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