Abstract: A display may have a pixel array such as a liquid crystal pixel array. The pixel array may be illuminated by a backlight unit that includes an array of light-emitting diodes (LEDs). The backlight unit may determine the type of content in the image data. The backlight unit may decide to prioritize either mitigating halo or mitigating clipping based on the type of content. The determination of the type of content in the image data may be used to determine the brightness values for the LEDs in the LED array. If the content is determined to be a first type of content, at least one given LED in the LED array may have a different brightness value than if the content is determined to be a second, different type of content. Classifying content in the image data may be useful in optimizing visible artifacts such as visible halo and clipping.

Abstract: Systems, methods, and devices are provided to reduce a likelihood of image burn-in on an electronic display. Such an electronic device may include image processing circuitry and an electronic display. The image processing circuitry may receive image data and analyze the image data for risk of image burn-in and, based at least in part on the analysis of the image data, reduce a risk of image burn-in at least in part by reducing a local maximum pixel luminance value in at least one of a plurality of regions of the image data over time or by reducing a dynamic range headroom of the image data. The electronic display may display the image data with a reduced risk of image burn-in on the pixels of the electronic display.

Abstract: A light emitting diode (LED) display can calculate a common voltage charge of a line of pixels in the LED display, the common voltage charge comprising a difference between a first line of pixels and a second line of pixels. If the calculated common voltage charge exceeds a predetermined threshold, a toggle matrix can be generated for the line of pixels. The toggle matrix can include a matrix of charge values generated by calculating a difference in charge values for each subpixel a first line of subpixels with each subpixel a second line of subpixels. The LED display can identify one or more regions of subpixels exhibiting the predetermined toggle pattern in the toggle matrix. The LED display can generate a voltage correction charge to apply to affected regions of the display. Alternatively, the subpixels or pixels could be swapped with adjacent pixels to reduce toggling or settling error.

Abstract: Aspects of the subject technology relate to an electronic device with a display. The display includes a plurality of light-emitting diodes and first and second driver circuits coupled to the plurality of light-emitting diodes. The first driver circuit is configured to receive a first pulse-width modulated (PWM) signal to control a first current mirror branch and the second driver circuit to receive a second PWM signal to control a second current mirror branch to provide an extra N bits of resolution for controlling the plurality of the light-emitting diodes.

Abstract: A display may have an active area that includes display pixels. The display may include an inactive notch region that extends into the active area. Data lines may provide image data from display driver circuitry to the display pixels. The image data may include data signals that correspond to portions of the display that do not include pixels, such as the inactive notch region. The null data signals may cause nonuniformities in the displayed image. The null data signals may be adjusted to minimize the nonuniformities. Null data signals corresponding to the inactive notch region may be adjusted to have gray levels that gradually decrease with distance from the border between the inactive notch and the active area. All of the data signals corresponding to the inactive notch may be set to a uniform gray level.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of liquid crystal display pixels for displaying image frames of the content. The image frames may be displayed with positive and negative polarities to help reduce charge accumulation effects. A charge accumulation tracker may analyze the image frames to determine when there is a risk of excess charge accumulation. The charge accumulation tracker may analyze information on gray levels, frame duration, and frame polarity. The charge accumulation tracker may compute a charge accumulation metric for entire image frames or may process subregions of each frame separately. When subregions are processed separately, each subregion may be individually monitored for a risk of excess charge accumulation.

Abstract: A display may have a pixel array such as a liquid crystal pixel array. The pixel array may be illuminated by a backlight unit that includes an array of light-emitting diodes. A backlight brightness selection circuit may select brightness values for the light-emitting diodes. The backlight brightness selection circuit may select the brightness values based on image data, based on brightness values used in previous image frames, based on device information, and/or based on sensor information. The backlight brightness selection circuit may select the backlight brightness levels to mitigate visible artifacts such as flickering and halo. The backlight levels selected by the backlight brightness selection may be modified by a power consumption compensation circuit. The power consumption compensation circuit may estimate the amount of power consumption required to operate the backlight using the target brightness levels and may modify the target brightness levels to meet maximum power consumption requirements.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of liquid crystal display pixels for displaying image frames of the content. The image frames may be displayed with positive and negative polarities to help reduce charge accumulation effects. A charge accumulation tracker may analyze the image frames to determine when there is a risk of excess charge accumulation. The charge accumulation tracker may analyze information on gray levels, frame duration, and frame polarity. The charge accumulation tracker may compute a charge accumulation metric for entire image frames or may process subregions of each frame separately. When subregions are processed separately, each subregion may be individually monitored for a risk of excess charge accumulation.

Abstract: An electronic device may be provided with a display. A content generator may generate frames of image data to be displayed on the display. Control circuitry in the electronic device may be used in implementing a tone mapping engine. The tone mapping engine may display content from the content generator on the display in accordance with a content-luminance-to-display luminance mapping. The content-luminance-to-display-luminance mapping is characterized by tone mapping parameters such as a black level, a reference white level, and a specular white level. The tone mapping engine may adjust the tone mapping parameters based on ambient light levels, user brightness settings, content statistics, and display characteristics.

Abstract: A display may have a pixel array such as a liquid crystal pixel array. The pixel array may be illuminated by a backlight unit that includes an array of light-emitting diodes. A backlight brightness selection circuit may select brightness values for the light-emitting diodes. The backlight brightness selection circuit may select the brightness values based on image data, based on brightness values used in previous image frames, based on device information, and/or based on sensor information. The backlight brightness selection circuit may select the backlight brightness levels to mitigate visible artifacts such as flickering and halo. The backlight levels selected by the backlight brightness selection may be modified by a power consumption compensation circuit. The power consumption compensation circuit may estimate the amount of power consumption required to operate the backlight using the target brightness levels and may modify the target brightness levels to meet maximum power consumption requirements.

Abstract: Systems, methods, and computer readable media to improve the operation of display systems are disclosed. In general, techniques are disclosed for dynamically adjusting backlight elements based on image content. More particularly, a backlight element's intensity may be targeted for boosting (i.e., increasing) based on content of the backlight element's corresponding image region, where after a check may be made to determine if the proposed increase is likely to risk generation of a halo. If the proposed intensity increase would risk a halo, the backlight element's proposed intensity may be dimmed. Repeating the boost/dim cycle in an iterative fashion permits an image to be displayed with brighter highlights and deeper blacks.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of liquid crystal display pixels for displaying image frames of the content. The image frames may be displayed with positive and negative polarities to help reduce charge accumulation effects. A charge accumulation tracker may analyze the image frames to determine when there is a risk of excess charge accumulation. The charge accumulation tracker may analyze information on gray levels, frame duration, and frame polarity. The charge accumulation tracker may compute a charge accumulation metric for entire image frames or may process subregions of each frame separately. When subregions are processed separately, each subregion may be individually monitored for a risk of excess charge accumulation.

Abstract: Access in a knowledge graph, comprising nodes and edges connecting two or more nodes, is controlled by assigning each node to a non-intersecting zone. A first and second zone identifier, each indicative of a zone occupied by a node where an edge ends, are each stored. Determining an access graph comprising an access node for each zone, access edges representing edges between the zones, and a first list of the zones. Each entry in the first list relates to a zone and a second list of node identifiers, each indicative of a node occupying the zone. A first and second access control list, each related to a zone where an access edge ends and to which a access node in the access graph relates, are stored in each access edge.

Abstract: Aspects of the subject technology relate to electronic devices with displays and ambient light sensors. An electronic device modifies the color of images to be displayed based on measured ambient light color. The modification is performed in a perceptually uniform color space and includes a determination of a bleaching effect of reflected ambient light, and a determination of a color correction factor to be applied within the perceptually uniform color space, based on the determined bleaching effect. The modification may also include an application of a strength factor that mitigates out-of-gamut colors in color compensated images.

Abstract: Systems and methods for improving perceived image quality of an electronic display, which includes a display region with a rounded border and a display pixel at a pixel position adjacent the rounded border. A display pipeline communicatively coupled to the electronic display receives first image data that indicates target luminance at the pixel position in a rectangular image frame; determines a gain value associated with the pixel position from a gain map, in which the gain value is inversely proportional to distance between the display pixel and the rounded border; determines second image data that indicates target luminance of the display pixel by processing the first image data based at least in part on the gain value; and outputs the second image data to the electronic display to facilitate displaying a non-rectangular portion of the image frame on the display region.

Abstract: A display may have an active area that includes display pixels. The display may include an inactive notch region that extends into the active area. Data lines may provide image data from display driver circuitry to the display pixels. The image data may include data signals that correspond to portions of the display that do not include pixels, such as the inactive notch region. The null data signals may cause nonuniformities in the displayed image. The null data signals may be adjusted to minimize the nonuniformities. Null data signals corresponding to the inactive notch region may be adjusted to have gray levels that gradually decrease with distance from the border between the inactive notch and the active area. All of the data signals corresponding to the inactive notch may be set to a uniform gray level.

Abstract: A display device may include a processor that may receive image data, such that the image data may include gray level data and display brightness value (DBV) data for a first pixel of a display. The processor may then determine a gain compensation factor associated with the first pixel based on a correction spatial map, a brightness adaptation lookup table (LUT), the gray level data, and the DBV data. The processor may then determine an offset compensation factor associated with the first pixel based on the correction spatial map, the brightness adaptation lookup table (LUT), the gray level data, and the DBV data. The processor may generate compensated gray level data by applying the gain compensation factor and the offset compensation factor to the gray level data and transmit the compensated gray level data to pixel driving circuitry associated with the first pixel.

Abstract: Systems and methods reduce likelihood of hysteresis that reduces perceived image quality of a subsequent image frame by toggling the display pixels to relax the display pixels by overwriting previous image frame data. During non-emission periods of the pixels, the pixels may be pre-toggled or exercised to improve response time and accuracy of the pixel. Data for pixels being programmed may also be used to pre-toggle other pixels reducing overhead but increasing cross-talk. Since the amount of cross-talk is related to content of the pixels being pre-toggled, a line buffer may be used to store image data for the pixels being pre-toggled. This stored image data may be used to determine how much pre-compensation is to be applied to data for the pixels being programmed. In other words, an amount of compensation applied is based at least in part on the content (e.g., greyscale levels) of the image data.

Abstract: Source content super-sampled to a first resolution in an extended range space is obtained. A representation of a subpixel geometry of a display panel displaying the source content is obtained. The display panel includes, for every pixel, plural subpixel elements for three or more color primaries. A native resolution of the display panel is lower than the first resolution of the source content. An optimization operation is performed based on a set mode of the display panel and the representation of the subpixel geometry to derive a global optimization for determining, for a given pixel value based on the source content, an energy distribution between the plurality of subpixel elements of a corresponding pixel of the display panel. The source content in the extended range space is converted into intermediate content in a display space based on the global optimization. The intermediate content is further optimized based on error minimization.

Abstract: An electronic device may be provided with a display. The display may include a backlight having an array of locally dimmable light sources. Control circuitry may provide control signals to the backlight to produce light at different brightness levels. When the brightness level is below a threshold, the control circuitry may use pulse-width-modulation control signals to control the light sources in the backlight. When the brightness level is above the brightness threshold, the control circuitry may use analog control signals to control the light sources in the backlight. The control circuitry may adjust the threshold to achieve different dimming ranges for different brightness settings. A low brightness setting, for example, may have a lower threshold and lower dimming range than a high brightness setting, which may help produce darker darks when the display operates in a low brightness setting.