354 lines
8.2 KiB
C
354 lines
8.2 KiB
C
/* Build a LUT from a set of x/y points.
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*
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* Written on: 26/9/06
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* - from im_invertlut()
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* 9/10/06
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* - don't output x values
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* 18/3/09
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* - saner limit and rounding behaviour
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* 30/3/09
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* - argh, fixed again
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* 22/6/09
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* - more fixes for tables that don't start at zero (thanks Jack)
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* 23/3/10
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* - gtkdoc
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* 2/7/13
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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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/*
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#define DEBUG
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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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/* Our state.
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*/
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typedef struct _VipsBuildlut {
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VipsCreate parent_instance;
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VipsImage *input; /* Input matrix */
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int xlow; /* Index 0 in output is this x */
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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; /* Ouput buffer */
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} VipsBuildlut;
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typedef VipsCreateClass VipsBuildlutClass;
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G_DEFINE_TYPE( VipsBuildlut, vips_buildlut, VIPS_TYPE_CREATE );
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static void
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vips_buildlut_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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}
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VIPS_FREE( lut->data );
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VIPS_FREE( lut->buf );
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G_OBJECT_CLASS( vips_buildlut_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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vips_buildlut_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_buildlut_build_init( VipsBuildlut *lut )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( lut );
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VipsCreate *create = VIPS_CREATE( lut );
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int x, y, i;
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int xlow, xhigh;
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/* Need xlow and xhigh to get the size of the LUT we build.
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*/
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xlow = xhigh = input->coeff[0];
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for( y = 0; y < input->ysize; y++ ) {
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double v = input->coeff[y * input->xsize];
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if( floor( v ) != v ) {
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im_error( "im_buildlut",
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"%s", _( "x value not an int" ) );
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return( -1 );
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}
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if( v < xlow )
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xlow = v;
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if( v > xhigh )
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xhigh = v;
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}
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state->xlow = xlow;
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state->lut_size = xhigh - xlow + 1;
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if( state->lut_size < 1 ) {
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im_error( "im_buildlut", "%s", _( "x range too small" ) );
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return( -1 );
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}
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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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if( !(state->buf = IM_ARRAY( NULL,
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state->lut_size * (input->xsize - 1), double )) )
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return( -1 );
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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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/* Fill our state.
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*/
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static int
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vips_buildlut_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_buildlut_parent_class )->build( object ) )
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return( -1 );
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if( vips_buildlut_build_init( lut ) )
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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_buildlut_class_init( VipsTextClass *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_buildlut_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 = "buildlut";
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vobject_class->description = _( "build a look-up table" );
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vobject_class->build = vips_buildlut_build;
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VIPS_ARG_IMAGE( class, "in", 4,
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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( VipsImage, input ),
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NULL );
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}
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static int
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buildlut( State *state )
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{
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const int xlow = state->xlow;
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const DOUBLEMASK *input = state->input;
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const int ysize = input->ysize;
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const int xsize = input->xsize;
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const int bands = xsize - 1;
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const int xlast = state->data[ysize - 1][0];
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int b, i, x;
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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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for( i = 0; i < ysize - 1; i++ ) {
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const int x1 = state->data[i][0];
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const int x2 = state->data[i + 1][0];
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const int dx = x2 - x1;
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const double y1 = state->data[i][b + 1];
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const double y2 = state->data[i + 1][b + 1];
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const double dy = y2 - y1;
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for( x = 0; x < dx; x++ )
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state->buf[b + (x + x1 - xlow) * bands] =
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y1 + x * dy / dx;
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}
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/* We are inclusive: pop the final value in by hand.
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*/
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state->buf[b + (xlast - xlow) * bands] =
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state->data[ysize - 1][b + 1];
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}
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return( 0 );
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}
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/**
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* im_buildlut:
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* @input: input mask
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* @output: output image
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*
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* This operation builds a lookup table from a set of points. Intermediate
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* values are generated by piecewise linear interpolation.
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*
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* For example, consider this 2 x 2 matrix of (x, y) coordinates:
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*
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* <tgroup cols='2' align='left' colsep='1' rowsep='1'>
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* <tbody>
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* <row>
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* <entry>0</entry>
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* <entry>0</entry>
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* </row>
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* <row>
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* <entry>255</entry>
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* <entry>100</entry>
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* </row>
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* </tbody>
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* </tgroup>
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*
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* We then generate:
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*
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* <tgroup cols='2' align='left' colsep='1' rowsep='1'>
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* <thead>
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* <row>
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* <entry>Index</entry>
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* <entry>Value</entry>
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* </row>
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* </thead>
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* <tbody>
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* <row>
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* <entry>0</entry>
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* <entry>0</entry>
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* </row>
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* <row>
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* <entry>1</entry>
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* <entry>0.4</entry>
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* </row>
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* <row>
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* <entry>...</entry>
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* <entry>etc. by linear interpolation</entry>
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* </row>
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* <row>
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* <entry>255</entry>
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* <entry>100</entry>
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* </row>
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* </tbody>
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* </tgroup>
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*
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* This is then written as the output image, with the left column giving the
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* index in the image to place the value.
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*
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* The (x, y) points don't need to be sorted: we do that. You can have
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* several Ys, each becomes a band in the output LUT. You don't need to
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* start at zero, any integer will do, including negatives.
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*
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* See also: im_identity(), im_invertlut().
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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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im_buildlut( DOUBLEMASK *input, IMAGE *output )
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{
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State state;
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if( !input || input->xsize < 2 || input->ysize < 1 ) {
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im_error( "im_buildlut", "%s", _( "bad input matrix size" ) );
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return( -1 );
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}
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if( build_state( &state, input ) ||
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buildlut( &state ) ) {
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free_state( &state );
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return( -1 );
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}
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im_initdesc( output,
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state.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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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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