Dynamic edge enhancement in video

Abstract

A dynamic edge enhancement system includes a light sensor, a circuit, and a microcontroller. The light sensor is operable to generate a light background signal by measuring ambient light falling on a display. The circuit is operable to generate a histogram of gray scale values of a plurality of frames of an input video signal received by the circuit, detect a plurality of edges in the input video signal, enhance the plurality of edges in response to a gray scale transfer table and an edge mask intensity value, and generate an output video signal suitable for driving the display after enhancing the edges. The microcontroller is operable to generate the gray scale transfer table based on the histogram generated by the circuit, and generate the edge mask intensity value in response to the gray scale transfer table, the light background signal, a nighttime brightness threshold, and a daytime brightness threshold.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 604,187, filed November 29, 2023, which is hereby incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure generally relates to systems and methods for dynamic edge enhancement in video. Background Technology

[0003] In automotive display applications, light sensors have been used to automatically control display brightness based on ambient lighting conditions. As the ambient light increases, the display brightness increases to maintain image visibility. Edge enhancement is used to keep symbols on the display clearly visible to the viewer. Automatic brightness control methods maintain a comfortable viewing brightness level and reduce display power consumption when ambient light decreases. While automatic brightness control methods maintain the visibility of symbols at peak white grayscale, the visibility of lower grayscale values ​​may be affected. Fixed edge enhancement sometimes presents problems under low ambient light conditions. Summary of the Invention

[0004] This paper presents a dynamic edge enhancement system. The dynamic edge enhancement system includes a light sensor, circuitry, and a microcontroller. The light sensor is operable to generate a backlight signal by measuring ambient light falling on the display. The circuitry is operable to generate a histogram of grayscale values ​​for multiple frames of an input video signal received by the circuitry, detect multiple edges in the input video signal, enhance the multiple edges in response to a grayscale transfer table and edge mask intensity values, and generate an output video signal suitable for driving the display after enhancing the multiple edges. The microcontroller is operable to generate a grayscale transfer table based on the histogram generated by the circuitry and generate edge mask intensity values ​​in response to the grayscale transfer table, the backlight signal, a nighttime brightness threshold, and a daytime brightness threshold.

[0005] In one or more embodiments of the dynamic edge enhancement system, in response to receiving an unmasked value of the edge mask intensity value, the circuit enhances multiple edges to eliminate multiple edges.

[0006] In one or more embodiments of the dynamic edge enhancement system, the microcontroller is further operable to set the edge mask intensity value to a maskless value in response to a light background signal being darker than a nighttime brightness threshold.

[0007] In one or more embodiments of a dynamic edge enhancement system, multiple edges are darkened by circuitry in response to a full mask value that receives an edge mask intensity value.

[0008] In one or more embodiments of the dynamic edge enhancement system, the microcontroller is further operable to set the edge mask intensity value to the full mask value in response to a light background signal being brighter than a daytime brightness threshold.

[0009] In one or more embodiments of the dynamic edge enhancement system, multiple edges that are eliminated in response to a no-mask value approximately match a local background color in the input video signal, multiple edges that are darkened in response to a full-mask value approximately match a zero-value version of the local background color in the Munsell color system, and multiple edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the no-mask value and the full-mask value.

[0010] In one or more embodiments of the dynamic edge enhancement system, as the light background signal varies between a nighttime brightness threshold and a daytime brightness threshold, the negative slope of the transfer function curve of the edge mask intensity value decreases as the transfer function curve approaches the daytime brightness threshold.

[0011] In one or more implementations of a dynamic edge enhancement system, multiple edges are detected when the contrast is greater than an edge threshold.

[0012] In one or more embodiments of the dynamic edge enhancement system, the display forms part of the vehicle.

[0013] This paper presents a method for dynamic edge enhancement. The method includes: generating a backlight signal by measuring ambient light falling on a display using a light sensor; generating a histogram of grayscale values ​​for multiple frames of an input video signal received at a circuit; generating a grayscale transfer table based on the histogram; generating edge mask intensity values ​​using a microcontroller in response to the grayscale transfer table, the backlight signal, a nighttime brightness threshold, and a daytime brightness threshold; detecting multiple edges in the input video signal; enhancing the multiple edges in the input video signal in response to the grayscale transfer table and the edge mask intensity values; and generating an output video signal suitable for driving the display after enhancing the multiple edges.

[0014] In one or more embodiments of the method, multiple edges are enhanced in response to an unmasked value that receives an edge mask intensity value, thereby eliminating multiple edges.

[0015] In one or more embodiments, the method includes setting an edge mask intensity value to a maskless value in response to a light background signal being darker than a nighttime brightness threshold.

[0016] In one or more embodiments of the method, multiple edges are enhanced by darkening the full mask value in response to receiving the edge mask intensity value.

[0017] In one or more embodiments, the method includes setting an edge mask intensity value to a full mask value in response to a light background signal being brighter than a daytime brightness threshold.

[0018] In one or more embodiments of the method, multiple edges that are eliminated in response to a no-mask value are approximately matched with a local background color in the input video signal, multiple edges that are darkened in response to a full-mask value are approximately matched with a zero-value version of the local background color in the Munsell color system, and multiple edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the no-mask value and the full-mask value.

[0019] In one or more embodiments of the method, as the light background signal varies between a nighttime brightness threshold and a daytime brightness threshold, the negative slope of the transfer function curve of the edge mask intensity value decreases as the transfer function curve approaches the daytime brightness threshold.

[0020] In one or more embodiments of the method, the plurality of edges are detected when the contrast is greater than an edge threshold.

[0021] In one or more embodiments of the method, enhancement of multiple edges in the input video signal is performed in a vehicle.

[0022] This document provides a vehicle. The vehicle includes a display, a light sensor, and an electronic control unit. The light sensor is operable to generate a light background signal by measuring ambient light falling on the display. The electronic control unit is operable to generate a histogram of grayscale values ​​of multiple frames of an input video signal received by the electronic control unit; generate a grayscale transfer table based on the histogram; generate edge mask intensity values ​​in response to the grayscale transfer table, the light background signal, a nighttime brightness threshold, and a daytime brightness threshold; detect multiple edges in the input video signal; enhance the multiple edges in response to the grayscale transfer table and the edge mask intensity values; and after enhancing the multiple edges, generate an output video signal for driving the display.

[0023] In one or more embodiments of the vehicle, a plurality of edges that are eliminated in response to the unmasked value of the edge mask intensity value approximately match the local background color in the input video signal, a plurality of edges that are darkened in response to the full mask value of the edge mask intensity value approximately match the zero-value version of the local background color in the Munsell color system, and the plurality of edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the unmasked value and the full mask value.

[0024] The above-mentioned features and advantages, as well as other features and advantages, of this doctrine will be readily understood from the following detailed description of the best mode for carrying out the doctrine in conjunction with the accompanying drawings. Attached Figure Description

[0025] Figure 1 The scene depicts the vehicle.

[0026] Figure 2 A side view of the driver relative to the display is shown according to one or more exemplary embodiments.

[0027] Figures 3A to 3E Sections of graphical images seen at various edge mask intensity values ​​according to one or more exemplary embodiments are shown.

[0028] Figure 4 A schematic functional block diagram of an electronic control unit according to one or more exemplary embodiments is shown.

[0029] Figure 5 A graph showing the transfer function of the edge mask intensity value as a function of the ambient light value is presented.

[0030] Figure 6 A graph showing the display brightness as a function of input grayscale according to one or more exemplary embodiments is shown.

[0031] Figure 7 A grayscale enhancement diagram is shown according to one or more exemplary embodiments.

[0032] Figure 8 A schematic diagram of the Munsell color system according to an exemplary embodiment is shown.

[0033] This disclosure may have various modifications and alternatives, and some representative embodiments are illustrated by way of example in the accompanying drawings and will be described in detail herein. The novel aspects of this disclosure are not limited to the specific forms illustrated in the foregoing drawings. Rather, this disclosure is intended to cover modifications, equivalents, and combinations that fall within the scope of this disclosure as defined by the appended claims. Detailed Implementation

[0034] Embodiments of this disclosure typically provide dynamic edge enhancement that places one or more dark pixels around symbols in the input video signal that exceed a predetermined contrast threshold (e.g., edge threshold > 5). By examining the input video signal rather than the image-enhanced output video signal, symbols in the input video signal can be intelligently constructed to have high contrast to maintain visibility. Dynamic edge enhancement typically adjusts the dark pixels based on the background light level. For brighter background light, edge pixels are darkened. For lighter background light, edge pixels are made more transparent. For medium background light, edge pixels are adjusted to a middle level.

[0035] Figure 1A scenario of vehicle 90 is illustrated. Vehicle 90 typically includes a body 92, an electronic control unit 94, and an instrument panel 96 having one or more displays 100a-100c. The body 92 can represent the interior of vehicle 90. Vehicle 90 can include mobile vehicles such as automobiles, trucks, motorcycles, boats, trains, and / or aircraft. In some embodiments, body 92 can be part of a stationary object. Stationary objects may include, but are not limited to, billboards, newsstands, and / or tents. Other types of vehicle 90 can be implemented to meet the design criteria of specific applications.

[0036] The electronic control unit 94 can implement one or more display driving circuits. The electronic control unit 94 is generally operable to generate control signals to drive displays 100a-100c. In various embodiments, the control signals can be configured to provide instrument information (e.g., speed, tachometer, fuel, temperature, etc.) to at least one of the displays 100a-100c (e.g., 100a). In one embodiment, the control signals can also be configured to provide video (e.g., rearview camera video, frontview camera video, in-vehicle DVD player, etc.) to the displays 100a-100c. In other embodiments, the control signals can be further configured to provide alphanumeric information displayed on one or more of the displays 100a-100c.

[0037] In various embodiments, the electronic control unit 94 typically includes at least one microcontroller. The at least one microcontroller may include one or more processors, each of which may be embodied as a separate processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a dedicated electronic control unit. The at least one microcontroller may be any type of electronic processor (implemented in hardware, software executing on hardware, or a combination of both). The at least one microcontroller may also include tangible, non-transitory memory (e.g., read-only memory in the form of optical, magnetic, and / or flash memory). For example, the at least one microcontroller may include accompanying hardware in the form of a suitable amount of random access memory, read-only memory, flash memory, and other types of electrically erasable programmable read-only memory, as well as high-speed clocks or timers, analog-to-digital and digital-to-analog circuit systems, and input / output circuit systems and devices, and appropriate signal conditioning and buffering circuit systems.

[0038] The computer-readable and executable instructions embodying this method may be stored in memory and executed as described herein. The executable instructions may be a series of instructions for running an application on at least one microcontroller (in the foreground or background). At least one microcontroller may receive commands and information in the form of one or more input signals from various controls or components in vehicle 90, and transmit instructions to displays 100a-100c via one or more control signals to control displays 100a-100c.

[0039] The instrument panel 96 implements a structure (or instrument panel) that supports displays 100a-100c. As shown, display 100a can be an instrument display positioned for driver use. Display 100b can be a console display positioned for both driver and passenger use. Display 100c can be a passenger display positioned for passenger use.

[0040] Displays 100a-100c are typically mounted to the instrument panel 96. In various embodiments, one or more of displays 100a-100c may be located inside the vehicle 90. In other embodiments, one or more of displays 100a-100c may be located outside the vehicle 90. One or more of displays 100a-100c can realize an enhanced vehicle display that is visible to the driver under various lighting conditions. Control signals for generating images on displays 100a-100c can be received from the electronic control unit 94 as electrical communications.

[0041] Figure 2 A side view of an example driver 98 relative to a display 100x is shown according to one or more exemplary embodiments. Display 100x may represent displays 100a-100c (e.g., 100a). The driver 98 is shown seated in a driver's seat of vehicle 90 behind display 100a. In other embodiments, the driver 98 may be a passenger seated in another seat and / or behind another display 100b and / or 100c. Display 100x typically has a surface (or front surface) 112 visible to the driver 98. Vehicle 90 includes an electronic control unit 94, a windshield 102, and an ambient light sensor 108.

[0042] Ambient light 124 inside the vehicle can be reflected from display 100x and directed to driver 98. Ambient light 124 can be generated by the reflection of light from the sun, other lights around vehicle 90 (e.g., streetlights), lights inside vehicle 90 (e.g., roof lights), headlights of other vehicles, etc. When driver 98 looks down at the front surface 112 of display 100x and / or the instrument panel 96, driver 98 sees the reflected ambient light 124 superimposed on the graphic image 116 generated by display 100x.

[0043] The electronic control unit 94 communicates electrically with the ambient light sensor 108 and the display 100x. The electronic control unit 94 receives an ambient brightness value from the ambient light sensor 108 in the background light signal 110. The ambient brightness value is proportional to the intensity of the reflected ambient light 124 sensed by the ambient light sensor 108.

[0044] The electronic control unit 94 is operable to dynamically adjust the display brightness of the display 100x using an ambient brightness value via a display brightness control value 114. In bright conditions, when the driver 98's pupils are narrow, the electronic control unit 94 increases the overall brightness of the display 100x (e.g., increases the projection light source within the display) to prevent the image on the display 100x from fading. Therefore, the driver 98 can comfortably view the brightened image on the display 100x. In dark conditions, when the driver 98's pupils are wide, the electronic control unit 94 decreases the overall brightness of the display 100x (e.g., decreases the projection light source) to prevent the image on the display 100x from being distracting. Decreasing the brightness of the display 100x also helps reduce the power consumption of the display 100x.

[0045] The electronic control unit 94 is further operable to dynamically adjust edge enhancement of the output video signal 106 transmitted to the display 100x using ambient brightness values ​​in the background light signal 110. When the ambient brightness value is low, the electronic control unit 94 adjusts (e.g., eliminates) visible edge enhancement in the graphic image 116. Elimination typically adjusts the edge value level (as viewed in the Munsell color system) to match the local background color in the input video signal. In practice, the edges can be considered transparent. For example, when the local background color is blue, the edges will be adjusted to the same or similar blue. In practice, the driver 98 cannot see the black boundaries depicting symbols (e.g., letters, numbers, graphic characters, semiotics, etc.) in the graphic image 116. When low-reflectivity ambient light 124 is present, the symbols in the graphic image 116 may be clear to the driver 98.

[0046] When the ambient light value is high, the reflected ambient light 124 reduces the contrast of what the driver 98 sees, making the symbols in the graphic image 116 blurry against the background. Therefore, the electronic control unit 94 darkens the edge values ​​to approximately match a zero-value version of the local background color in the graphic image 116. In effect, the edges may become almost black. As the driver 98 perceives, the darker edges generally become sharper, making the symbols more visible relative to the background.

[0047] Although the ambient brightness value is at a midpoint between low and high, the reflected ambient light 124 is also at a midpoint. Therefore, the electronic control unit 94 adjusts the edge value level to a midpoint between almost black and transparent.

[0048] Figures 3A to 3E Example segments of graphical images 116 as seen at various edge mask intensity values ​​according to one or more exemplary embodiments are shown. Figure 3A An edge mask intensity value of 0.00 is shown (e.g., dark edge pixel 118a). Figure 3B The edge mask intensity value is shown as 0.25 (brighter edge pixel 118b). Figure 3C The edge mask intensity value is shown as 0.50 (even brighter edge pixels 118c). Figure 3D The edge mask intensity value is shown as 0.75 (particularly bright edge pixel 118d). Figure 3E An edge mask strength value of 1.00 is shown (e.g., transparent edge pixel 118e).

[0049] As ambient lighting increases, dynamic edge enhancement amplifies the effect of dark (or "black") edges. In various implementations, a black edge is not simply RGB=0. The edge mask can be adjusted using a variable multiplier ranging from 0 to 1 (e.g., 0.25). A value of 0.00 will result in the current edge-finding technique, while a value of 1.00 will essentially disable edge processing (RGB x 1.0 = RGB, without changing the background). Any value in between will alter the edge intensity. It's important to note that the intermediate intensity of the edge pixels is not black, but rather a lower value level of the original background color adjacent to the edge.

[0050] Figure 4A schematic functional block diagram of an exemplary implementation of an electronic control unit 94 according to one or more exemplary embodiments is shown. The electronic control unit 94 typically includes a video generator 140, circuitry 150, and a microcontroller 200. The video generator 140 generates and provides an input video signal 142 to the circuitry 150. The circuitry 150 generates and transmits a frame histogram to the microcontroller 200. An encapsulation signal 206 is generated by the microcontroller 200 and received by the circuitry 150. The circuitry 150 generates an output video signal 106 and presents the output video signal to a display 100x.

[0051] Circuit 150 includes a first conversion circuit 152, a second conversion circuit 160, a frame histogram circuit 164, a multi-line buffer circuit 168, an edge detection circuit 172, a grayscale allocation circuit 176, a dynamic edge enhancement circuit 180, a third conversion circuit 182, a package logic circuit 184, and a dual-port random access memory (RAM) circuit 188.

[0052] The microcontroller 200 includes a grayscale transfer circuit 202 and an edge mask intensity circuit 204. The grayscale transfer circuit 202 and the edge mask intensity circuit 204 together generate an encapsulation signal 206. The encapsulation signal 206 is presented to an encapsulation logic circuit 184. The edge mask intensity circuit 204 also receives a light background signal 110 and multiple parameters (e.g., nighttime brightness threshold, daytime brightness threshold, and gamma value).

[0053] RGB video signal 154 is generated from input video signal 142 by first conversion circuit 152 (e.g., LVDS to RGB conversion) and passed to second conversion circuit 160. Video signal 156 is generated from input video signal 142 by first conversion circuit 152 and passed to grayscale distribution circuit 176. Luminosity video signal 162 is generated from RGB video signal 154 by second conversion circuit 160 and passed to frame histogram circuit 164 and multi-line buffer circuit 168. Frame histogram circuit 164 passes the frame histogram in luminosity transfer histogram signal 166 to both grayscale transfer circuit 202 and edge mask intensity circuit 204.

[0054] Multi-line buffer circuit 168 generates a buffered signal 170 received by edge detection circuit 172. Edge detection signal 174 is generated by edge detection circuit 172 and passed to dynamic edge enhancement circuit 180. Grayscale allocation circuit 176 generates grayscale allocation table signal 178, which is presented to dynamic edge enhancement circuit 180. Encapsulation signal 206 is passed from the combination of grayscale transfer circuit 202 and edge mask intensity circuit 204 to encapsulation logic circuit 184. Encapsulation logic circuit 184 passes grayscale transfer signal 186 and edge mask intensity signal 187 to dual-port RAM circuit 188. Buffered grayscale transfer signal 190 is sent from dual-port RAM circuit 188 to grayscale allocation circuit 176. Buffered edge mask intensity signal 192 is passed from dual-port RAM circuit 188 to dynamic edge enhancement circuit 180. Dynamic edge enhancement circuit 180 performs edge enhancement and true color correction to produce enhanced video signal 181. The enhanced video signal 181 is passed to the third conversion circuit 182. The third conversion circuit 182 converts the video (e.g., RGB to LVDS conversion) to produce the output video signal 106.

[0055] Video generator 140 implements a graphics processor. Video generator 140 is operable to generate input video signal 142. Input video signal 142 typically transmits a graphic image to be displayed on display 100x.

[0056] Circuit 150 implements edge detection and dynamic edge enhancement circuitry. In various embodiments, circuit 150 can be implemented as a field-programmable gate array (FPGA). Circuit 150 is operable to generate a grayscale histogram of frames in the input video signal 142, buffer multiple rows of the frames, detect edges in the frames, dynamically enhance the detected edges, and present the dynamically enhanced frames (e.g., graphics) in the output video signal 106.

[0057] Microcontroller 200 implements one or more processor circuits. Microcontroller 200 is operable to generate a grayscale transfer table and corresponding edge mask intensity values. The grayscale transfer table and edge mask intensity values ​​are bundled in an encapsulation signal 206 and passed to circuit 150. In various embodiments, the encapsulation signal may be an 8-bit (0-255) value that is a function of a light background signal 110, a nighttime brightness threshold 210, a daytime brightness threshold 212, and a gamma value 214.

[0058] The example implementation of the dynamic edge enhancement system has two parts. First, the edge mask intensity is determined using microcontroller 200 relative to the background luminance (LBG). For this purpose, Equation 1 is implemented in the edge mask intensity circuit 204, as follows: Figure 4 As shown. In various implementation schemes, T Night、 T DayThe gamma (γ) is fixed at 30, 530, and 2.2, respectively, and can be manually adjusted using a graphical user interface feature. Other values ​​can be implemented to meet the design criteria of specific applications. Once the edge mask strength is determined, it is placed in the second byte of a 517-byte packet to be sent to circuit 150 along with control signals, a frame counter, and a transfer function.

[0059] Circuit 150 receives the edge mask intensity from packaged logic circuit 184 and parses the edge mask intensity signal 187. Edge enhancement can now be performed in dynamic edge enhancement circuit 180. Dynamic edge enhancement technology considers two cases: edge pixels and non-edge pixels. For edge pixels, when edge enhancement is enabled, RGB subpixels can be multiplied by the edge mask intensity value and divided by 256 (this division is to scale the RGB subpixel values ​​by 0 to 1). When edge enhancement is disabled, no scaling is performed, and normal RGB subpixels are allocated.

[0060] Figure 5 Figure 220 shows an example transfer function of the edge mask intensity value as a function of the ambient light value. Figure 220 has an x-axis 222 and a y-axis 224. The x-axis 222 can be in units of ambient light value. The y-axis 224 can be in units of edge mask intensity value. Curve 226 illustrates the example transfer function. The relationship between the edge mask intensity value and the light background signal 110 typically has the following properties.

[0061] A nighttime brightness threshold of 210 (e.g., TNight) establishes a lower threshold below which no mask is visible (e.g., edge mask intensity value = 1.00). A daytime brightness threshold of 212 (e.g., Tday) establishes an upper limit threshold above which the edge mask is dark (e.g., edge mask intensity value = 0).

[0062] The transfer function curve 226 rapidly decreases from a nighttime intensity of 1.00 (e.g., a transparent edge) to a daytime intensity of 0.00 (e.g., a black edge), and the negative slope of the transfer function curve 226 decreases as it approaches the daytime brightness threshold 212. The basic formula for the intensity determination function is provided as follows according to Equation 1: Where γa is the first gamma value, 214.

[0063] Dynamic edge enhancement preserves background color at the edges. Color is preserved by multiplying the red, green, and blue grayscale values ​​by the same "intensity" value, except for the lowest grayscale, which may be rounded. However, since the lowest grayscale is close to black, rounding may not be significant. The "intensity" multiplication can be performed before or after color correction. The brightness of each RGB subpixel is shown in Equation 2-4 as follows: Where "L" represents luminance, "GS" represents grayscale, and "γb" is the second gamma value. In various embodiments, the value used for γa may differ from the value used for γb. In some embodiments, the value used for γa may be the same as the value used for γb.

[0064] If each grayscale value is multiplied by the intensity value "s", then equations 2 to 4 are transformed into equations 5 to 7, as follows: Color typically depends on the brightness ratio, so if a secondary color is a mixture of two other colors (e.g., red and green), the brightness ratio R can be determined according to Equation 8 as follows: Note that dividing Equation 2 by Equation 3 yields the same result, proving that the color coordinates will be preserved. In various implementations, the "intensity" multiplication can be applied after image enhancement.

[0065] Figure 6 Figure 240 illustrates an example display brightness as a function of input grayscale according to one or more exemplary embodiments. Figure 240 has a first axis 242 and a second axis 244. The first axis 242 generally shows the input grayscale available in the input video signal 142. The second axis 244 shows the display brightness in nits. Nits can be candela per square meter (cd / m²). 2 ) measurement.

[0066] Curve 246 shows the display gamma at 1000 nits. For bright (or high) grayscale (e.g., for an 8-bit image, greater than about 200 in a maximum of 255), the display brightness ranges from about 600 nits at grayscale 200 to about 1000 nits at a maximum grayscale 255. For dark (or low) grayscale (e.g., less than about 50), the display brightness changes very little with grayscale and remains close to zero nits.

[0067] Curve 248 shows the display gamma at 500 nits. For bright (or high) grayscales (e.g., greater than about 200 out of a maximum of 255), the range of display brightness can be from about 300 nits at a grayscale of 200 to about 500 nits at a grayscale of 255. For dark (or low) grayscales (e.g., less than about 50), the display brightness changes little with the change in grayscale and remains close to zero nits. Other ranges of grayscales and / or other subdivisions of this range into bright, intermediate, and dark can be implemented to meet the design criteria of specific applications.

[0068] The problem with automatic brightness control is that dark grayscales are not very visible under various ambient light conditions. Merely increasing the display brightness has little effect on the visibility of dark grayscales, mainly due to the nature of the gamma function (γ) used in displays 100a - 100c, according to Equation 9 below: where GS is a specific grayscale, GSmax is the maximum grayscale of the image received by the display, L max is the maximum brightness of the display, γ is the gamma function of display 100x, and L GrayShade is the display brightness at a specific grayscale GS.

[0069] Most of the pixels in many automotive images are in dark grayscales (e.g., GS < about 50) and intermediate grayscales (e.g., about 51 < GS < about 200), and a few pixels have higher (bright) grayscale content (e.g., GS > about 200). Therefore, for good visibility of dark and intermediate grayscales, the dark grayscale level and the intermediate grayscale level are dynamically adjusted upward to higher grayscale levels as a function of the ambient light conditions. This dynamic adjustment is called dynamic image enhancement (DIA). Dynamic image enhancement can be achieved by measuring the current light conditions and dynamically adjusting the image content for image visibility. In the case of combining dynamic image enhancement with automatic brightness control, the displayed image can remain visible under various light conditions, and the peak white brightness can be adjusted for comfortable viewing. Limiting the peak white brightness provides the benefit of reducing display power consumption.

[0070] Figure 7 FIG. 260 shows an example enhancement of grayscale according to one or more exemplary embodiments. FIG. 260 has a first axis 262 and a second axis 264. The first axis 262 generally shows the input grayscale available in the input video signal 142. The input grayscale in the example has a range of 0 to 255. The second axis 264 shows the output grayscale available in the output video signal 106. The output grayscale in the example also has a range of 0 to 255. Other ranges of grayscales (e.g., for a 10 - bit image, 0 to 1023) can be implemented to meet the design criteria of specific applications.

[0071] Curve 266 (e.g., a straight line) illustrates the non-enhanced grayscale transfer from the input video signal 142 to the output video signal 106. Each grayscale in the output video signal 106 matches the corresponding grayscale in the input video signal 142. In typical automotive applications, a small percentage (e.g., <5%) of the image in the input video signal 142 will have grayscale content further to the right (e.g., brighter) than line 270 in the bright grayscale region 278. Most of the grayscale content is typically in the dark grayscale region 274 between zero grayscale and line 272, and in the intermediate grayscale region 276 between line 270 and line 272.

[0072] Curve 268 illustrates the enhanced grayscale transfer from the input video signal 142 to the output video signal 106. This enhancement increases the output grayscale in the dark grayscale region 274 and the mid-grayscale region 276, while keeping the bright grayscale region 278 almost unchanged. Therefore, the dark and mid-grayscale values ​​are brighter on the display 100x, making them easier for the driver 98 to see under brighter lighting conditions.

[0073] Figure 8 A schematic diagram of an example Munsell color system 300 according to an exemplary embodiment is shown. The Munsell color system 300 defines a color space based on hue 302 (or color), chroma 304 (or saturation), and value 306 (or color intensity). When applied to edges under low ambient light conditions, edges can be eliminated by adjusting the value 306 of the edge pixels to match the local background color. For example, if the local background color has a hue 302 of purple-blue 310, a value of 5 (cylinder 312), and a chroma 304 value of 6 (wedge 314), the edge pixels can be adjusted to the same purple-blue, value 5, and chroma 6. When applied to edges under high ambient light conditions, edge pixels can be darkened by decreasing the value 306 of the edge pixels.

[0074] Embodiments of this disclosure typically provide a dynamic edge detection system and / or method that dynamically enhances symbol edges based on ambient lighting conditions. Edge enhancement is not advantageous under nighttime lighting conditions because it introduces image artifacts that do not contribute to image visibility. As reflective ambient lighting conditions increase, increasing the visibility of dark boundaries around the symbol becomes helpful.

[0075] Those skilled in the art will recognize that terms such as “above,” “below,” “front,” “back,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively herein without implying any limitation on the scope of this disclosure. Furthermore, this teaching may describe functional and / or logical block components and / or various processing steps. Such block components may consist of various hardware components, software components executing on hardware, and / or firmware components executing on hardware.

[0076] The foregoing detailed description and accompanying drawings support and illustrate this disclosure, but the scope of this disclosure is defined only by the claims. As will be understood by those skilled in the art, various alternative designs and embodiments may exist to practice the disclosure as defined in the appended claims.

Claims

1. A dynamic edge enhancement system, comprising: A light sensor operable to generate a light background signal by measuring ambient light falling on the display; The circuit is operable to: Generate a histogram of grayscale values ​​for multiple frames of the input video signal received by the circuit; Detect multiple edges in the input video signal; In response to the grayscale transfer table and edge mask intensity values, the plurality of edges are enhanced; as well as After enhancing the plurality of edges, an output video signal suitable for driving the display is generated; as well as A microcontroller, operable to: The grayscale transfer table is generated based on the histogram generated by the circuit. as well as The edge mask intensity value is generated in response to the grayscale transfer table, the light background signal, the nighttime brightness threshold, and the daytime brightness threshold.

2. The dynamic edge enhancement system according to claim 1, wherein: The circuit enhances the elimination of the plurality of edges in response to a maskless value received from the edge mask intensity value.

3. The dynamic edge enhancement system according to claim 2, wherein: The microcontroller is further operable to set the edge mask intensity value to the no-mask value in response to the light background signal being darker than the nighttime brightness threshold.

4. The dynamic edge enhancement system according to claim 2, wherein: The circuit enhances the plurality of edges by darkening them in response to the full mask value received from the edge mask intensity value.

5. The dynamic edge enhancement system according to claim 4, wherein: The microcontroller is further operable to set the edge mask intensity value to the full mask value in response to the light background signal being brighter than the daytime brightness threshold.

6. The dynamic edge enhancement system according to claim 4, wherein: The plurality of edges that are eliminated in response to the maskless value approximately match the local background color in the input video signal; The plurality of edges, darkened in response to the full mask value, approximately match the zero-value version of the local background color in the Munsell color system; and The plurality of edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the no-mask value and the full-mask value.

7. The dynamic edge enhancement system according to claim 4, wherein: As the light background signal varies between the nighttime brightness threshold and the daytime brightness threshold, the negative slope of the transfer function curve of the edge mask intensity value decreases as the transfer function curve approaches the daytime brightness threshold.

8. The dynamic edge enhancement system according to claim 1, wherein: The plurality of edges are detected when the contrast is greater than the edge threshold.

9. The dynamic edge enhancement system according to claim 1, wherein, The display is part of the vehicle.

10. A method for dynamic edge enhancement, comprising: A light background signal is generated by measuring the ambient light falling on the display using a light sensor; Generate a histogram of grayscale values ​​for multiple frames of the input video signal received by the circuit; A grayscale transfer table is generated based on the histogram; In response to the grayscale transfer table, the light background signal, the nighttime brightness threshold, and the daytime brightness threshold, an edge mask intensity value is generated using a microcontroller; Detect multiple edges in the input video signal; In response to the grayscale transfer table and the edge mask intensity value, the plurality of edges in the input video signal are enhanced; as well as After enhancing the plurality of edges, an output video signal suitable for driving the display is generated.

11. The method of claim 10, wherein: The enhancement of the plurality of edges in response to the unmasked value received by the edge mask intensity value eliminates the plurality of edges.

12. The method of claim 11, further comprising: In response to the light background signal being darker than the nighttime brightness threshold, the edge mask intensity value is set to the no-mask value.

13. The method according to claim 11, wherein: The enhancement darkens the plurality of edges in response to the full mask value received by the edge mask intensity value.

14. The method of claim 13, further comprising: In response to the background light signal being brighter than the daytime brightness threshold, the edge mask intensity value is set to the full mask value.

15. The method according to claim 13, wherein: The plurality of edges that are eliminated in response to the maskless value approximately match the local background color in the input video signal; The plurality of edges, darkened in response to the full mask value, approximately match the zero-value version of the local background color in the Munsell color system; and The plurality of edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the no-mask value and the full-mask value.

16. The method of claim 13, wherein: As the light background signal varies between the nighttime brightness threshold and the daytime brightness threshold, the negative slope of the transfer function curve of the edge mask intensity value decreases as the transfer function curve approaches the daytime brightness threshold.

17. The method of claim 10, wherein: The plurality of edges are detected when the contrast is greater than the edge threshold.

18. The method of claim 10, wherein the enhancement of the plurality of edges in the input video signal is performed in a vehicle.

19. A vehicle comprising: monitor; A light sensor operable to generate a light background signal by measuring ambient light falling on the display; as well as Electronic control unit, the electronic control unit being operable to: Generate a histogram of grayscale values ​​for multiple frames of the input video signal received by the electronic control unit; A grayscale transfer table is generated based on the histogram; The edge mask intensity value is generated in response to the grayscale transfer table, the light background signal, the nighttime brightness threshold, and the daytime brightness threshold. Detect multiple edges in the input video signal; In response to the grayscale transfer table and the edge mask intensity value, the plurality of edges are enhanced; as well as After enhancing the plurality of edges, an output video signal is generated to drive the display.

20. The vehicle according to claim 19, wherein: The plurality of edges that are eliminated in response to the unmasked value of the edge mask intensity value approximately match the local background color in the input video signal; The plurality of edges, darkened in response to the full mask value of the edge mask intensity value, approximately match the zero-value version of the local background color in the Munsell color system; and The plurality of edges are adjusted to a value level between the local background color and the zero-value version of the local background color, wherein the edge mask intensity value is between the no-mask value and the full-mask value.

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