[Work] Image resize

Paul Heckbert's homepage
Paul Heckbert's zoom

/*----------------------------------------------------------------------
 * The mapping from source coordinates to dest coordinates:
 * (Notation: prefix 'a' denotes source coords, 'b' denotes destination coords)
 *
 * bx = sx*ax+tx
 * by = sy*ay+ty
 *
 * where (ax,ay) and (bx,by) are DISCRETE source and dest coords, respectively.
 *
 * An important fine point on terminology: there are two kinds of pixel coords:
 * DISCRETE COORDINATES take on integer values at pixel centers
 * CONTINUOUS COORDINATES take on integer values halfway between pixels
 * For example, an image with discrete coordinate range [0..511] has a
 * continuous coordinate range of [0..512].  The pixel with
 * discrete coords (x,y) has its center at continuous coords (x+.5,y+.5)
 * and its continuous coord domain is [x..x+1] in X and [y..y+1] in Y.
 * Note: discrete coords are not always stored in ints and continuous coords
 * are not always stored in floats.
 *
 * conversion:
 * if c = continuous coord and d = discrete coord, then
 * c = d+.5
 * d = floor(c)
 *
 * To map a discrete src interval [a0..a1] to a discrete dst interval [b0..b1]:
 *
 * b-b0+.5 = bn/an*(a-a0+.5)
 *  or b = (bn/an)*a + (b0-.5)-(bn/an)*(a0-.5)
 *   = scale*a+tran
 *
 * where a and b are the discrete source and dest coords (either x or y)
 * and an and bn are the interval lengths: an=a1-a0+1, bn=b1-b0+1.
 * a0, an, b0, bn are the mapping parameters used by the zoom routine below.
 * In general, however, for sub-pixel scale and translate control, we allow
 * any real numbers for scale and tran (although there should usually be some
 * correspondence between the mapping function and the src and dst windows).
 *
 * We'll often want the inverse mapping, from discrete dst coord b to
 * continuous src coord ac, relative to the interval origins a0 and b0:
 *
 * b+b0 = s*(ac+a0-.5)+t
 *  so ac = (b+b0-s*(a0-.5)-t)/s
 *    = (b+offset)/scale = MAP(b, scale, offset)
 *
 * The mapping fields ux and uy in the Mapping structure
 * are these offsets in x & y respectively.
 */
/* the mapping from discrete dest coord b to continuous source coord: */
#define MAP(b, scale, offset)  (((b)+(offset))/(scale))

#!/bin/bash

for filter in point box triangle quadratic cubic catrom mitchell gaussian sinc bessel hanning hamming blackman kaiser
do
#  echo ${filter}
#  echo ./bin/zoom -src $1 -dst `basename $1 .tif`_${filter}.tif  -s 0 0 340 260 -d 0 0 680 520 -filt ${filter}
  ./bin/zoom -src $1 -dst `basename $1 .tif`_big_${filter}.tif  -s 0 0 406 500 -d 0 0 812 1000 -filt ${filter}
  ./bin/zoom -src $1 -dst `basename $1 .tif`_small_${filter}.tif  -s 0 0 406 500 -d 0 0 203 250 -filt ${filter}
done

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