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Documentation for calibrate.py

Overview

This module provides functions for camera calibration, loading calibration data, extracting frames from videos, undistorting videos, and adjusting calibration matrices. The primary use case is to calibrate a camera using chessboard images and then use the calibration data to undistort images and videos.

Functions

calibrate_camera

def calibrate_camera(src: str, dest: str, base_filename: str = '', chessboard_size: tuple = (6,9), show: bool = False, verbose: bool = False):

Calibrates the camera using chessboard images.

Args:

  • src (str): Path to the folder containing calibration images.
  • dest (str): Path to the folder to save camera matrices.
  • base_filename (str): Prefix for saved files.
  • chessboard_size (tuple): Size of the chessboard used for calibration.
  • show (bool): Whether to show undistorted images.
  • verbose (bool): Whether to print detailed information.

Returns:

  • None

load_camera_calibration_data

def load_camera_calibration_data(matrix_path: str, distance_coefficient_path: str) -> tuple:

Loads camera calibration data from saved files.

Args:

  • matrix_path (str): Path to the camera matrix file.
  • [distance_coefficient_path](command:_github.copilot.openSymbolFromReferences?%5B%7B%22%24mid%22%3A1%2C%22path%22%3A%22%2FUsers%2Fgordondoore%2FDocuments%2FGitHub%2FvidWFT%2FvidWFT%2Fcore%2Fcalibrate.py%22%2C%22scheme%22%3A%22file%22%7D%2C%7B%22line%22%3A105%2C%22character%22%3A52%7D%5D ../vidWFT/core/calibrate.py) (str): Path to the distance coefficient file.

Returns:

  • tuple: Camera matrix and distance coefficients.

extract_calibration_frames

def extract_calibration_frames(filepath: str, nframes: int) -> list[np.ndarray]:

Randomly grabs nframes frames from the video at filepath and returns them as a list of numpy arrays.

Args:

  • filepath (str): Path to the video file.
  • nframes (int): Number of frames to extract.

Returns:

  • list[np.ndarray]: List of extracted frames.

undistort_video

def undistort_video(filepath: str, mtx: np.ndarray, dist: np.ndarray, save_path: str, show: bool = False):

Undistorts a video using the camera matrix and distance coefficients.

Args:

  • filepath (str): Path to the video file.
  • mtx (np.ndarray): Camera matrix.
  • dist (np.ndarray): Distance coefficients.
  • save_path (str): Path to save the undistorted video.
  • show (bool): Whether to show the undistorted video.

Returns:

  • None

crop_and_undistort

def crop_and_undistort(video_path: str, matrix_path: str, dist_path: str, crop_region: tuple, output_path: str):

Crops and undistorts a video using the camera matrix and distance coefficients.

Args:

  • video_path (str): Path to the video file.
  • matrix_path (str): Path to the camera matrix file.
  • dist_path (str): Path to the distance coefficient file.
  • crop_region (tuple): Crop region defined as (x, y, width, height).
  • output_path (str): Path to save the cropped and undistorted video.

Returns:

  • None

adjust_calibration_matrices

def adjust_calibration_matrices(camera_matrix: np.ndarray, dist_coeffs: np.ndarray, crop_region: tuple, W: int, H: int) -> tuple:

Adjusts the camera matrix and distance coefficients to account for cropping.

Args:

  • camera_matrix (np.ndarray): Camera matrix.
  • dist_coeffs (np.ndarray): Distance coefficients.
  • crop_region (tuple): Crop region defined as (x, y, width, height).
  • W (int): Width of the original image.
  • H (int): Height of the original image.

Returns:

  • tuple: Adjusted camera matrix and distance coefficients.

Examples:

Example 1: Calibrate Camera

import cv2
import numpy as np
import os
import yaml
import glob
import tqdm
from calibrate import calibrate_camera

# Paths
src = 'path/to/calibration/images'
dest = 'path/to/save/matrices'
base_filename = 'calibration_'

# Calibrate the camera
calibrate_camera(src, dest, base_filename, chessboard_size=(6, 9), show=True, verbose=True)

Example 2: Load Camera Calibration Data

from calibrate import load_camera_calibration_data

# Paths
matrix_path = 'path/to/save/matrices/calibration_camera_matrix.npy'
distance_coefficient_path = 'path/to/save/matrices/calibration_dist_coeff.npy'

# Load the calibration data
camera_matrix, dist_coeffs = load_camera_calibration_data(matrix_path, distance_coefficient_path)
print("Camera Matrix:\n", camera_matrix)
print("Distortion Coefficients:\n", dist_coeffs)

Example 3: Extract Calibration Frames from a Video

from calibrate import extract_calibration_frames

# Path to video file
filepath = 'path/to/video.mp4'
nframes = 10

# Extract frames
frames = extract_calibration_frames(filepath, nframes)
for i, frame in enumerate(frames):
    cv2.imshow(f'Frame {i}', frame)
    cv2.waitKey(0)
cv2.destroyAllWindows()

Example 4: Undistort a Video

from calibrate import undistort_video

# Paths
filepath = 'path/to/video.mp4'
save_path = 'path/to/save/undistorted_video.mp4'
matrix_path = 'path/to/save/matrices/calibration_camera_matrix.npy'
distance_coefficient_path = 'path/to/save/matrices/calibration_dist_coeff.npy'

# Load the calibration data
camera_matrix = np.load(matrix_path)
dist_coeffs = np.load(distance_coefficient_path)

# Undistort the video
undistort_video(filepath, camera_matrix, dist_coeffs, save_path, show=True)

Example 5: Crop and Undistort a Video

from calibrate import crop_and_undistort

# Paths
video_path = 'path/to/video.mp4'
matrix_path = 'path/to/save/matrices/calibration_camera_matrix.npy'
dist_path = 'path/to/save/matrices/calibration_dist_coeff.npy'
output_path = 'path/to/save/cropped_undistorted_video.mp4'

# Crop region (x, y, width, height)
crop_region = (100, 100, 400, 400)

# Crop and undistort the video
crop_and_undistort(video_path, matrix_path, dist_path, crop_region, output_path)