.TH LINES 3 "14 May 1991"
.SH NAME
im_cntlines, im_profile \- calculate transitions between black and white pels horizontally or vertically
.SH SYNOPSIS
.B #include <vips/vips.h>

.B int im_profile(in, out, dir)
.br
.B IMAGE *in, *out;
.br
.B int dir;

.B int im_cntlines(in, nolines, dir)
.br
.B IMAGE *in;
.br
.B double *nolines;
.br
.B int dir;

.SH DESCRIPTION

.B im_profile(3)
searches inward from the edge of the image and finds the first non-zero pixel.
It outputs an image containing a list of the offsets for each row or column.

If 
.B dir
==0, then
.B im_profile(3)
searches down from the top edge, writing an image as wide as the input
image, but only 1 pixel high, containing the number of pixels down to the
first non-zero pixel for each column of input pixels.

If 
.B dir
==1, then
.B im_profile(3)
searches across from the left edge, writing an image as high as the input
image, but only 1 pixel wide, containing the number of pixels across to the
first non-zero pixel for each row of input pixels.

.B im_cntlines(3)
calculates the number of transitions between black and white pixels of
an image.  If dir is 1 then all transitions across the
vertical direction are calculated for all Xsize lines of the image.  If dir
is 0 then all transitions along the horizontal direction for all Ysize
lines are calculated.  The function returns the number of transitions
divided by twice the number of the corresponding Xsize of Ysize lines.
The program is primarily used to calculate the number of unbroken horizontal 
(dir=0) or vertical lines (dir=1) that exist within an image.
Input image in can have only one channel.

.SH RETURN VALUE
All functions returns 0 on success and -1 on error.
.SH SEE ALSO
im_erode(3), im_dilate(3).