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From: brian@ucselx.sdsu.edu (Brian Ho)
Newsgroups: comp.graphics
Subject: Scaling Transformation on Bitmap Characters.
Message-ID: <1990Nov5.022837.15506@ucselx.sdsu.edu>
Date: 5 Nov 90 02:28:37 GMT
Organization: San Diego State University Computing Services
Lines: 106

Hello out-there,
  I am some problems which you may give me a hand.  I am trying to scale
  some bitmap images, those images are characters (e.g. A B a b 1 2 ..etc)
  which have the same font but with different sizes.  The goal of the scaling
  transformation is to normalized those characters into the same size, 20pt.
  Currently, I am using a very simple transformation algorithm, which is
  looking for the height/width from the original image, then determine the
  scaling factor, sx and sy. And apply the scaling factor to the old image.
  The result is not as good as we expected.  Somehow, characters with different
  sizes resulting different shapes after the transformation, and it is
  no way to tell they are actually has the same font.  The goal we are
  trying to achieve is to retain the shape/features of the character after
  transformation.

  My questions are:

  1> Does anyone has a better algorithm/reference for scaling tranformation
     which retain the features of the original image (in my case - characters
     with different sizes).

  2> I have heard from my advisor that there is a some sort of mathematic
     model/equations  to create characters in different size.  Operator
     can simply type in the size of the desired character(s). And the
     program will generate the character by itself. I am wondering if
     anyone has heard of this model, and can you please give me some
     information on that subject.

     Thank you very much......
     Please send reponses by e-mall :

     brian@ucselx.sdsu.edu
     brian@yucatec.sdsu.edu

     Brian Ho.

     Following are the results from my scaling transformation algorithm.
     The target image is 20pt. Characters are in Times font.

original character = 8 pts

00000000000000000000
00000000000011111110
00000000000011111110
00000000000011111110
00000000000011111110
00000000111100011110
00000000111100011110
00000000111100011110
00000111111111111110
00000111111111111110
00000111111111111110
00000111111111111110
00000111000000011110
00000111000000011110
00000111000000011110
01111111000000011110
01111111000000011110
01111111000000011110
01111111000000011110
00000000000000000000

original character = 12 pts

00000000000000000000
00000000000011111000
00000000000011111000
00000000000011111000
00000000000011111000
00000000001100011000
00000000001100011000
00000000110000011000
00000000110000011000
00000000110000011000
00000000110000011000
00000011111111111000
00000011111111111000
00000011000000011000
00000011000000011000
00011100000000011000
00011100000000011000
01111111000011111110
01111111000011111110
00000000000000000000

original character = 24 pts

00000000000000000000
00000000000000011000
00000000000001111000
00000000000001111000
00000000000010011000
00000000000110011000
00000000000100011000
00000000001100011000
00000000011000011000
00000000010000011000
00000000110000011000
00000001100000011000
00000001111111111000
00000011000000011000
00000010000000011000
00001110000000011000
00011100000000011000
00111100000000011000
01111110000011111110
00000000000000000000