int im_mpercent( in, percent, thresh )
IMAGE *in;
int percent;
int *thresh;
DESCRIPTION
im_mpercent() returns (through the thresh parameter) the threshold above which
there are percent values of the input image. If for example percent=.1, the
number of pels of the input image with values greater than the returned int
will correspond to 10% of all pels of the image.
The function is applied on one band FMTUCHAR images only. It can be
used in order to threshold the scaled result of a filtering operation.
RETURN VALUE
The function returns 0 on success and -1 on error.