153 lines
3.5 KiB
C
153 lines
3.5 KiB
C
/* make a test pattern to show the eye's frequency response
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*
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* Copyright: 1990, 1991, N.Dessipris.
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*
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* Author N. Dessipris
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* Written on 30/05/1990
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* Updated on: 27/01/1991, 07/03/1991,
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* 22/7/93 JC
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* - im_outcheck() added
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* 30/8/95 JC
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* - modernized
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* 1/2/11
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* - gtk-doc
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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/**
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* im_feye:
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* @out: output image
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* @xsize: image size
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* @ysize: image size
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* @factor: image size
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*
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* Create a test pattern with increasing spatial frequence in X and
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* amplitude in Y. @factor should be between 0 and 1 and determines the
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* maximum spatial frequency.
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*
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* Creates an one band float image with values in +1 to -1.
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*
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* See also: im_eye().
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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_feye( IMAGE *out, const int xsize, const int ysize, const double factor )
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{
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int x, y;
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double constant;
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double *lut;
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float *line;
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/* Check input args
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*/
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if( im_outcheck( out ) )
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return( -1 );
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if( factor > 1.0 || factor <= 0.0 ) {
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im_error( "im_feye", "%s", _( "factor should be in [1,0)" ) );
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return( -1 );
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}
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/* Set image descriptor
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*/
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im_initdesc( out, xsize, ysize, 1, IM_BBITS_FLOAT, IM_BANDFMT_FLOAT,
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IM_CODING_NONE, IM_TYPE_B_W, 1.0, 1.0, 0, 0 );
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if( im_setupout( out ) )
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return( -1 );
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/* Allocate space for line buffer.
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*/
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if( !(line = IM_ARRAY( out, xsize, float )) )
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return( -1 );
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/* Make a lut for easy calculations.
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*/
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if( !(lut = IM_ARRAY( out, xsize, double )) )
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return( -1 );
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constant = factor * IM_PI / (2 * (xsize - 1));
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for( x = 0; x < xsize; x++ )
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lut[x] = cos( constant * x * x ) / ((ysize - 1) * (ysize - 1));
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/* Make image.
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*/
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for( y = 0; y < ysize; y++ ) {
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for( x = 0; x < xsize; x++ )
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line[x] = y * y * lut[x];
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if( im_writeline( y, out, (PEL *) line ) )
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return( -1 );
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}
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return( 0 );
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}
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/**
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* im_eye:
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* @out: output image
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* @xsize: image size
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* @ysize: image size
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* @factor: image size
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*
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* Exactly as im_feye(), but make a UCHAR image with pixels in the range [0,
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* 255].
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*
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* See also: im_feye().
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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_eye( IMAGE *out, const int xsize, const int ysize, const double factor )
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{
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IMAGE *t[2];
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/* Change range to [0,255].
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*/
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if( im_open_local_array( out, t, 2, "im_grey", "p" ) ||
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im_feye( t[0], xsize, ysize, factor ) ||
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im_lintra( 127.5, t[0], 127.5, t[1] ) ||
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im_clip2fmt( t[1], out, IM_BANDFMT_UCHAR ) )
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return( -1 );
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return( 0 );
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}
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