multiple endpoints in the full brightness level, the area formed between two adjacent endpoints is an independent overcompensation protection interval.

[0071] Unlike steps 103A to 103B above, which use interpolation between endpoints for overcompensation protection, overcompensation protection can also be achieved by setting the same value in each overcompensation protection interval. Specifically, Figure 4b A flowchart illustrating another method for improving image display quality is shown, such as... Figure 4b Specifically, this may include the following steps:

[0072] Step 103a: Set several overcompensation protection intervals. Each overcompensation protection interval corresponds to an overcompensation protection value.

[0073] Step 103b: Obtain the overcompensation protection range where the speckle compensation grayscale is located, and determine whether the speckle compensation grayscale is less than the corresponding overcompensation protection value: if so, generate and output the improved input grayscale, which is the overcompensation protection grayscale. It is understandable that within the overcompensation protection range, interpolation or segmented setting of the same value can flexibly cover the overcompensation protection requirements under all gamma states.

[0074] Specifically, in one implementation of the above embodiment, a first endpoint, a second endpoint, and a third endpoint can be set sequentially between the lowest brightness level and the maximum brightness level, dividing the area between the lowest brightness level and the maximum brightness level into four over-compensation protection intervals. Each over-compensation protection interval corresponds to an independent over-compensation protection value. The speckle compensation grayscale is compared with the over-compensation protection value between the corresponding over-compensation protection intervals to determine whether the corresponding over-compensation protection needs to be performed.

[0075] In the above embodiments, furthermore, there is no intersection between any two overcompensation protection intervals, and all overcompensation protection intervals can cover all input gray levels.

[0076] In the above embodiments, the setting between the overcompensation protection zones can be associated with the refresh rate of the image display device and / or the display color of the image; similarly, the setting of the overcompensation protection value can also be associated with the refresh rate of the image display device and / or the display color of the image.

[0077] Those skilled in the art will understand that the number and position of endpoints in the full brightness level, as well as the overcompensation protection value in each overcompensation protection interval, can be designed and adaptively set according to the screen voltage adjustment or PWM dimming state of the display device to cover the full gamma brightness range, and are not limited herein.

[0078] The above adjustments apply to speckle compensation for single primary color light. If applied to white light speckle compensation, i.e., the same speckle compensation amount is applied to red, green and blue light, then after PWM dimming gamma readjustment, or at other frequencies, overcompensation protection judgment and adaptive processing in all dimensions are also required.

[0079] In some embodiments of this disclosure, Figure 5 A schematic diagram of an image display quality improvement system is shown. Figure 5 As shown, this image display quality improvement system may specifically include:

[0080] Acquisition unit 001 is used to acquire the input grayscale of the image.

[0081] The speckle compensation unit 002 is used to perform speckle compensation on the input gray level when the input gray level is not zero, and generate the corresponding speckle compensation gray level.

[0082] The overcompensation identification unit 003 is used to determine whether the speckle removal compensation grayscale is greater than the preset overcompensation protection grayscale, and to generate the corresponding judgment result.

[0083] The overcompensation unit 004 is used to generate and output an improved input gray level when the determination result is that the despot compensation gray level is less than the overcompensation protection gray level. The improved input gray level is the overcompensation protection gray level.

[0084] It is understood that the functions performed by the acquisition unit 001 to the overcompensation unit 004 are consistent with the actions performed by steps 101 to 104 in the aforementioned embodiments, and will not be described in detail here.

[0085] like Figure 5 As shown, the image display quality improvement system provided in the above embodiment further includes an overcompensation interval division unit 005, used to set several overcompensation protection intervals, each overcompensation protection interval corresponding to an overcompensation protection value. Correspondingly, the overcompensation identification unit 003 is also used to obtain the overcompensation protection interval in which the speckle compensation grayscale is located, and to determine whether the speckle compensation grayscale is less than the corresponding overcompensation protection value, and to generate a corresponding judgment result; the overcompensation compensation unit 004 is also used to generate and output an improved input grayscale when the judgment result is that the speckle compensation grayscale is less than the corresponding overcompensation protection value, wherein the improved input grayscale is overcompensated.

[0086] In summary, the technical solution provided in this disclosure, based on speckle reduction compensation technology, identifies scenes of overcompensation and then protects overcompensated black spot areas, effectively cutting off downward grayscale compensation and preventing compensation to the point where pixels display black. This ensures the uniformity of speckle reduction compensation while preventing the appearance of compensated black spots, thus improving image display quality. Similarly, if overcompensation occurs in high brightness / high grayscale, a similar method can be used for cutoff protection, making it worthy of widespread application.

[0087] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this disclosure and should not be construed as limiting the specific implementation of this disclosure to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this disclosure, and all such modifications and substitutions should be considered within the scope of protection of this disclosure.

Claims

1. A method for improving image display quality, characterized in that, Includes the following steps: Obtain the input grayscale of the image; If the input grayscale is not zero, perform speckle compensation on the input grayscale and generate a corresponding speckle compensation grayscale. Determine whether the grayscale level for removing speckles is less than the preset overcompensation protection grayscale level, and generate the corresponding determination result; If the determination result is that the despotting compensation grayscale is less than the overcompensation protection grayscale, an improved input grayscale is generated and output, wherein the improved input grayscale is the overcompensation protection grayscale.

2. The image display quality improvement method as described in claim 1, characterized in that, If the determination result is that the despotting compensation grayscale is greater than or equal to the overcompensation protection grayscale, the despotting compensation grayscale is used as the improved input grayscale and output.

3. The image display quality improvement method as described in claim 1, characterized in that, When the input gray level is zero, the input gray level is used as the improved input gray level and output.

4. The image display quality improvement method as described in claim 1, characterized in that, The step of performing speckle compensation on the input grayscale and generating a corresponding speckle-compensated grayscale includes the following steps: Based on the preset minimum binding point gray level, a first compensation amount is set, which is the spot removal compensation amount when the input gray level is equal to the minimum binding point gray level. When the input grayscale is within the range from zero to the lowest binding point grayscale, linear interpolation is used to perform speckle compensation on the input grayscale.

5. The image display quality improvement method as described in claim 1, characterized in that, It also includes the following steps: Several overcompensation protection intervals are defined, and each endpoint of the overcompensation protection interval corresponds to an overcompensation protection gray level. Obtain the overcompensation protection interval in which the speckle compensation grayscale is located, and within the overcompensation protection interval, use the overcompensation protection value corresponding to the endpoint of the overcompensation protection interval to perform interval linear interpolation to obtain the overcompensation protection value corresponding to the speckle compensation grayscale, so as to generate and output the improved input grayscale.

6. The image display quality improvement method as described in claim 1, characterized in that, It also includes the following steps: Several overcompensation protection intervals are defined, and each overcompensation protection interval corresponds to an overcompensation protection value; Obtain the overcompensation protection range in which the spot removal compensation grayscale is located, and determine whether the spot removal compensation grayscale is less than the corresponding overcompensation protection value; If so, generate and output the improved input grayscale, which is the overcompensated protection grayscale.

7. The image display quality improvement method as described in claim 5 or claim 6, characterized in that, There is no intersection between any two of the overcompensated protection intervals; and All of the overcompensation protection intervals cover all of the input gray levels.

8. The image display quality improvement method as described in claim 5 or claim 6, characterized in that, The overcompensation protection interval is associated with the refresh rate of the display device of the image and / or the display color of the image; The overcompensation protection value is associated with the refresh rate of the display device of the image and / or the display color of the image.

9. An image display quality improvement system, characterized in that, include: The acquisition unit is used to acquire the input grayscale of the image; The speckle reduction compensation unit is used to perform speckle reduction compensation on the input gray level when the input gray level is not zero, and generate a corresponding speckle reduction compensation gray level. The overcompensation identification unit is used to determine whether the speckle removal compensation grayscale is greater than the preset overcompensation protection grayscale, and generate a corresponding judgment result; The overcompensation unit is used to generate and output an improved input grayscale when the determination result is that the despot compensation grayscale is less than the overcompensation protection grayscale, wherein the improved input grayscale is the overcompensation protection grayscale.

10. The image display quality improvement system as described in claim 9, characterized in that, Also includes: An overcompensation interval division unit is used to set several overcompensation protection intervals, each of which corresponds to an overcompensation protection value. The overcompensation identification unit is also used to obtain the overcompensation protection range in which the speckle compensation grayscale is located, determine whether the speckle compensation grayscale is less than the corresponding overcompensation protection value, and generate a corresponding judgment result. The overcompensation unit is further configured to generate and output the improved input grayscale when the determination result is that the despotting compensation grayscale is less than the corresponding overcompensation protection value, wherein the improved input grayscale is the overcompensation protection grayscale.

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