75 строки
2.0 KiB
C
75 строки
2.0 KiB
C
/*
|
|
* Copyright (c) 2015 The WebM project authors. All Rights Reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <stdlib.h>
|
|
|
|
#include "./vpx_config.h"
|
|
#include "./vpx_dsp_rtcd.h"
|
|
|
|
#include "vpx/vpx_integer.h"
|
|
#include "vpx_ports/mem.h"
|
|
|
|
void vpx_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 vpx_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];
|
|
}
|