2 * filter_gamma.c -- gamma filter
3 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
4 * Author: Charles Yates <charles.yates@pandora.be>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software Foundation,
18 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21 #include "filter_gamma.h"
23 #include <framework/mlt_frame.h>
32 static int filter_get_image( mlt_frame
this, uint8_t **image
, mlt_image_format
*format
, int *width
, int *height
, int writable
)
34 mlt_frame_get_image( this, image
, format
, width
, height
, 1 );
36 uint8_t *q
= *image
+ *width
* *height
* 2;
38 // Get the gamma value
39 double gamma
= mlt_properties_get_double( mlt_frame_properties( this ), "gamma" );
41 // Calculate the look up table
42 double exp
= 1 / gamma
;
43 uint8_t lookup
[ 256 ];
46 for( i
= 0; i
< 256; i
++ )
47 lookup
[ i
] = ( uint8_t )( pow( ( double )i
/ 255.0, exp
) * 255 );
58 /** Filter processing.
61 static mlt_frame
filter_process( mlt_filter
this, mlt_frame frame
)
63 double gamma
= mlt_properties_get_double( mlt_filter_properties( this ), "gamma" );
64 gamma
= gamma
<= 0 ?
2 : gamma
;
65 mlt_frame_push_get_image( frame
, filter_get_image
);
66 mlt_properties_set_double( mlt_frame_properties( frame
), "gamma", gamma
);
70 /** Constructor for the filter.
73 mlt_filter
filter_gamma_init( char *arg
)
75 mlt_filter
this = calloc( sizeof( struct mlt_filter_s
), 1 );
78 mlt_filter_init( this, NULL
);
79 this->process
= filter_process
;
81 mlt_properties_set_double( mlt_filter_properties( this ), "gamma", atof( arg
) );