2007-08-29 18:23:50 +02:00
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.TH IM_BUILDLUT 3 "June 2006"
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.SH NAME
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im_buildlut \- build a LUT from a set of x/y points
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.SH SYNOPSIS
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#include <vips/vips.h>
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int
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.br
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im_buildlut( DOUBLEMASK *input, IMAGE *output )
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.SH DESCRIPTION
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.B im_buildlut(3)
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constructs a LUT, interpolating a set of x/y points. Interpolation is strictly
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piecewise linear. For example, if the input is:
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2009-03-18 17:47:17 +01:00
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0 0
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128 20
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255 100
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2007-08-29 18:23:50 +02:00
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2009-06-22 18:07:09 +02:00
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we generate the values:
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2007-08-29 18:23:50 +02:00
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2009-06-22 18:07:09 +02:00
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index value
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0 0
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1 0.01
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2009-03-18 17:47:17 +01:00
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.. etc. linear interpolation
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2009-06-22 18:07:09 +02:00
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128 20
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129 20.5
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2009-03-18 17:47:17 +01:00
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.. etc. linear interpolation
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2009-06-22 18:07:09 +02:00
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255 100
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(we don't generate the index column, that's just there to show the
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position in the table)
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2007-08-29 18:23:50 +02:00
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2009-06-22 18:07:09 +02:00
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The x/y points don't need to be
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sorted: we do that. You can have several Ys: each becomes a band in the
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output LUT. X can start at any integer value, including negatives.
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2007-08-29 18:23:50 +02:00
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.SH RETURN VALUE
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-1 on error, otherwise 0
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.SH SEE ALSO
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im_invertlut(3), im_identity(3).
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.SH COPYRIGHT
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2006, Imperial College
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