Browse Prior Art Database

Method to Determine the Scale Factor Set to Implement a Given Scale Factor

IP.com Disclosure Number: IPCOM000103911D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Smith, DA: AUTHOR

Abstract

A video image scaling technique is provided which is suitable for hardware implementation with real-time operation.

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

Method to Determine the Scale Factor Set to Implement a Given Scale Factor

      A video image scaling technique is provided which is suitable
for hardware implementation with real-time operation.

      The technique determines an optimal scale factor set which
provides good picture quality.  The scale factor set is defined as
the set of numbers representing the number of pixels that have been
dropped, or eliminated, and the set of numbers representing the
different combinations of pixels that have been averaged, i.e., the
number of pixels kept, or retained, the number of dual averaging
operations and the number of quad averaging operations.  To drop a
pixel is to completely eliminate that pixel and to keep a pixel is to
retain all the information that is contained in that pixel.  Dual
averaging, or 2 .sup 1 averages the information in two pixels into
one pixel, quad averaging, or 2 .sup 2, averages the information in
four pixels into one pixel, with 2 .sup N averaging 2 .sup N pixels
into one pixel.

      It should be understood that each pixel contains red, green and
blue information, or luminence/red color difference/blue color
difference (YUV), with the intensity of each of these colors being
generally identified in units from 0 to 255 for 24 bit color and with
each color being represented by eight bits.

      B represents the base number of the scale factor, e.g., 100
being the base number when the scale factor is given in percent.  S
represents the scale factor, i.e., a range from 0 to B, Dr the number
of dropped pixels, K the number of pixels kept, D the number of dual
averaging pixel operations and Q the number of quad averaging pixel
operations.  The scaling hardware needs the scale factor set in terms
of Dr, K, D and Q for the desired scale factor.

     For B >= S >= B/2,
             Dr = 0
             D  = B - S
             K  = S - D and
             Q  = 0.

     For B/2 >= S >= B/4,
             Dr = 0
             K  = 0
             Q  = B/2 - S and
             D  = S - Q.

    ...