.TH IM_COOC_MATRIX 3 "2 Dec 1991"
.SH NAME
im_cooc_matrix, im_cooc_asm, im_cooc_contrast, im_cooc_correlation, 
im_cooc_entropy \- calculate the co-occurrence matrix and features on it
.SH SYNOPSIS
.B #include <vips/vips.h>

int im_cooc_matrix(im, m, xp, yp, xs, ys, dx, dy, sym)
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.B IMAGE *im, *m;
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.B int xp, yp, xs, ys;
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.B int dx, dy;
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.B int sym;

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.B int im_cooc_asm(m, asmoment)
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.B IMAGE *m;
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.B double *asmoment;

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.B int im_cooc_contrast(m, contrast)
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.B IMAGE *m;
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.B double *contrast;

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.B int im_cooc_correlation(m, correlation)
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.B IMAGE *m;
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.B double *correlation;

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.B int im_cooc_entropy(m, entropy)
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.B IMAGE *m;
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.B double *entropy;

.SH DESCRIPTION
.B im_cooc_matrix()
creates a 256 by 256 one channel co-occurrence matrix of the box determined by
the parameters (xp, yp; xs, ys) within the image pointed by the IMAGE
descriptor im.  The matrix is written onto the IMAGE descriptor m.  The
displacement vector is determined by (dx, dy).  The user must ensure that
there is enough border pixels around the box within im dictated by the
displacement vector (dx,dy) or else the program fails.  All entries of the
co-occurrence matrix are double normalised to the number of pairs involved.
This function is a direct implementation of the paper:  Haralick R. M.,
Shanmugan K. and Dinstein I., 'Textural features for image classification',
IEEE Transactions on Systems, Man, and Cybernetics, Vol. SMC-3, No 6, Nov.
1973, pp 610-621. Input im should be one band unsigned char image.

If flag sym is 1, the created co-occurrence matrix is symmetric that is
dispacement vectors (dx, dy), (-dx, -dy) create exactly the same matrix.  If
sym is 0, the created co-occurrence matrix is not symmetric that is
dispacement vectors (dx, dy), (-dx, -dy) create different matrices.

.B im_cooc_asm()
calculates the angular second moment of the co-occurrence matrix held by m.
The result is returned into the location pointed by asmoment.

.B im_cooc_contrast()
calculates the contrast of the co-occurrence matrix held by m.
The result is returned into the location pointed by contrast.

.B im_cooc_correlation()
calculates the correlation of the co-occurrence matrix held by m.
The result is returned into the location pointed by correlation.

.B im_cooc_entropy()
calculates the entropy of the co-occurrence matrix held by m.
The result is returned into the location pointed by entropy.
.SH RETURNED VALUES
All functions returns 0 on success and -1 on error.
.SH SEE\ ALSO
im_glds_matrix(3)
.SH COPYRIGHT
.br
N. Dessipris
.SH AUTHOR
N. Dessipris \- 2/12/1991