1IM_CORREL(3) Library Functions Manual IM_CORREL(3)
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6 im_correl - search for image match
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9 #include <vips/vips.h>
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11 int
12 im_correl( IMAGE *ref, IMAGE *sec,
13 int xref, int yref, int xsec, int ysec,
14 int hwindowsize, int hsearchsize,
15 double *correlation, int *x, int *y )
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19 im_correl() is the base image-searching function used by the mosaicing
20 functions im_lrmosaic() and im_tbmosaic(), and by the matching funtions
21 im_match_linear() and im_match_linear_search().
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23 It finds the position of the secondary image sec within ref. It
24 searches the area around xsec , ysec for the best match for the area
25 around xref , yref. It searches an area of size hsearchsize for a
26 match of size hwindowsize. The position of the best match is returned,
27 together with the correlation at that point.
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29 Only the first band of each image is correlated. ref and sec may be
30 very large --- the function extracts and generated just the parts
31 needed. Correlation is done with im_spcor(); the position of the maxi‐
32 mum is found with im_maxpos().
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35 im_fastcor(3), im_spcor(3), im_maxpos(3), im_match_linear(3), im_lrmo‐
36 saic(3).
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39 J.Cupitt - 22/02/93
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42 The National Gallery and Birkbeck College, 1989-1996.
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46 13 May 1991 IM_CORREL(3)