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90 lines
2.4 KiB
90 lines
2.4 KiB
/*
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* filter_gamma.c -- gamma filter
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* Copyright (C) 2003-2004 Ushodaya Enterprises Limited
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* Author: Charles Yates <charles.yates@pandora.be>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "filter_gamma.h"
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#include <framework/mlt_frame.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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/** Do it :-).
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*/
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static int filter_get_image( mlt_frame this, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
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{
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int error = mlt_frame_get_image( this, image, format, width, height, 1 );
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if ( error == 0 && *format == mlt_image_yuv422 )
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{
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// Get the gamma value
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double gamma = mlt_properties_get_double( MLT_FRAME_PROPERTIES( this ), "gamma" );
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if ( gamma != 1.0 )
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{
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uint8_t *p = *image;
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uint8_t *q = *image + *width * *height * 2;
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// Calculate the look up table
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double exp = 1 / gamma;
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uint8_t lookup[ 256 ];
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int i;
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for( i = 0; i < 256; i ++ )
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lookup[ i ] = ( uint8_t )( pow( ( double )i / 255.0, exp ) * 255 );
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while ( p != q )
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{
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*p = lookup[ *p ];
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p += 2;
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}
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}
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}
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return 0;
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}
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/** Filter processing.
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*/
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static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
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{
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double gamma = mlt_properties_get_double( MLT_FILTER_PROPERTIES( this ), "gamma" );
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gamma = gamma <= 0 ? 1 : gamma;
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mlt_properties_set_double( MLT_FRAME_PROPERTIES( frame ), "gamma", gamma );
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mlt_frame_push_get_image( frame, filter_get_image );
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return frame;
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}
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/** Constructor for the filter.
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*/
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mlt_filter filter_gamma_init( char *arg )
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{
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mlt_filter this = mlt_filter_new( );
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if ( this != NULL )
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{
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this->process = filter_process;
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mlt_properties_set( MLT_FILTER_PROPERTIES( this ), "gamma", arg == NULL ? "1" : arg );
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}
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return this;
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}
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