1 /*
2 * Copyright (c) 2015 The WebM project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include <math.h>
12 #include <stdlib.h>
13
14 #include "./vpx_config.h"
15 #include "./vpx_dsp_rtcd.h"
16
17 #include "vpx/vpx_integer.h"
18 #include "vpx_dsp/postproc.h"
19 #include "vpx_ports/mem.h"
20
vpx_plane_add_noise_c(uint8_t * start,const int8_t * noise,int blackclamp,int whiteclamp,int width,int height,int pitch)21 void vpx_plane_add_noise_c(uint8_t *start, const int8_t *noise, int blackclamp,
22 int whiteclamp, int width, int height, int pitch) {
23 int i, j;
24 int bothclamp = blackclamp + whiteclamp;
25 for (i = 0; i < height; ++i) {
26 uint8_t *pos = start + i * pitch;
27 const int8_t *ref = (const int8_t *)(noise + (rand() & 0xff)); // NOLINT
28
29 for (j = 0; j < width; ++j) {
30 int v = pos[j];
31
32 v = clamp(v - blackclamp, 0, 255);
33 v = clamp(v + bothclamp, 0, 255);
34 v = clamp(v - whiteclamp, 0, 255);
35
36 pos[j] = v + ref[j];
37 }
38 }
39 }
40
gaussian(double sigma,double mu,double x)41 static double gaussian(double sigma, double mu, double x) {
42 return 1 / (sigma * sqrt(2.0 * 3.14159265)) *
43 (exp(-(x - mu) * (x - mu) / (2 * sigma * sigma)));
44 }
45
vpx_setup_noise(double sigma,int8_t * noise,int size)46 int vpx_setup_noise(double sigma, int8_t *noise, int size) {
47 int8_t char_dist[256];
48 int next = 0, i, j;
49
50 // set up a 256 entry lookup that matches gaussian distribution
51 for (i = -32; i < 32; ++i) {
52 const int a_i = (int)(0.5 + 256 * gaussian(sigma, 0, i));
53 if (a_i) {
54 for (j = 0; j < a_i; ++j) {
55 if (next + j >= 256) goto set_noise;
56 char_dist[next + j] = (int8_t)i;
57 }
58 next = next + j;
59 }
60 }
61
62 // Rounding error - might mean we have less than 256.
63 for (; next < 256; ++next) {
64 char_dist[next] = 0;
65 }
66
67 set_noise:
68 for (i = 0; i < size; ++i) {
69 noise[i] = char_dist[rand() & 0xff]; // NOLINT
70 }
71
72 // Returns the highest non 0 value used in distribution.
73 return -char_dist[0];
74 }
75