Line data    Source code

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