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_ports/mem.h"
19
vpx_plane_add_noise_c(uint8_t * start,const int8_t * noise,int blackclamp,int whiteclamp,int width,int height,int pitch)20 void vpx_plane_add_noise_c(uint8_t *start, const int8_t *noise, int blackclamp,
21 int whiteclamp, int width, int height, int pitch) {
22 int i, j;
23 int bothclamp = blackclamp + whiteclamp;
24 for (i = 0; i < height; ++i) {
25 uint8_t *pos = start + i * pitch;
26 const int8_t *ref = (const int8_t *)(noise + (rand() & 0xff)); // NOLINT
27
28 for (j = 0; j < width; ++j) {
29 int v = pos[j];
30
31 v = clamp(v - blackclamp, 0, 255);
32 v = clamp(v + bothclamp, 0, 255);
33 v = clamp(v - whiteclamp, 0, 255);
34
35 pos[j] = v + ref[j];
36 }
37 }
38 }
39
gaussian(double sigma,double mu,double x)40 static double gaussian(double sigma, double mu, double x) {
41 return 1 / (sigma * sqrt(2.0 * 3.14159265)) *
42 (exp(-(x - mu) * (x - mu) / (2 * sigma * sigma)));
43 }
44
vpx_setup_noise(double sigma,int8_t * noise,int size)45 int vpx_setup_noise(double sigma, int8_t *noise, int size) {
46 int8_t char_dist[256];
47 int next = 0, i, j;
48
49 // set up a 256 entry lookup that matches gaussian distribution
50 for (i = -32; i < 32; ++i) {
51 const int a_i = (int)(0.5 + 256 * gaussian(sigma, 0, i));
52 if (a_i) {
53 for (j = 0; j < a_i; ++j) {
54 char_dist[next + j] = (int8_t)i;
55 }
56 next = next + j;
57 }
58 }
59
60 // Rounding error - might mean we have less than 256.
61 for (; next < 256; ++next) {
62 char_dist[next] = 0;
63 }
64
65 for (i = 0; i < size; ++i) {
66 noise[i] = char_dist[rand() & 0xff]; // NOLINT
67 }
68
69 // Returns the highest non 0 value used in distribution.
70 return -char_dist[0];
71 }
72