Eastman-kodak Company

Nea-Yea Woo

Teh-Hsuang Lee

Kwok-Leung Yip

Evan A Edwards

Roger E Baldwin

The dynamic range of a continuous tone laser printer is extended by directly modulating a diode laser while simultaneously modulating the optical output of the diode laser with an acousto-optic modulator. The digital image value is input to two look-up tables (LUTs) that convert the image value to two digital words; one to set the power level of the diode laser, and the other to set the diffraction efficiency of the acousto-optic modulator (AOM). The first look-up table is constructed from the performance characteristics of the diode laser, and the second look-up table is constructed from the performance characteristics of the AOM. The look-up table digital outputs are applied to respective digital to analog converters whose analog outputs respectively drive a voltage to current driver for the diode laser and a radio frequency dirver for the AOM. The resulting power of the writing laser beam is a linear function of the input image value.

Extension of dynamic range for continuous tone laser printers

Beam intensity controlling device includes an acoustooptic cell which receives an input light beam and produces an undiffracted or zero-order light beam and a diffracted beam in response to an RF signal at a predetermined frequency. An error signal is produced which is a function of the differences in the intensity of the zero-order beam from a desired level. This error signal is used to control the amplitude of the RF signal which in turn changes the intensity in the diffracted and zero-order beams such that the zero-order beam intensity is maintained relatively constant and can be provided as an input to a modulating device. The error signal has two components, a DC component which corrects for slow drift of the zero-order light beam intensity and an AC component which corrects for higher frequency changes in the zero-order light beam intensity.

Light beam intensity controlling apparatus

Fixed pattern noise manifested as percentage variations between the apparent sensitivities of sensor elements in a solid state image sensing array is reduced by removing one or more percentage portions of charge from a charge packet generated by an element of the sensing array. In a preferred embodiment, a percentage portion of charge is removed by dumping the portion of charge appearing under one part of a split electrode in a charge coupled device (CCD) shift register. A programmed memory controls the operation of the split electrode CCD device to provide the required corrections. To program the memory, the output of the image sensing array is measured with a non-image-wise input; and a particular charge packet size (e.g. the smallest useable charge packet produced by the array) is chosen as a reference. The percentage corrections required to adjust the relative sizes of the other charge packets from the array to make them equal in size to the reference charge packet are calculated and converted to corresponding control signals for the split electrode CCD device. The control signals are then stored in the memory. During subsequent operation of the image sensing array, the size of a charge packet is adjusted in the split electrode CCD shift register, under control of the control signals stored in the memory, to remove fixed pattern noise.

Method and apparatus for pattern noise correction

A self-contained video camera/recorder includes means for generating a video signal at a slow-frame rate corresponding to a submultiple of a standard television field rate. The slow-frame signal is recorded and played back at the slow-frame rate thereby reducing the bandwidth requirements of the recorder. Upon playback, the slow-frame signal is buffered, frame by frame. The buffered signal is time compressed, and each frame is repeated a number of times to yield a video signal wherein the frames occur at a standard field rate. According to the preferred embodiment of the invention, the means for generating the slow-frame video signal, and for buffering, time compressing and repeating the frames during playback, is a solid-state image sensing and signal processing device having an image sensing array, a first input register disposed for introducing signals into the sensing array, a storage array, a second input register disposed between the sensing array and the storage array for introducing signals into the storage array, and an output register for reading signals out of the storage array.

Slow-frame video camera/recorder and image-sensing and signal processing

An off-the-air color video recorder employs frequency interleaved chroma and luminance signal information for purposes of bandwidth compression. During playback, the interleaved luminance and chroma signal information are combed apart, the luminance signal information, however, being subjected to at least one additional stage of comb filtering, preferably limited to that part of the playback spectrum containing the interleaved signal information. With such a technique, playback luminance signal information is comprised of two spectrum parts, one being, say, half the signal resolution of the other.

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Rochester, NY, United States of America

Nea-Yea Woo