The technology described in this document can be embodied in a method that includes receiving, at one or more processing devices of a headset that includes a sidetone generation circuit, an input signal representing ambient audio, and determining, by the one or more processing devices of the headset, that at least a portion of the input signal represents voice activity that satisfies a threshold condition. The method also includes, responsive to determining that the voice activity in the input signal satisfies the threshold condition, a control signal configured to cause the sidetone generation circuit to generate sidetone signals, and generating, by an acoustic transducer of the headset, an audio signal that represents, at least in part, the sidetone signals generated in accordance with the control signal.

The technology described in this document can be embodied in a method that includes receiving, at one or more processing devices of a headset that includes a sidetone generation circuit, an input signal representing ambient audio, and determining, by the one or more processing devices of the headset, that at least a portion of the input signal represents voice activity that satisfies a threshold condition. The method also includes, responsive to determining that the voice activity in the input signal satisfies the threshold condition, a control signal configured to cause the sidetone generation circuit to generate sidetone signals, and generating, by an acoustic transducer of the headset, an audio signal that represents, at least in part, the sidetone signals generated in accordance with the control signal.

An image processing apparatus has a first color conversion unit that converts a signal value at an achromatic grid point in a first color space among achromatic grid points in a color space, the signal value being closer to white than a first predetermined signal value, into a signal value that is even closer to white, and a second color conversion unit that converts a signal value at a grid point among grid points in the color space, the signal value being closer to white than a second predetermined signal value, into white are provided. The image processing apparatus converts a signal value of an input image using the first color conversion unit, and thereafter converting the signal value using the second color conversion unit.

An image processing apparatus has a first color conversion unit that converts a signal value at an achromatic grid point in a first color space among achromatic grid points in a color space, the signal value being closer to white than a first predetermined signal value, into a signal value that is even closer to white, and a second color conversion unit that converts a signal value at a grid point among grid points in the color space, the signal value being closer to white than a second predetermined signal value, into white are provided. The image processing apparatus converts a signal value of an input image using the first color conversion unit, and thereafter converting the signal value using the second color conversion unit.

Described is an echo cancellation method including buffering the at least one frame of a first voice signal, the at least one frame of the first voice signal including an echo signal, when the at least one frame of signal is preprocessed, separately obtaining, in a first timing period, the at least one frame of the first voice signal from a buffer and at least one frame of a reference signal matching the at least one frame of first voice signal from a reference signal queue, so that an estimated latency value, between each frame of first voice signal and a corresponding reference signal, remains within a preset range, performing echo cancellation processing on the echo signal in the at least one frame of first voice signal using the at least one frame of reference signal, to obtain a second voice signal, and outputting the second voice signal.

A signal processor (105) for a headset (101) configured with a microphone terminal (106) for receiving a microphone signal, a loudspeaker terminal (107) for outputting a loudspeaker signal, and a far-end terminal (108) for communicating an inbound signal and an outbound signal with a far-end; comprising: a side-tone path (110) configured to generate a side-tone signal from the microphone signal via a controllable side-tone filter; wherein a side-tone filter controller (114) receives the microphone signal and computes a first noise estimate with a signal-to-noise level of the microphone signal at respective frequency bands and based thereon controls the side-tone filter (111) to improve or optimize a signal-to-noise ratio.

An image processing apparatus has a first color conversion unit that converts a signal value at an achromatic grid point in a first color space among achromatic grid points in a color space, the signal value being closer to white than a first predetermined signal value, into a signal value that is even closer to white, and a second color conversion unit that converts a signal value at a grid point among grid points in the color space, the signal value being closer to white than a second predetermined signal value, into white are provided. The image processing apparatus converts a signal value of an input image using the first color conversion unit, and thereafter converting the signal value using the second color conversion unit.

An image processing apparatus has a first color conversion unit that converts a signal value at an achromatic grid point in a first color space among achromatic grid points in a color space, the signal value being closer to white than a first predetermined signal value, into a signal value that is even closer to white, and a second color conversion unit that converts a signal value at a grid point among grid points in the color space, the signal value being closer to white than a second predetermined signal value, into white are provided. The image processing apparatus converts a signal value of an input image using the first color conversion unit, and thereafter converting the signal value using the second color conversion unit.

Under-color removal of show-through background from a scanned original, so as to retain chromatic highlights of the scanned image of the original. An under-color level defines a value at which signals having a higher luminance than a luminance of the under-color level are converted into white. Before under-color removal, and based on the scanned image of the original, an achromatic color is converted into a color closer to white than the under-color level for an achromatic color closer whose luminance falls in a specified range lower than the luminance of the under-color level; and a chromatic color is converted into a chromatic color having a lower luminance than the luminance of the under-color level for a chromatic color in the specified range. Under-color removal of the converted achromatic and chromatic colors is thereafter applied using the under-color level, by which signal values having a higher luminance than a luminance of the under-color level are converted into white.

Under-color removal of show-through background from a scanned original, so as to retain chromatic highlights of the scanned image of the original. An under-color level defines a value at which signals having a higher luminance than a luminance of the under-color level are converted into white. Before under-color removal, and based on the scanned image of the original, an achromatic color is converted into a color closer to white than the under-color level for an achromatic color closer whose luminance falls in a specified range lower than the luminance of the under-color level; and a chromatic color is converted into a chromatic color having a lower luminance than the luminance of the under-color level for a chromatic color in the specified range. Under-color removal of the converted achromatic and chromatic colors is thereafter applied using the under-color level, by which signal values having a higher luminance than a luminance of the under-color level are converted into white.