Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!ut-sally!im4u!milano!begeman From: begeman@milano.UUCP Newsgroups: comp.graphics Subject: Re: Intelligent scaling of bit-mapped graphics (Help!) Message-ID: <3385@milano.UUCP> Date: Thu, 15-Jan-87 13:05:55 EST Article-I.D.: milano.3385 Posted: Thu Jan 15 13:05:55 1987 Date-Received: Fri, 16-Jan-87 01:44:24 EST References: <2872@gitpyr.gatech.EDU> <2406@well.UUCP> Sender: begeman@milano.UUCP Organization: MCC, Austin, TX Lines: 37 Summary: Surface fitting > In article <2872@gitpyr.gatech.EDU> dave@gitpyr.gatech.EDU (David Corbin) writes: > >I am looking for information (programs, algorithms, references to texts) > >on how to scale a bit-mapped image from one resolution to another, in an > >intelligent manner.... Ok, here goes. There may be cheaper ways, but in my book there's one *right* way. What you have is an interpolation problem. Imagine your image (1st resolution) as a set of sampled data values. What you want is to derive other data values which are "in between" these. What you need to do is find a surface-fitting algorithm. You will feed it your data as (X, Y, Z==pixel_value) tuples. The algorithm will fit a surface to the data. Then you can use the surface to compute New_Z = f(New_X, New_Y) where f is the interpolation function as applied to the surface. This software falls into the domain of Numerical Analysis. I don't know of any public domain code which I can point you to, but I know that lots of PD NA software *does* exist. By the way, there will be a number of different surface-fitting algorithms to choose from - usually differing in the order of the polynomials used and your ability to "tension" the surface to remove any spikey anomalies which the mathematical representation of your original data may have introduced. Hit your local Numerical Analyst for guidance here. Good luck! ------- Of all the things I've lost, I miss my mind the most. Michael L. Begeman Microelectronics and Computer Technology Corp Software Technology Program Austin (where the sun always shines) Texas uucp: {ihnp4, seismo, harvard, gatech, pyramid}!ut-sally!im4u!milano!begeman arpa: begeman@mcc.com