**NAME**

im_lrmerge, im_tbmerge, im_lrsmerge, im_tbsmerge, im_lrmergeb,
im_tbmergeb - merges two images with a given dx and dy

**SYNOPSIS**

#include <vips/vips.h>
int im_lrmerge( ref, sec, out, dx, dy, mwidth )
IMAGE *ref, *sec, *out;
int dx, dy;
int mwidth;
int im_tbmerge( ref, sec, out, dx, dy, mwidth )
IMAGE *ref, *sec, *out;
int dx, dy;
int mwidth;

**DESCRIPTION**

im_lrmerge() and im_tbmerge() merge the images held by the image
descriptors reference and secondary (ref and sec) according to the
values dx and dy. dx and dy give the displacement of sec relative to
ref. The result is written on the image descriptor out. The program
carries out a smooth merge using a raised cosine function. Both work
for any image type, including LABPACK.
The functions treat pixels with the value zero as "transparent", that
is, zero pixels in the overlap area do not contribute to the merge.
This makes it possible to join non-rectangular images.
The "mwidth" parameter limits the maximum width (or height) of the
blend area. A value of "-1" means "unlimited". All other negative
values are errors.

**RETURN** **VALUE**

Both functions return 0 on success and -1 on error.

**SEE ALSO**

im_lrmosaic(3), im_tbmosaic(3), im_match_linear(3).
13 May 1991