start on vips_invertlut()
This commit is contained in:
John Cupitt
parent
56df56c737
commit
222a7abdbf
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/* invert a lut
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*
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* Written on: 5/6/01
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* Modified on :
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*
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* 7/7/03 JC
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* - generate image rather than doublemask (arrg)
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* 23/3/10
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* - gtkdoc
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* 23/5/13
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* - fix 1 high input matrices
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* - fix file output
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* 4/9/13
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* - convert to a class
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <vips/vips.h>
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#include "pcreate.h"
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/*
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#define DEBUG
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*/
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/* Our state.
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*/
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typedef struct _VipsInvertlut {
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VipsCreate parent_instance;
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/* Input image.
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*/
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VipsImage *in;
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/* .. and cast to a matrix.
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*/
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VipsImage *mat;
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int lut_size; /* Number of output elements to generate */
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double **data; /* Rows of unpacked matrix */
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double *buf; /* Output buffer */
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} VipsInvertlut;
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typedef VipsCreateClass VipsInvertlutClass;
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G_DEFINE_TYPE( VipsInvertlut, vips_invertlut, VIPS_TYPE_CREATE );
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static void
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vips_invertlut_dispose( GObject *gobject )
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{
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VipsBuildlut *lut = (VipsBuildlut *) gobject;
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if( lut->data ) {
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int i;
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for( i = 0; i < lut->input->ysize; i++ )
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VIPS_FREE( lut->data[i] );
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VIPS_FREE( lut->data );
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}
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VIPS_FREE( lut->buf );
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VIPS_UNREF( lut->mat );
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G_OBJECT_CLASS( vips_invertlut_parent_class )->dispose( gobject );
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}
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/* Use this to sort our input rows by the first column.
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*/
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static int
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compare( const void *a, const void *b )
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{
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double **r1 = (double **) a;
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double **r2 = (double **) b;
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double diff = r1[0][0] - r2[0][0];
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if( diff > 0 )
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return( 1 );
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else if( diff == 0 )
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return( 0 );
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else
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return( -1 );
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}
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static int
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vips_invertlut_build_init( VipsInvertlut *lut )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( lut );
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/* Fill our state.
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*/
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static int
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build_state( State *state, DOUBLEMASK *input, IMAGE *output, int lut_size )
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{
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int x, y, i;
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state->input = input;
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state->output = output;
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state->lut_size = lut_size;
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state->data = NULL;
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if( !(state->buf = im_malloc( NULL, IM_IMAGE_SIZEOF_LINE( output ) )) )
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return( -1 );
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if( !(state->data = IM_ARRAY( NULL, input->ysize, double * )) )
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return( -1 );
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for( y = 0; y < input->ysize; y++ )
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state->data[y] = NULL;
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for( y = 0; y < input->ysize; y++ )
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if( !(state->data[y] = IM_ARRAY( NULL, input->xsize, double )) )
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return( -1 );
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for( i = 0, y = 0; y < input->ysize; y++ )
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for( x = 0; x < input->xsize; x++, i++ )
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state->data[y][x] = input->coeff[i];
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/* Sanity check for data range.
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*/
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for( y = 0; y < input->ysize; y++ )
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for( x = 0; x < input->xsize; x++ )
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if( state->data[y][x] > 1.0 ||
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state->data[y][x] < 0.0 ) {
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im_error( "im_invertlut",
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_( "element (%d, %d) is %g, "
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"outside range [0,1]" ),
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x, y, state->data[y][x] );
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return( -1 );
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}
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/* Sort by 1st column in input.
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*/
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qsort( state->data, input->ysize, sizeof( double * ), compare );
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#ifdef DEBUG
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printf( "Input table, sorted by 1st column\n" );
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for( y = 0; y < input->ysize; y++ ) {
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printf( "%.4d ", y );
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for( x = 0; x < input->xsize; x++ )
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printf( "%.9f ", state->data[y][x] );
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printf( "\n" );
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}
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#endif /*DEBUG*/
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return( 0 );
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}
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static int
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vips_invertlut_build_create( VipsBuildlut *lut )
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{
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DOUBLEMASK *input = state->input;
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int ysize = input->ysize;
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int xsize = input->xsize;
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double *buf = state->buf;
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int bands = xsize - 1;
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double **data = state->data;
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int lut_size = state->lut_size;
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int b;
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/* Do each output channel separately.
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*/
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for( b = 0; b < bands; b++ ) {
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/* The first and last lut positions we know real values for.
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*/
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int first = data[0][b + 1] * (lut_size - 1);
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int last = data[ysize - 1][b + 1] * (lut_size - 1);
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int k;
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/* Extrapolate bottom and top segments to (0,0) and (1,1).
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*/
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for( k = 0; k < first; k++ ) {
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/* Have this inside the loop to avoid /0 errors if
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* first == 0.
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*/
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double fac = data[0][0] / first;
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buf[b + k * bands] = k * fac;
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}
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for( k = last; k < lut_size; k++ ) {
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/* Inside the loop to avoid /0 errors for last ==
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* (lut_size - 1).
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*/
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double fac = (1 - data[ysize - 1][0]) /
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((lut_size - 1) - last);
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buf[b + k * bands] =
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data[ysize - 1][0] + (k - last) * fac;
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}
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/* Interpolate the data sections.
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*/
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for( k = first; k < last; k++ ) {
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/* Where we're at in the [0,1] range.
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*/
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double ki = (double) k / (lut_size - 1);
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double irange, orange;
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int j;
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/* Search for the lowest real value < ki. There may
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* not be one: if not, just use 0. Tiny error.
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*/
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for( j = ysize - 1; j >= 0; j-- )
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if( data[j][b + 1] < ki )
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break;
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if( j == -1 )
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j = 0;
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/* Interpolate k as being between row data[j] and row
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* data[j + 1].
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*/
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irange = data[j + 1][b + 1] - data[j][b + 1];
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orange = data[j + 1][0] - data[j][0];
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buf[b + k * bands] = data[j][0] +
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orange * ((ki - data[j][b + 1]) / irange);
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}
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}
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return( 0 );
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}
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static int
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vips_invertlut_build( VipsObject *object )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
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VipsCreate *create = VIPS_CREATE( object );
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VipsBuildlut *lut = (VipsBuildlut *) object;
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if( VIPS_OBJECT_CLASS( vips_invertlut_parent_class )->build( object ) )
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return( -1 );
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if( vips_check_matrix( class->nickname, lut->in, &lut->mat ) )
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return( -1 );
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if( vips_invertlut_build_init( lut ) ||
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vips_invertlut_build_create( lut ) )
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return( -1 );
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vips_image_init_fields( create->out,
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lut->lut_size, 1, lut->mat->Xsize - 1,
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VIPS_FORMAT_DOUBLE, VIPS_CODING_NONE,
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VIPS_INTERPRETATION_HISTOGRAM, 1.0, 1.0 );
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if( vips_image_write_line( create->out, 0, (VipsPel *) lut->buf ) )
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return( -1 );
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return( 0 );
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}
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static void
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vips_invertlut_class_init( VipsBuildlutClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
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gobject_class->dispose = vips_invertlut_dispose;
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gobject_class->set_property = vips_object_set_property;
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gobject_class->get_property = vips_object_get_property;
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vobject_class->nickname = "invertlut";
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vobject_class->description = _( "build an inverted look-up table" );
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vobject_class->build = vips_invertlut_build;
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VIPS_ARG_IMAGE( class, "in", 0,
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_( "Input" ),
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_( "Matrix of XY coordinates" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsBuildlut, in ) );
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}
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static void
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vips_invertlut_init( VipsBuildlut *lut )
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{
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}
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/**
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* im_invertlut:
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* @input: input mask
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* @output: output LUT
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* @lut_size: generate this much
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*
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* Given a mask of target values and real values, generate a LUT which
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* will map reals to targets. Handy for linearising images from
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* measurements of a colour chart. All values in [0,1]. Piecewise linear
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* interpolation, extrapolate head and tail to 0 and 1.
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*
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* Eg. input like this:
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*
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* <tgroup cols='4' align='left' colsep='1' rowsep='1'>
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* <tbody>
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* <row>
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* <entry>4</entry>
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* <entry>3</entry>
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* </row>
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* <row>
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* <entry>0.1</entry>
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* <entry>0.2</entry>
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* <entry>0.3</entry>
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* <entry>0.1</entry>
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* </row>
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* <row>
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* <entry>0.2</entry>
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* <entry>0.4</entry>
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* <entry>0.4</entry>
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* <entry>0.2</entry>
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* </row>
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* <row>
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* <entry>0.7</entry>
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* <entry>0.5</entry>
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* <entry>0.6</entry>
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* <entry>0.3</entry>
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* </row>
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* </tbody>
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* </tgroup>
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*
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* Means a patch with 10% reflectance produces an image with 20% in
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* channel 1, 30% in channel 2, and 10% in channel 3, and so on.
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*
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* Inputs don't need to be sorted (we do that). Generate any precision
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* LUT, typically you might ask for 256 elements.
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*
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* It won't work too well for non-monotonic camera responses
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* (we should fix this). Interpolation is simple piecewise linear; we ought to
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* do something better really.
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*
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* See also: vips_buildlut().
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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vips_invertlut( VipsImage *in, VipsImage **out, ... )
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{
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va_list ap;
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int result;
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va_start( ap, out );
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result = vips_call_split( "invertlut", ap, in, out );
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va_end( ap );
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return( result );
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}
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int
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im_invertlut( DOUBLEMASK *input, IMAGE *output, int lut_size )
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{
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State state;
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if( !input ||
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input->xsize < 2 ||
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input->ysize < 1 ) {
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im_error( "im_invertlut", "%s", _( "bad input matrix" ) );
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return( -1 );
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}
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if( lut_size < 1 ||
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lut_size > 65536 ) {
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im_error( "im_invertlut", "%s", _( "bad lut_size" ) );
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return( -1 );
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}
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im_initdesc( output,
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lut_size, 1, input->xsize - 1,
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IM_BBITS_DOUBLE, IM_BANDFMT_DOUBLE,
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IM_CODING_NONE, IM_TYPE_HISTOGRAM, 1.0, 1.0, 0, 0 );
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if( im_setupout( output ) )
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return( -1 );
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if( build_state( &state, input, output, lut_size ) ||
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invertlut( &state ) ||
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im_writeline( 0, output, (VipsPel *) state.buf ) ) {
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free_state( &state );
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return( -1 );
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}
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free_state( &state );
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return( 0 );
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}
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