Browse Prior Art Database

Combined Image Enlargement and Dithering

IP.com Disclosure Number: IPCOM000104057D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Feig, E: AUTHOR [+3]

Abstract

Disclosed is an algorithm for simultaneously enlarging, palettizing and dithering an image.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Combined Image Enlargement and Dithering

      Disclosed is an algorithm for simultaneously enlarging,
palettizing and dithering an image.

      This shows that the image is to be expanded by a factor of M
horizontally and N vertically.  Corresponding to every pixel in the
original image are 3 basic color values, v1, v2, v3, typically for
red-green-blue or Y-U-V (luminance and 2 chrominance components),
which range in value from 0 to Vi (or from any Wi to Vi-Wi).  The
enlarged image will have its (i,j)-th pixel values replaced by an M x
N matrix of indices for palette values.  These may be obtained as
follows:

o   first form three M times N matrices S1, S2, S3 whose entries are
    all, respectively, v1, v2, v3.

o   subject each Si to a dither distortion using any standard set of
    dither patterns and obtain matrices T1, T2, T3, respectively.  If
    Di is the dither pattern for the i-th basic color, then Ti = Si +
    Di.

o   fix a set of quantized values in each of the 3 basic colors, and
    quantize each entry in Ti relative to these values (i.e., replace
    each entry in Ti by its closest quantized value) yielding
    matrices Qi.  For each i, there will be Ni distinct matrices Qi.

o   form a table, indexed by N1,N2,N3, of all possible distinct
    dither patterns, where the dithered-palettized patterns are
    obtained by doing a pointwise palette lookup on each entry of
    each M x N

      One creates mappi...