Xerox Corporation

Sidney W Marshall

Steven Jay Harrington

Yao Rong Wang

Kwok-Leung Yip

Pierre A Lavallee

Eric Jackson

Ronald L Antos

Allen L Brown, Jr

A method for implementing sliding-window image processing for associative operators such as MIN, MAX, AND, and OR is disclosed. For one dimension, the present method divides the image into blocks according to the sliding window size and for each block calculates two sets of partial results, one working from the left boundary of the block and the other working from the right boundary of the block. The partial results from two adjacent blocks can then be combined in one operation to give a final value for any window straddling two adjacent blocks. The total number of operations is proportional to 3M; where M is the scan length as compared to (n&minus;1)M using prior art; where n is the length of the sliding window. The present invention can be extended to two-dimensional arrays and can be extended to support arbitrary window sizes.

Method for sliding window image processing of associative operators

A mapping system for converting an input signal value to an output value wherein certain outputs are predetermined to be critical. An engine for converting input values to output values is associated with an input value transforming system wherein certain input values corresponding to the critical output values are transformed prior to input to the engine for adjusting the input value so that the engine generates a particularly desired output. The transforming comprises selecting a set of basis functions for effecting a warping of input values near the input value corresponding to the critical output value. The basis functions determine the extent and gradient of input value adjustment for nearby values to the critical value. The basis functions are included within an objective function defining the purpose of the system and the functions are solved to generate the desired adjusted input value. The system has particular applicability to color gamut mapping in a print system wherein output color needs to be accurately printed and colors nearby the critical color can be generated with minimal image artifacts.

Color gamut mapping for accurately mapping certain critical colors and corresponding transforming of nearby colors and enhancing global smoothness

Some document languages such as the Standard Generalized Markup Language (SGML) represent documents as trees with each node of the tree labelled with a tag and each node's immediate descendants taken in order having tags that satisfy a production corresponding to the parent's tag. Thus, a document is represented as a complete parse tree satisfying the production rules of a grammar. To simplify maintaining a valid document/parse tree at all stages, an efficient check is made whether a document is valid or can be extended to a valid document and furthermore to show how a document could be changed to be valid. A document can be extended to a valid document if is equal to a valid document with possibly some nodes deleted. External (leaf) nodes can just be deleted. Internal nodes are deleted by replacing the arc from the parent with multiple arcs (in the same order) from the parent to each of the children of the deleted node. A grammar is constructed from the given grammar that includes those documents that can be completed to a valid document and is called a gapped grammar. A method is provided to teach how a gapped grammar can be constructed from a grammar, a parser/checker is efficiently implemented.

Method of determining whether a document tree is weakly valid

The stop for the Schlieren imaging optics which are used in an electro-optic line printer to image a multigate light valve onto a photosensitive recording medium has smoothly tapered sides to reduce crosstalk between the pixels of the image. As a result, the transmittance of the imaging aperture, as viewed along the modulation axis of the printer, rolls off relatively gradually and more or less continuously along the edges of the stop, thereby reducing the high angle diffraction off the stop so that the troublesome sidelobes of the coherent amplitude point spread function of the imaging system are suppressed. The stop preferably is in the shape of a parallelogram selected to substantially attenuate either the zero order or the higher order diffraction components of the phase front modulated light beam exiting from the light valve so that the intensity profile of the remaining or unattenuated light has the required image characteristics. Variations in the basic parallelogram shape wherein the stop sides have specially curved configurations to optimize triangular, cosine, and Gaussian light amplitude transmittance profiles are also disclosed.

Light blocking stop for electro-optic line printers

The present invention is concerned with compression encoding and, in particular, the encoding of the second difference of the position of the boundary of a character on consecutive scanlines. Special code sequences represent the starting location for two new character boundaries relative to the last position in the scanline generated, the next two character boundaries that do not extend into the next scanline, and the end of a line when the preceeding scanline had no intersections with a character boundary. Also included are code sequences representing the first item on the last scanline of the character to terminate the code and at the right of all other boundaries on the current scanline.

Character compression technique

In an electro-optic line printer of the type having a bit addressable linear modulator for modulating a sheet-like beam of light in response to pixel bits to expose the printer recording medium in line by line fashion. To suppress interference between the beam upper and lower sidebands, the beam is vertically polarized and a halfwave plate, disposed so that the axis thereof is at 45.degree. to the fourier transform plane, is inserted into the path of one of the sidebands to change the polarization of the one sideband from vertical to non-interferring horizontal. In a second embodiment, a halfwave plate is inserted into the path of each sideband, the axes of the plates being such as to form a 45.degree. angle therebetween whereby the sidebands are polarized at an angle of 90.degree. to one another, avoiding interference therebetween.

Interface suppression apparatus and method for a linear modulator

A tracking apparatus for the read/write head of a recording disk. Positive and negative servo marks on the disk provide sine and cosine head position signals. A calculator generates sine and cosine signal approximations from the high frequency signal outputs of variable and fixed frequency oscillators. A comparator compares the sine and cosine head position signals with the sine and cosine signal approximations and generates a corrective signal where a difference exists. The corrective signal is used to set the frequency of the variable frequency oscillator until the corrective signal is brought to zero. The signal outputs of variable and fixed frequency oscillators are fed to the up and down inputs of a head actual position counter. A second comparator compares the count on the counter with the count on a head desired position register to provide a servo error signal for operating a servo motor which moves the head to the desired track. A feedback loop supplements the corrective signal with a signal derived from actuation of the servo motor to enhance response.

Tracking apparatus for read/write head

A raster scanner with laser for generating a scanning beam and compact, folded optical system for transmitting the beam to the object to be scanned. The optical system includes a first mirror for guiding the laser beam forward along a downwardly inclined slope to the modulator, a second mirror below the modulator for intercepting the beam from the modulator and folding the intercepted beam to guide the beam backwards along a horizontal plane to a third mirror which folds the beam and guides the beam forward along an upwardly inclined slope against the mirrored facets of a rotating polygon, the polygon scanning the beam through a preset scan arc and returning the beam via a focusing lens to the third mirror, the third mirror folding the scan beam and guiding the scan beam forward, and a fourth mirror for intercepting the scan beam and guiding the beam to the object to be scanned.

Double pass scanning system

A signal generating apparatus driven by the reference beam of an image scanning system is disclosed. The apparatus includes an apertured codeplate across which the reference beam sweeps, light from the beam triggering a photodetector to produce a signal pulse output. A grating is inserted into the beam path to split the reference beam into a plurality of spaced apart beams effective to offset blockage or irregularity of one or more of the codeplate apertures.

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Webster, NY, United States of America

Sidney W Marshall