FONT/filter1.py

import cv2
#import pickle
import time
import numpy as np
import copy

from matplotlib import pyplot as plt
from tqdm import tqdm




class LowPassFilter:
  def __init__(self):
    self.prev_raw_value = None
    self.prev_filtered_value = None

  def process(self, value, alpha):
    if self.prev_raw_value is None:
      s = value
    else:
      s = alpha * value + (1.0 - alpha) * self.prev_filtered_value
    self.prev_raw_value = value
    self.prev_filtered_value = s
    return s


class OneEuroFilter:
  def __init__(self, mincutoff=1.0, beta=0.0, dcutoff=1.0, freq=30):
    self.freq = freq
    self.mincutoff = mincutoff
    self.beta = beta
    self.dcutoff = dcutoff
    self.x_filter = LowPassFilter()
    self.dx_filter = LowPassFilter()

  def compute_alpha(self, cutoff):
    te = 1.0 / self.freq
    tau = 1.0 / (2 * np.pi * cutoff)
    return 1.0 / (1.0 + tau / te)

  def process(self, x):
    prev_x = self.x_filter.prev_raw_value
    dx = 0.0 if prev_x is None else (x - prev_x) * self.freq
    edx = self.dx_filter.process(dx, self.compute_alpha(self.dcutoff))
    cutoff = self.mincutoff + self.beta * np.abs(edx)
    return self.x_filter.process(x, self.compute_alpha(cutoff))