62 lines
1.7 KiB
Groff
62 lines
1.7 KiB
Groff
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.TH IM_SIMILARITY_AREA 3 "13 January 1992"
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.SH NAME
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im_similarity_area, im_similarity \- apply a similarity transform to an image
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.SH SYNOPSIS
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.B #include <vips/vips.h>
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int im_similarity_area(in, out, s, a, dx, dy, x, y, w, h)
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.br
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.B IMAGE *in, *out;
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.br
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.B double s, a, dx, dy;
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.br
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.B int x, y;
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.br
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.B int w, h;
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int im_similarity(in, out, s, a, dx, dy)
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.br
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.B IMAGE *in, *out;
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.br
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.B double s, a, dx, dy;
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.SH DESCRIPTION
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.B im_similarity_area()
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applies a similarity transformation on the image held by the IMAGE descriptor
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in and puts the result at the location pointed by the IMAGE descriptor out. in
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many have any number of bands, be any size, and have any non-complex type.
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The transformation is described by s, a, dx, dy. The point (x,y) in the input
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is mapped onto point (X,Y) in the output by
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X = s * x - a * y + dx
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Y = a * x + s * y + dy
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s and a do not correspond to scale and angle of the transformation; the actual
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scale and angle are given by the equations:
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scale = sqrt(s*s + a*a)
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angle = arctan(s/a).
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The area of the output image given by x, y, w, h is generated. (0,0) is
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the position of the transformed top-left-hand corner of the input image.
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Function im_similarity_area resamples the transformed image using bilinear
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interpolation.
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im_similarity works exactly as im_similarity_area, but calculates x, y, w, h
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for you such that the rectangle described just encloses all of the transformed
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input pixels.
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.SH RETURN VALUE
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The functions return 0 on success and -1 on error.
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.SH BUGS
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As with most resamplers, im_similarity performs poorly at the edges of
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images.
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.SH SEE\ ALSO
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similarity(1), similarity_area(1)
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.SH AUTHORS
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N. Dessipris -\ 13/01/1992
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.br
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J.Ph. Laurent -\ 12/12/92
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.br
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J. Cupitt -\ 22/02/93
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