Abstract: Image sensors, imaging systems, and methods for eliminating blooming artifacts in high dynamic range imaging. The image sensor includes a pixel array and a controller. The controller is configured to detect that a first pixel signal is at or below a barrier value. The first pixel signal is generated during a first exposure. The controller is also configured to compare neighboring pixel signals to the barrier value. The controller is further configured to determine a first image value for the center pixel based on a second pixel signal when at least one of the neighboring pixel signals is above the barrier value. The second pixel signal is generated during a second exposure that is shorter than the first exposure. The controller is also configured to set the first image value to the first pixel signal when each of the neighboring pixel signals is at or below the barrier value.

Abstract: Image sensors, imaging systems, and methods for high dynamic range imaging. The image sensor includes image sensor pixels, a light filter, and a controller. The light filter is configured to attenuate transmission of incident light to the image sensor pixels. The controller is configured to set the light filter to a high-transmission state and capture a first image generated by the image sensor pixels during a first exposure. The controller is also configured to set the light filter to a low-transmission state and capture a second image generated by the image sensor pixels during a second exposure. The controller is further configured to combine the first and second images to generate a high dynamic range image. The controller is also configured to adjust an attenuation of the light filter for a next iteration of the low-transmission state based on pixel signals generated during the second exposure.

Abstract: An image sensor may have an array of pixels and readout circuitry. The array may include image pixels that generate signals in response to image light and reference pixels that generate signals in response to electrical noise. The readout circuitry may obtain first pixel values from the image pixels and may obtain second pixel values from the reference pixels. The readout circuitry may generate an extended precision pixel value based on the second pixel values that have an extended bit width relative to the each of the second pixel values. The readout circuitry may generate multiple dithered correction values by adding randomized sequences of least significant bits to the extended precision pixel value. The readout circuitry may mitigate visible quantization error and noise such as row-correlated and column-correlated noise in the final image by subtracting the dithered correction values from corresponding first pixel values.

Abstract: A method for removing background signal values from readout signal values generated by image pixels in a pixel array may include generating background signal values using optically black pixels formed around a border of the pixel array. The background signal values may be separated into blocks. Block average values may be calculated based on the background signal values included in each of the blocks. Corner regions of the pixel array may be free of image pixels and optically black pixels. Corner background signal values may be extrapolated based on the block average values. Image pixel background signal values may be interpolated based on the block average values and the corner background signal values. The image pixel background signal values may be subtracted from the readout values.

Abstract: A method for removing background signal values from readout signal values generated by image pixels in a pixel array may include generating background signal values using optically black pixels formed around a border of the pixel array. The background signal values may be separated into blocks. Block average values may be calculated based on the background signal values included in each of the blocks. Corner regions of the pixel array may be free of image pixels and optically black pixels. Corner background signal values may be extrapolated based on the block average values. Image pixel background signal values may be interpolated based on the block average values and the corner background signal values. The image pixel background signal values may be subtracted from the readout values.

Abstract: An image sensor may have an array of pixels and readout circuitry. The array may include image pixels that generate signals in response to image light and reference pixels that generate signals in response to electrical noise. The readout circuitry may obtain first pixel values from the image pixels and may obtain second pixel values from the reference pixels. The readout circuitry may generate an extended precision pixel value based on the second pixel values that have an extended bit width relative to the each of the second pixel values. The readout circuitry may generate multiple dithered correction values by adding randomized sequences of least significant bits to the extended precision pixel value. The readout circuitry may mitigate visible quantization error and noise such as row-correlated and column-correlated noise in the final image by subtracting the dithered correction values from corresponding first pixel values.