Browse Prior Art Database

METHOD FOR IMAGE RESOLUTION CONVERSION

IP.com Disclosure Number: IPCOM000026992D
Original Publication Date: 1994-Oct-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 6 page(s) / 290K

Publishing Venue

Xerox Disclosure Journal

Abstract

This invention relates to conversion of images encoded at a first resolution to a second resolution, and more particularly to a method of mapping areas of the image at a first resolution, to areas of the image at a second resolution using error diffusion.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 34% of the total text.

Page 1 of 6

XEROX DISCLOSURE JOURNAL

METHOD FOR IMAGE Proposed Classification

RESOLUTION CONVERSION U.S. C1.358/445

anonymous Int. C1. H04n 1/40

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FIG. I

XEROX DISCLOSURE JOURNAL - Vol. 19, No. 5 SeptembedOctober 1994 401

[This page contains 1 picture or other non-text object]

Page 2 of 6

METHOD FOR IMAGE RESOLUTION CONVERSION(Cont'd)

f-'00 f-'02

-1 l300"

FIG. 2

GRAYLEVEL:l 11:l 1 1:l 11:3 3 3:3 3 3:3 3 3:2 2 2:2 2 2:2 1 1:l:

3:3: o 3i3 o 3i3 o 3!3 3 3:3 3 3i3 3 oi3 3 o:o 3 oio 3 GRAYPRINTED~O GRAYERROR 1-1 1 0:-1 1 0:-I 1 0:O 0 010 0 010 0 011 -1 011 -1 011 -1 OI1 I

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IS2{

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FIG. 3

402 XEROX DISCLOSURE JOURNAL - Vol. 19, No. 5 Septernber/October 1994

[This page contains 1 picture or other non-text object]

Page 3 of 6

METHOD FOR IMAGE RESOLUTION CONVERSION(Cont'd)

This invention relates to conversion of images encoded at a first resolution to a second resolution, and more particularly to a method of mapping areas of the image at a first resolution, to areas of the image at a second resolution using error diffusion.

Printers usually have equal resolutions in two dimensions, i.e.: K=L and M=N, but there is no such requirement. The most common printers (binary printers) have two levels, in which the first level is represented by a white spot, and the second level is represented by a black spot. Printers have been described with 4 levels, where levels 0 and 3 are represented respectively by white and black spots, and levels 1 and 2 are represented by intermediate gray levels. More levels than 2 or 4 are not prohibited.

Referring now to the drawings where the showings are for the purpose of illustrating a preferred embodiment of the invention and not for limiting same, as shown schematically in Figure 1, a cornmon printer contemplated for use with the present invention provides an electrophotographic engine 10 including a photoreceptor, development means 14 for developing a latent image formed on the photoreceptor with toner, and transfer means 16 for transferring the toned image to a final substrate 18, a source of collimated light 20 (usually a laser), a modulator 22 which modulates light from the source in accordance with an image signal, and a multi-faceted mirror or prism 24 mounted for rotation for reflecting the light beam in a path across photoreceptor 12. Resolution in the slow scan direction, the direction parallel to that of photoreceptor movement, is determined primarily by the speed of rotation of the multi-faceted mirror, and is generally not variable for a particular printer. Resolution in the fast scan direction, the direction across the photoreceptor, is determined by the speed of the modulator, and may vary with the image signal to the modulator.

With reference to Figure 2, in a conversion of a binary bitmap at 300 x 300 spi to a binary bitmap at 400 x 900 spi, a grouping 100 of three scan lines, IS1, IS2, IS3, is mapped to a grouping 102 of four scan lines OSl,OS2,OS3,0S4, in the slow scan direction,...