Abstract: This document describes techniques and apparatuses for performing color calibration of display modules using a reduced number of display characteristic measurements. In aspects, methods include generating a measured lookup table (50) for a source display module (32), using dynamic optimization to down-sample the measured lookup table and select a set of color patches, sending the color patches to a testing display module; measuring output values for the testing display module; generating a sparse lookup table (52) relating the color patches and the measured output values, up-sampling the sparse lookup table to a forward lookup table (54), and inverting the forward lookup table to generate a reverse lookup table (56). The reverse lookup table (56) can be utilized to determine correct output values (29) for driving a target display module to generate color lights within a display module color gamut.

Abstract: This document describes techniques and apparatuses for performing color calibration of display modules using a reduced number of display characteristic measurements. In aspects, methods include generating a measured lookup table (50) for a source display module (32), using dynamic optimization to down-sample the measured lookup table and select a set of color patches, sending the color patches to a testing display module; measuring output values for the testing display module; generating a sparse lookup table (52) relating the color patches and the measured output values, up-sampling the sparse lookup table to a forward lookup table (54), and inverting the forward lookup table to generate a reverse lookup table (56). The reverse lookup table (56) can be utilized to determine correct output values (29) for driving a target display module to generate color lights within a display module color gamut.

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 be provided with a display mounted in a housing. A color sensing ambient light sensor may measure the color of ambient light. The color sensing ambient light sensor may produce sensor output signals in a device-dependent color space. Control circuitry in the electronic device may convert the sensor output signals from the device-dependent color space to a device-independent color space using a color converting matrix. The color converting matrix may be determined using stored training data. The training data may include color data for different training light sources. The training data may be weighted to selectively control the influence of the training data on the color converting matrix. The training data may be weighted based on a distance between the training color data and a target color in the detected ambient light.

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 be provided with a display mounted in a housing. A color sensing ambient light sensor may measure the color of ambient light. The color sensing ambient light sensor may produce sensor output signals in a device-dependent color space. Control circuitry in the electronic device may convert the sensor output signals from the device-dependent color space to a device-independent color space using a color converting matrix. The color converting matrix may be determined using stored training data. The training data may include color data for different training light sources. The training data may be weighted to selectively control the influence of the training data on the color converting matrix. The training data may be weighted based on a distance between the training color data and a target color in the detected ambient light.