1 /* equaliz0r.cpp
2  * Copyright (C) 2005 Jean-Sebastien Senecal (js@drone.ws)
3  * This file is a Frei0r plugin.
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18  */
19 
20 #include "frei0r.hpp"
21 #include "frei0r_math.h"
22 #include <string.h>
23 
24 #include <cstring>
25 
26 class equaliz0r : public frei0r::filter
27 {
28   // Look-up tables for equaliz0r values.
29   unsigned char rlut[256];
30   unsigned char glut[256];
31   unsigned char blut[256];
32 
33   // Intensity histograms.
34   unsigned int rhist[256];
35   unsigned int ghist[256];
36   unsigned int bhist[256];
37 
updateLookUpTables(const uint32_t * in)38   void updateLookUpTables(const uint32_t* in)
39   {
40     unsigned int size = width*height;
41 
42     // First pass : build histograms.
43 
44     // Reset histograms.
45     memset(rhist, 0, 256*sizeof(unsigned int));
46     memset(ghist, 0, 256*sizeof(unsigned int));
47     memset(bhist, 0, 256*sizeof(unsigned int));
48 
49     // Update histograms.
50     const unsigned char *in_ptr = (const unsigned char*) in;
51     for (unsigned int i=0; i<size; ++i)
52     {
53       // update 'em
54       rhist[*in_ptr++]++;
55       ghist[*in_ptr++]++;
56       bhist[*in_ptr++]++;
57       in_ptr++; // skip alpha
58     }
59 
60     // Second pass : update look-up tables.
61     in_ptr = (const unsigned char*) in;
62 
63     // Cumulative intensities of histograms.
64     unsigned int
65       rcum = 0,
66       gcum = 0,
67       bcum = 0;
68 
69     for (int i=0; i<256; ++i)
70     {
71       // update cumulatives
72       rcum += rhist[i];
73       gcum += ghist[i];
74       bcum += bhist[i];
75 
76       // update 'em
77       rlut[i] = CLAMP0255( (rcum << 8) / size ); // = 256 * rcum / size
78       glut[i] = CLAMP0255( (gcum << 8) / size ); // = 256 * gcum / size
79       blut[i] = CLAMP0255( (bcum << 8) / size ); // = 256 * bcum / size
80 
81       in_ptr++; // skip alpha
82     }
83 
84   }
85 
86 public:
equaliz0r(unsigned int width,unsigned int height)87   equaliz0r(unsigned int width, unsigned int height)
88   {
89   }
90 
update(double time,uint32_t * out,const uint32_t * in)91   virtual void update(double time,
92                       uint32_t* out,
93                       const uint32_t* in)
94   {
95     std::copy(in, in + width*height, out);
96     updateLookUpTables(in);
97     unsigned int size = width*height;
98     const unsigned char *in_ptr = (const unsigned char*) in;
99     unsigned char *out_ptr = (unsigned char*) out;
100     for (unsigned int i=0; i<size; ++i)
101     {
102       *out_ptr++ = rlut[*in_ptr++];
103       *out_ptr++ = glut[*in_ptr++];
104       *out_ptr++ = blut[*in_ptr++];
105       *out_ptr++ = *in_ptr++; // copy alpha
106     }
107   }
108 };
109 
110 
111 frei0r::construct<equaliz0r> plugin("Equaliz0r",
112                                     "Equalizes the intensity histograms",
113                                     "Jean-Sebastien Senecal (Drone)",
114                                     0,2,
115                                     F0R_COLOR_MODEL_RGBA8888);
116 
117