Signal processing device, signal processing method, and program

Abstract

This signal processing device comprises a correction value derivation unit that derives a correction value used in color correction processing for correcting the colors of an image displayed on a display panel comprising light-emitting elements serving as light sources for display. The derivation is based on temperature information that indicates the temperature of the display panel, and screen luminance information that indicates the screen luminance value of the display panel.

Description

Signal processing device, signal processing method, and program

[0001] The present technology relates to a signal processing device, a signal processing method, and a program, and in particular to a technical field related to color correction of a displayed image.

[0002] For example, it is known that light-emitting elements used as light sources for display in display devices, such as LEDs (Light Emitting Diodes) and OLEDs (Organic LEDs), emit light with varying colors depending on temperature, and therefore the color (color temperature) of an image displayed on a display device using such light-emitting elements may vary depending on temperature.

[0003] Patent Document 1 listed below discloses a technology for correcting temperature-dependent color changes in a displayed image in an LCD (Liquid Crystal Display) that uses LEDs as a backlight source by adjusting the gain of each of the R, G, and B LEDs according to the temperature.

[0004] JP 2010-72281 A

[0005] However, the cause of color change in light-emitting elements used as light sources for display is not limited to temperature, and color change can also occur due to factors other than temperature.

[0006] The present technology has been made in view of the above circumstances, and aims to improve the accuracy of correction of color changes in a display image on a display panel having light-emitting elements as a light source for display.

[0007] A signal processing device according to the present technology includes a correction value derivation unit that derives a correction value used in a color correction process for correcting the color of an image displayed on a display panel, based on temperature information indicating the temperature of the display panel including light-emitting elements as a display light source and screen luminance information indicating the screen luminance of the display panel. When the screen luminance changes, the amount of color change corresponding to the temperature also changes. Therefore, the correction value for correcting the temperature-dependent color change is derived based on the screen luminance information as well as the temperature information of the display panel, as described above. This makes it possible to achieve color correction that can absorb changes in the amount of color change corresponding to the screen luminance.

[0008] 10 is a block diagram showing an example of a configuration of a signal processing device as an embodiment according to the present technology. FIG. 11 is a diagram showing an example of a menu screen for adjusting screen brightness. FIG. 12 is a block diagram showing an example of a configuration of a display control unit and a display unit included in a signal processing device as an embodiment. FIG. 13 is a diagram showing an example of imparting a delay characteristic corresponding to a temperature rise. FIG. 14 is a diagram showing an example of imparting a delay characteristic corresponding to a temperature drop. FIG. 15 is an explanatory diagram of a hysteresis characteristic realized by imparting a delay characteristic as an embodiment. FIG. 16 is a diagram showing an example of correspondence information based on table information. FIG. 17 is a diagram showing a graph of B gain values ​​stored in the table information. FIG. 18 is a diagram showing a graph of R gain values ​​stored in the table information. FIG. 19 is a flowchart showing an example of specific processing procedures to be executed in order to realize color correction as an embodiment. FIG. 19 is a flowchart showing an example of specific processing procedures to be executed in order to realize color correction as an embodiment, together with FIG. 10 . FIG. 19 is an explanatory diagram of components when a correction value derivation unit is configured by a microcomputer. FIG. 19 is a diagram for explaining an example of a configuration of a signal processing device as a first modified example. FIG. 19 is a diagram for explaining the relationship between a luminance histogram and image brightness. FIG. 20 is a block diagram showing an example of a configuration of a signal processing device as a second modified example.

[0009] Hereinafter, with reference to the accompanying drawings, embodiments of the present technology will be described in the following order: <1. Configuration example of signal processing device> <2. Color correction as an embodiment> <3. Processing procedure> <4. Modification example> <5. Summary of embodiment> <6. Present technology>

[0010] 1 is a block diagram showing a configuration example of a signal processing device 1 according to an embodiment of the present technology. In the embodiment, the signal processing device 1 is configured as an imaging device including an image sensor.

[0011] As shown in the figure, the signal processing device 1 includes an image sensor 2, an image signal processing unit 3, a camera control unit 4, a memory unit 5, a display control unit 6, a display unit 7, and an operation unit 8. In the signal processing device 1 as an imaging device, the camera control unit 4 performs overall control of the signal processing device 1. The camera control unit 4 is configured with a microcomputer having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes processing in accordance with a program stored in the ROM to perform various controls and arithmetic processing.

[0012] As shown in the figure, the camera control unit 4 is connected to the image sensor 2, image signal processing unit 3, camera control unit 4, memory unit 5, and display control unit 6 via a bus 9, and is capable of data communication between these units.

[0013] The imaging element 2 is configured as an image sensor (solid-state imaging element), such as a CMOS (Complementary Metal Oxide Semiconductor) type or a CCD (Charge Coupled Device) type. The imaging element 2 has a pixel array section in which pixels, each having a light-receiving element such as a photodetector, are arranged two-dimensionally. This pixel array section receives light from a subject that is incident via an imaging optical system (not shown) to obtain a captured image of the subject. Specifically, the imaging element 2 performs, for example, CDS (Correlated Double Sampling) processing, AGC (Automatic Gain Control) processing, etc. on the light-receiving signal obtained for each pixel in the pixel array section, and further performs A / D (Analog to Digital) conversion processing to obtain a captured image as digital data. The captured image obtained by the imaging element 2 is output to the image signal processing unit 3.

[0014] The image signal processing unit 3 is configured, for example, by a DSP (Digital Signal Processor) and performs various types of image signal processing on the captured image input from the imaging element 2. In this example, the image signal processing unit 3 performs file creation processing on the captured image from the imaging element 2. The file creation processing generates files for recording and communication by performing compression encoding for recording and communication, formatting, and generating and adding metadata. For example, image files in formats such as JPEG (Joint Photographic Experts Group), TIFF (Tagged Image File Format), and GIF (Graphics Interchange Format) are generated as still image files. It is also possible to generate image files in formats such as MP4, which is used for recording moving picture and audio compliant with MPEG-4 (Moving Picture Experts Group).

[0015] The image signal processing unit 3 also generates a through image based on the captured image from the image sensor 2. The through image means a captured image that is displayed on an image display unit such as the display unit 7 to show the user the state of the subject being captured, and can also be called a live view image.

[0016] The image signal processing unit 3 is capable of outputting the image files generated in the file formation process described above and the captured images as through images via the bus 9. For example, the image files can be output to the memory unit 5 based on instructions from the camera control unit 4. This makes it possible to record the captured images that have been converted into image files in the memory unit 5. Furthermore, the captured images as through images can be output to the display control unit 6 based on instructions from the camera control unit 4. This makes it possible to display the captured images as through images on the display unit 7.

[0017] The memory unit 5 represents a storage device used to record image files, and is configured, for example, as a recording medium such as a flash memory built into the signal processing device 1 and a write / read circuit for the same. Alternatively, the memory unit 5 may be configured as a card recording / playback unit that performs recording / playback access to a recording medium that can be attached to or detached from the signal processing device 1, such as a memory card (portable flash memory, etc.). When the memory unit 5 is configured with a recording medium built into the signal processing device 1, data (including programs) used by the camera control unit 4 for various controls may also be stored in the memory unit 5.

[0018] The display unit 7 is a display device for presenting various types of information to the user, and has a display panel (display panel 71 described later) capable of displaying images. In the signal processing device 1 serving as an imaging device, the display unit 7 can be in the form of an EVF (Electronic View Finder) or a so-called rear monitor. The rear monitor can be a display panel with a larger screen size than the EVF, which is integrally provided with the housing of the signal processing device 1, or a display panel with an adjustable orientation. In the display unit 7, the display panel capable of displaying images can be, for example, a liquid crystal display (LCD) panel or an organic electroluminescence (EL) panel.

[0019] In this embodiment, the display unit 7 is configured as an EVF.

[0020] The display control unit 6 performs processing to display an image on the display unit 7 based on an instruction from the camera control unit 4. For example, based on an instruction from the camera control unit 4, the display control unit 6 displays a reproduced image of an image file stored in the memory unit 5 on the display unit 7, or the above-mentioned through image on the display unit 7. Furthermore, based on an instruction from the camera control unit 4, the display control unit 6 displays various operation menus, icons, messages, etc., i.e., images as a GUI (Graphical User Interface), on the display unit 7. The internal configuration of the display control unit 6 in this embodiment will be described again later.

[0021] The operation unit 8 collectively represents input devices for the user to input various operations. Specifically, the operation unit 8 represents various operators, a touch panel, a touch pad, etc. provided on the housing of the signal processing device 1. The touch panel may be formed on the display screen of the rear panel described above. In this case, some touch panels are capable of detecting a touch position on the display screen (a position where a touch operation is performed). The operation unit 8 detects a user operation, and a signal corresponding to the input operation is sent to the camera control unit 4.

[0022] The camera control unit 4 executes various processes in response to operations detected by the operation unit 8. For example, the camera control unit 4 executes processes for capturing an image, recording an image, and playing or displaying a recorded image file in response to operations detected by the operation unit 8. The camera control unit 4 also executes processes for displaying the above-described through image or GUI in response to operations detected by the operation unit 8.

[0023] Here, the camera control unit 4 in this embodiment has a screen brightness adjustment function Fa. The screen brightness adjustment function Fa is a function for adjusting the screen brightness of the display unit 7. The screen brightness means the overall brightness (brightness) of the display screen.

[0024] In this embodiment, the screen brightness adjustment function Fa adjusts the screen brightness in either an automatic mode or a manual mode. The automatic mode or manual mode can be selected using a menu screen, such as the one shown in FIG. 2. This menu screen is displayed on the display unit 7.

[0025] In the figure, "Screen Brightness" corresponds to the item of screen luminance, and the user can select between manual, shown in the figure, and auto, not shown, by operation. If manual is selected, the user can select any screen luminance value from multiple screen luminance values. Specifically, in this example, five screen luminance value candidates are provided, and the user can select one screen luminance value from these five screen luminance value candidates via a menu screen. In this example, the screen luminance value is a value representing the display luminance when the gradation value of the display image signal is set to the maximum value (e.g., 256 in the case of 256 gradations).

[0026] When auto is selected, a screen luminance value corresponding to the brightness of the ambient light of the signal processing device 1 is automatically selected. In the auto mode of this example, one screen luminance value corresponding to the brightness of the ambient light is selected from among the candidate screen luminance values ​​selectable in manual mode. Specifically, in this example, one screen luminance value corresponding to the brightness of the ambient light is selected from the five candidate screen luminance values ​​described above.

[0027] In the manual mode, the camera control unit 4 instructs the display control unit 6 to use a screen brightness value selected by the user, causing the display control unit 6 to set the screen brightness of the display unit 7 to a screen brightness corresponding to the user's selection operation. In the auto mode, the camera control unit 4 selects a screen brightness value corresponding to the brightness of the ambient light estimated based on the image captured by the image sensor 2, and instructs the display control unit 6 to use the selected screen brightness value, causing the display control unit 6 to set the screen brightness of the display unit 7 to a screen brightness corresponding to the brightness of the ambient light.

[0028] Although the above example gives an example of estimating the brightness of ambient light based on the captured image, it is also possible to obtain information on the brightness of ambient light by, for example, detecting it using a sensor provided separately from the image sensor 2, and the specific acquisition method is not particularly limited.

[0029] 3 is a block diagram showing an example of the configuration of the display control unit 6 and the display unit 7. As shown in the figure, the display control unit 6 has an image generation and adjustment unit 61 and an image output unit 62, and the display unit 7 has a display panel 71. Note that the display unit 7 has a temperature sensor 72 in addition to the display panel 71, and the display control unit 6 has a correction value derivation unit 63 and an A / D converter 64 in addition to the image generation and adjustment unit 61 and the image output unit 62; however, the temperature sensor 72, correction value derivation unit 63, and A / D converter 64 will be described again later.

[0030] In the display control unit 6, the image generation and adjustment unit 61 is composed of, for example, a DSP, and performs various adjustment processes for generating the display image for the display unit 7 and the display image based on instructions from the camera control unit 4 shown in Fig. 1. For example, when a playback image of an image file stored in the memory unit 5 is to be displayed, the display control unit 6 generates a display image based on the playback image based on instructions from the camera control unit 4, and when a through image is to be displayed, the display control unit 6 generates a display image based on the through image based on instructions from the camera control unit 4.

[0031] The image generation and adjustment unit 61 is also configured to be able to perform the above-mentioned screen brightness adjustment process and WB (white balance) adjustment (correction) process as display image adjustment processes. As the screen brightness adjustment process, gain adjustment of the brightness value of the display image is performed based on the screen brightness value instructed by the camera control unit 4. As for WB adjustment, gain adjustment is performed for at least one of the brightness values ​​of R (red), G (green), and B (blue) of the display image.

[0032] The image output unit 62 outputs the display image input from the image generation and adjustment unit 61 to the display unit 7 using a transmission method in accordance with a predetermined data transmission standard. In this example, the image output unit 62 outputs the display image to the display unit 7 using an LDVS (Low Voltage Differential Signaling) method.

[0033] In the display unit 7, the display image output from the image output unit 62 is displayed on the display panel 71. In this example, an organic EL panel is used as the display panel 71. OLEDs (Organic Light Emitting Diodes) are used as the light source for display of the display panel 71, i.e., the light-emitting elements. Specifically, in this case, the display panel 71 is formed by a two-dimensional array of pixels having OLEDs of each color of R, G, and B.

[0034] 2. Color Correction as an Embodiment As described above, it is known that the light-emitting elements used as display light sources change their emitted color depending on temperature, and as a result, the color of the displayed image (color temperature) changes depending on temperature. In particular, when OLEDs are used as light-emitting elements, as in the display panel 71 of this example, such temperature-dependent color changes in the displayed image tend to occur easily.

[0035] Here, experiments by the present inventors have revealed that the amount of temperature-dependent color change in a displayed image changes in accordance with changes in the screen luminance of the display panel 71. Therefore, in this embodiment, a method is adopted in which color correction of a displayed image is performed taking into consideration not only the temperature of the display panel 71 but also the screen luminance.

[0036] The signal processing device 1 is configured to achieve such color correction by including a temperature sensor 72, an A / D converter 64, and a correction value derivation unit 63, as shown in FIG. 3 . The temperature sensor 72 is provided in the display unit 7 and outputs a signal indicating the temperature as a sensor temperature signal. In the display unit 7 of this example, the temperature sensor 72 is disposed outside the display panel 71 and detects the temperature of the display panel 71 indirectly rather than directly. That is, an error occurs between the temperature detected by the temperature sensor 72 and the actual temperature of the display panel 71 depending on the distance between the display panel 71 and the temperature sensor 72.

[0037] It is not essential that the temperature sensor 72 be disposed outside the display panel 71 , and it is of course possible to provide it inside the display panel 71 .

[0038] In this example, the temperature sensor 72 is a thermistor, and outputs a sensor temperature signal in the form of an analog signal.

[0039] In the display control unit 6, the A / D converter 64 obtains sensor temperature information in the form of a digital value by performing A / D conversion (i.e., digital sampling) on ​​the sensor temperature signal input from the temperature sensor 72. The sensor temperature information obtained by the A / D converter 64 is input to the correction value derivation unit 63.

[0040] The correction value derivation unit 63 derives a correction value used in a color correction process for correcting the color of an image displayed on the display panel 71, based on temperature information indicating the temperature of the display panel 71 and screen luminance information indicating the value of the screen luminance of the display panel 71. In this example, the screen luminance value of the display panel 71 is a value instructed to the image generation / adjustment unit 61 by the camera control unit 4 shown in FIG. 1 and input to the correction value derivation unit 63 via the image generation / adjustment unit 61.

[0041] In this example, the correction value derivation unit 63 performs a process of offsetting the temperature value detected by the temperature sensor 72 in response to the fact that the temperature sensor 72 is provided outside the display panel 71 as described above. Specifically, the correction value derivation unit 63 adds an offset value to the temperature value indicated by the sensor temperature information to cancel out an error corresponding to the distance between the display panel 71 and the temperature sensor 72. By adding such an offset, it becomes possible to obtain temperature information indicating the temperature of the display panel 71 even when the temperature sensor 72 cannot be installed inside the display panel 71 and the temperature of the display panel 71 cannot be directly detected.

[0042] Hereinafter, the temperature obtained by applying the offset will be referred to as the “detected temperature” since it can be used as the detected temperature of the display panel 71 .

[0043] In this embodiment, the correction value derivation unit 63 performs a delay process to delay the change in the correction value in response to a change in the temperature of the display panel 71. The "delay" here means that, when the rate of "change in the correction value in response to a change in temperature" is defined as a "reference rate" when the correction value corresponding to the temperature is used as is for correction, the rate of "change in the correction value in response to a change in temperature" is made slower than the "reference rate."

[0044] In this embodiment, such a "delay" is performed using the following two methods: The first delay method is a method of adding a delay characteristic to the temperature information, and the second delay method is a method of limiting the range of change in the correction value to a predetermined value.

[0045] In this example, the correction value derivation unit 63 performs processing to impart hysteresis characteristics to the change in the correction value in response to a change in the temperature of the display panel 71. The hysteresis characteristics here mean that the relationship between the input value and the output value is made different on the increasing side and the decreasing side of the input value.

[0046] A specific example of the correction value derivation process as an embodiment, including the addition of the delay and hysteresis characteristics as described above, will be described below.

[0047] 4 to 6 are explanatory diagrams of the process of imparting a delay characteristic to the temperature information as the first delay method described above. In this example, the delay characteristic imparted to the temperature information is given a hysteresis characteristic, so that the change in the correction value in response to a change in the temperature of the display panel 71 also has a hysteresis characteristic.

[0048] In the following description, temperature values ​​are exemplified, but the units of the exemplified temperatures are assumed to be degrees Celsius. Furthermore, the detected temperature of the display panel 71 (which in this example is the temperature after the aforementioned offset is applied) is assumed to be detected in units of 0.1 degrees. In other words, the resolution of the detected temperature is in units of 0.1 degrees.

[0049] 4 and 5 are explanatory diagrams showing examples of applying a delay characteristic to the detected temperature, with Fig. 4 showing an example of applying a delay characteristic corresponding to a temperature rise, and Fig. 5 showing an example of applying a delay characteristic corresponding to a temperature drop. In Figs. 4 and 5, the horizontal axis represents the detected temperature, and the vertical axis represents the characteristic application temperature, which is the temperature after the delay characteristic is applied. In order to provide a hysteresis characteristic to the change in the correction value in response to a change in the temperature of the display panel 71, different processing is performed when the temperature rises and when the temperature drops in this example.

[0050] 4 shows the temperature delay characteristic for the increase in the detected temperature from 18.9° C. to 23.1° C. In this example, the delay characteristic is applied by updating the characteristic application temperature to a value associated with the temperature threshold each time the detected temperature reaches a temperature threshold set at a predetermined interval.

[0051] In this example, it is assumed that the minimum change width of the characteristic-imparting temperature is 2 degrees, that is, the resolution of the characteristic-imparting temperature is 2 degrees, and the temperature threshold is set at intervals of 2 degrees. Specifically, in this example, the temperature threshold is set to "characteristic-imparting temperature - 0.1 degrees."

[0052] As shown in the illustrated example, when the detected temperature rises above a temperature threshold of 18.9 degrees, 19 degrees, which corresponds to the 18.9 degree temperature threshold, is assigned as the characteristic-imparting temperature. Thereafter, in a region where the detected temperature is equal to or greater than 18.9 degrees but less than the next temperature threshold of 20.9 degrees, 19 degrees is maintained as the characteristic-imparting temperature. When the detected temperature reaches a temperature threshold of 20.9 degrees, 21 degrees, which corresponds to the 20.9 degree temperature threshold, is assigned as the characteristic-imparting temperature. In a region where the detected temperature is equal to or greater than 20.9 degrees but less than the next temperature threshold of 22.9 degrees, 21 degrees is maintained as the characteristic-imparting temperature. Furthermore, when the detected temperature reaches a temperature threshold of 22.9 degrees, 23 degrees, which corresponds to the 22.9 degree temperature threshold, is assigned as the characteristic-imparting temperature. In a region where the detected temperature is equal to or greater than 22.9 degrees but less than the next temperature threshold of 24.9 degrees (not shown), 23 degrees is maintained as the characteristic-imparting temperature.

[0053] In this way, the process of assigning a delay characteristic to the detected temperature is carried out by updating the characteristic-assigning temperature to a value corresponding to the temperature threshold each time the detected temperature reaches the temperature threshold, and maintaining the characteristic-assigning temperature at the updated value until just before the detected temperature reaches the next temperature threshold (that is, in this example, until it reaches the next temperature threshold -0.1 degrees).

[0054] Similarly, when the detected temperature decreases, a delay characteristic is applied to the detected temperature using a temperature threshold. In the example shown in FIG. 5 , when the detected temperature starts increasing and then decreasing from a state in which the characteristic-applying temperature is 25°C and falls below the temperature threshold of 22.9°C, the characteristic-applying temperature is updated to 23°C, which is the characteristic-applying temperature associated with the temperature threshold of 22.9°C. Then, in a region where the detected temperature is below 22.9°C and higher than the next temperature threshold of 20.9°C, 23°C is maintained as the characteristic-applying temperature. Thereafter, when the detected temperature falls below the temperature threshold of 20.9°C, 21°C, which is associated with the 20.9°C temperature threshold, is assigned as the characteristic-applying temperature. In a region where the detected temperature is below 20.9°C and lower than the next temperature threshold of 18.9°C, 21°C is maintained as the characteristic-applying temperature. Furthermore, when the detected temperature falls below the temperature threshold of 18.9 degrees, 19 degrees, which corresponds to the temperature threshold of 18.9 degrees, is assigned as the characteristic-imparting temperature, and in the region where the detected temperature is below 18.9 degrees and below the next temperature threshold of 16.9 degrees (not shown), 19 degrees is maintained as the characteristic-imparting temperature.

[0055] By carrying out the above-described process of imparting a delay characteristic, the characteristic-imparting temperature is given a hysteresis characteristic in which the value changes differently with respect to the detected temperature when the detected temperature rises and when the detected temperature falls, as shown in FIG. 6 as an example.

[0056] In the above, as an example for the purpose of explanation, an example was given in which the resolution of the characteristic-imparting temperature is 2 degrees, but this is merely an example, and other resolutions such as 1 degree or 3 degrees can also be used.

[0057] As described above, by applying a delay characteristic to the temperature information of the display panel 71, it is possible to apply a delay characteristic to the correction value derived based on the temperature information. This makes it possible to prevent the color of the displayed image from changing suddenly in response to a sudden change in temperature, making the color change of the displayed image due to the correction less noticeable, and realizing a more natural color correction that reduces the sense of incongruity.

[0058] Furthermore, by providing hysteresis characteristics to the temperature information as described above, it is possible to prevent the correction value from overly sensitively following temperature changes when the temperature changes from rising to falling, or from falling to rising, and thereby prevent noticeable color changes in the displayed image, thereby achieving more natural color correction.

[0059] In this example, the correction value derivation unit 63 derives the correction value using the characteristic-imparting temperature obtained by the delay characteristic imparting process described above, and at this time, the correction value is derived based on the correspondence information Ir that indicates the correspondence between the temperature of the display panel 71, the screen brightness value, and the target correction value for color correction.

[0060] In this example, color correction of the displayed image based on the temperature and screen brightness value of the display panel 71 is performed by adjusting the gains of the R, G, and B components of the displayed image, excluding the G component. The reason why the gain of the G component is not adjusted as part of the color correction is that adjusting the gain of the G component may make changes in the brightness of the displayed image more noticeable. Hereinafter, the gain of the R component will be referred to as "R gain" and the gain of the B component will be referred to as "B gain."

[0061] In this example, the correspondence relationship information Ir is table information such as that shown in Fig. 7. Specifically, this is table information in which R gain and B gain values ​​as target correction values ​​are associated with each combination of the temperature of the display panel 71 and the screen luminance value.

[0062] In this example, the table information serving as the correspondence information Ir includes information indicating target correction values ​​corresponding to each predetermined unit temperature. Specifically, the table information in this example is information indicating target correction values ​​corresponding to each unit temperature of 10 degrees, as shown in the figure. As a result, the table information stores target correction values ​​for each temperature at equal intervals. If the temperature intervals were not equal, it would be impossible to properly represent the correspondence between the temperature and the target correction value in areas where the temperature intervals are large, which could result in a decrease in the accuracy of color correction. However, by setting the temperature intervals to equal intervals as described above, it is possible to properly represent the correspondence between the temperature and the target correction value for the temperature range to be corrected, thereby improving the accuracy of color correction.

[0063] As described above, in this example, the screen luminance value is selected from five candidate values ​​in both manual mode and auto mode, so the table information is configured as information indicating the corresponding target correction value for each combination of these five candidate values ​​and each unit temperature, as shown in the figure. In the figure, the five candidate values ​​for the screen luminance value are 1000 cd / m ２ , 500 cd / m ２ , 200 cd / m ２ , 120 cd / m ２ , 50 cd / m ２ However, these are illustrative examples and are not limited to the numerical values ​​shown.

[0064] In addition, in the table information, the values ​​of the B gain and R gain as the target correction values ​​are exemplified as values ​​with 256 gradations, but this is merely an example, and the number of gradations (number of quantization bits) of the target correction values ​​is not limited to this.

[0065] In this example, the table information defines a range of 10 degrees to 60 degrees as the temperature of the display panel 71, and for the region where the temperature of the display panel 71 is 10 degrees or less and the region where the temperature is 60 degrees or more, the same value corresponding to each temperature is derived as the target correction value for the screen luminance value. Specifically, in the region where the temperature of the display panel 71 is 10 degrees or less, a target correction value corresponding to the corresponding screen luminance value is commonly derived from among the target correction values ​​for each screen luminance value associated with the unit temperature of "10 degrees or less" in the table information. Also, in the region where the temperature of the display panel 71 is 60 degrees or more, a target correction value corresponding to the corresponding screen luminance value is commonly derived from among the target correction values ​​for each screen luminance value associated with the unit temperature of "60 degrees or more" in the table information.

[0066] 8 and 9 show graphs of the B gain and R gain values ​​stored in the table information. Specifically, in these figures, the screen luminance value is 50 cd / m ２ 10 shows graphs of the B gain and R gain values ​​for each unit temperature associated with the temperature.

[0067] The B gain shown in Fig. 8 has a characteristic of increasing with increasing temperature, as a change characteristic with respect to the temperature of the display panel 71. In contrast, the R gain shown in Fig. 9 has a characteristic of increasing in some regions and decreasing in others, as a change characteristic with respect to the temperature of the display panel 71.

[0068] Although not graphed, the table information shown in FIG. 7 indicates that the B gain and R gain as target correction values ​​should be changed in response to changes in the screen luminance value. For example, for a unit temperature of 20 degrees, the R gain value is 200 cd / m ２ to 500 cd / m ２ For example, when the unit temperature is 50 degrees, the value of the B gain is 0x80 for the same screen luminance value of 200 cd / m ２ to 500 cd / m ２It can be seen that the value should be changed from "0x8C" to "0x88" in response to the change to "0x8C".

[0069] In this example, the temperature resolution of the table information as the correspondence relationship information Ir is set to a lower resolution than the temperature resolution of the temperature information of the display panel 71. Specifically, the temperature resolution of the temperature information of the display panel 71 in this example is set to 2 degree units because of the delay characteristic imparting process described above, whereas the temperature resolution of the table information is set to 10 degree units as described above. By setting the temperature resolution of the table information to a lower resolution, it is possible to reduce the data volume of the table information.

[0070] In response to the temperature resolution of the table information being set to low resolution in this way, the correction value derivation unit 63 of this example applies interpolation processing to derive a target correction value corresponding to the temperature information of the display panel 71. Specifically, the correction value derivation unit 63 of this example identifies two temperatures among the temperatures in the table information that have a relationship that includes the temperature indicated by the temperature information of the display panel 71 (the characteristic-applying temperature described above in this example), and calculates a target correction value corresponding to the temperature indicated by the temperature information by interpolation processing using the target correction values ​​associated with each of the identified temperatures. For example, when the screen luminance value is 500 cd / m ２ If the characteristic-applying temperature is 21 degrees, the correction value derivation unit 63 identifies temperatures of "20 degrees" and "30 degrees" that include 21 degrees in the table information, and calculates the screen luminance value of 500 cd / m corresponding to the temperatures of "20 degrees" and "30 degrees" respectively. ２ By performing interpolation using the acquired target correction values, the screen luminance value is calculated as follows: ２ For example, when the screen luminance value is 200 cd / m, the target correction value corresponding to the characteristic-applying temperature is 21 degrees. ２ If the characteristic-applying temperature is 11 degrees, the correction value derivation unit 63 identifies temperatures of "10 degrees or less" and "20 degrees" that include 11 degrees in the table information, and calculates a screen luminance value of 200 cd / m ２By performing interpolation using the acquired target correction values, the screen luminance value is calculated as follows: ２ For the target correction value corresponding to the characteristic-imparting temperature = 11 degrees, a target correction value corresponding to the characteristic-imparting temperature = 11 degrees is derived. Note that, as the interpolation process in this case, for example, linear interpolation process may be performed, but the specific method of interpolation is not particularly limited.

[0071] The correction value derivation unit 63 of this example derives a target correction value using the above-described table information (correspondence information Ir), and then performs processing for imparting delay characteristics using the above-described second delay method. First, as a premise, the correction value derivation unit 63 of this example repeatedly executes, on a time axis, a process of deriving a target correction value using the above-described correspondence information Ir and a process of calculating an used correction value, which is a correction value to be used for color correction based on the target correction value. Each time the correction value derivation unit 63 of this example derives a target correction value, the correction value derivation unit 63 executes a process of determining whether the most recently derived target correction value is larger or smaller than a used correction value, which is a used correction value used in a color correction performed before the most recently derived target correction value, and a process of adding or subtracting a predetermined value to or from the used correction value depending on the determined size relationship to calculate the most recently used correction value.

[0072] Specifically, each time the correction value derivation unit 63 derives a target correction value, it determines whether the most recently derived target correction value (hereinafter referred to as the "derived target correction value") is larger or smaller than the used correction value used in the color correction performed the previous time, which is the time of derivation immediately prior to the most recent derivation, by determining one of three cases: "derived target correction value > used correction value," "derived target correction value = used correction value," and "derived target correction value < used correction value." If the result is "derived target correction value > used correction value," the correction value used this time is determined to be the value obtained by adding a predetermined value to the used correction value. If the result is "derived target correction value < used correction value," the correction value used this time is determined to be the value obtained by subtracting a predetermined value from the used correction value. If the result is "derived target correction value = used correction value," the correction value used this time is determined to be the value obtained by subtracting a predetermined value from the used correction value.

[0073] When the correction value derivation unit 63 derives the target correction value for the first time, the derived target correction value is applied as is as the correction value to be used. In other words, the method of using the "predetermined value" as described above is applied when deriving the target correction value for the second time or later.

[0074] According to the above method, even if the temperature of the display panel 71 changes suddenly and the target correction value changes suddenly, the amount of change in the correction value that is actually used can be limited to a "predetermined value." As can be understood from this point, the method of adding / subtracting a predetermined value to / from the used correction value depending on the magnitude relationship between the derived target correction value and the used correction value functions as a method of delaying the change in the correction value in response to a change in the temperature of the display panel 71.

[0075] Furthermore, according to the above-described method, by selecting the "predetermined value," it is possible to arbitrarily adjust the amount of delay in the change in the correction value in response to a change in the temperature of the display panel 71. This makes it possible to simplify the adjustment of the amount of delay, thereby reducing the workload of developers.

[0076] The correction value derivation unit 63 instructs the image generation / adjustment unit 61 on the correction values ​​to be used calculated by the above method, specifically the B gain and R gain values ​​in this example, as color correction values ​​for the display image.

[0077] The image generation and adjustment unit 61 performs WB adjustment processing on the display image using the B gain and R gain values ​​thus specified, thereby correcting color changes in the display image that occur due to the temperature and screen luminance value of the display panel 71.

[0078] 3. Processing Procedure An example of a specific processing procedure to be executed by the correction value derivation unit 63 to achieve the color correction according to the embodiment described above will be described with reference to the flowcharts of Fig. 10 and Fig. 11. Fig. 10 is a flowchart of processing corresponding to the initial derivation of the target correction value.

[0079] 10 , the correction value derivation unit 63 executes a process of acquiring the detected temperature in step S101. That is, the correction value derivation unit 63 acquires the detected temperature of the display panel 71 by adding the offset value described above to the temperature value indicated by the temperature information (sensor temperature information) input from the A / D converter 64.

[0080] In step S102 following step S101, the correction value derivation unit 63 performs a delay characteristic imparting process for the detected temperature. That is, the correction value derivation unit 63 converts the detected temperature into a characteristic imparting temperature by using the temperature threshold value and the characteristic imparting temperature associated with the temperature threshold value to perform processes corresponding to the rise and fall of the detected temperature, as described above with reference to FIGS. 4 and 5 .

[0081] In step S103 following step S102, the correction value derivation unit 63 performs a process of acquiring the screen brightness value instructed by the camera control unit 4 to the image generation / adjustment unit 61 as a process of acquiring the screen brightness value.

[0082] In step S104 following step S103, the correction value derivation unit 63 derives a target correction value based on the detected temperature after the characteristic is imparted, the screen luminance value, and the correspondence information Ir. That is, the target correction value is derived based on the characteristic imparting temperature acquired in step S102, the screen luminance value acquired in step S103, and the correspondence information Ir. As described above, in this example, the temperature resolution of the table information as the correspondence information Ir is set to a lower resolution than the temperature resolution of the characteristic imparting temperature, and therefore the above-mentioned interpolation process is performed to derive the target correction value corresponding to the acquired characteristic imparting temperature.

[0083] In step S105 following step S104, the correction value derivation unit 63 sets the derived target correction value as the correction value to be used in a register of the image generation / adjustment unit 61. In this example, the image generation / adjustment unit 61 is provided with a register for receiving instructions on the B gain and R gain values ​​to be used in the WB adjustment process. In step S105, the correction value derivation unit 63 performs processing to set the B gain and R gain values ​​derived in step S104 as the target correction values ​​in the register. This makes it possible to correct color changes in the image displayed on the display panel 71 that occur due to the temperature and screen luminance value of the display panel 71.

[0084] In step S106 following step S105, the correction value derivation unit 63 waits for a predetermined time. The waiting process of step S106 and the waiting process of step S117, which will be described later, function as processes for repeatedly deriving the target correction value (i.e., the used correction value in this example) at predetermined time intervals on the time axis.

[0085] After executing the standby process in step S106, the correction value derivation unit 63 proceeds to step S107 shown in Fig. 11. Fig. 11 is a flowchart of the process corresponding to the derivation of the target correction value from the second time onwards.

[0086] In FIG. 11, the processes from step S107 to step S110 are the same as the processes from step S101 to step S104 described in FIG. 10, and therefore a duplicate description will be avoided.

[0087] In response to deriving the target correction value in step S110, the correction value derivation unit 63 proceeds to step S111 to determine whether or not the "derived target correction value>the previously used correction value" is satisfied. If it is determined in step S111 that the "derived target correction value>the previously used correction value" is not satisfied, the correction value derivation unit 63 proceeds to step S112 to determine whether or not the "derived target correction value<the previously used correction value" is satisfied.

[0088] In step S111, if it is determined that the derived target correction value is greater than the previously used correction value, the correction value derivation unit 63 proceeds to step S113 and sets a value obtained by adding a predetermined value to the previously used correction value in the register of the image generation / adjustment unit 61.

[0089] In step S112, if it is determined that the derived target correction value is less than the previously used correction value, the correction value derivation unit 63 proceeds to step S114 and sets the value obtained by subtracting a predetermined value from the previously used correction value in the register of the image generation / adjustment unit 61.

[0090] Furthermore, if the correction value derivation unit 63 determines in step S112 that the "derived target correction value<the previously used correction value" is not true (i.e., if the "derived target correction value=the previously used correction value"), the process proceeds to step S115, where the correction value derivation unit 63 sets the previously used correction value in the register of the image generation / adjustment unit 61. Note that, in order to maintain the previously used correction value as the used correction value for color correction, it is not essential to reset the previously used correction value in the register.

[0091] In response to execution of any of the setting processes of steps S113, S114, and S115, the correction value derivation unit 63 proceeds to step S116 to determine whether or not the process has ended. The process of step S116 determines whether or not a predetermined process end condition has been established that indicates that the series of processes shown in Figures 10 and 11 should be ended, such as the display of a through image on the display panel 71 having to be ended or the power supply of the signal processing device 1 having been turned off.

[0092] If the processing end condition is not satisfied in step S116 and a negative result is obtained indicating that the processing is not to be ended, the correction value derivation unit 63 proceeds to step S117, where it waits for a predetermined time, and then returns to step S107. As a result, the processing for deriving the target correction value from the second time onward is repeatedly executed at predetermined time intervals.

[0093] On the other hand, if the above-mentioned processing end condition is met in step S116 and a positive result is obtained indicating that processing is to be ended, the correction value derivation unit 63 ends the series of processing shown in FIGS.

[0094] 10 and 11 , the method of updating the used correction value based on the magnitude relationship between the target correction value and the used correction value can be rephrased as performing the following process with respect to a delay process that delays a change in the correction value in response to a change in the temperature of the display panel 71. That is, the delay process includes a target setting process that derives a target correction value, which is a target value of the correction value, based on temperature information and screen luminance information, and an update process that updates the used correction value, which is a correction value used in the color correction process, based on the target correction value derived in the target setting process, and the update process includes a process of increasing the used correction value to be updated when the used correction value to be updated is smaller than the target correction value derived in the target setting process, and a process of decreasing the used correction value to be updated when the used correction value to be updated is larger than the target correction value derived in the target setting process, and the correction value derivation unit performs the delay process at least once.

[0095] Here, when the correction value derivation unit 63 is configured by a microcomputer having a CPU, the processes of FIGS. 10 and 11 can be realized as software processing of the CPU.

[0096] 12 is an explanatory diagram of components when the correction value derivation unit 63 is configured as a microcomputer. As shown in the figure, the correction value derivation unit 63 in this case is configured to have a CPU 63a, a ROM 63b, and a RAM 63c. In this case, a program for realizing the series of processes shown in Figures 10 and 11 is stored in the ROM 63b, and the series of processes shown in Figures 10 and 11 are realized by the CPU 63a executing processes in accordance with the program.

[0097] Furthermore, in the series of processes shown in FIGS. 10 and 11, the correspondence relationship information Ir is used, and it is conceivable that the correspondence relationship information Ir is stored in the ROM 63b as shown, for example.

[0098] It should be noted that, in the color correction according to the embodiment, the process of deriving the correction value is not limited to being realized by software processing as described above, but may be realized by hardware processing using, for example, a digital logic circuit, etc. Alternatively, it may be possible to realize part of the process by software processing and other parts by hardware processing.

[0099] Furthermore, the color correction process based on the derived correction value may be realized by either hardware processing or software processing.

[0100] Although the above example shows the use of table information as the correspondence information Ir, it is also possible for the correspondence information Ir to be information of a function with variables being the temperature and screen brightness value of the display panel 71. When a function is used as the correspondence information Ir, the target correction value corresponding to the substituted temperature value is directly determined, and therefore the interpolation process described above is not necessary.

[0101] Although not specifically mentioned above, when a through image is displayed on the display unit 7, image-related information such as an image capture mode icon, shutter speed, F-number, etc. may be displayed together with the through image. When a playback image is displayed on the display unit 7, related information for the playback image, such as the image file name, capture date and time, and capture location, may also be displayed together with the playback image. One possible form for displaying such related information together with the through image or playback image is to display an image showing the related information in an area separate from the area displaying the through image or playback image. In such a case, color correction processing may be performed only on the through image or playback image, excluding the image portion of the related information.

[0102] As a form of displaying related information together with a through image or a playback image, an image showing the related information may be superimposed on the through image or the playback image. In this case, color correction processing may be performed on the through image or the playback image before the image of the related information is superimposed.

[0103] In the former case, it is possible to perform color correction processing on the entire image area including the image portion of the related information, and in the latter case, it is possible to perform color correction processing on the through image or the reproduced image after the image of the related information is superimposed.

[0104] Furthermore, in the above example, the delay characteristic and hysteresis characteristic are imparted to the temperature information, but it is also possible to impart the delay characteristic and hysteresis characteristic directly to the correction value instead of the temperature information.

[0105] 4. Modifications Although various embodiments according to the present technology have been described above, the present technology is not limited to the specific examples described above and may adopt various modified configurations. For example, although the above example describes detecting the temperature of the display panel 71 using a temperature sensor 72 such as a thermistor, it is not essential to use the temperature sensor 72 to detect the temperature of the display panel 71. For example, a method of estimating the temperature of the display panel 71 based on a luminance histogram of a displayed image may be used.

[0106] 13 is a diagram illustrating a configuration example of a signal processing device 1A as a first modified example that estimates the temperature of a display panel 71 based on a luminance histogram. Note that the signal processing device 1A differs from the signal processing device 1 in that a display control unit 6A is provided instead of the display control unit 6, and a display unit 7A is provided instead of the display unit 7. Since the other configuration is the same as that of the signal processing device 1, configuration other than the display control unit 6A and the display unit 7A is not shown in FIG.

[0107] The display control unit 6A differs from the display control unit 6 in that the A / D converter 64 is omitted and a temperature estimation unit 65 is added. The display unit 7A also differs from the display unit 7 in that the temperature sensor 72 is omitted.

[0108] In the display control unit 6A, the temperature estimation unit 65 inputs the display image from the image generation and adjustment unit 61, and estimates the temperature of the display panel 71 based on the luminance histogram of the display image.

[0109] Fig. 14 is a diagram for explaining the relationship between a luminance histogram and image brightness, with Fig. 14A showing an example of a relatively dark image and its luminance histogram, and Fig. 14B showing an example of a relatively bright image and its luminance histogram. Comparing Fig. 14A and Fig. 14B shows that it is possible to estimate image brightness from the luminance histogram.

[0110] It can be said that the brighter the displayed image, the greater the amount of heat generated by the display panel 71. Therefore, it is possible to estimate the temperature of the display panel 71 based on the brightness of the displayed image and the duration of the brightness.

[0111] The temperature estimation unit 65 generates a brightness histogram for the input display image and calculates a brightness index value for the display image based on the generated brightness histogram. Correspondence information (hereinafter referred to as "panel temperature conversion information") indicating a correspondence relationship between the temperature of the display panel 71 and the combination of this brightness index value and the duration of that brightness is set in the temperature estimation unit 65, and the temperature of the display panel 71 is derived based on the panel temperature conversion information. The derived temperature information is then output to the correction value derivation unit 63 as estimated panel temperature information.

[0112] The brightness index value may be calculated for each frame of the displayed image, or may be calculated every several frames, such as once every five frames, or every predetermined time, such as once every three seconds. The brightness index value may also be calculated based on the average value of the brightness histogram over several frames.

[0113] Here, it is also possible to suppress temperature changes in the display panel 71 using a temperature control element. Fig. 15 is a block diagram showing an example configuration of a signal processing device 1B as a second modified example that uses a temperature control element to suppress temperature changes in the display panel 71. The differences from the signal processing device 1 are that a display unit 7B is provided instead of the display unit 7, and that the camera control unit 4 has a panel temperature control function Fb. The display unit 7B differs from the display unit 7 in that it is provided with a temperature control element 73.

[0114] The temperature control element 73 is disposed near the display panel 71 and is capable of cooling or heating the display panel 71. The cooling temperature control element 73 may be, for example, a Peltier element or a cooling fan. The heating temperature control element 73 may be, for example, a heating element such as a heating wire.

[0115] In this case, the camera control unit 4 has a panel temperature control function Fb that controls the drive of the temperature control element 73 based on a detection signal from the temperature sensor 72 in the display unit 7B, thereby maintaining the temperature of the display panel 71 at a predetermined temperature. For example, the camera control unit 4 controls the drive of the temperature control element 73 with the goal of making the temperature detected by the temperature sensor 72 coincide with the predetermined temperature.

[0116] The signal processing device 1B as described above can suppress color changes in the displayed image by suppressing temperature changes in the display panel 71. In practice, it is difficult to completely prevent temperature changes using the panel temperature control function Fb, so it is effective to perform color correction as an embodiment.

[0117] Here, the color seen on the display panel 71 changes depending on the viewing angle. Therefore, it is conceivable that the correction process for the temperature-dependent color change is performed so as to also correct this viewing angle-dependent color change. Specifically, the position of the user's eyes looking at the display panel 71 is detected, and color correction is performed based on the positional relationship between the user's eyes and the display panel 71.

[0118] In particular, when the display unit 7 is configured as an EVF, if the user is wearing glasses, it is possible to reduce the screen display of the display panel 71. In this case, it is possible to determine whether the user is wearing glasses based on the detection result of a proximity sensor, line of sight detection, etc.

[0119] Furthermore, if the user is wearing sunglasses, it is conceivable to increase the screen brightness value of the display panel 71. In this case, it is conceivable to determine whether the user is wearing sunglasses based on line of sight detection or the like.

[0120] As a measure for visually impaired people, it is also possible to determine the level of visual impairment of the user and correct the colors to make them visible. The level of visual impairment can be determined based on iris authentication, gaze detection, etc.

[0121] Furthermore, color correction of the displayed image may be performed based on color information of the displayed image detected by a color sensor. As the color sensor, for example, an image sensor that captures the image displayed by the display panel 71 may be used. By performing color correction based on the color information from the color sensor, it is possible to correct not only color changes due to temperature but also color changes due to aging.

[0122] Furthermore, it is also conceivable to configure the color correction function to be switchable on and off, which is effective, for example, in adjusting the color of a display image at the time of shipping from the factory, because it makes it possible to turn off the color correction function according to the embodiment.

[0123] While the above description cites an example in which the signal processing device according to the present technology is applied to an imaging device, the imaging device referred to here broadly includes devices having an imaging function, such as smartphones and tablet terminals. Furthermore, the signal processing device according to the present technology can also be suitably applied to devices other than imaging devices. For example, the signal processing device according to the present technology can be applied to television receivers, head-mounted displays (HMDs), eyeglass-type display devices, electron microscopes, binoculars, telescopes, various inspection devices, and the like.

[0124] 5. Summary of the Embodiments As described above, the signal processing device (signal processing device 1, 1A, 1B) according to the embodiments includes a correction value derivation unit (correction value derivation unit 63) that derives a correction value used in color correction processing for correcting the color of an image displayed on a display panel based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a display light source and screen luminance information indicating the screen luminance value of the display panel. When the screen luminance changes, the amount of color change corresponding to the temperature also changes. Therefore, the correction value for correcting the temperature-dependent color change is derived based on the screen luminance information as well as the temperature information of the display panel as described above. This makes it possible to achieve color correction that can absorb changes in the amount of color change corresponding to the screen luminance. Therefore, the accuracy of correction of color change in a displayed image can be improved for a display panel having light-emitting elements as a display light source. In particular, by performing correction based on the screen luminance, appropriate color correction can be achieved according to the usage environment and usage conditions of a device having a display panel. For example, since the screen luminance tends to be increased in a bright environment and decreased in a dark environment, appropriate color correction can be achieved according to such environmental changes.

[0125] In the signal processing device according to the embodiment, the screen luminance is selected and set from a plurality of candidates by operation, thereby improving the accuracy of color correction in response to the case where the screen luminance is selectively set by operation.

[0126] Furthermore, in the signal processing device according to the embodiment, the screen brightness is adjusted according to the brightness of the ambient light of the device having the display panel, thereby improving the accuracy of color correction in cases where the screen brightness is automatically adjusted according to the brightness of the ambient light.

[0127] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit derives the correction value by using temperature information obtained by offsetting the temperature value detected by the temperature sensor by an offset value determined according to the distance between the temperature sensor and the display panel. This makes it possible to obtain temperature information indicating the temperature of the display panel by offsetting the detected temperature value, even if the temperature sensor cannot be installed inside the display panel and the temperature of the display panel cannot be directly detected. Therefore, color correction can be performed appropriately even if the temperature sensor cannot be installed inside the display panel.

[0128] In addition, in the signal processing device according to the embodiment, the correction value derivation unit performs a delay process that delays the change in the correction value in response to a change in the temperature of the display panel. By delaying the change in the correction value in response to a change in temperature as described above, it is possible to prevent the color of the displayed image from changing suddenly in response to a sudden change in temperature. Therefore, it is possible to make the color change of the displayed image due to the correction less noticeable, thereby realizing a more natural color correction that reduces the sense of incongruity.

[0129] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit performs a process of imparting a delay characteristic to the temperature information as a delay process. By imparting a delay characteristic to the temperature information as described above, it is possible to impart a delay characteristic to the correction value derived based on the temperature information. Therefore, it is possible to prevent the color of the displayed image from changing suddenly in response to a sudden change in temperature, and it is possible to make the color change of the displayed image due to the correction less noticeable, thereby realizing a more natural color correction that reduces the sense of incongruity.

[0130] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit imparts hysteresis to the change in the correction value in response to a change in the temperature of the display panel. By providing such hysteresis, it is possible to prevent the correction value from overly sensitively following a temperature change when the temperature changes from rising to falling, or from falling to rising, thereby preventing noticeable color changes in the displayed image. This allows for more natural color correction.

[0131] In addition, in a signal processing device according to an embodiment, the delay process includes a target setting process for deriving a target correction value, which is a target value for the correction value, based on temperature information and screen luminance information, and an update process for updating an active correction value, which is a correction value used in the color correction process, based on the target correction value derived in the target setting process. The update process includes a process for increasing the active correction value to be updated if the active correction value to be updated is smaller than the target correction value derived in the target setting process, and a process for decreasing the active correction value to be updated if the active correction value to be updated is larger than the target correction value derived in the target setting process. The correction value derivation unit performs the delay process at least once. According to the above configuration, the delay amount of the change in the correction value (active correction value) in response to changes in the temperature of the display panel can be adjusted arbitrarily by selecting a value to be added or subtracted from the active correction value to be updated. This facilitates the adjustment of the delay amount, thereby reducing the workload on developers.

[0132] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit derives an R correction value for correcting the red component of the image and a B correction value for correcting the blue component, thereby making it possible to appropriately correct color changes in a displayed image when the color change due to temperature change is mainly manifested as a change in color temperature.

[0133] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit derives only the R correction value and the B correction value from among the R correction value, the B correction value, and the G correction value that corrects the green component of the image. With this configuration, the G correction value is not required in color correction, so the amount of data required for color correction can be reduced.

[0134] In addition, in the signal processing device according to the embodiment, the correction value derivation unit derives the correction value used in the color correction process based on correspondence information (correspondence information Ir) indicating the correspondence between the temperature of the display panel, the screen luminance value, and the target correction value of the color correction process, which is the target value of the correction value. This makes it possible to appropriately derive the correction value for appropriately correcting color changes caused by the temperature of the display panel and the screen luminance.

[0135] Furthermore, in the signal processing device according to the embodiment, the correspondence information is in the form of table information, which eliminates the need for calculation using a function to derive the correction value, thereby reducing the processing load related to color correction.

[0136] Furthermore, in the signal processing device according to the embodiment, the table information includes information indicating target correction values ​​corresponding to each predetermined unit temperature. As a result, the table information stores target correction values ​​for each unit temperature, such as every 5 degrees or every 10 degrees. In other words, the target correction values ​​are stored for each temperature at equal intervals. If the temperature intervals are not equal, it may be impossible to properly represent the correspondence between the temperature and the target correction value in areas where the temperature intervals are large, which may result in a decrease in the accuracy of color correction. However, by setting the temperature intervals to be equal as described above, it is possible to properly represent the correspondence between the temperature and the target correction value for the temperature range to be corrected, thereby improving the accuracy of color correction.

[0137] Furthermore, in the signal processing device according to the embodiment, the temperature resolution of the table information is set to be lower than the temperature resolution of the temperature information. For example, the temperature information indicates the temperature of the display panel in units of 2 degrees, while the table information indicates the target correction value in units of 10 degrees, and so on. By setting the temperature resolution of the table information to be lower, it is possible to reduce the data volume of the table information.

[0138] Furthermore, in the signal processing device according to the embodiment, the correction value derivation unit identifies two temperatures in the table information that have a relationship that includes the temperature indicated by the temperature information, and calculates a target correction value corresponding to the temperature indicated by the temperature information by interpolation processing using the target correction value associated with each identified temperature. As a result, even if the temperature resolution of the table information is set to a lower resolution than the temperature resolution of the temperature information, it is possible to appropriately derive a target correction value at the temperature resolution of the temperature information.

[0139] Furthermore, in the signal processing device according to the embodiment, the display panel is a self-luminous display panel having OLEDs as light-emitting elements. In a self-luminous display panel using OLEDs as a display light source, color changes in the displayed image due to temperature and screen brightness occur relatively significantly. Therefore, it is preferable to perform color correction according to the embodiment.

[0140] Furthermore, the signal processing device according to the embodiment includes a color correction unit (image generation and adjustment unit 61) that performs color correction processing based on the correction values ​​derived by the correction value derivation unit, thereby realizing a device that not only derives correction values ​​for color correction, but also performs color correction using the derived correction values.

[0141] Furthermore, the signal processing device according to the embodiment is configured as an imaging device including an imaging unit (image sensor 2) that captures an image of a subject. In devices intended for outdoor use, such as imaging devices, direct sunlight can significantly increase the temperature of the display panel, and a high screen brightness value tends to be set, resulting in a large amount of color change in the displayed image. Therefore, it is preferable to perform color correction according to the embodiment.

[0142] In a signal processing method according to an embodiment, a signal processing device derives a correction value to be used in a color correction process for correcting the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating the screen luminance of the display panel. This signal processing method can also achieve the same functions and effects as the signal processing device according to the above-described embodiment.

[0143] Here, as an embodiment, a program that causes, for example, a CPU, a DSP, or a device including these, to execute the processing of the correction value derivation unit 63 described with reference to Figures 10 and 11, etc., can be considered. That is, the program of the embodiment is a computer-readable program that causes the computer to realize a function of deriving correction values ​​used in color correction processing that corrects the colors of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating the screen luminance of the display panel. Such a program can realize the functions of a signal processing device as an embodiment, such as the signal processing device 1 described above.

[0144] The above-described programs can be pre-recorded on a solid-state drive (SSD) or hard disk drive (HDD) as a storage device built into a computer or other device, or on a ROM or the like within a microcomputer having a CPU. Alternatively, the programs can be temporarily or permanently stored (recorded) on a removable recording medium such as a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a Magneto Optical (MO) disc, a Digital Versatile Disc (DVD), a Blu-ray Disc (Blu-ray Disc (registered trademark)), a magnetic disk, a semiconductor memory, or a memory card. Such removable recording media can be provided as so-called packaged software. Furthermore, such programs can be installed on a personal computer or the like from a removable recording medium, or can be downloaded from a download site via a network such as a local area network (LAN) or the Internet.

[0145] Furthermore, the above-described program is suitable for providing the signal processing device according to the embodiment in a wide range of applications. For example, by downloading the program to a personal computer, a portable information processing device, a mobile phone, a game device, a video device, a PDA (Personal Digital Assistant), or the like, the personal computer or the like can function as a device that realizes the processing of the signal processing device according to the embodiment.

[0146] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0147] <6. Present Technology> The present technology may also have the following configurations. (1) A signal processing device including a correction value derivation unit that derives a correction value used in color correction processing for correcting the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating a value of the screen luminance of the display panel. (2) The signal processing device according to (1), in which the screen luminance is set by selecting from a plurality of candidates via an operation. (3) The signal processing device according to (1) or (2), in which the screen luminance is adjusted according to the brightness of ambient light of a device having the display panel. (4) The signal processing device according to any of (1) to (3), in which the correction value derivation unit uses the temperature information obtained by offsetting a temperature value detected by a temperature sensor by an offset value determined according to a distance between the temperature sensor and the display panel, to derive the correction value. (5) The signal processing device according to any of (1) to (4), in which the correction value derivation unit performs delay processing to delay a change in the correction value with respect to a change in the temperature of the display panel. (6) The signal processing device according to (5), wherein the correction value derivation unit performs the delay process by imparting a delay characteristic to the temperature information. (7) The signal processing device according to (5) or (6), wherein the correction value derivation unit imparts a hysteresis characteristic to a change in the correction value in response to a change in the temperature of the display panel. (8) The signal processing device described in any of (5) to (7), wherein the delay processing includes: a target setting processing that derives a target correction value that is a target value of the correction value based on the temperature information and the screen luminance information; and an update processing that updates a used correction value that is the correction value used in the color correction processing based on the target correction value derived in the target setting processing, wherein the update processing includes: a processing that increases the used correction value to be updated when the used correction value to be updated is smaller than the target correction value derived in the target setting processing; and a processing that decreases the used correction value to be updated when the used correction value to be updated is larger than the target correction value derived in the target setting processing, wherein the correction value derivation unit performs the delay processing at least once.(9) The signal processing device according to any one of (1) to (8), wherein the correction value derivation unit derives, as the correction values, an R correction value for correcting a red component of the image and a B correction value for correcting a blue component. (10) The signal processing device according to (9), wherein the correction value derivation unit derives, as the correction values, only the R correction value and the B correction value out of the R correction value, the B correction value, and a G correction value for correcting a green component of the image. (11) The signal processing device according to any one of (1) to (10), wherein the correction value derivation unit derives the correction values ​​used in the color correction processing based on correspondence information indicating a correspondence relationship between a temperature of the display panel, a value of the screen luminance, and a target correction value of the color correction processing, which is a target value of the correction value. (12) The signal processing device according to (11), wherein the correspondence information is table information. (13) The signal processing device according to (12), wherein the table information includes information indicating the target correction value corresponding to each predetermined unit temperature. (14) The signal processing device according to (13), wherein the temperature resolution of the table information is lower than the temperature resolution of the temperature information. (15) The signal processing device according to (13), wherein the correction value derivation unit identifies two temperatures among the temperatures in the table information that have a relationship that includes the temperature indicated by the temperature information, and calculates the target correction value corresponding to the temperature indicated by the temperature information by interpolation processing using the target correction values ​​associated with each of the identified temperatures. (16) The signal processing device according to any of (1) to (15), wherein the display panel is a self-luminous display panel having OLEDs as the light-emitting elements. (17) The signal processing device according to any of (1) to (16), further comprising a color correction unit that performs the color correction processing based on the correction values ​​derived by the correction value derivation unit. (18) The signal processing device according to any one of (1) to (17), configured as an imaging device having an imaging unit that images a subject. (19) A signal processing method in which the signal processing device derives a correction value used in color correction processing that corrects the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured having light-emitting elements as a light source for display and screen luminance information indicating the value of screen luminance of the display panel.(20) A program readable by a computer device, which causes the computer device to realize a function of deriving a correction value used in a color correction process for correcting the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating the value of the screen luminance of the display panel.

[0148] REFERENCE SIGNS LIST 1, 1A, 1B Signal processing device 2 Imaging element 3 Image signal processing unit 4 Camera control unit 5 Memory unit 6, 6A Display control unit 7, 7A, 7B Display unit 8 Operation unit 9 Bus Fa Screen brightness adjustment function 61 Image generation / adjustment unit 62 Image output unit 63 Correction value derivation unit 64 A / D converter 71 Display panel 72 Temperature sensor 63a CPU 63b ROM 63c RAM Ir Correspondence relationship information 65 Temperature estimation unit Fb Panel temperature adjustment function 73 Temperature adjustment element

Claims

1. A signal processing device having a correction value derivation unit that derives correction values ​​used in color correction processing to correct the colors of an image displayed on a display panel based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen brightness information indicating the value of the screen brightness of the display panel.

2. The signal processing device according to claim 1, wherein the screen brightness is set by selecting from a plurality of candidates through an operation.

3. The signal processing device according to claim 1, wherein the screen brightness is adjusted according to the brightness of the ambient light of the device having the display panel.

4. A signal processing device as described in claim 1, wherein the correction value derivation unit uses the temperature information obtained by offsetting the temperature value detected by the temperature sensor by an offset value determined according to the distance between the temperature sensor and the display panel to derive the correction value.

5. The signal processing device according to claim 1, wherein the correction value derivation section performs delay processing to delay a change in the correction value relative to a change in the temperature of the display panel.

6. The signal processing device according to claim 5, wherein the correction value derivation section performs the delay processing by applying a delay characteristic to the temperature information.

7. The signal processing device according to claim 5, wherein the correction value derivation section imparts hysteresis characteristics to changes in the correction value in response to changes in the temperature of the display panel.

8. The signal processing device described in claim 5, wherein the delay processing includes: a target setting processing that derives a target correction value that is a target value of the correction value based on the temperature information and the screen brightness information; and an update processing that updates a used correction value that is the correction value used in the color correction processing based on the target correction value derived in the target setting processing, wherein the update processing includes: a processing that increases the used correction value to be updated when the used correction value to be updated is smaller than the target correction value derived in the target setting processing; and a processing that decreases the used correction value to be updated when the used correction value to be updated is larger than the target correction value derived in the target setting processing, wherein the correction value derivation unit performs the delay processing at least once.

9. The signal processing device according to claim 1, wherein the correction value derivation unit derives, as the correction values, an R correction value for correcting a red component of the image and a B correction value for correcting a blue component.

10. A signal processing device as described in claim 9, wherein the correction value derivation unit derives only the R correction value and the B correction value as the correction values ​​from among the R correction value, the B correction value, and the G correction value that corrects the green component of the image.

11. A signal processing device as described in claim 1, wherein the correction value derivation unit derives the correction value to be used in the color correction process based on correspondence information indicating the correspondence between the temperature of the display panel, the value of the screen brightness, and the target correction value of the color correction process, which is the target value of the correction value.

12. The signal processing device according to claim 11, wherein the correspondence information is in the form of table information.

13. The signal processing device according to claim 12, wherein the table information includes information indicating the target correction value corresponding to each predetermined unit temperature.

14. A signal processing device according to claim 13, wherein the temperature resolution of the table information is lower than the temperature resolution of the temperature information.

15. A signal processing device as described in claim 13, wherein the correction value derivation unit identifies two temperatures among the temperatures in the table information that have a relationship that includes the temperature indicated by the temperature information, and calculates the target correction value corresponding to the temperature indicated by the temperature information by interpolation processing using the target correction value associated with each of the identified temperatures.

16. The signal processing device according to claim 1, wherein the display panel is a self-luminous display panel having OLEDs as the light-emitting elements.

17. The signal processing device according to claim 1, further comprising a color correction section that performs the color correction process based on the correction value derived by the correction value derivation section.

18. The signal processing device according to claim 1, configured as an imaging device having an imaging section for imaging a subject.

19. A signal processing method in which a signal processing device derives a correction value used in color correction processing to correct the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating the value of the screen luminance of the display panel.

20. A computer-readable program that causes the computer to realize the function of deriving a correction value used in color correction processing to correct the color of an image displayed on a display panel, based on temperature information indicating the temperature of a display panel configured with light-emitting elements as a light source for display and screen luminance information indicating the screen luminance value of the display panel.

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