56 lines
1.7 KiB
Groff
56 lines
1.7 KiB
Groff
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.TH MATCH_LINEAR 3 "13 May 1991"
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.SH NAME
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im_match_linear_search, im_match_linear \- resample to make a match
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.SH SYNOPSIS
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#include <vips/vips.h>
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int
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.br
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im_match_linear( IMAGE *ref, IMAGE *sec, IMAGE *out,
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.br
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int xr1, int yr1, int xs1, int ys1,
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.br
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int xr2, int yr2, int xs2, int ys2 )
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int
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.br
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im_match_linear_search( IMAGE *ref, IMAGE *sec, IMAGE *out,
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.br
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int xr1, int yr1, int xs1, int ys1,
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.br
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int xr2, int yr2, int xs2, int ys2,
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.br
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int hwindowsize, int hsearchsize )
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.SH DESCRIPTION
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im_match_linear_search() attempts to transform sec to make it match
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ref. The transformation is linear, that is, it only involves scale,
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rotate and translate.
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im_match_linear_search() requires a pair of tie points to fix the parameters of
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its transformation. You should pick points as far apart as possible to
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increase accuracy. im_match_linear_search() will search the area in the image
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around each tie point for a good fit, so your selection of points need not
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be exact. WARNING! This searching process will fail for rotations of more
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than about 10 degrees or for scales of more than about 10 percent.
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The best you can hope for is < 1 pixel error, since the command does not
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attempt sub-pixel correlation.
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hwindowsize and hsearchsize set the size of the area to be searched: we
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recommend values of 5 and 14.
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The output image is positioned and clipped so that you can immediately
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subtract it from orig to obtain pixel difference images.
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im_match_linear() works exactly as im_match_linear_search(), but does not
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attempt to correlate to correct your tie points. It can thus be used for any
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angle and any scale, but you must be far more careful in your selection.
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.SH SEE ALSO
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im_lrmosaic().
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.SH AUTHORS
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J.Ph.Laurent \- 12/12/92
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.br
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J.Cupitt \- 22/02/93
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