1MATCH_LINEAR(3) Library Functions Manual MATCH_LINEAR(3)
2
6 im_match_linear_search, im_match_linear - resample to make a match
7
9 #include <vips/vips.h>
10 int
12 im_match_linear( IMAGE *ref, IMAGE *sec, IMAGE *out,
13 int xr1, int yr1, int xs1, int ys1,
14 int xr2, int yr2, int xs2, int ys2 )
15 int
17 im_match_linear_search( IMAGE *ref, IMAGE *sec, IMAGE *out,
18 int xr1, int yr1, int xs1, int ys1,
19 int xr2, int yr2, int xs2, int ys2,
20 int hwindowsize, int hsearchsize )
21
24 im_match_linear_search() attempts to transform sec to make it match
25 ref. The transformation is linear, that is, it only involves scale,
26 rotate and translate.
27 im_match_linear_search() requires a pair of tie points to fix the
29 parameters of its transformation. You should pick points as far apart
30 as possible to increase accuracy. im_match_linear_search() will search
31 the area in the image around each tie point for a good fit, so your
32 selection of points need not be exact. WARNING! This searching process
33 will fail for rotations of more than about 10 degrees or for scales of
34 more than about 10 percent. The best you can hope for is < 1 pixel
35 error, since the command does not attempt sub-pixel correlation.
36 hwindowsize and hsearchsize set the size of the area to be searched: we
38 recommend values of 5 and 14.
39 The output image is positioned and clipped so that you can immediately
41 subtract it from orig to obtain pixel difference images.
42 im_match_linear() works exactly as im_match_linear_search(), but does
44 not attempt to correlate to correct your tie points. It can thus be
45 used for any angle and any scale, but you must be far more careful in
46 your selection.
47
50 im_lrmosaic().
51
53 J.Ph.Laurent - 12/12/92
54 J.Cupitt - 22/02/93
55 13 May 1991 MATCH_LINEAR(3)