Browse Prior Art Database

Formation of Iconic Representations of Large Images

IP.com Disclosure Number: IPCOM000114151D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Bird, CL: AUTHOR [+3]

Abstract

Disclosed is a method of displaying large images so as to retain as much information on the screen as possible. A "large" image is defined here as being greater in width or height than the respective dimension (in pixels) of the display screen. An example would be a geographic map, perhaps subdivided into areas according to use or ownership.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Formation of Iconic Representations of Large Images

      Disclosed is a method of displaying large images so as to
retain as much information on the screen as possible.  A "large"
image is defined here as being greater in width or height than the
respective dimension (in pixels) of the display screen.  An example
would be a geographic map, perhaps subdivided into areas according to
use or ownership.

      When viewing large images, usually with the intention of
identifying regions of interest, the user may choose to look at only
a portion of the image at a time or, particularly for very large
images, to reduce the size and create an iconic representation.  In
the latter case, it is important to preserve as much as possible of
the information content of the original image.  It is the problem of
generating iconic representations which retain as much of the detail
as possible which requires solving.  In existing methods the size of
an image may be reduced or increased by a process known as chopping,
which involves pixel deletion or replication.  Alternatively, pixel
values in the new, smaller or larger, image may be set by one of the
known processes of interpolation.  While the latter approach is less
drastic in its effect on the information content, it is
computationally more demanding.  In many cases, interpolation may be
overkill in the context of providing a new image which is to be
viewed for selecting regions of interest.

      The new solution as a first step has the original image
subdivided into a number of blocks, where each block will give rise
to a single pixel at the corresponding position in the iconic
representation.  In itself, this is no more than one would expect, so
the substance of this invention lies in the means whereby the
contents of the block translates to a value for the pixel in the
target icon.  At an abstract level, the process involves analysing
the block to assess its total information content.  A decision can
then be made as to whether that content is sufficient to switch on
the target pixel.  The analysis is best described by means of several
examples.  In discussing these, the assumption is made than an
ON-pixel will appear on the screen as white; and an OFF-pixel as
black.
  1.  Consider a large binary image with a low total information
       content; that is, containing much black space.  In this case
the
       criterion adopted is that ANY bit ON in the block will be
       sufficient to switch the target pixel ON.  The following
       sub-section discusses ways of implementing this criterion.
No...