Video processing system, video processing method, and program

Abstract

A video processing system (2) is provided with: a first input interface (21); a second input interface (22); and a CPU (231). The first input interface (21) acquires a video signal to be outputted to a display panel (10) of a display (1). The second input interface (22) acquires color temperature information indicating the color temperature of environment light emitted toward the display panel (10). The CPU (231) calculates a correction amount of the color temperature of the video signal so as to conform to the color temperature of the environment light. The CPU (231) subtracts the absolute value of the correction amount of the color temperature of the video signal so as to cancel the color temperature of the environment light when the pixel luminance of the video signal is less than a luminance threshold value. The CPU (231) outputs the video signal having the color temperature of the video signal corrected in accordance with the correction amount.

Description

Image processing system, image processing method, and program

[0001] The present disclosure relates to an image processing system for processing images displayed on a display panel of a display.

[0002] For example, Patent Document 1 discloses a television device that includes an external light detector that detects the illuminance and hue of ambient light, and an image quality controller that adjusts the image quality of the image displayed on the display panel. The image quality controller adjusts the color temperature of the image to be displayed in accordance with the illuminance and hue values ​​detected by the external light detector.

[0003] JP 2010-124197 A

[0004] The present disclosure provides an image processing system and the like that can easily and accurately correct the color temperature of an image displayed on a display panel of a display.

[0005] An image processing system according to one aspect of the present disclosure includes a first input interface, a second input interface, and a processor. The first input interface acquires a video signal to be output to a display panel of a display. The second input interface acquires color temperature information indicating the color temperature of ambient light irradiated onto the display panel. The processor calculates a correction amount for the color temperature of the video signal so as to follow the color temperature of the ambient light. When pixel luminance of the video signal is below a luminance threshold, the processor reduces the absolute value of the correction amount so as to cancel out the color temperature of the ambient light. The processor outputs the video signal with the color temperature of the video signal corrected according to the correction amount.

[0006] In a video processing method according to one aspect of the present disclosure, a video signal to be output to a display panel of a display is acquired, color temperature information indicating the color temperature of ambient light irradiated onto the display panel is acquired, a correction amount for the color temperature of the video signal is calculated so as to follow the color temperature of the ambient light, and if the pixel brightness of the video signal is below a brightness threshold, the absolute value of the correction amount is reduced so as to cancel out the color temperature of the ambient light, and the video signal with the color temperature of the video signal corrected according to the correction amount is output.

[0007] A program according to one aspect of the present disclosure causes one or more processors to execute the video processing method.

[0008] The image processing system and the like according to the present disclosure has the advantage that it is easy to accurately correct the color temperature of an image displayed on a display panel of a display.

[0009] FIG. 1 is an explanatory diagram of a problem in correcting the color temperature of a video signal based on the color temperature of ambient light. FIG. 2 is a block diagram showing an overall configuration including a video processing system according to an embodiment. FIG. 3 is a flowchart showing an example of operation of the video processing system according to an embodiment. FIG. 4 is a flowchart showing an example of operation for calculating a sub-correction amount for the color temperature of a video signal. FIG. 5 is an explanatory diagram of operation for calculating a sub-correction amount for the color temperature of a video signal. FIG. 6 is a diagram showing an example of correction of the color temperature of a video signal. FIG. 7 is a diagram showing another example of correction of the color temperature of a video signal. FIG. 8 is a diagram showing the correlation between the correction amount for the color temperature of a video signal and pixel luminance. FIG. 9 is an explanatory diagram of advantages of the video processing system according to an embodiment.

[0010] [1. Findings that Form the Basis of the Present Disclosure] First, the inventor's viewpoint will be explained below.

[0011] A conventional technique for correcting white balance involves detecting ambient light irradiating a display using an RGB sensor and then correcting the color temperature of a video signal to match the color temperature of the ambient light using information about the ambient light detected by the RGB sensor. Here, "ambient light" refers to light irradiated onto a display from its surroundings, such as sunlight or light emitted by lighting fixtures. With this technique, for example, if the color temperature of the ambient light is higher than a reference color temperature, the color temperature of the video signal is corrected to be higher. If the color temperature of the ambient light is lower than the reference color temperature, the color temperature of the video signal is corrected to be lower. Correcting the color temperature of the video signal in this manner makes it easier to display images on a display at an appropriate color temperature that takes into account the chromatic adaptation of human vision.

[0012] However, the above technology has the following problems. Fig. 1 is an explanatory diagram of the problems with the process of correcting the color temperature of a video signal based on the color temperature of ambient light. In each of Fig. 1(a) and (c), arrow A1 represents ambient light irradiating the display 1, and arrow A2 represents ambient light reflected by the display panel 10 of the display 1. Also, in each of Fig. 1(a) and (c), arrow A3 represents light output from the display panel 10 of the display 1 based on a video signal. The size of arrow A3 represents the magnitude of the luminous flux output from the display panel 10 of the display 1, in other words, the level of luminance of the video signal.

[0013] (b) and (d) in Fig. 1 respectively show grayscales displayed on the display panel 10 of the display 1. Note that in Fig. 1 (b) and (d), a higher dot density indicates a darker image, and a lower dot density indicates a brighter image. (b) in Fig. 1 shows a grayscale when the luminance of the video signal is relatively high, as shown in (a) in Fig. 1. As shown in (b) in Fig. 1, when the luminance of the video signal is relatively high, the intensity of the ambient light is relatively low compared to the light output from the display panel 10 of the display 1, so the influence of the ambient light does not appear in the grayscale, or appears very little.

[0014] On the other hand, (d) of Fig. 1 shows a grayscale when the luminance of the video signal is relatively low, as shown in (c) of Fig. 1. As shown in (d) of Fig. 1, when the luminance of the video signal is relatively low, the intensity of the ambient light is relatively high compared to the light output from the display panel 10 of the display 1, and therefore the influence of the ambient light appears in the grayscale. Specifically, in region G1, which indicates a relatively bright gradation, the influence of the ambient light is not apparent or is barely apparent, but in region G2, which indicates a relatively dark gradation, the influence of the ambient light appears, as indicated by the diagonal hatching. For example, if the ambient light is bluish light and the luminance of the video signal is relatively low, a bluish color appears in region G2, which indicates a relatively dark gradation.

[0015] As described above, when correcting the color temperature of a video signal based on the color temperature of ambient light, there is a problem in that, depending on the brightness of the video signal, it may be difficult to accurately correct the color temperature of the video displayed on the display panel 10 of the display 1.

[0016] In view of the above, the inventors have come up with the present disclosure.

[0017] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, steps, step order, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0018] It should be noted that the drawings are schematic diagrams and are not necessarily strict illustrations. In addition, in the drawings, substantially the same components are denoted by the same reference numerals, and overlapping descriptions may be omitted or simplified.

[0019] (Embodiment) [2. Configuration] [2-1. Overall Configuration] First, the overall configuration including a video processing system according to an embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the overall configuration including a video processing system 2 according to an embodiment. The video processing system 2 is a system that executes a process to correct a video signal that is output to the display panel 10 of the display 1 and outputs the corrected video signal. In the embodiment, the video processing system 2 is built into the display 1. Note that the video processing system 2 may also be provided outside the display 1.

[0020] The display panel 10 is configured by, for example, a liquid crystal panel or an organic EL (Electro-Luminescence) panel. The display panel 10 displays video, including moving images or still images, represented by acquired video data. The video data is included in the corrected video signal output from the video processing system 2.

[0021] The video signal includes, for example, terrestrial broadcast video data obtained by converting an analog signal received by an antenna into a digital signal and decoding the converted digital signal. Note that the video signal may also include video data transmitted over a network such as the Internet from a server providing a video distribution service. The video signal may also include, for example, video data stored in a recording device connected to the display 1.

[0022] An RGB sensor 3 is provided around the display 1. The RGB sensor 3 is a sensor for detecting ambient light irradiating the display panel 10 of the display 1. Specifically, the RGB sensor 3 has three photodiodes corresponding to R (red), G (green), and B (blue), respectively, and detects the component intensities of the ambient light irradiating each photodiode. The RGB sensor 3 then outputs RGB information according to the component intensities of the detected ambient light. Here, the component intensities of the ambient light include the light intensity of the R component of the ambient light, the light intensity of the G component of the ambient light, and the light intensity of the B component of the ambient light. The RGB information output by the RGB sensor 3 is input to the video processing system 2.

[0023] [2-2. Video Processing System] Next, a specific description will be given of the configuration of the video processing system 2. As shown in Fig. 2, the video processing system 2 includes a first input interface (hereinafter referred to as "first input I / F (Interface)") 21, a second input interface (hereinafter referred to as "second input I / F") 22, and a SoC (System on a Chip) 23. The SoC 23 includes a CPU (Central Processing Unit) 231, a memory 232, and a video processing circuit 233.

[0024] The first input I / F 21 is, for example, a wired communication interface, and acquires a video signal to be output to the display panel 10 of the display 1. The first input I / F 21 may be a wireless communication interface. A tuner that receives broadcast waves and outputs a video signal may be connected to the first input I / F 21.

[0025] The second input I / F 22 is, for example, a wired communication interface, and acquires color temperature information indicating the color temperature of ambient light irradiated onto the display panel 10. In the embodiment, the second input I / F 22 acquires RGB information (color temperature information) from the RGB sensor 3 by performing wired communication with the RGB sensor 3. Note that the second input I / F 22 may be a wireless communication interface.

[0026] The CPU 231 performs information processing to correct the video signal acquired by the first input I / F 21 based on the color temperature information acquired by the second input I / F 22, and outputs the corrected video signal to the video processing circuit 233. The above-mentioned information processing is realized by the CPU 231 executing a computer program stored in the memory 232. The CPU 231 is an example of a processor of the video processing system 2.

[0027] The correction process described above includes a first correction calculation process and a second correction calculation process. The first correction calculation process calculates a correction amount for the color temperature of the video signal so that the correction amount follows the color temperature of the ambient light, taking into account the chromatic adaptation of human vision. The second correction calculation process reduces the absolute value of the correction amount calculated in the first correction calculation process so as to cancel out the color temperature of the ambient light according to the pixel luminance of the video signal. In other words, the second correction calculation process adjusts the correction amount for the color temperature of the video signal in the first correction calculation process, which may be excessive depending on the pixel luminance of the video signal, to an appropriate correction amount by reducing the absolute value. The first correction calculation process and the second correction calculation process will be described in detail in [3. Operation] below.

[0028] The memory 232 is a storage device that stores computer programs executed by the CPU 231 and information necessary for implementing various functions. The memory 232 is realized by, for example, a semiconductor memory. Note that the memory 232 may be realized as an internal memory of the CPU 231, rather than as an external memory of the CPU 231.

[0029] The video processing circuit 233 outputs the video signal, the color temperature of which has been corrected by the CPU 231, to the display panel 10. Note that the video processing circuit 233 may perform correction processes other than the color temperature correction process of the video signal, such as contour correction or noise removal, on the corrected video signal. Furthermore, if the video signal input from the first input I / F 21 is coded or encrypted, the video processing circuit 233 decodes it and performs various video processes, including correction, on the decoded video signal. Furthermore, in the embodiment, the CPU 231 is configured separately from the video processing circuit 233, but this is not limiting and the CPU 231 may be a part of the video processing circuit 233.

[0030] 3. Operation An example of the operation of the video processing system 2 according to the embodiment, that is, a video processing method, will be described below.

[0031] 3-1. Correction Process of Color Temperature of Video Signal First, the correction process of color temperature of a video signal, which is a main operation of the video processing system 2 according to the embodiment, will be described with reference to Fig. 3. Fig. 3 is a flowchart showing an example of the operation of the video processing system 2 according to the embodiment.

[0032] First, the first input I / F 21 of the video processing system 2 acquires a video signal (S101). In this embodiment, the video signal acquired by the first input I / F 21 is an RGB signal converted from a YUV signal or a YCbCr signal. Furthermore, the second input I / F 22 of the video processing system 2 acquires RGB information output from the RGB sensor 3 (S102). Steps S101 and S102 are not limited to this order, and may be executed in the reverse order or in parallel.

[0033] Next, the CPU 231 of the video processing system 2 calculates and acquires illuminance information indicating the illuminance of the ambient light and color temperature information indicating the color temperature of the ambient light based on the acquired RGB information (S103). Specifically, the CPU 231 acquires illuminance information by performing a calculation to convert the light intensity of the R component of the ambient light, the light intensity of the G component of the ambient light, and the light intensity of the B component of the ambient light included in the acquired RGB information into the illuminance of the ambient light using an appropriate conversion formula. The CPU 231 also acquires color temperature information by performing a calculation to convert the light intensity of the R component of the ambient light, the light intensity of the G component of the ambient light, and the light intensity of the B component of the ambient light included in the acquired RGB information into the color temperature of the ambient light using an appropriate conversion formula different from the above conversion formula.

[0034] Next, the CPU 231 calculates a correction amount A for the color temperature of the video signal (S104). Step S104 corresponds to the first correction calculation process described above. Specifically, the CPU 231 calculates a correction amount A for the color temperature of the video signal based on the color temperature of the ambient light calculated in step S103 so that the color temperature follows the color temperature of the ambient light.

[0035] For example, if the ambient light is bluish, that is, if the color temperature of the ambient light is higher than a reference color temperature (for example, approximately 5000 K indicating daylight white), the CPU 231 calculates a correction amount A corresponding to the difference between the color temperature of the ambient light and the reference color temperature. In this case, the color temperature of the video signal is corrected to be higher, so the correction amount A is a positive value. On the other hand, if the ambient light is reddish, that is, if the color temperature of the ambient light is lower than the reference color temperature, the CPU 231 calculates a correction amount A corresponding to the difference between the color temperature of the ambient light and the reference color temperature. In this case, the color temperature of the video signal is corrected to be lower, so the correction amount A is a negative value.

[0036] Furthermore, the CPU 231 calculates a sub-correction amount for the color temperature of the video signal (S105). Here, the sub-correction amount is a value to be added to the correction amount A for the color temperature of the video signal calculated in step S104. The calculation process of the sub-correction amount will be described in detail in [3-2. Calculation process of sub-correction amount] below. The order of steps S104 and S105 is not limited to this, and steps S104 and S105 may be executed in the reverse order or in parallel.

[0037] Next, the CPU 231 compares the pixel luminance of each pixel of the video signal with a luminance threshold Th3 (see FIG. 8 ) (S106). The luminance threshold Th3 is a luminance corresponding to the boundary between the region G1 showing relatively bright gradations and the region G2 showing relatively dark gradations, as described in [1. Knowledge forming the basis of the present disclosure], for example. The luminance threshold Th3 is set in advance by, for example, a designer of the video processing system 2, and stored in the memory 232.

[0038] If the pixel luminance is equal to or greater than the luminance threshold Th3 (S106: No), the CPU 231 does not perform correction using the sub-correction amount (S107). That is, in this case, the CPU 231 does not add the sub-correction amount for the color temperature of the video signal calculated in step S105 to the correction amount A for the color temperature of the video signal calculated in step S104. On the other hand, if the pixel luminance is below the luminance threshold Th3 (S106: Yes), the CPU 231 performs correction using the sub-correction amount (S108). That is, in this case, the CPU 231 adds the sub-correction amount for the color temperature of the video signal calculated in step S105 to the correction amount A for the color temperature of the video signal calculated in step S104.

[0039] Next, the CPU 231 corrects the color temperature of the video signal (here, the pixel to be processed) (S109). Specifically, if step S107 has been completed, the CPU 231 corrects the color temperature of the video signal based on the correction amount A for the color temperature of the video signal calculated in step S104. On the other hand, if step S108 has been completed, the CPU 231 corrects the color temperature of the video signal based on the correction amount obtained by adding the sub-correction amount calculated in step S105 to the correction amount A for the color temperature of the video signal calculated in step S104. In other words, if the correction amount referred to in step S109 is "correction amount B," then if step S107 has been completed, then "correction amount B = correction amount A," and if step S108 has been completed, then "correction amount B = correction amount A + sub-correction amount." Steps S105 to S108 correspond to the second correction calculation process described above.

[0040] Thereafter, the CPU 231 executes the above-described steps S106 to S109 for each pixel until processing is completed for all pixels of the video signal (while the result of S110 is No). Then, when processing is completed for all pixels of the video signal (S110: Yes), the CPU 231 outputs the corrected video signal to the video processing circuit 233 (S111). As a result, an image whose color temperature has been corrected based on the color temperature of the ambient light is displayed on the display panel 10 of the display 1.

[0041] 3-2. Calculation Process of Sub-Correction Amount of Color Temperature of Video Signal Next, calculation process of the sub-correction amount of color temperature of the video signal by the video processing system 2 according to the embodiment will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a flowchart showing an example of operation for calculating the sub-correction amount of color temperature of the video signal. Fig. 5 is an explanatory diagram of operation for calculating the sub-correction amount of color temperature of the video signal.

[0042] 5A is a diagram showing correlation data between the illuminance of ambient light and the correction coefficient, with the vertical axis representing the correction coefficient and the horizontal axis representing the illuminance of ambient light. The "correction coefficient" may also be a "correction ratio." As shown in FIG. 5A, the correction coefficient is zero when the illuminance of ambient light is equal to or less than an illuminance threshold Th1, and increases in proportion to the illuminance of ambient light when the illuminance of ambient light exceeds the illuminance threshold Th1. The correction coefficient then becomes a constant value when the illuminance of ambient light is equal to or greater than a predetermined illuminance value Th10.

[0043] FIG. 5B is a diagram illustrating the relationship between the color temperature of ambient light and the correction amount C, with the vertical axis representing the correction amount C and the horizontal axis representing the color temperature of ambient light. As shown in FIG. 5B, the correction amount C is zero when the color temperature of ambient light is within a predetermined range R1. Here, the predetermined range R1 is the range in which the color temperature of ambient light is equal to or greater than the first color threshold Th21 and equal to or less than the second color threshold Th22. The correction amount C becomes a positive value when the color temperature of ambient light is below the first color threshold Th21, and its absolute value increases in proportion to the color temperature of ambient light. The correction amount C becomes a constant value when the color temperature of ambient light is equal to or less than the predetermined color value Th210. On the other hand, the correction amount C becomes a negative value when the color temperature of ambient light exceeds the second color threshold Th22, and its absolute value increases in proportion to the color temperature of ambient light. The correction amount C becomes a constant value when the color temperature of ambient light is equal to or greater than the predetermined color value Th220.

[0044] The relationship data shown in each of FIGS. 5A and 5B is set by, for example, the designer of the video processing system 2 and stored in advance in the memory 232.

[0045] 4, first, the CPU 231 compares the illuminance of the ambient light acquired in step S103 with the illuminance threshold Th1 (step S201). If the illuminance of the ambient light is equal to or less than the illuminance threshold Th1 (S201: No), the CPU 231 sets the correction coefficient to zero (S202). In other words, in this case, the CPU 231 does not reduce the absolute value of the correction amount of the color temperature of the video signal according to the illuminance of the ambient light.

[0046] On the other hand, if the illuminance of the ambient light exceeds the illuminance threshold Th1 (S201: Yes), the CPU 231 determines a correction coefficient according to the illuminance of the ambient light by referring to the relationship data shown in Fig. 5A (S203). That is, in this case, the CPU 231 performs a process of reducing the absolute value of the correction amount of the color temperature of the video signal according to the illuminance of the ambient light.

[0047] The CPU 231 also compares the color temperature of the ambient light acquired in step S103 with a predetermined range R1 (S204). If the color temperature of the ambient light is within the predetermined range R1, that is, the range between the first color threshold value Th21 and the second color threshold value Th22 (S204: Yes), the CPU 231 sets the correction amount C to zero (S205). In other words, in this case, the CPU 231 does not reduce the absolute value of the correction amount for the color temperature of the video signal in accordance with the color temperature of the ambient light.

[0048] On the other hand, if the color temperature of the ambient light falls outside the predetermined range R1 (S204: No), the CPU 231 refers to the relationship data shown in Fig. 5(b) and determines the correction amount C according to the color temperature of the ambient light (S206). That is, in this case, the CPU 231 performs a process of reducing the absolute value of the correction amount for the color temperature of the video signal according to the color temperature of the ambient light.

[0049] In the embodiment, the CPU 231 executes the processes of steps S201 to S203 and the processes of steps S204 to S206 in parallel, but this is not limited to this. For example, the CPU 231 may execute the processes of steps S201 to S203 and then execute the processes of steps S204 to S206, or may execute them in the reverse order.

[0050] Then, the CPU 231 calculates a sub-correction amount by multiplying the correction coefficient calculated in the processes of steps S201 to S203 by the correction amount C calculated in the processes of steps S204 to S206 (S207).

[0051] Here, the significance of calculating the sub-correction amount will be explained. First, when the color temperature of the video signal is corrected using the correction amount A calculated in step S104, the color temperature of the video signal is corrected so as to follow the color temperature of the ambient light. For example, if the color temperature of the ambient light is high, the color temperature of the video signal will be raised by correcting using the correction amount A.

[0052] However, when the luminance of the video signal is relatively low (i.e., the pixel luminance of the video signal is below the luminance threshold Th3), correcting the color temperature of the video signal using correction amount A tends to result in excessive correction. For example, when the color temperature of the ambient light is high and the luminance of the video signal is relatively low, if correction is performed using correction amount A, the color temperature of the video viewed by the user will be too high due to the influence of the ambient light, and the video will appear bluish.

[0053] Therefore, in the embodiment, when the luminance of the video signal is relatively low, the sub-correction amount is added to the correction amount A, thereby reducing the absolute value of the correction amount A. This makes it possible to prevent the color temperature of the video perceived by the user from being excessively corrected by the color temperature correction of the video signal.

[0054] However, when the illuminance of the ambient light is relatively low (i.e., when the illuminance of the ambient light is below the illuminance threshold Th1), the influence of the ambient light is small, and therefore there is no need to reduce the absolute value of the correction amount A. In this case, the correction coefficient is set to zero, thereby making the sub-correction amount zero.

[0055] [3-3. Example of Correcting Color Temperature of Video Signal] In this embodiment, the CPU 231 corrects the color temperature of the video signal by correcting the correction amounts of the R component, G component, and B component of the video signal, i.e., the RGB values ​​of the video signal. An example of correcting the color temperature of the video signal will be described below with reference to FIGS. 6 and 7.

[0056] Fig. 6 is a diagram showing an example of correction of the color temperature of a video signal. Fig. 7 is a diagram showing another example of correction of the color temperature of a video signal. (a), (b), and (c) of Fig. 6 respectively show a relationship diagram between the correction amount of the R component of the video signal and pixel luminance, a relationship diagram between the correction amount of the G component of the video signal and pixel luminance, and a relationship diagram between the B component of the video signal and pixel luminance. (a), (b), and (c) of Fig. 7 are similar.

[0057] First, we will explain how to correct the color temperature of a video signal by adjusting the correction amounts of each of the R, G, and B components of the video signal. For example, by correcting the R component so that it is relatively smaller than the G and B components, it is possible to increase the color temperature of the video signal. Also, for example, by correcting the B component so that it is relatively smaller than the R and G components, it is possible to lower the color temperature of the video signal.

[0058] 6 and 7 show relationships to be referenced when correcting the color temperature of a video signal so as to cancel out the color temperature of ambient light, that is, when determining the sub-correction amount.

[0059] 6 shows a case where the ambient light is reddish, that is, where the R component of the ambient light is relatively large. As shown in FIG. 6, when the R component of the ambient light is relatively large, that is, when the color temperature of the ambient light is lower than the reference color temperature, the CPU 231 determines a sub-correction amount that cancels out the color temperature of the ambient light by increasing the correction amount of each of the G component and the B component.

[0060] 7 shows a case where the ambient light is bluish, that is, where the B component of the ambient light is relatively large. As shown in Fig. 7, when the B component of the ambient light is relatively large, that is, when the color temperature of the ambient light is higher than the reference color temperature, the CPU 231 determines a sub-correction amount that cancels out the color temperature of the ambient light by increasing the correction amount of each of the R component and the G component.

[0061] In this embodiment, the magnitude of each correction amount for the R, G, and B components changes depending on the magnitude of the correction coefficient, i.e., the illuminance of the ambient light. Specifically, when the illuminance of the ambient light is high, i.e., the correction coefficient is high, the CPU 231 increases the correction amount for each of the R, G, and B components. On the other hand, when the illuminance of the ambient light is low, i.e., the correction coefficient is small, the CPU 231 decreases the correction amount for each of the R, G, and B components.

[0062] FIG. 8 illustrates the correlation between the correction amount of the color temperature of the video signal and pixel luminance. Note that FIG. 8 illustrates a case where the illuminance of the ambient light is relatively high, equal to or greater than the illuminance threshold Th1. (a) of FIG. 8 illustrates the correlation between the correction amount A of the color temperature of the video signal calculated in step S104 and pixel luminance, with the vertical axis representing the correction amount A and the horizontal axis representing the pixel luminance. As shown in (a) of FIG. 8, the correction amount A calculated in step S104 is constant regardless of pixel luminance. Furthermore, when the color temperature of the ambient light is higher than the reference color temperature, the correction amount A is a positive value, as indicated by the white arrow, to correct the color temperature of the video signal to follow the color temperature of the ambient light. On the other hand, when the color temperature of the ambient light is lower than the reference color temperature, the correction amount A is a negative value, as indicated by the black arrow, to correct the color temperature of the video signal to follow the color temperature of the ambient light.

[0063] FIG. 8B is a diagram showing the correlation between the sub-correction amount calculated in step S105 and pixel luminance, with the vertical axis representing the sub-correction amount and the horizontal axis representing pixel luminance. As shown in FIG. 8B, the sub-correction amount is constant at zero when the pixel luminance is equal to or greater than the luminance threshold Th3. On the other hand, when the pixel luminance is below the luminance threshold Th3, the sub-correction amount assumes a value corresponding to the color temperature of the ambient light and the pixel luminance. Specifically, when the color temperature of the ambient light is higher than the reference color temperature, the sub-correction amount assumes a negative value, as indicated by the black arrow, to correct the color temperature of the video signal to offset the color temperature of the ambient light. On the other hand, when the color temperature of the ambient light is lower than the reference color temperature, the sub-correction amount assumes a positive value, as indicated by the white arrow, to correct the color temperature of the video signal to offset the color temperature of the ambient light.

[0064] 8C is a diagram showing the correlation between pixel luminance and correction amount B, which is obtained by adding the sub-correction amount calculated in step S105 to correction amount A of the color temperature of the video signal calculated in step S104, where the vertical axis represents correction amount B and the horizontal axis represents pixel luminance. As shown in FIG. 8C, when pixel luminance is equal to or greater than brightness threshold value Th3, correction amount B is constant. On the other hand, when pixel luminance is below brightness threshold value Th3, the absolute value of correction amount B is reduced according to the added sub-correction amount.

[0065] Specifically, when the color temperature of the ambient light is higher than the reference color temperature, the correction amount B is a positive value (see the white arrow on the right), but when the pixel luminance falls below the luminance threshold Th3, its absolute value is reduced according to the sub-correction amount (see the black arrow on the left).Furthermore, when the color temperature of the ambient light is lower than the reference color temperature, the correction amount B is a negative value (see the black arrow on the right), but when the pixel luminance falls below the luminance threshold Th3, its absolute value is reduced according to the sub-correction amount (see the white arrow on the left).

[0066] [4. Effects, etc.] Advantages of the video processing system 2 according to the embodiment will be described below with reference to FIG. 9 . FIG. 9 is an explanatory diagram of the advantages of the video processing system 2 according to the embodiment. FIG. 9 is a diagram showing the correlation between the color temperature and pixel luminance of an image displayed on the display panel 10 and viewed by a user, with the vertical axis representing color temperature and the horizontal axis representing pixel luminance. The color temperature of the image is influenced by the color temperature of the ambient light. Furthermore, in the region of FIG. 9 where the pixel luminance is equal to or less than the luminance threshold Th3, the two dotted lines, one above the other, represent a case where the color temperature of the video signal is corrected based only on the color temperature correction amount A of the video signal calculated in step S104. Meanwhile, in this region, the solid line represents a case where the color temperature of the video signal is corrected using a correction amount B obtained by adding the sub-correction amount calculated in step S105 to the color temperature correction amount A of the video signal calculated in step S104.

[0067] As shown in Fig. 9 , if the color temperature of the video signal is corrected based solely on the correction amount A of the video signal color temperature calculated in step S104, the color temperature will be over-corrected in areas where the pixel luminance is equal to or less than the luminance threshold Th3, i.e., areas showing relatively dark gradations. In the example shown in Fig. 9 , if the ambient light is bluish, i.e., the color temperature of the ambient light is relatively high, the color temperature will be high in areas showing relatively dark gradations, as indicated by the upper dotted line, and a bluish color will appear on the display panel 10. This is because areas with low pixel luminance are more strongly affected by the color temperature of the ambient light, and if the color temperature of the ambient light is high, the color temperature of those areas will appear high. If a correction based on the ambient light (i.e., a correction that increases the color temperature when the color temperature of the ambient light is high) is performed in these areas as well as in areas with high pixel luminance, the color temperature will be too high. Furthermore, if the ambient light is reddish, that is, if the color temperature of the ambient light is lower than the reference color temperature, the color temperature will be lower in areas showing relatively dark gradations, as indicated by the lower dotted line, and a reddish color will appear on the display panel 10. As described above, areas with low pixel luminance are more strongly affected by the color temperature of the ambient light, so if the color temperature of the ambient light is low, the color temperature of those areas will appear low. If a correction based on the ambient light is made there (a correction that lowers the color temperature when the color temperature of the ambient light is low) in the same way as in areas with high pixel luminance, the color temperature will become too low.

[0068] In contrast, the image processing system 2 according to the embodiment not only performs a first correction calculation process to calculate a correction amount for the color temperature of the image signal so as to follow the color temperature of the ambient light, as described above, but also performs a second correction calculation process to reduce the absolute value of the correction amount in accordance with the pixel luminance of the image signal to cancel out the color temperature of the ambient light. In the example shown in FIG. 9 , when the ambient light is bluish, i.e., when the color temperature of the ambient light is relatively high, the absolute value of the correction amount for the color temperature of the image signal is reduced in areas showing relatively dark gradations, as indicated by the black arrows. As a result, the color temperature of the image displayed on the display panel 10 remains roughly constant regardless of the pixel luminance, and bluish colors are less likely to appear on the display panel 10. On the other hand, when the ambient light is reddish, i.e., when the color temperature of the ambient light is relatively low, the absolute value of the correction amount for the color temperature of the image signal is reduced in areas showing relatively dark gradations, as indicated by the white arrows. As a result, the color temperature of the image displayed on the display panel 10 remains roughly constant regardless of the pixel luminance, and reddish colors are less likely to appear on the display panel 10.

[0069] In this way, the video processing system 2 according to the embodiment corrects the color temperature of the video signal to follow the color temperature of the ambient light, and reduces the absolute value of the correction amount according to the pixel luminance of the video signal to cancel out the color temperature of the ambient light. Therefore, the video processing system 2 according to the embodiment is less likely to over-correct the color temperature of the video signal in areas showing relatively dark gradations, which has the advantage of making it easier to accurately correct the color temperature of the video displayed on the display panel 10 of the display 1.

[0070] 5. Other Embodiments Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments.

[0071] In the above embodiment, the image processing system 2 acquires illuminance information and color temperature information by performing calculations based on the RGB information output by the RGB sensor 3, but this is not limiting. For example, the image processing system 2 may acquire illuminance information by acquiring illuminance information output by an image sensor installed around the display 1. The image sensor may be configured, for example, with a CMOS (Complementary Metal-Oxide Semiconductor) sensor. In this way, a device that detects the illuminance of ambient light and a device that detects the color temperature of ambient light may be separate devices.

[0072] In the above embodiment, the image processing system 2 adjusts the sub-correction amount by referring to illuminance information indicating the illuminance of ambient light, but this is not limited to this. For example, the image processing system 2 may adjust the sub-correction amount by referring only to color temperature information indicating the color temperature of ambient light. In this case, steps S201 to S203 in the flowchart shown in FIG. 4 are unnecessary. In this case, the sub-correction amount becomes equal to the correction amount C in step S207.

[0073] In the above embodiment, the video processing system 2 corrects the color temperature of the video signal by correcting the RGB values ​​of the video signal, but this is not limiting. For example, if the video signal is a YCbCr signal, the video processing system 2 may correct the color temperature of the video signal by correcting the YCbCr values ​​of the video signal.

[0074] In the above embodiment, the video processing system 2 includes the video processing circuit 233, but is not limited to this. That is, the video processing system 2 only needs to include the first input I / F 21, the second input I / F 22, and the CPU 231 (processor).

[0075] In the above embodiment, the video processing system 2 is realized by a single device, but may be realized by multiple devices. When the video processing system 2 is realized by multiple devices, the functional components of the video processing system 2 may be distributed among the multiple devices in any manner.

[0076] Furthermore, the communication method between the devices in the above-described embodiments is not particularly limited. When two devices communicate with each other in the above-described embodiments, a relay device (not shown) may be interposed between the two devices.

[0077] The order of the processes described in the above embodiments is merely an example. The order of multiple processes may be changed, or multiple processes may be executed in parallel. Furthermore, a process executed by a specific processing unit may be executed by another processing unit. Furthermore, part of the digital signal processing described in the above embodiments may be realized by analog signal processing.

[0078] In the above-described embodiments, each component may be realized by executing a software program suitable for that component, or by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0079] Furthermore, each component may be realized by hardware. For example, each component may be a circuit (or integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Furthermore, each of these circuits may be a general-purpose circuit or a dedicated circuit.

[0080] Furthermore, general or specific aspects of the present disclosure may be realized as a system, device, method, integrated circuit, computer program, or computer-readable recording medium such as a CD-ROM. Also, they may be realized as any combination of a system, device, method, integrated circuit, computer program, and recording medium. For example, the present disclosure may be implemented as a video processing method executed by a computer, or as a program for causing a computer to execute such a video processing method. Also, the present disclosure may be realized as a computer-readable non-transitory recording medium on which such a program is recorded. Note that the program here includes an application program for causing a general-purpose information terminal to function as the video processing system of the above-described embodiment.

[0081] In addition, this disclosure also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the intent of this disclosure.

[0082] (Summary) As described above, the video processing system 2 according to the first aspect includes the first input I / F 21, the second input I / F 22, and the CPU 231. The CPU 231 is an example of a processor. The first input I / F 21 acquires a video signal to be output to the display panel 10 of the display 1. The second input I / F 22 acquires color temperature information indicating the color temperature of ambient light irradiated onto the display panel 10. The CPU 231 calculates a correction amount for the color temperature of the video signal so as to follow the color temperature of the ambient light. When the pixel luminance of the video signal is below a luminance threshold, the CPU 231 reduces the absolute value of the correction amount for the color temperature of the video signal so as to cancel out the color temperature of the ambient light. The CPU 231 outputs a video signal whose color temperature has been corrected according to the correction amount.

[0083] This has the advantage that the color temperature of the video signal is less likely to be over-corrected in areas showing relatively dark gradations, making it easier to accurately correct the color temperature of the video displayed on the display panel 10 of the display 1.

[0084] In the video processing system 2 according to the second aspect, the CPU 231 further acquires illuminance information indicating the illuminance of ambient light in the first aspect. When the pixel luminance of the video signal is lower than the luminance threshold value Th3, the CPU 231 adjusts the correction amount further based on the illuminance of ambient light.

[0085] This has the advantage that it becomes easier to correct the color temperature of the video with higher accuracy compared to when the illuminance of the ambient light is not referenced.

[0086] In addition, in the video processing system 2 relating to the third aspect, in the second aspect, the CPU 231 increases the absolute value of the correction amount as the illuminance of the ambient light becomes greater than the illuminance threshold value Th1 until the illuminance of the ambient light reaches the predetermined illuminance value Th10, and once the illuminance of the ambient light reaches the predetermined illuminance value Th10, the CPU 231 no longer increases the absolute value of the correction amount.

[0087] This has the advantage that excessive correction of the color temperature according to the illuminance of the ambient light is prevented, making it easier to correct the color temperature of the image with greater accuracy.

[0088] Furthermore, in the video processing system 2 relating to the fourth aspect, in any one of the first to third aspects, the CPU 231 increases the absolute value of the correction amount as the color temperature of the ambient light deviates from the predetermined range R1 until the color temperature of the ambient light reaches the predetermined color value Th210 (or Th220), and once the color temperature of the ambient light reaches the predetermined color value Th210 (or Th220), the CPU 231 no longer increases the absolute value of the correction amount.

[0089] This has the advantage that excessive correction of the color temperature according to the color temperature of the ambient light is suppressed, making it easier to correct the color temperature of the image with greater accuracy.

[0090] In addition, in the video processing system 2 according to a fifth aspect, in any one of the first to fourth aspects, the video signal is an RGB signal. The CPU 231 corrects the color temperature of the video signal by correcting the RGB values ​​of the video signal.

[0091] This has the advantage that the color temperature of the video signal is corrected by a simple method of correcting the RGB values, making it easy to carry out the correction process for the color temperature of the video signal.

[0092] Furthermore, in the video processing method according to the sixth aspect, a video signal to be output to the display panel 10 of the display 1 is obtained (S101), color temperature information indicating the color temperature of the ambient light irradiated onto the display panel 10 is obtained (S103), a correction amount for the color temperature of the video signal is calculated so as to follow the color temperature of the ambient light (S105), and if the pixel luminance of the video signal is below the luminance threshold value (S106: Yes), the absolute value of the correction amount for the color temperature of the video signal is reduced so as to cancel out the color temperature of the ambient light (S108), and a video signal in which the color temperature of the video signal has been corrected according to the correction amount is output (S111).

[0093] This has the advantage that the color temperature of the video signal is less likely to be over-corrected in areas showing relatively dark gradations, making it easier to accurately correct the color temperature of the video displayed on the display panel 10 of the display 1.

[0094] A program according to a seventh aspect causes one or more processors to execute the video processing method according to the sixth aspect.

[0095] This has the advantage that the color temperature of the video signal is less likely to be over-corrected in areas showing relatively dark gradations, making it easier to accurately correct the color temperature of the video displayed on the display panel 10 of the display 1.

[0096] The image processing system and the like of the present disclosure can be applied to a system that processes images displayed on a display panel of a display.

[0097] REFERENCE SIGNS LIST 1 Display 10 Display panel 2 Image processing system 21 First input I / F 22 Second input I / F 23 SoC 231 CPU 232 Memory 233 Image processing circuit 3 RGB sensor A1, A2, A3 Arrows G1, G2 Area R1 Predetermined range Th1 Illuminance threshold Th10 Illuminance predetermined value Th210, Th220 Color predetermined value Th21 First color threshold Th22 Second color threshold Th3 Brightness threshold

Claims

1. A first input interface for acquiring a video signal output to a display panel of a display; A second input interface for acquiring color temperature information indicating the color temperature of ambient light irradiated onto the display panel; A processor; and The processor: Calculates a correction amount for the color temperature of the video signal so as to follow the color temperature of the ambient light; When the pixel luminance of the video signal is below a luminance threshold, reduces the absolute value of the correction amount so as to cancel out the color temperature of the ambient light based on the pixel luminance of the video signal; Outputs the video signal with the color temperature of the video signal corrected according to the correction amount. A video processing system.

2. The processor: Further acquires illuminance information indicating the illuminance of the ambient light; When the pixel luminance of the video signal is below the luminance threshold, adjusts the correction amount further based on the illuminance of the ambient light. The video processing system according to claim 1.

3. Until the illuminance of the ambient light reaches a predetermined illuminance value, the processor increases the absolute value of the correction amount as the illuminance of the ambient light becomes greater than an illuminance threshold, and when the illuminance of the ambient light reaches the predetermined illuminance value, thereafter, does not increase the absolute value of the correction amount. The video processing system according to claim 2.

4. Until the color temperature of the ambient light reaches a predetermined color value, the processor increases the absolute value of the correction amount as the color temperature of the ambient light deviates from a predetermined range, and when the color temperature of the ambient light reaches the predetermined color value, thereafter, does not increase the absolute value of the correction amount. The video processing system according to any one of claims 1 to 3.

5. The video signal is an RGB signal, and The processor corrects the color temperature of the video signal by correcting the RGB values in the video signal. The video processing system according to any one of claims 1 to 3.

6. Acquire a video signal output to a display panel of a display; Acquire color temperature information indicating the color temperature of ambient light irradiated onto the display panel; Calculate a correction amount for the color temperature of the video signal so as to follow the color temperature of the ambient light; When the pixel luminance of the video signal is below a luminance threshold, reduce the absolute value of the correction amount so as to cancel out the color temperature of the ambient light based on the pixel luminance of the video signal; Output the video signal with the color temperature of the video signal corrected according to the correction amount. A video processing method.

7. Causing one or more processors to Execute the video processing method according to claim 6. Program.