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## NAME

```       im_avg,  im_deviate,  im_min,  im_minpos,  im_max, im_maxpos - find the
mean, standard deviation, minimum and maximum of an image

```

## SYNOPSIS

```       #include <vips/vips.h>

int im_avg(im, out)
IMAGE *im;
double *out;

int im_deviate(im, out)
IMAGE *im;
double *out;

int im_min(im, out)
IMAGE *im;
double *out;

int im_minpos(im, xpos, ypos, min)
IMAGE *im;
int *xpos, *ypos;
double *min;

int im_max(im, out)
IMAGE *im;
double *out;

int im_maxpos(im, xpos, ypos, max)
IMAGE *im;
int *xpos, *ypos;
double *max;

```

## DESCRIPTION

```       These functions find the mean, standard deviation, minimum, maximum  of
an  image.   They  operate  on  all  bands  of  the  input  image.  Use
im_stats(3)  if  you  need  to  calculate  on  bands  separately.   All
computations  are  carried  out  in  double  precision arithmetic.  The
standard deviation is calculated using the formula:

Var{E} = 1 / (N - 1) * (E{X^2} - E{X}^2 / N)
stdev{E} = sqrt(Var{E}).

im_avg(3) finds the average of an image pointed by im.  Takes as  input
any  non-complex  image  format  and  returns  a double at the location
pointed by out.

im_deviate(3) finds the standard deviation of an image pointed  by  im.
Takes as input any non-complex image format and returns a double at the
location pointed by out.

im_min(3) finds the the minimum value of the image pointed  by  im  and
returns  it  at  the location pointed by out.  Takes as input any image
format and returns a double at the location pointed by out.   If  input
is complex the min square amplitude (re*re+im*im) is returned.

im_minpos(3) finds the the minimum value of the image pointed by im and
returns it at the location pointed by out.  The coordinates of the last
occurrence  of  min is returned at locations pointed by xpos, ypos.  If
input is complex the min square amplitude (re*re+im*im) is returned.

im_max(3) finds the the maximum value of the image pointed  by  im  and
returns it at the location pointed by out.  If input is complex the max
square amplitude (re*re+im*im) is returned.

im_maxpos(3) finds the the maximum value of the image pointed by im and
returns it at the location pointed by max.  The coordinates of the last
occurrence of max is returned at locations pointed by xpos,  ypos.   If
input  is  complex  the max square amplitude (re*re+im*im) and its last
occurrence is returned.

```

## RETURNVALUE

```       All functions return 0 on success and -1 on error.

```

```       im_exptra(3), im_lintra(3), im_abs(3), im_stats(3).

```

```       N. Dessipris

```

## AUTHOR

```       N. Dessipris - 24/04/1991
J. Cupitt - 21/7/93

24 April 1991                        STATS(3)
```