**Name**

**fsaddles** Position and value of saddle points in bilinear interpolation

**Command Synopsis**

**fsaddles** *image* *saddles* *.*

image: Input fimage

saddles: Output fimage of saddle points

. (screen output) : Number of saddle points

**Function Summary**

int fsaddles (pImage , pSaddlesImage )

Fimage pImage , pSaddlesImage ;

**Description**

This module computes the values at the saddle points in a bilinear
interpolated image. The resulting image has one column and one line missing
compared to the original image. The value at (*i*, *j*) is the one at the saddle
point in the dual pixel of corners (*i*, *j*), (*i* + 1, *j*), (*i*, *j* + 1) and
(*i* + 1, *j* + 1) if there is one, and `FLT_MAX` (defined in `math.h`)
if there is no saddle point inside the dual pixel. A more appropriate value
would have been `NAN` (Not A Number), but this value is not always
defined in `math.h`.

As the resulting image contains values (or rather non-values) not easily
representable, it is not appropriate for viewing via the module `fview`
for example.

This module is mainly called by the module `flst_bilinear`.

**See Also**

`flstb_dualchain`, `flst_bilinear`, `flstb_tv`, `ll_boundaries2`, `ll_boundaries`, `ll_edges`, `ll_extract`.

**Version 1.0**

Last Modification date : Thu Nov 29 20:23:56 2001

**Author**

Pascal Monasse