48 lines
1.5 KiB
Groff
48 lines
1.5 KiB
Groff
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.TH IM_HISTPLOT 3 "10 May 1991"
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.SH NAME
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im_histplot \- graph an image of one horizontal or vertical line
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.SH SYNOPSIS
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#include <vips/vips.h>
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int im_histplot(in, out)
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.br
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IMAGE *in, *out;
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.SH DESCRIPTION
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.B im_histplot(3)
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plots a graph of a horizontal or vertical image file with
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one line. It is suitable for displaying the output of histogram functions
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such as im_histgr(3) and for displaying line profiles.
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Note that if you try to directly plot the result of
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.B im_histgr(3)
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you will often get a very, very large image, since
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.B im_histplot(3)
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will draw an image as high (or as wide) as the largest pixel
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value in the image (potentially huge). Use
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.B im_histnorm(3)
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to normalise the histogram maximum before plotting.
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The input image should be either one horizontal line (Ysize=1) or
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one vertical line (Xsize=1). If the image is FMTUCHAR, the graph is drawn
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as 256 by line-length pixels. For all other unsigned integer types,
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.B im_histplot(3)
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finds the image maximum, and draws the graph as max by line-length pixels.
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For signed integer types,
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.B im_histplot(3)
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finds minimum and maximum, moves min up to zero, and
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draws the graph as min + max by line-lenth pixels.
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For float types,
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.B im_histplot(3)
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finds minimum and maximum, and scales the image range so as to make the
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graph square.
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.SH RETURNED VALUE
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The function returns 0 on success and -1 on error.
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.SH SEE ALSO
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im_histgr(3), im_histnorm(3), im_extract(3).
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.SH COPYRIGHT
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National Gallery and Birkbeck College, 1995
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