1IM_DILATE(3)               Library Functions Manual               IM_DILATE(3)
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NAME

6       im_dilate,  im_dilate_raw, im_erode, im_erode_raw - perform morphologi‐
7       cal operations on a white object against a black background
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SYNOPSIS

10       #include <vips/vips.h>
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12       int im_dilate(in, out, m)
13       IMAGE *in, *out;
14       INTMASK *m;
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16       int im_erode(in, out, m)
17       IMAGE *in, *out;
18       INTMASK *m;
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20       int im_dilate_raw(in, out, m)
21       IMAGE *in, *out;
22       INTMASK *m;
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24       int im_erode_raw(in, out, m)
25       IMAGE *in, *out;
26       INTMASK *m;
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DESCRIPTION

30       The above functions are applications of morphological operations on one
31       channel  binary images ie. images with pixels that are either 0 (black)
32       or 255 (white).  All functions assume that input images  contain  white
33       objects against a black background.
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35       Mask  coefficients can be either 0 (for object) or 255 (for background)
36       or 128 (for do not care).
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38       The mask should have odd length sides and the origin of the mask is  at
39       location (m->xsize/2,m->ysize/2) integer division.  All algorithms have
40       been based on the book "Fundamentals of Digital Image Processing" by A.
41       Jain,  pp 384-388, Prentice-Hall, 1989.  Essentially, im_dilate(3) sets
42       pixels in the output  if  *any*  part  of  the  mask  matches,  whereas
43       im_erode(3) sets pixels only if *all* of the mask matches.
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45       im_dilate(3)  dilates  the  image  pointed by in, according to the mask
46       pointed by m and writes the result in the location pointed by the IMAGE
47       descriptor  out. The output image is the same size as the input, with a
48       black border in the manner of im_conv(3).
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50       im_dilate_raw(3) works as im_dilate(3), but does not add a  black  bor‐
51       der.
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53       im_erode(3)  erodes  the  image  pointed  by  in, according to the mask
54       pointed by m and writes the result in the location pointed by the IMAGE
55       descriptor out. Again, the output image is forced to have the same size
56       as the input.
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58       im_erode_raw(3) works as im_erode(3), but does not add a black border.
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60       See the boolean operations im_and(3), im_or(3) and im_eor(3)  for  ana‐
61       logues of the usual set difference and set union operations.
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RETURN VALUE

65       All functions returns 0 on success and -1 on error.
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SEE ALSO

68       im_read_imask(3), im_conv(3), im_and(3), im_rotate_imask(3).
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71       1991-1995, Birkbeck College and the National Gallery
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75                                  14 May 1991                     IM_DILATE(3)
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