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/************************************************************************/
/* */
/* vspline - a set of generic tools for creation and evaluation */
/* of uniform b-splines */
/* */
/* Copyright 2016 - 2023 by Kay F. Jahnke */
/* */
/* Permission is hereby granted, free of charge, to any person */
/* obtaining a copy of this software and associated documentation */
/* files (the "Software"), to deal in the Software without */
/* restriction, including without limitation the rights to use, */
/* copy, modify, merge, publish, distribute, sublicense, and/or */
/* sell copies of the Software, and to permit persons to whom the */
/* Software is furnished to do so, subject to the following */
/* conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the */
/* Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES */
/* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND */
/* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT */
/* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, */
/* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING */
/* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR */
/* OTHER DEALINGS IN THE SOFTWARE. */
/* */
/************************************************************************/
/// \file channels.cc
///
/// \brief demonstrates the use of 'channel views'
///
/// This example is derived from 'slice.cc', we use the same volume
/// as source data. But instead of producing an image output, we create
/// three separate colour channels of the bspline object and assert that
/// the evaluation of the channel views is identical with the evaluation
/// of the 'mother' spline.
/// For a more involved example using channel views, see ca_correct.cc
///
/// compile with:
/// clang++ -std=c++11 -march=native -o channels -O3 -pthread -DUSE_VC channels.cc -lvigraimpex -lVc
///
/// If you don't have Vc on your system, use
///
/// clang++ -std=c++11 -march=native -o channels -O3 -pthread channels.cc -lvigraimpex
/// note that the assertion at the end fails if the program is compiled
/// with -Ofast - then the result is only near equal.
#include <iostream>
#include <vspline/vspline.h>
#include <vigra/stdimage.hxx>
#include <vigra/imageinfo.hxx>
#include <vigra/impex.hxx>
int main ( int argc , char * argv[] )
{
// pixel_type is the result type, an RGB float pixel
typedef vigra::TinyVector < float , 3 > pixel_type ;
// voxel_type is the source data type
typedef vigra::TinyVector < float , 3 > voxel_type ;
// coordinate_type has a 3D coordinate
typedef vigra::TinyVector < float , 3 > coordinate_type ;
// warp_type is a 2D array of coordinates
typedef vigra::MultiArray < 2 , coordinate_type > warp_type ;
// target_type is a 2D array of pixels
typedef vigra::MultiArray < 2 , pixel_type > target_type ;
// we want a b-spline with natural boundary conditions
vigra::TinyVector < vspline::bc_code , 3 > bcv ( vspline::NATURAL ) ;
// create quintic 3D b-spline object containing voxels
vspline::bspline < voxel_type , 3 >
space ( vigra::Shape3 ( 10 , 10 , 10 ) , 5 , bcv ) ;
// here we create the channel views. Since these are merely views
// to the same data, no data will be copied, and it doesn't matter
// whether we create these views before or after prefiltering.
auto red_channel = space.get_channel_view ( 0 ) ;
auto green_channel = space.get_channel_view ( 1 ) ;
auto blue_channel = space.get_channel_view ( 2 ) ;
// fill the b-spline's core with a three-way gradient
for ( int z = 0 ; z < 10 ; z++ )
{
for ( int y = 0 ; y < 10 ; y++ )
{
for ( int x = 0 ; x < 10 ; x++ )
{
voxel_type & c ( space.core [ vigra::Shape3 ( x , y , z ) ] ) ;
c[0] = 25.5 * x ;
c[1] = 25.5 * y ;
c[2] = 25.5 * z ;
}
}
}
// prefilter the b-spline
space.prefilter() ;
// now make a warp array with 1920X1080 3D coordinates
warp_type warp ( vigra::Shape2 ( 1920 , 1080 ) ) ;
// we want the coordinates to follow this scheme:
// warp(x,y) = (x,1-x,y)
// scaled appropriately
for ( int y = 0 ; y < 1080 ; y++ )
{
for ( int x = 0 ; x < 1920 ; x++ )
{
coordinate_type & c ( warp [ vigra::Shape2 ( x , y ) ] ) ;
c[0] = float ( x ) / 192.0 ;
c[1] = 10.0 - c[0] ;
c[2] = float ( y ) / 108.0 ;
}
}
// get an evaluator for the b-spline
typedef vspline::evaluator < coordinate_type , voxel_type > ev_type ;
ev_type ev ( space ) ;
// the evaluators of the channel views have their own type:
typedef vspline::evaluator < coordinate_type , float > ch_ev_type ;
// we create the three evaluators for the three channel views
ch_ev_type red_ev ( red_channel ) ;
ch_ev_type green_ev ( green_channel ) ;
ch_ev_type blue_ev ( blue_channel ) ;
// and make sure the evaluation results match
// TODO: compiling with clang++, the two results are actually equal,
// but not with g++ - there, the results differ slightly.
for ( int y = 0 ; y < 1080 ; y++ )
{
for ( int x = 0 ; x < 1920 ; x++ )
{
coordinate_type & c ( warp [ vigra::Shape2 ( x , y ) ] ) ;
auto diff = fabs ( ev ( c ) [ 0 ] - red_ev ( c ) ) ;
if ( diff > 1e-4 )
{
std::cerr << "red result differs at c " << c << " "
<< ev ( c ) [ 0 ] << " != " << red_ev ( c )
<< std::endl ;
}
diff = fabs ( ev ( c ) [ 1 ] - green_ev ( c ) ) ;
if ( diff > 1e-4 )
{
std::cerr << "green result differs at c " << c << " "
<< ev ( c ) [ 1 ] << " != " << green_ev ( c )
<< std::endl ;
}
diff = fabs ( ev ( c ) [ 2 ] - blue_ev ( c ) ) ;
if ( diff > 1e-4 )
{
std::cerr << "blue result differs at c " << c << " "
<< ev ( c ) [ 2 ] << " != " << blue_ev ( c )
<< std::endl ;
}
}
}
std::cout << "success" << std::endl ;
exit ( 0 ) ;
}
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