Video signal processing device and method

Abstract

The present invention provides a video signal processing device and method. The video signal processing device includes a storage device and a processor. The storage device stores a plurality of brightness mapping relationships. If the set brightness corresponding to the brightness mapping relationship does not match a target brightness, the processor selects a first mapping relationship and a second mapping relationship of the set brightness close to the target brightness from the brightness mapping relationship. Based on the first mapping relationship, the second mapping relationship and the set brightness corresponding to them, an interpolation method is used to obtain a target mapping relationship corresponding to the target brightness. Based on the target mapping relationship, the processor converts nonlinear brightness information of a first video signal into linear brightness information of a second video signal.

Description

Technical Field

[0001] The present invention relates to a signal processing technology, and in particular to a video signal processing device and method. Background Art

[0002] In the HDR10 standard, the perceptual quantization (PQ) electro-optical transfer function (EOTF) used determines the corresponding conversion relationship between the image signal and the display brightness. However, the display brightness of the display panel is affected by both the image signal and the backlight intensity. When the backlight brightness of the display panel is adjusted without adjusting the PQ EOTF accordingly, the display brightness of the display panel will not be able to present the correct brightness effect. For example, if the PQ EOTF is established based on a maximum brightness of 324 nits, when the backlight brightness is adjusted to 250 nits, the display brightness will drop to 250 / 324 times. Summary of the invention

[0003] In view of this, an embodiment of the present invention proposes a video signal processing method, including: reading multiple brightness mapping relationships, the brightness mapping relationship represents a mapping relationship between a nonlinear brightness signal and a linear brightness signal, and each brightness mapping relationship corresponds to a different set brightness; if the set brightness corresponding to the brightness mapping relationship does not match a target brightness, selecting a first mapping relationship and a second mapping relationship of the set brightness close to the target brightness from the brightness mapping relationship, wherein the target brightness is between a first brightness and a second brightness, and the first mapping relationship corresponds to the first brightness, and the second mapping relationship corresponds to the second brightness; according to the first mapping relationship, the first brightness, the second mapping relationship and the second brightness, using an interpolation method to obtain a target mapping relationship corresponding to the target brightness; and according to the target mapping relationship, converting the nonlinear brightness information of a first video signal into the linear brightness information of a second video signal.

[0004] One embodiment of the present invention further proposes a video signal processing device, including a storage and a processor. The storage stores a plurality of brightness mapping relationships, wherein the brightness mapping relationship represents a mapping relationship between a nonlinear brightness signal and a linear brightness signal, and each brightness mapping relationship corresponds to a different set brightness. The processor is coupled to the storage. If the set brightness corresponding to the brightness mapping relationship does not match a target brightness, the processor selects a first mapping relationship and a second mapping relationship of the set brightness close to the target brightness from the brightness mapping relationship. The target brightness is between a first brightness and a second brightness, and the first mapping relationship corresponds to the first brightness, and the second mapping relationship corresponds to the second brightness. The processor also obtains a target mapping relationship corresponding to the target brightness by an interpolation method based on the first mapping relationship, the first brightness, the second mapping relationship and the second brightness, and converts the nonlinear brightness information of a first video signal into the linear brightness information of a second video signal according to the target mapping relationship.

[0005] According to the embodiments of the present invention, the target display brightness can be correctly displayed according to the set brightness without consuming a large amount of storage space to store the brightness mapping relationship corresponding to various set brightnesses, and the correct brightness can be displayed in response to any set brightness within the brightness control range, allowing the user to experience the feeling of stepless and fine brightness adjustment (gradual brightness change). BRIEF DESCRIPTION OF THE DRAWINGS

[0006] [ Figure 1 ] is a schematic diagram of the architecture of a video signal processing device according to an embodiment of the present invention.

[0007] [ Figure 2 ] is a flow chart of a video signal processing method according to an embodiment of the present invention.

[0008] [ Figure 3 ] is a schematic diagram of several brightness mapping relationships of an embodiment of the present invention.

[0009] [ Figure 4 ]for Figure 3 A partial enlarged view.

[0010] [ Figure 5 ] is a schematic diagram of several display brightnesses according to an embodiment of the present invention.

[0011] [ Figure 6 ]for Figure 5 A partial enlarged view. DETAILED DESCRIPTION

[0012] As used herein, the term "coupled" may mean that two or more elements are in direct physical or electrical contact with each other, or may also mean that two or more elements are in indirect electrical contact with each other.

[0013] Reference Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the structure of a video signal processing device 1 according to an embodiment of the present invention. The video signal processing device 1 includes a storage 2 and a processor 3. The processor 3 of the video signal processing device 1 is coupled to a display panel 4 to process the video signal and then send it to the display panel 4 for display.

[0014] Reference Figure 2 , Figure 2 This is a flow chart of a video signal processing method according to an embodiment of the present invention. The video signal processing method is executed by a processor 3. First, a plurality of brightness mapping relationships are read from a storage 2 (step S21). These brightness mapping relationships are pre-stored in the storage 2. The brightness mapping relationship represents a mapping relationship between non-linear brightness information and linear brightness information. Each brightness mapping relationship corresponds to a different set brightness. The set brightness refers to a specific brightness of the display panel 4 within a brightness control range (such as a backlight brightness control range). The maximum value of the brightness control range is the maximum luminous intensity, i.e., the peak brightness (Peak Luminance). For example, when the brightness control range is 40% to 100% of the peak brightness, the segmented brightness can be 40%, 55%, 70%, 85%, or 100% of the peak brightness.

[0015] For liquid crystal displays, peak brightness refers to the display brightness at the maximum backlight intensity. For organic light emitting diode displays, peak brightness refers to the maximum display brightness at different average picture levels (APL).

[0016] Taking the HDR10 standard as an example, the PQ EOTF used is the aforementioned brightness mapping relationship, as shown in Formula 1, and can convert nonlinear brightness information (here the target color space nonlinear code N) into linear brightness information (here the target color space linear code L). The value of the target color space linear code L is between 0 and 1. The value of the target color space nonlinear code N is a normalized value between 0 and 1. For example: if the code length is 10 bits, N is between [0 to 1023] / 1023. m1~m2 and c1~c3 are constants. For example: m1 is (2610 / 4096)×(1 / 4), m2 is 2523 / 4096×128, c1 is 3424 / 4096, c2 is 2413 / 4096×32, and c3 is 2392 / 4096×32. Furthermore, the target color gamut linear encoding L can be converted into output brightness C in nits (Nit) through Formula 2.

[0017] Formula 1

[0018]

[0019] Formula 2

[0020] C=10000L

[0021] In some embodiments, each brightness mapping relationship is stored in the form of a one-dimensional lookup table, that is, using the target color gamut nonlinear code N as an index, the target color gamut linear code L corresponding to each index is stored in the one-dimensional lookup table.

[0022] like Figure 2 As shown, in step S22, it is determined whether a set brightness corresponding to the brightness mapping relationship matches a target brightness. Here, the target brightness refers to the brightness setting to be adjusted to the display panel 4, which is within the brightness control range of the display panel 4. Continuing with the above-mentioned example where the segmented brightness is 40%, 55%, 70%, 85%, and 100% of the peak brightness, the target brightness is, for example, 80% of the peak brightness, then these set brightnesses do not match the target brightness, and step S23 is entered. In one example, if the target brightness is 70% of the peak brightness, one of the set brightnesses matches the target brightness, and step S25 is entered. Through step S23 or step S25, the target mapping relationship can be obtained. Finally, in step S24, based on this target mapping relationship, the nonlinear brightness information of the first video signal can be converted into linear brightness information of a second video signal, so that the display panel 4 can display the image accordingly.

[0023] In step S25, the brightness mapping relationship that matches the target brightness is directly used as the target mapping relationship.

[0024] In step S23, first select the brightness mapping relationship corresponding to two set brightnesses close to the target brightness from these brightness mapping relationships. Continuing with the above example, the two set brightnesses close to 80% of the peak brightness (hereinafter referred to as the first brightness and the second brightness, respectively) are 70% and 85% of the peak brightness. Here, the target brightness is between the first brightness and the second brightness. Hereinafter, the brightness mapping relationship corresponding to the first brightness will be referred to as the first mapping relationship, and the brightness mapping relationship corresponding to the second brightness will be referred to as the second mapping relationship. Then, based on the first mapping relationship, the first brightness, the second mapping relationship and the second brightness, the brightness mapping relationship corresponding to the target brightness (hereinafter referred to as the target mapping relationship) is obtained by interpolation. Specifically, it can be expressed as in Formula 3 and Formula 4. BR is the interpolation blend ratio (Blend Ratio). L T is the target brightness, L1 is the first brightness, and L2 is the second brightness. T (n) represents the target display brightness, expressed in EOTF T (n) represents the target mapping relationship, EOTF1(n) represents the first mapping relationship, and EOTF2(n) represents the second mapping relationship. n is an entry index.

[0025] Formula 3

[0026]

[0027] Formula 4

[0028] LV T (n) = EOTF T (n)×L T

[0029] =(1-BR)×EOTF1(n)×L1+BR×EOTF2(n)×L2

[0030] The following example illustrates how to use interpolation to obtain a target mapping relationship corresponding to target brightness. Figures 3 to 6 . Figure 3 It is a schematic diagram of several brightness mapping relationships according to an embodiment of the present invention. Figure 4 for Figure 3 A partial enlarged view. Figure 5 FIG. 4 is a schematic diagram of several display brightnesses according to an embodiment of the present invention. Figure 6 for Figure 5 In this example, the peak brightness is 300 nits, and each one-dimensional lookup table has 1024 index items, with a precision of 16 bits and a maximum value of 65472. Figure 3 As shown, there are brightness mapping relationships EOTF corresponding to 40%, 55%, 70%, 85%, and 100% of the peak brightness respectively. 40％ , EOTF 55％ , EOTF 70％ , EOTF 85％ , EOTF 100％ . Based on the above target brightness L T For example, if the peak brightness is 80%, the first brightness L1 and the second brightness L2 are 70% and 85% of the peak brightness respectively. Therefore, the first mapping relationship and the second mapping relationship are EOTF 70％ With EOTF 85％ .like Figure 4 As shown, taking the index item n as 600 as an example, EOTF 70％ (600) = 58570 (point A), EOTF 85％ (600) = 53440 (point C). BR is calculated according to formula 3: like Figure 6 As shown, the actual display brightness corresponding to the first brightness L1 Nit (point F). The actual display brightness corresponding to the second brightness L2 Nit (point D). According to formula 4, the target display brightness LV T(600) = 33% × 187.86 + 67% × 208.14 ≈ 201.45 nits (point E). Set the target display brightness to LV T (600) divided by the target brightness L T ,get (Point B).

[0031] from Figure 6 It can be seen that through the above method, the target display brightness can be correctly displayed according to the set brightness without consuming a large amount of storage space to store the brightness mapping relationship corresponding to various different set brightnesses, and the correct brightness can be displayed in response to any set brightness within the brightness control range, allowing users to experience the feeling of stepless and fine brightness adjustment (gradual brightness change).

[0032] In some embodiments, the set brightness corresponding to the brightness mapping relationship is evenly distributed within the brightness control range, thereby making the interpolation calculation values ​​performed in the segments between the set brightnesses balanced and accurate.

[0033] In some embodiments, the backlight brightness is controlled by pulse width dimming (PWM dimming). Therefore, the processor 3 can estimate the target brightness according to the pulse width modulation (PWM) information.

[0034] In some embodiments, the processor 3 may further perform other processing on the second video signal, such as tone mapping, color gamut coding conversion, gamma correction, etc. Since the maximum corresponding brightness of the PQ EOTF is 10,000 nits, and the brightness capability of most display panels 4 is approximately within 1,000 nits, tone mapping can correspond the brightness to the display capability range of the display panel 4. Color gamut coding conversion is to convert the target color gamut linear coding L into the linear coding corresponding to the color gamut of the display panel 4, so that the same color is presented after the coding conversion. Gamma correction can linearize the characteristics of the display panel 4.

[0035] In some embodiments, the first video signal is obtained by the processor 3 from other devices, such as other processing devices, video signal interfaces, other storage devices, etc.

[0036] The processor 3 may be, for example, a microprocessor, a system on chip (SOC), etc. The storage 2 is a non-volatile storage medium, such as a non-volatile memory, such as a flash memory, an electrically erasable programmable read-only memory (EEPROM), etc. In some embodiments, the processor 3 may be implemented by a plurality of processing devices. In some embodiments, the processor 3 and the storage 2 may be integrated into a single device, such as a scaler IC. In some embodiments, the processor 3 and the storage 2 are separate independent devices.

[0037] In summary, according to some embodiments of the present invention, the target display brightness can be correctly displayed according to the set brightness without consuming a large amount of storage space to store the brightness mapping relationship corresponding to various different set brightnesses, and the correct brightness can be displayed in response to any set brightness within the brightness control range, allowing the user to experience the feeling of stepless and fine brightness adjustment (gradual brightness change).

[0038]

Explanation of symbols

[0039] 1: Video signal processing device

[0040] 2: Storage

[0041] 3: Processor

[0042] 4: Display Panel

[0043] S21~S25: steps.

Claims

1. A video signal processing method, comprising: Reading a plurality of brightness mapping relationships, wherein the plurality of brightness mapping relationships represent a mapping relationship between a nonlinear brightness signal and a linear brightness signal, and each of the brightness mapping relationships corresponds to a different set brightness; If the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships do not match a target brightness, a first mapping relationship and a second mapping relationship of the set brightnesses close to the target brightness are selected from the plurality of brightness mapping relationships, wherein the target brightness is between a first brightness and a second brightness, and the first mapping relationship corresponds to the first brightness, and the second mapping relationship corresponds to the second brightness; Obtaining a target mapping relationship corresponding to the target brightness by using an interpolation method according to the first mapping relationship, the first brightness, the second mapping relationship and the second brightness; and According to the target mapping relationship, nonlinear brightness information of a first video signal is converted into linear brightness information of a second video signal; wherein the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships are within a brightness control range of a display panel; and The plurality of set brightnesses corresponding to the plurality of brightness mapping relationships are evenly distributed within the brightness control range. 2 . The video signal processing method according to claim 1 , wherein each of the brightness mapping relationships is stored in a one-dimensional lookup table.

3. The video signal processing method according to claim 1, further comprising: If one of the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships matches the target brightness, the brightness mapping relationship that matches the target brightness is used as the target mapping relationship.

4. A video signal processing device, comprising: A storage device storing a plurality of brightness mapping relationships, wherein the plurality of brightness mapping relationships represent a mapping relationship between a nonlinear brightness signal and a linear brightness signal, and each of the brightness mapping relationships corresponds to a different set brightness; and a processor coupled to the storage, and if the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships do not match a target brightness, selecting a first mapping relationship and a second mapping relationship of the set brightness close to the target brightness from the plurality of brightness mapping relationships, wherein the target brightness is between a first brightness and a second brightness, and the first mapping relationship corresponds to the first brightness, and the second mapping relationship corresponds to the second brightness, the processor obtains a target mapping relationship corresponding to the target brightness by an interpolation method according to the first mapping relationship, the first brightness, the second mapping relationship, and the second brightness, and converts nonlinear brightness information of a first video signal into linear brightness information of a second video signal according to the target mapping relationship; wherein the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships are within a brightness control range of a display panel; and The plurality of set brightnesses corresponding to the plurality of brightness mapping relationships are evenly distributed within the brightness control range. 5 . The video signal processing device according to claim 4 , wherein each of the brightness mapping relationships is stored in a one-dimensional lookup table format. 6 . The video signal processing device according to claim 4 , wherein if one of the plurality of set brightnesses corresponding to the plurality of brightness mapping relationships matches the target brightness, the processor uses the brightness mapping relationship that matches the target brightness as the target mapping relationship.

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