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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <math.h>
#include <stdlib.h>
#include "./aom_config.h"
#include "./aom_dsp_rtcd.h"
#include "aom/aom_integer.h"
#include "aom_ports/mem.h"
void aom_plane_add_noise_c(uint8_t *start, char *noise, char blackclamp[16],
char whiteclamp[16], char bothclamp[16],
unsigned int width, unsigned int height, int pitch) {
unsigned int i, j;
for (i = 0; i < height; ++i) {
uint8_t *pos = start + i * pitch;
char *ref = (char *)(noise + (rand() & 0xff)); // NOLINT
for (j = 0; j < width; ++j) {
int v = pos[j];
v = clamp(v - blackclamp[0], 0, 255);
v = clamp(v + bothclamp[0], 0, 255);
v = clamp(v - whiteclamp[0], 0, 255);
pos[j] = v + ref[j];
}
}
}
static double gaussian(double sigma, double mu, double x) {
return 1 / (sigma * sqrt(2.0 * 3.14159265)) *
(exp(-(x - mu) * (x - mu) / (2 * sigma * sigma)));
}
int aom_setup_noise(double sigma, int size, char *noise) {
char char_dist[256];
int next = 0, i, j;
// set up a 256 entry lookup that matches gaussian distribution
for (i = -32; i < 32; ++i) {
const int a_i = (int)(0.5 + 256 * gaussian(sigma, 0, i));
if (a_i) {
for (j = 0; j < a_i; ++j) {
char_dist[next + j] = (char)i;
}
next = next + j;
}
}
// Rounding error - might mean we have less than 256.
for (; next < 256; ++next) {
char_dist[next] = 0;
}
for (i = 0; i < size; ++i) {
noise[i] = char_dist[rand() & 0xff]; // NOLINT
}
// Returns the highest non 0 value used in distribution.
return -char_dist[0];
}
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