US 5,204,916 AGranted

Tile-oriented technique for collectively performing image rotation, scaling and digital halftone screening

AssigneeEastman Kodak Company

InventorsJohn F. Hamilton, Jr., Anthony J. Leone, III

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Abstract

A tile-oriented technique and associated apparatus for manipulating a continuous tone (contone) image through image rotation, anamorphic scaling and digital halftone screening for use in illustratively implementing a page description language. Specifically, an incoming contone image is first partitioned into aligned non-abutting tiles. Overlapping blocks are then defined which will hold output data for corresponding tiles. To effect rotation and anamorphic scaling of the contone image, two-dimensional sampling increments, in fast and slow scan directions, are defined to relate movement between successive pixels in an output block to movement between corresponding pixels in the contone image. Similar, though independent, sampling increments, based in part upon screen angle and screen ruling, are defined for movement between successive pixels in a halftone reference cell. Incremental sampling occurs in the contone image to yield a corresponding sampled contone value. This value, in conjunction with incremental halftone sampling addresses, then defines a sampling location that is read in a halftone reference plane, the resulting output of which is single bit halftone data that defines a writing spot. Each tile in the contone image is successively processed with resulting output data for that tile being written into appropriate pixel locations in a corresponding block in the output image. Clipping variables, incrementally varying in two-dimensional fashion and in unison with the contone pixel sampling location, define valid output data for a contone tile that is to be written into a corresponding block.

Claims22

Dependent claims

A method for producing a scaled, rotated and halftoned output image from an input continuous tone (contone) image comprising the steps of:

(A) defining pixel sampling increments, said pixel sampling increments specifying incremental movement between successive sampling locations in a contone tile in said contone image and specifying movement between two adjacent pixel locations in a block of said output image, said defining step includes the steps of:
(1) determining tile increments, wherein said tile increments specify incremental movement between corresponding locations of successive contone tiles in said contone image and said output image is formed of an array of blocks, each of said blocks spatially corresponding to and storing output data for a different one of said contone tiles, wherein said pixel sampling increments and tile increments are a function of a scale factor, an angle of rotation for said contone image and a screen angle;
(2) determining, in response to the scale factor and the angle of rotation, a size of the contone tile, such that the contone image is broken into an array of non-overlapping ones of said contone tiles, each contone tile containing a portion of said contone image;
(3) determining, in response to the scale factor and the angle of rotation, a size of each block in the output image;
and
(4) establishing starting locations of a current block in the output image, that is to be written with output data, and of a current tile in the contone image corresponding to said current block that is to be processed;
(B) in response to corresponding ones of said pixel sampling increments:
(1) generating addresses that represent incremental movement through the current block to produce a sequence of output pixel locations;
(2) sampling through said contone image to yield a sampled contone value associated with each addressed output pixel location so as to produce a plurality of sampled contone values;
and
(3) producing, in response to each of said sampled contone values and a predefined pattern, a corresponding halftone output value for each addressed output pixel location in said sequence to yield a plurality of halftone output values;
(C) writing each of the halftone output values in the corresponding addressed output pixel location in the current block in the event said each halftone output value is associated with a pixel location situated within the current contone tile;
and
(D) repeating, in response to said tile increments, steps (A) (4), (B), and (C) for each successive output block in the output image as the current block and for each successive tile in said contone image as the current tile until the output image has been completely formed as the output data resulting from processing all of the tiles in the contone image.

11 more elements

Apparatus for producing a scaled, rotated and halftoned output image from an input continuous tone (contone) image comprising:

(A) means for defining pixel sampling increments, said pixel sampling increments specifying incremental movement between successive sampling locations in a contone tile in said contone image and specifying movement between two adjacent pixel locations in a block of said output image, said defining means further comprises:
(1) means for determining tile increments, wherein said tile increments specify incremental movement between corresponding locations of successive contone tiles in said contone image and said output image is formed of an array of blocks, each of said blocks spatially corresponding to and storing output data for a different one of said contone tiles, wherein said pixel sampling increments and tile increments are a function of a scale factor, an angle of rotation for said contone image and a screen angle;
(2) means for determining, in response to the scale factor and the angle of rotation, a size of the contone tile, such that the contone image is broken into an array of non-overlapping ones of said contone tiles, each contone tile containing a portion of said contone image;
(3) means for determining, in response to the scale factor and the angle of rotation, a size of each block in the output image;
and
(4) means for establishing starting locations of a current block in the output image, that is to be written with output data, and of a current tile in the contone image corresponding to said current block that is to be processed;
(B) means, responsive to corresponding ones of said pixel sampling increments, for:
(1) generating addresses that represent incremental movement through the current block to produce a sequence of output pixel locations;
(2) sampling through said contone image to yield a sampled contone value associated with each addressed output pixel location so as to produce a plurality of sampled contone values;
and
(3) producing, in response to each of said sampled contone values and a pre-defined pattern, a corresponding halftone output value for each addressed output pixel location in said sequence to yield a plurality of halftone output values;
and
(C) means for writing each of the halftone output values in the corresponding addressed output pixel location in the current block in the event said each halftone output value is associated with a pixel location situated within the current contone tile.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/741,877Filed 6 Aug 1991
Granted: 20 Apr 1993
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H04N 1/3935
Enlarging or reducing: with modification of image resolution, i.e. determining the values of picture elements at new relative positions
G06T 3/02
Geometric image transformations in the plane of the image: affine transformations
G06T 3/4038
Scaling of whole images or parts thereof, e.g. expanding or contracting: image mosaicing, e.g. composing plane images from plane sub-images
G06T 3/602
Rotation of whole images or parts thereof: by block rotation, e.g. by recursive reversal or rotation