Abstract: An electronic device may be provided with a display, display control circuitry that operates the display, and a color ambient light sensor that gathers ambient light information. Display color cast may be adjusted based on the ambient light information. When the color of ambient light is within an acceptable range of colors, the color cast of the display may be adjusted to more closely match the color of ambient light. When the color of ambient light is outside of the acceptable range of colors, display control circuitry may determine an adjusted ambient light color that is within the acceptable range. The adjusted ambient light color may have the same color temperature as the measured ambient light color. After determining an adjusted ambient light color that is within the acceptable range, the color cast of the display may be adjusted to more closely match the adjusted ambient light color.

Abstract: An electronic device may have a display. Input-output circuitry in the electronic device may be used to gather input from a viewer of the display. The input-output circuitry may include a gaze tracking system that gathers point-of-gaze information, vergence information, and head position information, may be a biometric sensor, may be an input device such as a button or touch sensor, may capture hand gestures, and/or may gather other information. The display may include a pixel array for producing images. An adjustable reflectance and transmittance layer may overlap the pixel array. Control circuitry in the electronic device may individually adjust different areas of the adjustable reflectance and transmittance layer. The control circuitry may place each area in a reflective mirror more or in a content-displaying mode and may move the areas in response to the information.

Abstract: An electronic device may be provided with a display mounted in a housing. An ambient light sensor may measure the color of ambient light through an ambient light sensor window in the display. The ambient light sensor may have an array of light detectors on a semiconductor die. The light detectors may include color matching function light detectors that have spectral sensitivity profiles that match standard observer color matching functions and may include spectral sensing light detectors. The spectral sensing light detectors may have narrower full width at half maximum bandwidths than the color matching function light detectors and may be used with the color matching function light detectors to measure an ambient light spectrum. The color matching function light detectors may be used to measure the color of ambient light.

Abstract: An electronic device may include a display having an array of display pixels and having display control circuitry that controls the operation of the display. The display control circuitry may adaptively adjust the spectral characteristics of display light emitted from the display to achieve a desired effect on the human circadian system. For example, the display control circuitry may adjust the spectral characteristics of blue light emitted from the display based on the time of day such that a user's exposure to the display light may result in a circadian response similar to that which would be experienced in natural light. The spectral characteristics of blue light emitted from the display may be adjusted by adjusting the relative maximum power levels provided to blue pixels in the display or by shifting the peak wavelength associated with blue light emitted from the display.

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,7 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: An electronic device may include a display for displaying image content to a user and dynamic image stabilization circuitry for dynamically compensating the image content if the device is moving unpredictably to help keep the image content aligned with the user's gaze. The electronic device may include sensors for detecting the displacement of the device. The dynamic image stabilization circuitry may include a usage scenario detection circuit and a content displacement compensation calculation circuit. The usage scenario detection circuit receives data from the sensors and infers a usage scenario based on the sensor data. The content displacement compensation calculation circuit uses the inferred usage scenario to compute a displacement amount by which to adjust image content. When motion stops, the image content may gradually drift back to the center of the display.

Abstract: An electronic device may be provided with a display. Standard and high dynamic range content may be produced by content generators operating on control circuitry. In a first mode of operation, standard dynamic range content is displayed. In a second mode of operation, high dynamic range content is displayed. In a third mode of operation, standard dynamic range content and high dynamic range content are simultaneously displayed. Tone mapping parameters may be produced by a tone mapping engine for use in displaying the standard and high dynamic range content. The tone mapping parameters may be selected based on factors such as ambient light level, user brightness setting, content statistics, and display characteristics. Tone mapping parameters may be selected to accommodate simultaneous display of standard and high dynamic range content and to accommodate transitions between standard and high dynamic range content.

Abstract: Systems, methods, and computer readable media to improve the operation of electronic display systems. Techniques for inverse tone mapping operations for selected standard dynamic range (SDR) images are described. The converted images may be presented on high dynamic range (HDR) displays so as to increase a user's viewing experience (through an expanded dynamic range) while preserving the artistic content of the displayed information. Techniques disclosed herein selectively transform SDR images to HDR images by determining if the SDR images were created from HDR images (e.g., through the fusion of multiple SDR images) and if their quality is such as to permit the conversion without introducing unwanted visual artifacts. The proposed techniques apply a sigmoidal inverse tone mapping function configured to provide a perceptual-based tone mapping. Values for the function's tuning parameters may be set based on what may be determined about the original HDR-to-SDR mapping operation.

Abstract: An electronic device may have a display and a gaze tracking system. Control circuitry in the electronic device can produce a saliency map in which items of visual interest are identified among content that has been displayed on a display in the electronic device. The saliency map may identify items such as selectable buttons, text, and other items of visual interest. User input such as mouse clicks, voice commands, and other commands may be used by the control circuitry in identifying when a user is gazing on particular items within the displayed content. Information on a user's actual on-screen point of gaze that is inferred using the saliency map information and user input can be compared to measured eye position information from the gaze tracking system to calibrate the gaze tracking system during normal operation of the electronic device.

Abstract: Scalable color balancing techniques for processing images to be presented on displays are described. One technique includes receiving ambient light color information from an ambient light sensor and input image data to be presented via a display coincident with receiving the ambient light color information. The display may have a first white point at a time prior to receiving the input image data. The technique may include determining a second white point for the display based on the input image data and the ambient light color information. The first and second white points may differ from each other. The technique may also include generating one or more chromatic adaptation transforms (CATs) based on the white points. Output image data may be generated based on applying the one or more CATs to the input image data. The output image data may be presented via the display. Other embodiments are described.

Abstract: An electronic device may be provided with a display mounted in a housing. Color ambient light sensors may make measurements of ambient light intensity and color through windows in an inactive border region of the display or other portions of the device. The electronic device may process the ambient light measurements based on ambient light information from the ambient light sensors and based on information from additional sensors such as an image sensor, a force sensor, a capacitive touch sensor, a proximity sensor, an orientation sensor, and other devices. Control circuitry in the electronic device may produce reliable ambient light measurements by combining readings from multiple reliable sources and by discarding readings from ambient light sensors that are blocked by a user's fingers or other external objects. Display color cast and intensity may be adjusted based on ambient light information.

Abstract: An electronic device may be provided with a display having a backlight with light sources of different colors. The electronic device may include a color ambient light sensor that measures the color of ambient light and control circuitry that adjusts the color of light emitted from the backlight based on the color of ambient light. The light sources may include at least first and second light-emitting diodes that emit light having different color temperatures. The control circuitry may adjust the intensity of light emitted from the first light-emitting diode relative to the intensity of light emitted from the second light-emitting diode to produce a backlight color that more closely matches the color of ambient light. The first and second light-emitting diodes may include an ultraviolet light-emitting diode die and a blue light-emitting diode die that are mounted in a common semiconductor package.

Abstract: An electronic device may include a display having an array of display pixels and having display control circuitry that controls the operation of the display. The display control circuitry may operate the display in different modes. In a paper mode, display control circuitry may use stored spectral reflectance data to adjust display colors such that the colors appear as they would on a printed sheet of paper. In a low light mode when the ambient light level is below a threshold, the light emitted from the display may be adjusted to mimic the appearance of an incandescent light source. In a bright light mode when the ambient light level exceeds a threshold, the light emitted from the display may be adjusted to maximize readability in bright light. The target white point of the display may be adjusted based on which mode the display is operating in.

Abstract: An electronic device may generate content that is to be displayed on a display. The display may have an array of pixels each of which includes subpixels of different colors. The content that is to be displayed on the display may include an object such as a black object that is moved across a background. Due to differences in subpixel values in the background for subpixels of different colors, there is a potential for color motion blur to develop along a trailing edge portion of the object as the object is moved across the background. The electronic device may have a blur abatement image processor that processes the content to reduce color motion blur. The blur abatement image processor may identify which pixels are located in the trailing edge and may adjust subpixel values for pixels in the trailing edge.

Abstract: An electronic device may be provided with a display mounted in a housing. Color ambient light sensors may make measurements of ambient light intensity and color through windows in an inactive border region of the display or other portions of the device. The electronic device may process the ambient light measurements based on ambient light information from the ambient light sensors and based on information from additional sensors such as an image sensor, a force sensor, a capacitive touch sensor, a proximity sensor, an orientation sensor, and other devices. Control circuitry in the electronic device may produce reliable ambient light measurements by combining readings from multiple reliable sources and by discarding readings from ambient light sensors that are blocked by a user's fingers or other external objects. Display color cast and intensity may be adjusted based on ambient light information.

Abstract: An electronic device may have a main display and an ancillary display that forms a dynamic function row. The device may also have a backlit keyboard with glyphs. The keyboard may have light-emitting diodes that emit backlight illumination. The backlight illumination has a backlight illumination color and intensity. A color ambient light sensor may measure ambient light color and intensity. Control circuitry in the laptop computer may make white point adjustments to the main and ancillary displays. White point adjustments may be made based on factors such as the backlight illumination intensity, information on the nominal white point of a display (which may be comparable to the color of the backlight illumination), information on the ambient light color and intensity, and a white point adaptation scaling factor.

Abstract: An electronic device may have components that experience performance variations as the device changes orientation relative to a user. Changes in the orientation of the device relative to the user can be monitored using a motion sensor. A camera may be used to periodically capture images of a user's eyes. By processing the images to produce accurate orientation information reflecting the position of the user's eyes relative to the device, the orientation of the device tracked by the motion sensor can be periodically updated. The components may include audio components such as microphones and speakers and may include a display with an array of pixels for displaying images. Control circuitry in the electronic device may modify pixel values for the pixels in the array to compensate for angle-of-view-dependent pixel appearance variations based on based on the orientation information from the motion sensor and the camera.

Abstract: An electronic device may include a display having an array of display pixels and having display control circuitry that controls the operation of the display. The display control circuitry may operate the display in different modes. In a paper mode, display control circuitry may use stored spectral reflectance data to adjust display colors such that the colors appear as they would on a printed sheet of paper. In a low light mode when the ambient light level is below a threshold, the light emitted from the display may be adjusted to mimic the appearance of an incandescent light source. In a bright light mode when the ambient light level exceeds a threshold, the light emitted from the display may be adjusted to maximize readability in bright light. The target white point of the display may be adjusted based on which mode the display is operating in.

Abstract: Scalable color balancing techniques for processing images to be presented on displays are described. One technique includes receiving ambient light color information from an ambient light sensor and input image data to be presented via a display coincident with receiving the ambient light color information. The display may have a first white point at a time prior to receiving the input image data. The technique may include determining a second white point for the display based on the input image data and the ambient light color information. The first and second white points may differ from each other. The technique may also include generating one or more chromatic adaptation transforms (CATs) based on the white points. Output image data may be generated based on applying the one or more CATs to the input image data. The output image data may be presented via the display. Other embodiments are described.

Abstract: Systems, methods, and computer readable media to improve the operation of electronic display systems are disclosed. Techniques for inverse tone mapping operations for selected standard dynamic range (SDR) images are described. The converted images may be presented on high dynamic range (HDR) displays so as to increase a user's viewing experience (through an expanded dynamic range) while preserving the artistic content of the displayed information. Techniques disclosed herein selectively transform SDR images to HDR images by determining if the SDR images were created from HDR images (e.g., through the fusion of multiple SDR images) and if their quality is such as to permit the conversion without introducing unwanted visual artifacts. The proposed techniques apply a sigmoidal inverse tone mapping function configured to provide a perceptual-based tone mapping. Values for the function's tuning parameters may be set based on what may be determined about the original HDR-to-SDR mapping operation.