added a color threshold filter that can make effects similar to "the

yellow guy" in sin city or the red dressed girl in the beginning of
schindlers list

configure.ac

@@ -1091,7 +1091,7 @@ VLC_ADD_PLUGINS([fixed32tos16 s16tofixed32 u8tofixed32 mono])
 VLC_ADD_PLUGINS([trivial_resampler ugly_resampler])
 VLC_ADD_PLUGINS([trivial_channel_mixer trivial_mixer])
 VLC_ADD_PLUGINS([playlist export sgimb nsc xtag])
-VLC_ADD_PLUGINS([i420_rgb rawvideo blend scale image logo magnify puzzle])
+VLC_ADD_PLUGINS([i420_rgb rawvideo blend scale image logo magnify puzzle colorthres])
 VLC_ADD_PLUGINS([wav araw subtitle vobsub adpcm a52sys dtssys au ty voc xa nuv])
 VLC_ADD_PLUGINS([access_directory access_file access_udp access_tcp])
 VLC_ADD_PLUGINS([access_http access_mms access_ftp ipv4])

modules/video_filter/Modules.am

@@ -26,4 +26,5 @@ SOURCES_opencv_example = opencv_example.cpp filter_event_info.h
 SOURCES_rotate = rotate.c
 SOURCES_noise = noise.c
 SOURCES_puzzle = puzzle.c
+SOURCES_colorthres = colorthres.c
 noinst_HEADERS = filter_common.h

modules/video_filter/colorthres.c

+/*****************************************************************************
+ * colorthres.c: Theshold color based on similarity to reference color
+ *****************************************************************************
+ * Copyright (C) 2000-2006 the VideoLAN team
+ * $Id$
+ *
+ * Authors: Sigmund Augdal <dnumgis@videolan.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <errno.h>
+#include <stdlib.h>                                      /* malloc(), free() */
+#include <string.h>
+#include <math.h>
+
+#include <vlc/vlc.h>
+#include <vlc/sout.h>
+#include <vlc/decoder.h>
+
+#include "vlc_filter.h"
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static int  Create    ( vlc_object_t * );
+static void Destroy   ( vlc_object_t * );
+
+static picture_t *Filter( filter_t *, picture_t * );
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+#define COLOR_TEXT N_("Color")
+#define COLOR_LONGTEXT N_("Colors similar to this will be kept, others will be "\
+    "grayscaled. This must be an hexadecimal (like HTML colors). The first two "\
+    "chars are for red, then green, then blue. #000000 = black, #FF0000 = red,"\
+    " #00FF00 = green, #FFFF00 = yellow (red + green), #FFFFFF = white" )
+static int pi_color_values[] = {
+  0x00FF0000, 0x00FF00FF, 0x00FFFF00, 0x0000FF00, 0x000000FF, 0x0000FFFF }; 
+
+static char *ppsz_color_descriptions[] = {
+  N_("Red"), N_("Fuchsia"), N_("Yellow"), N_("Lime"), N_("Blue"), N_("Aqua") };
+
+
+vlc_module_begin();
+    set_description( _("Color threshold filter") );
+    set_shortname( _("Color threshold" ));
+    set_category( CAT_VIDEO );
+    set_subcategory( SUBCAT_VIDEO_VFILTER );
+    set_capability( "video filter2", 0 );
+    add_integer( "colorthres-color", 0x00FF0000, NULL, COLOR_TEXT,
+                 COLOR_LONGTEXT, VLC_FALSE );
+        change_integer_list( pi_color_values, ppsz_color_descriptions, 0 );
+    add_integer( "colorthres-saturationthres", 20, NULL, "saturaton threshold",
+                 "", VLC_FALSE );
+    add_integer( "colorthres-similaritythres", 15, NULL, "similarity threshold",
+                 "", VLC_FALSE );
+    set_callbacks( Create, Destroy );
+vlc_module_end();
+
+/*****************************************************************************
+ * filter_sys_t: adjust filter method descriptor
+ *****************************************************************************/
+struct filter_sys_t
+{
+};
+
+/*****************************************************************************
+ * Create: allocates adjust video thread output method
+ *****************************************************************************
+ * This function allocates and initializes a adjust vout method.
+ *****************************************************************************/
+static int Create( vlc_object_t *p_this )
+{
+    filter_t *p_filter = (filter_t *)p_this;
+
+    /* XXX: we might need to add/remove some FOURCCs ... */
+    if(   p_filter->fmt_in.video.i_chroma != VLC_FOURCC('I','4','2','0') )
+    {
+        msg_Err( p_filter, "Unsupported input chroma (%4s)",
+                 (char*)&(p_filter->fmt_in.video.i_chroma) );
+        return VLC_EGENERIC;
+    }
+
+    if( p_filter->fmt_in.video.i_chroma != p_filter->fmt_out.video.i_chroma )
+    {
+        msg_Err( p_filter, "Input and output chromas don't match" );
+        return VLC_EGENERIC;
+    }
+
+    var_Create( p_filter, "colorthres-color", VLC_VAR_INTEGER|VLC_VAR_DOINHERIT );
+    var_Create( p_filter, "colorthres-similaritythres", VLC_VAR_INTEGER|VLC_VAR_DOINHERIT );
+    var_Create( p_filter, "colorthres-saturationthres", VLC_VAR_INTEGER|VLC_VAR_DOINHERIT );
+    /* Allocate structure */
+    p_filter->p_sys = malloc( sizeof( filter_sys_t ) );
+    if( p_filter->p_sys == NULL )
+    {
+        msg_Err( p_filter, "out of memory" );
+        return VLC_ENOMEM;
+    }
+
+    p_filter->pf_video_filter = Filter;
+
+    return VLC_SUCCESS;
+}
+
+/*****************************************************************************
+ * Destroy: destroy adjust video thread output method
+ *****************************************************************************
+ * Terminate an output method created by adjustCreateOutputMethod
+ *****************************************************************************/
+static void Destroy( vlc_object_t *p_this )
+{
+    filter_t *p_filter = (filter_t *)p_this;
+    free( p_filter->p_sys );
+}
+
+/*****************************************************************************
+ * Render: displays previously rendered output
+ *****************************************************************************
+ * This function send the currently rendered image to adjust modified image,
+ * waits until it is displayed and switch the two rendering buffers, preparing
+ * next frame.
+ *****************************************************************************/
+static picture_t *Filter( filter_t *p_filter, picture_t *p_pic )
+{
+    picture_t *p_outpic;
+    uint8_t *p_in_y, *p_in_u, *p_in_v, *p_in_end_u;
+    uint8_t *p_out_y, *p_out_u, *p_out_v;
+    int i_simthres = var_GetInteger( p_filter, "colorthres-similaritythres" );
+    int i_satthres = var_GetInteger( p_filter, "colorthres-saturationthres" );
+    int i_color = var_GetInteger( p_filter, "colorthres-color" );
+
+    if( !p_pic ) return NULL;
+
+    p_outpic = p_filter->pf_vout_buffer_new( p_filter );
+    if( !p_outpic )
+    {
+        msg_Warn( p_filter, "can't get output picture" );
+        if( p_pic->pf_release )
+            p_pic->pf_release( p_pic );
+        return NULL;
+    }
+
+    p_in_u = p_pic->p[U_PLANE].p_pixels;
+    p_in_v = p_pic->p[V_PLANE].p_pixels;
+    p_in_y = p_pic->p[Y_PLANE].p_pixels;
+    p_in_end_u = p_in_u + p_pic->p[U_PLANE].i_visible_lines
+                        * p_pic->p[U_PLANE].i_pitch - 8;
+
+    p_out_y = p_outpic->p[Y_PLANE].p_pixels;
+    p_out_u = p_outpic->p[U_PLANE].p_pixels;
+    p_out_v = p_outpic->p[V_PLANE].p_pixels;
+
+    /* Create grayscale version of input */
+    memcpy( p_out_y, p_in_y, p_pic->p[Y_PLANE].i_visible_lines
+            * p_pic->p[Y_PLANE].i_pitch - 8 );
+    memset( p_out_u, 0x80, p_pic->p[U_PLANE].i_visible_lines
+            * p_pic->p[U_PLANE].i_pitch - 8 );
+    memset( p_out_v, 0x80, p_pic->p[U_PLANE].i_visible_lines
+            * p_pic->p[U_PLANE].i_pitch - 8 );
+
+   
+    /*
+     * Do the U and V planes
+     */
+    int i_red = ( i_color & 0xFF0000 ) >> 16;
+    int i_green = ( i_color & 0xFF00 ) >> 8;
+    int i_blue = i_color & 0xFF;
+    int i_u = (int8_t)(( -38 * i_red - 74 * i_green +
+                     112 * i_blue + 128) >> 8) + 128;
+    int i_v = (int8_t)(( 112 * i_red  -  94 * i_green -
+                      18 * i_blue + 128) >> 8) + 128;
+    int refu = i_u - 0x80;         /*bright red*/
+    int refv = i_v - 0x80;
+    int reflength = sqrt(refu*refu+refv*refv);
+
+    while( p_in_u < p_in_end_u ) {
+        /* Length of color vector */
+        int inu = (*p_in_u) - 0x80;
+        int inv = (*p_in_v) - 0x80;
+        int length = sqrt(inu*inu+inv*inv);
+
+        int diffu = refu * length - inu *reflength;
+        int diffv = refv * length - inv *reflength;
+        long long int difflen2=diffu*diffu;
+        difflen2 +=diffv*diffv;
+        long long int thres = length*reflength;
+        thres *= thres;
+        if( length > i_satthres && (difflen2*i_simthres< thres ) ) {
+            *p_out_u = *p_in_u;
+            *p_out_v = *p_in_v;
+//        fprintf(stderr,"keeping color %d %d\n", length, difflen2);
+        }
+        p_in_u++;
+        p_in_v++;
+        p_out_u++;
+        p_out_v++;
+            
+        
+    }
+
+    p_outpic->date = p_pic->date;
+    p_outpic->b_force = p_pic->b_force;
+    p_outpic->i_nb_fields = p_pic->i_nb_fields;
+    p_outpic->b_progressive = p_pic->b_progressive;
+    p_outpic->b_top_field_first = p_pic->b_top_field_first;
+
+    if( p_pic->pf_release )
+        p_pic->pf_release( p_pic );
+
+    return p_outpic;
+}