/* Call im_matinv via arg vector.
*/
static int
matinv_vec( im_object *argv )
{
im_mask_object *in = argv[0];
im_mask_object *out = argv[1];
if( !(out->mask =
im_matinv( in->mask, out->name )) )
return( -1 );
return( 0 );
}
/* Given a pair of points, return scale, angle, dx, dy to resample the 2nd
* image with.
*/
int
im__coeff( int xr1, int yr1, int xs1, int ys1,
int xr2, int yr2, int xs2, int ys2,
double *a, double *b, double *dx, double *dy )
{
DOUBLEMASK *in, *out;
if( !(in = im_create_dmask( "in", 4, 4 )) ) {
im_errormsg( "im__coeff: unable to allocate matrix" );
return( -1 );
}
in->coeff[0] = (double)xs1;
in->coeff[1] = (double)-ys1;
in->coeff[2] = 1.0;
in->coeff[3] = 0.0;
in->coeff[4] = (double)ys1;
in->coeff[5] = (double)xs1;
in->coeff[6] = 0.0;
in->coeff[7] = 1.0;
in->coeff[8] = (double)xs2;
in->coeff[9] = (double)-ys2;
in->coeff[10] = 1.0;
in->coeff[11] = 0.0;
in->coeff[12] = (double)ys2;
in->coeff[13] = (double)xs2;
in->coeff[14] = 0.0;
in->coeff[15] = 1.0;
if( !(out = im_matinv( in, "out" )) ) {
im_free_dmask( in );
im_errormsg( "im__coeff: unable to invert matrix" );
return( -1 );
}
*a = out->coeff[0]*xr1 + out->coeff[1]*yr1 +
out->coeff[2]*xr2 + out->coeff[3]*yr2;
*b = out->coeff[4]*xr1 + out->coeff[5]*yr1 +
out->coeff[6]*xr2 + out->coeff[7]*yr2;
*dx= out->coeff[8]*xr1 + out->coeff[9]*yr1 +
out->coeff[10]*xr2 + out->coeff[11]*yr2;
*dy= out->coeff[12]*xr1 + out->coeff[13]*yr1 +
out->coeff[14]*xr2 + out->coeff[15]*yr2;
im_free_dmask( in );
im_free_dmask( out );
return( 0 );
}
/* Calculate the inverse transformation.
*/
int
im__transform_calc_inverse( Transformation *trn )
{
DOUBLEMASK *msk, *msk2;
if( !(msk = im_create_dmaskv( "boink", 2, 2,
trn->a, trn->b, trn->c, trn->d )) )
return( -1 );
if( !(msk2 = im_matinv( msk, "boink2" )) ) {
(void) im_free_dmask( msk );
return( -1 );
}
trn->ia = msk2->coeff[0];
trn->ib = msk2->coeff[1];
trn->ic = msk2->coeff[2];
trn->id = msk2->coeff[3];
(void) im_free_dmask( msk );
(void) im_free_dmask( msk2 );
return( 0 );
}
