73 lines
2.2 KiB
Groff
73 lines
2.2 KiB
Groff
.TH IM_DILATE 3 "14 May 1991"
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.SH NAME
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im_dilate, im_dilate_raw, im_erode, im_erode_raw \- perform morphological operations on a white object against a black background
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.SH SYNOPSIS
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.B #include <vips/vips.h>
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.B int im_dilate(in, out, m)
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.br
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.B IMAGE *in, *out;
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.br
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.B INTMASK *m;
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.B int im_erode(in, out, m)
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.br
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.B IMAGE *in, *out;
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.br
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.B INTMASK *m;
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.B int im_dilate_raw(in, out, m)
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.br
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.B IMAGE *in, *out;
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.br
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.B INTMASK *m;
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.B int im_erode_raw(in, out, m)
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.br
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.B IMAGE *in, *out;
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.br
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.B INTMASK *m;
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.SH DESCRIPTION
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The above functions are applications of morphological operations on one
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channel binary images ie. images with pixels that are either 0 (black) or 255
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(white). All functions assume that input images contain white objects against
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a black background.
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Mask coefficients can be either 0 (for object) or 255 (for background) or 128
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(for do not care).
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The mask should have odd length sides and the origin of the mask is at location
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(m-\>xsize/2,m-\>ysize/2) integer division. All algorithms have been based on
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the book "Fundamentals of Digital Image Processing" by A. Jain, pp 384-388,
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Prentice-Hall, 1989. Essentially, im_dilate(3) sets pixels in the output if
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*any* part of the mask matches, whereas im_erode(3) sets pixels only if *all*
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of the mask matches.
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im_dilate(3)
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dilates the image pointed by in, according to the mask pointed by m and writes
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the result in the location pointed by the IMAGE descriptor out. The output
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image is the same size as the input, with a black border in the manner of
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im_conv(3).
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im_dilate_raw(3)
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works as im_dilate(3), but does not add a black border.
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im_erode(3)
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erodes the image pointed by in, according to the mask pointed by m and writes
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the result in the location pointed by the IMAGE descriptor out. Again, the
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output image is forced to have the same size as the input.
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im_erode_raw(3)
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works as im_erode(3), but does not add a black border.
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See the boolean operations im_and(3), im_or(3) and im_eor(3) for analogues
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of the usual set difference and set union operations.
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.SH RETURN VALUE
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All functions returns 0 on success and -1 on error.
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.SH SEE ALSO
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im_read_imask(3), im_conv(3), im_and(3), im_rotate_imask(3).
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.SH COPYRIGHT
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1991-1995, Birkbeck College and the National Gallery
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