49 lines
1.3 KiB
Groff
49 lines
1.3 KiB
Groff
.TH IM_AFFINE 3 "21 December 1999"
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.SH NAME
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im_affine \- apply an affine 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_affine(in, out, a, b, c, d, 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 a, b, c, d, 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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.SH DESCRIPTION
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.B im_affine()
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applies an affine 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 a, b, c, d, dx, dy. The point (x,y) in
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the input is mapped onto point (X,Y) in the output by
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X = a * x + b * y + dx
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Y = c * x + d * y + dy
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The area of the output image given by w, h, x, y 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_affine resamples the transformed image using bilinear
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interpolation.
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You can use
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.B im_affine(3)
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to resize an image with something like:
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scale xfac yfac im
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= im_affine im xfac 0 0 yfac 0 0 0 0
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(im.width * xfac) (im.height * yfac);
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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_affine(3) performs poorly at the edges of
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images.
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.SH SEE ALSO
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im_similarity(3)
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