Imaging system and method with mid-tone enhancement

Claim 2

In a method for forming an image of an object on an output medium, the steps of: scanning the object to provide a video signal which varies in level in accordance with the object, processing the video signal to provide a generally rectangular signal comprising a series of pulses of predetermined height and a width which varies in accordance with the level of the video signal, decreasing the width of each one of the pulses by a predetermined fixed amount, scanning a writing beam across the output medium and modulating the beam in accordance with the pulses of decreased width to form an image of the object on the output medium.

Claim 3

The method of claim 1 wherein the generally rectangular signal is provided by applying the video signal to a threshold detector.

Claim 4

The method of claim 1 wherein each of the pulses has a leading edge and a trailing edge, and the width of each pulse is decreased by the predetermined amount at the leading edge of the pulse.

Claim 5

In a system for forming an image of an object on an output medium: means for scanning the object to provide a video signal which varies in level in accordance with the object, means responsive to the video signal for providing a generally rectangular signal comprising a series of pulses of predetermined height and a width which varies with the level of the video signal, means for decreasing the width of each one of the pulses by a predetermined fixed amount, means for scanning a writing beam across the output medium, and means responsive to the generally rectangular signal for modulating the writing beam to form an image of the object on the output medium.

Claim 6

In a system for forming an image of an object on an output medium: means for scanning the object to provide a video signal which varies in level in accordance with the object, means responsive to the video signal for providing a generally rectangular signal comprising a series of pulses of predetermined height and a width which varies with the level of the video signal, means for decreasing the width of each one of the pulses by a predetermined fixed amount, means for scanning a writing beam across the output medium, and means responsive to the generally rectangular signal for modulating the writing beam to form an image of the object on the output medium.

Claim 7

The system of claim 4 wherein the means for decreasing the width of the pulses comprises a delay network responsive to the generally rectangular signal for providing a delayed signal having the same waveform as the generally rectangular signal but displaced in time by an amount corresponding to the predetermined amount by which the pulse width is to be decreased, and coincidence gate means responsive to the generally rectangular signal and to the delayed signal for providing an output signal corresponding to the logical AND function of the generally rectangular signal and the delayed signal.

Claim 8

The system of claim 4 wherein the means for scanning the object comprises a laser which produces a reading beam, means for deflecting the reading beam across the object in raster fashion, and means responsive to light reflected by the object from the reading beam for providing an electrical signal which varies in accordance with the object.

Claim 9

The system of claim 6 wherein the means responsive to light reflected by the object comprises a photomultiplier tube and a fiber optic array for directing light from the object to the photomultiplier tube.

Claim 10

The system of claim 4 wherein the writing beam comprises a laser beam which is scanned across the output medium in raster fashion.

Claim 11

In a laser imaging system for forming an image of input copy on an output medium such as film or a printing plate: means for scanning the input copy with a laser beam to provide an electrical signal comprising a series of pulses which vary in width in accordance with the input copy, means for decreasing the width of each of the pulses by a predetermined fixed amount, a laser for providing a writing beam, means for scanning the writing beam across the output medium in raster fashion, and means for modulating the writing beam in accordance with the pulses of decreased width to form an image of the input copy on the output medium.

Claim 12

In a laser imaging system for forming an image of input copy on an output medium such as film or a printing plate: means for scanning the input copy with a laser beam to provide an electrical signal comprising a series of pulses which vary in width in accordance with the input copy, means for decreasing the width of each of the pulses by a predetermined fixed amount, a laser for providing a writing beam, means for scanning the writing beam across the output medium in raster fashion, and means for modulating the writing beam in accordance with the pulses of decreased width to form an image of the input copy on the output medium.

Claim 13

The system of claim 9 wherein the means for scanning the input copy comprises means for deflecting the laser beam across the copy in raster fashion, means responsive to light reflected by the copy from the beam for providing an electrical signal which varies in level in accordance with the input copy, and level responsive means for converting the electrical signal to a generally rectangular waveform.