Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: An electronic device may have a display. The display may have light-emitting diode pixels or other pixels. Due to aging-induced degradation of the pixels, the output intensity and color of the pixels may vary over the lifetime of the display. Control circuitry in the device may use an ambient light sensor to measure ambient light and stray display light. The display light measurements may be used in monitoring aging effects so that the control circuitry can compensate for aging-induced pixel degradation. Display light measurements may be made over a sequence of image frames. The image frames in the sequence of frames may include white and black frames or frames of different colors interleaved with black frames. Different frame intensities may be used during measurements of stray display light to gather gamma curves for the display.

Abstract: An electronic device may have a display with an array of pixels configured to display images for a user. The electronic device may have an ambient light sensor for gathering ambient light information. A set of the pixels may overlap the ambient light sensor so that ambient light measurements may be made on ambient light passing through the set of pixels. Control circuitry in the electronic device may control light transmission through the set of pixels so that different light transmission levels can be used in different ambient light conditions. Directional light measurements may be made by moving transparent pixels dynamically across the surface of the display overlapping the light sensor and/or by using pixelated light modulators to vary the angle of light rays measured by the ambient light sensor.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: An electronic device such as a portable electronic device may include a single-shot alignment-free spectrometer with no moving parts. The spectrometer may include a diffractive member, such as a grating, an aperture, and an image sensor that generates data in response to incident light. The diffractive member may diffract the incident light based on its wavelength and angle of incidence, and the aperture may further encode the light. The data generated by the image sensor may be used by control circuitry in combination with correlations between spectrometer measurements and known light profiles to determine the wavelength and angle of incidence of the light. These correlations may be determined using a deep neural network. Control circuitry may adjust one or more settings of the electronic device based on the wavelength and angle of incidence, or may use the wavelength and angle of incidence to determine information regarding an external object.

Abstract: An electronic device such as a portable electronic device may include a single-shot alignment-free spectrometer with no moving parts. The spectrometer may include a diffractive member, such as a grating, an aperture, and an image sensor that generates data in response to incident light. The diffractive member may diffract the incident light based on its wavelength and angle of incidence, and the aperture may further encode the light. The data generated by the image sensor may be used by control circuitry in combination with correlations between spectrometer measurements and known light profiles to determine the wavelength and angle of incidence of the light. These correlations may be determined using a deep neural network. Control circuitry may adjust one or more settings of the electronic device based on the wavelength and angle of incidence, or may use the wavelength and angle of incidence to determine information regarding an external object.

Abstract: A device such as a computer stylus may have a color sensor. The color sensor may have a plurality of photodetectors each of which measures light for a different respective color channel. The color sensor may also have one or more light-emitting devices. Control circuitry may use the light-emitting devices to illuminate an external object while using the photodetectors to measure reflected light to determine the color of the external object. The electronic device may have a housing with an elongated shaft. The shaft may have a tip and an opposing end. The tip may be configured to emit electromagnetic signals that are detected by a touch sensor in a touch sensitive display. The color sensor may be located at the end opposite the tip, may be located at the tip, or may be optically coupled to the tip using a light guide.

Abstract: A display may include pixels (such as light-emitting diode pixels) that are susceptible aging effects (burn-in). To help avoid visible artifacts caused by burn-in during operation of the display, compensation circuitry may be used to compensate image data for the display. An optical sensor may be included behind the pixels to directly measure pixel brightness levels. The optical sensor may provide optical sensor data from testing operations to the compensation circuitry. The optical sensor may gather data during burn-in testing operations. During the burn-in testing operations, pixel groups including both high-usage pixels and low-usage pixels may sequentially emit light while the optical sensor gathers data. Brightness differences between the high-usage pixels and low-usage pixels may be used to characterize pixel aging in the display and compensate image data to mitigate visible artifacts caused by burn-in. The optical sensor may also gather data during global brightness testing operations.

Abstract: A device such as a computer stylus may have a color sensor. The color sensor may have a plurality of photodetectors each of which measures light for a different respective color channel. The color sensor may also have one or more light-emitting devices. Control circuitry may use the light-emitting devices to illuminate an external object while using the photodetectors to measure reflected light to determine the color of the external object. The electronic device may have a housing with an elongated shaft. The shaft may have a tip and an opposing end. The tip may be configured to emit electromagnetic signals that are detected by a touch sensor in a touch sensitive display. The color sensor may be located at the end opposite the tip, may be located at the tip, or may be optically coupled to the tip using a light guide.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: An electronic device may have a display. The display may have light-emitting diode pixels or other pixels. Due to aging-induced degradation of the pixels, the output intensity and color of the pixels may vary over the lifetime of the display. Control circuitry in the device may use an ambient light sensor to measure ambient light and stray display light. The display light measurements may be used in monitoring aging effects so that the control circuitry can compensate for aging-induced pixel degradation. Display light measurements may be made over a sequence of image frames. The image frames in the sequence of frames may include white and black frames or frames of different colors interleaved with black frames. Different frame intensities may be used during measurements of stray display light to gather gamma curves for the display.

Abstract: An electronic device may have a display with an array of pixels configured to display images for a user. The electronic device may have an ambient light sensor for gathering ambient light information. A set of the pixels may overlap the ambient light sensor so that ambient light measurements may be made on ambient light passing through the set of pixels. Control circuitry in the electronic device may control light transmission through the set of pixels so that different light transmission levels can be used in different ambient light conditions. Directional light measurements may be made by moving transparent pixels dynamically across the surface of the display overlapping the light sensor and/or by using pixelated light modulators to vary the angle of light rays measured by the ambient light sensor.

Abstract: A device such as a computer stylus may have a color sensor. The color sensor may have a plurality of photodetectors each of which measures light for a different respective color channel. The color sensor may also have one or more light-emitting devices. Control circuitry may use the light-emitting devices to illuminate an external object while using the photodetectors to measure reflected light to determine the color of the external object. The electronic device may have a housing with an elongated shaft. The shaft may have a tip and an opposing end. The tip may be configured to emit electromagnetic signals that are detected by a touch sensor in a touch sensitive display. The color sensor may be located at the end opposite the tip, may be located at the tip, or may be optically coupled to the tip using a light guide.

Abstract: A handheld imaging device has a data receiver that is configured to receive reference encoded image data. The data includes reference code values, which are encoded by an external coding system. The reference code values represent reference gray levels, which are being selected using a reference grayscale display function that is based on perceptual non-linearity of human vision adapted at different light levels to spatial frequencies. The imaging device also has a data converter that is configured to access a code mapping between the reference code values and device-specific code values of the imaging device. The device-specific code values are configured to produce gray levels that are specific to the imaging device. Based on the code mapping, the data converter is configured to transcode the reference encoded image data into device-specific image data, which is encoded with the device-specific code values.

Abstract: Shape reconstruction of physical objects using structured light patterns and multiple layers of movable sheets which each include a transparent region and a pattern region. Shape reconstruction of specular regions on the surface of the object may proceed by a first phase in which a first sheet is moved to the pattern region and all other sheets are moved to the transparent region, and a first sequence of images is captured for patterns projected on the pattern region of the first sheet; and by a second phase in which the first sheet is moved to the transparent region and all other sheets are moved to the pattern region, and a second sequence of images is captured for patterns projected on the pattern region of the second sheet. Based on the captured images, the shape of the surface of an object, particularly objects having a mirror-like or specular surface having at least some specular characteristics, is reconstructed.