US 5,297,217 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 (e.g. 215.sub.1, 215.sub.2, . . . , 215.sub.9). Overlapping blocks (e.g. 217.sub.1, 217.sub.2, . . . , 217.sub.9) are then defined which will hold output data for corresponding tiles. 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, also in the fast and slow scan directions and based in part upon screen angle and screen ruling, are defined for movement between successive pixels in a halftone reference cell. To generate output data for each successive pixel location in a block, 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 (e.g. 242.sub.181), the resulting output of which is single bit halftone data that defines a writing spot. Each tile in the contone image is successively processed, using two nested loops (1950, 1960), with resulting output data for that tile being written into appropriate pixel locations in a corresponding block in the output image.

Claims22

Dependent claims

A method for producing a scaled, rotated and halftoned output image from an input continuous tone (contone) image, wherein said output image depicts said input image scaled by a pre-defined scale factor and rotated through a pre-defined angle of rotation, said method comprising the steps of:

(A) defining pixel sampling increments, said pixel sampling increments specifying incremental movement between successive sampling locations in one of a plurality of contone tiles in said contone image, said incremental movement corresponding to movement between two adjacent pixel locations in a corresponding block of said output image, said output image being formed of a plurality of spatially overlapping blocks wherein each of said blocks spatially corresponds to and stores output data for a different one of said contone tiles;
said pixel sampling increments being a function of the scale factor, the angle of rotation and the screen angle;
a said contone tile being sized as a function of the scale factor and the angle of rotation such that the contone image is broken into an array of non-overlapping ones of said contone tiles, each of said contone tiles containing a portion of said contone image, and wherein the defining step comprises the step of sizing the corresponding block as a function of a size of the tile and the angle of rotation with an extent of the overlap between two adjacent ones of said blocks being governed by the angle of rotation;
(B) in response to corresponding ones of said pixel sampling increments:
(1) generating addresses that represent incremental movement through the corresponding block to produce a sequence of addressed output pixel locations;
(2) sampling through said contone image to yield a sampled contone value associated with each of said addressed output pixel locations 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) writing each of the halftone output values in the corresponding addressed output pixel location in the corresponding block in the event said each halftone output value is associated with a pixel location situated within the one contone tile.

7 more elements

Apparatus for producing a scaled, rotated and halftoned output image from an input continuous tone (contone) image, wherein said output image depicts said input image scaled by a pre-defined scale factor and rotated through a pre-defined angle of rotation, said apparatus comprising:

means for defining pixel sampling increments, said pixel sampling increments specifying incremental movement between successive sampling locations in one of a plurality of contone tiles in said contone image, said incremental movement corresponding to movement between two adjacent pixel locations in a corresponding block of said output image, said output image being formed of a plurality of spatially overlapping blocks wherein each of said blocks spatially corresponds to and stores output data for a different one of said contone tiles;
said pixel sampling increments being a function of the scale factor, the angle of rotation and the screen angle;
said contone tile being sized as a function of the scale factor and the angle of rotation such that the contone image is broken into an array of non-overlapping ones of said contone tiles, each of said contone tiles containing a portion of said contone image, and wherein said defining means comprises means for sizing the corresponding block as a function of a size of the tile and the angle of rotation with an extent of the overlap between two adjacent ones of said blocks being governed by the angle of rotation;
means, responsive to corresponding ones of said pixel sampling increments, for:
(1) generating addresses that represent incremental movement through the corresponding block to produce a sequence of addressed output pixel locations;
(2) sampling through said contone image to yield a sampled contone value associated with each of said addressed output pixel locations 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
means for writing each of the halftone output values in the corresponding addressed output pixel location in the corresponding block in the event said each halftone output value is associated with a pixel location situated within the one contone tile.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/934,090Filed 21 Aug 1992 · continuation
Priority: 6 Aug 1991
Granted: 22 Mar 1994
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