Method and apparatus for calibrating halftone output from an imagesetting device

Claim 1

A method of calibrating halftone output images from an imagesetting device, comprising: providing a halftone input image, each said input image including a plurality of requested gray value densities, each said input image being a function of image resolution, exposure intensity and screen frequency; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each said requested gray value of each said halftone input image by a densitometer; generating a plurality of calibration sets in accordance with said measuring step, each said calibration set corresponding to any variation between said requested gray value density and said respective measured density reading for each said halftone input image at various said image resolutions, said exposure intensity and said screen frequency; and, converting subsequent plurality of halftone input images to a respective plurality of calibrated halftone output images according to changes made to said subsequent halftone input images by said calibration sets.

Claim 2

A method of calibrating halftone output images from an imagesetting device, comprising: providing a halftone input image, each said input image including a plurality of requested gray value densities, each said input image being a function of image resolution, exposure intensity and screen frequency; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each said requested gray value of each said halftone input image by a densitometer; generating a plurality of calibration sets in accordance with said measuring step, each said calibration set corresponding to any variation between said requested gray value density and said respective measured density reading for each said halftone input image at various said image resolutions, said exposure intensity and said screen frequency; and, converting subsequent plurality of halftone input images to a respective plurality of calibrated halftone output images according to changes made to said subsequent halftone input images by said calibration sets.

Claim 9

A method of calibrating halftone output images from an imagesetting device, comprising: providing a halftone input image, each said halftone image having a set of requested gray value densities, wherein each gray value density is dependent upon image resolution, exposure intensity and screen frequency of said input image; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each gray value of each halftone input image by a densitometer for chosen values of said image resolution, said exposure intensity and said screen frequency; generating a plurality of calibration sets corresponding to the variation between said requested gray value density and the density measured by said densitometer for each said halftone input image at varying values of said image resolution, said exposure intensity, said screen frequency and whether the resultant said halftone output images are placed on either paper or film; and, mapping said halftone input images through a transfer function process capable of transferring either positive or negative gray value densities of said halftone input images to either positive or negative gray value densities of said halftone output images.

Claim 10

A method of calibrating halftone output images from an imagesetting device, comprising: providing a halftone input image, each said halftone image having a set of requested gray value densities, wherein each gray value density is dependent upon image resolution, exposure intensity and screen frequency of said input image; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each gray value of each halftone input image by a densitometer for chosen values of said image resolution, said exposure intensity and said screen frequency; generating a plurality of calibration sets corresponding to the variation between said requested gray value density and the density measured by said densitometer for each said halftone input image at varying values of said image resolution, said exposure intensity, said screen frequency and whether the resultant said halftone output images are placed on either paper or film; and, mapping said halftone input images through a transfer function process capable of transferring either positive or negative gray value densities of said halftone input images to either positive or negative gray value densities of said halftone output images.

Claim 11

A method of producing calibrated halftone output images from an imagesetting device, comprising: providing a halftone input image, each said halftone image having a set of requested gray values corresponding to varying density readings wherein each gray value is dependent upon image resolution, exposure intensity and screen frequency selected; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each gray value of each halftone input image by a densitometer for chosen values of said image resolution, said exposure intensity and said screen frequency; generating a plurality of calibration sets corresponding to the variation between said requested gray value density and the density measured by said densitometer for each said halftone input image at varying values of said image resolution, said exposure intensity, said screen frequency and whether the resultant said halftone output images are placed on either paper or film; mapping subsequent halftone input images through a transfer function process to produce positive or negative sense gray values for any subsequent halftone input image; storing said calibration sets and said transfer function having local memory medium; inputting said subsequent halftone input images, each said subsequent halftone input image having a plurality of gray value densities; and, converting said gray value densities of each said subsequent halftone input image to a respective gray value densities of said calibrated halftone output images according to programmed retrieval of selected said stored calibration sets and said transfer function.

Claim 12

A method of producing calibrated halftone output images from an imagesetting device, comprising: providing a halftone input image, each said halftone image having a set of requested gray values corresponding to varying density readings wherein each gray value is dependent upon image resolution, exposure intensity and screen frequency selected; reproducing said halftone images onto a photographic media; chemically processing said media to manifest the exposure thereon; measuring the density of each gray value of each halftone input image by a densitometer for chosen values of said image resolution, said exposure intensity and said screen frequency; generating a plurality of calibration sets corresponding to the variation between said requested gray value density and the density measured by said densitometer for each said halftone input image at varying values of said image resolution, said exposure intensity, said screen frequency and whether the resultant said halftone output images are placed on either paper or film; mapping subsequent halftone input images through a transfer function process to produce positive or negative sense gray values for any subsequent halftone input image; storing said calibration sets and said transfer function having local memory medium; inputting said subsequent halftone input images, each said subsequent halftone input image having a plurality of gray value densities; and, converting said gray value densities of each said subsequent halftone input image to a respective gray value densities of said calibrated halftone output images according to programmed retrieval of selected said stored calibration sets and said transfer function.

Claim 14

An apparatus for generating calibrated halftone output images from an imagesetting device, comprising: a halftone input image including a plurality of gray values, each said gray value having a requested density value; means for converting said input image into a page description language; a raster image processor having a channel for receiving said page description language and converting said language into a raster representation of said halftone input image; a recorder connected to said raster image processor, said recorder includes a modulated light source to expose said raster representation onto a photographic media; a photoprocessor configured to receive said photographic media for chemically developing said media; a densitometer for measuring amount of density of each said gray value of said developed photographic medium; a computer for receiving a plurality of programmed calibration sets, said sets include variations between measured density of said densitometer and corresponding said requested density; a subsequent uncalibrated halftone input image, said subsequent halftone input image converted into said page description language and inputted to said computer; a selector accessed by said computer for receiving said subsequent halftone input images and selecting a corresponding said calibration set stored in said computer to programmably adjust said uncalibrated halftone input image to said calibrated output halftone image; and, mapping means for mapping either positive or negative sense representations of said subsequent uncalibrated halftone input images through said raster image processor, said recorder, said photoprocessor and outputted as calibrated said halftone output images on said photographic media.

Claim 15

An apparatus for generating calibrated halftone output images from an imagesetting device, comprising: a halftone input image including a plurality of gray values, each said gray value having a requested density value; means for converting said input image into a page description language; a raster image processor having a channel for receiving said page description language and converting said language into a raster representation of said halftone input image; a recorder connected to said raster image processor, said recorder includes a modulated light source to expose said raster representation onto a photographic media; a photoprocessor configured to receive said photographic media for chemically developing said media; a densitometer for measuring amount of density of each said gray value of said developed photographic medium; a computer for receiving a plurality of programmed calibration sets, said sets include variations between measured density of said densitometer and corresponding said requested density; a subsequent uncalibrated halftone input image, said subsequent halftone input image converted into said page description language and inputted to said computer; a selector accessed by said computer for receiving said subsequent halftone input images and selecting a corresponding said calibration set stored in said computer to programmably adjust said uncalibrated halftone input image to said calibrated output halftone image; and, mapping means for mapping either positive or negative sense representations of said subsequent uncalibrated halftone input images through said raster image processor, said recorder, said photoprocessor and outputted as calibrated said halftone output images on said photographic media.