read_or_capture.py

# -----------------------------------------------------------------------------------------------
###                                         Imports                                         ###
# -----------------------------------------------------------------------------------------------

import cv2 as cv
import numpy as np
import matplotlib.pyplot as plt
from imutils import rotate_bound

# -----------------------------------------------------------------------------------------------
###                                         Greetings                                      ###
# -----------------------------------------------------------------------------------------------


def greetings():
    print(
        """Greetings!!! Before you proceed to use this application please note the following -- 
    1. Since the A4 paper is white, placing white objects on the paper will 
    most likely produce faulty outcome.
    2. Place only one object on the A4 paper at a time. To reduce false detection, only the highest 
    perimeter object is filtered from all the possible detections.
    3. This application only uses OpenCV and no deep learning model. So, due 
    to constraints of classical computer vision the results may not be 
    100% accurate. Long story short, Use at your own risk.

To improve the chance of correct recognition and measurement you can do the following --
    1. Capture the image in a clean background.
    2. Try to fit the whole A4 paper inside the frame.
    3. Lighting condition should not be too dark or too bright."""
    )


# -----------------------------------------------------------------------------------------------
###                                         Read Image                                      ###
# -----------------------------------------------------------------------------------------------


def read_image(img_path):
    try:
        img = cv.imread(img_path)
        return img
    except:
        print("Invalid Image Path")


# -----------------------------------------------------------------------------------------------
###                                         Capture Live Image                              ###
# -----------------------------------------------------------------------------------------------
def take_picture(device_id=0):
    cap = cv.VideoCapture(device_id)

    cap.set(cv.CAP_PROP_FRAME_HEIGHT, 720)
    cap.set(cv.CAP_PROP_FRAME_WIDTH, 700)

    try:
        if cap.isOpened() is False:
            cap.open()
    except:
        print("Maybe try with another device. Exiting...\n")
        return None

    while True:
        ret, frame = cap.read()

        if ret is False:
            print("Could not read any frame. Exiting.... \n")
            break

        cv.imshow("To capture an image, press 'c' and to quit, press 'q'", frame)

        key_pressed = cv.waitKey(1)  # wait 1 mili second for key press

        if key_pressed == ord("c"):
            captured_image = frame
            break
        if key_pressed == ord("q"):
            captured_image = None
            print("No image was captured. Quitting..... \n")
            break

    cap.release()
    cv.destroyAllWindows()

    return captured_image


# -----------------------------------------------------------------------------------------------
###                                         User Input                                      ###
# -----------------------------------------------------------------------------------------------


def usr_prompt():
    """
    Prompt the user to provide a valid image path or a valid device id to capture one.

    Returns: User input
    """
    try:
        img_path_or_capture = int(
            input(
                "Please select \n 1. to provide an image path or, 2. to take a live picture \n (1, 2): \t"
            )
        )
    except:
        raise

    print(f"img_path_or_capture: {img_path_or_capture}")

    if img_path_or_capture not in [1, 2]:
        print("Invalid input. Please choose either 1 or 2.")

    if img_path_or_capture == 1:
        img_path = input("Please provide a valid image path : \t")
        return img_path

    if img_path_or_capture == 2:
        video_capture_device_id = input(
            "Please provide a device id (to capture the image with, default is 0): \t"
        )

        if video_capture_device_id == "":
            video_capture_device_id = 0

        try:
            video_capture_device_id = int(video_capture_device_id)
            return video_capture_device_id

        except:
            raise


# -----------------------------------------------------------------------------------------------
###                                     Read or Capture Image                               ###
# -----------------------------------------------------------------------------------------------


def read_or_capture(prompt_usr=True, img_path=None, device_id=None):
    greetings()

    if prompt_usr:
        usr_input = usr_prompt()

        if type(usr_input) == str:
            img = read_image(usr_input)

        if type(usr_input) == int:
            img = take_picture(usr_input)

            if img is None:
                print("Please capture another image or provide a valid image path. \n")
                return None

    if not prompt_usr and img_path:
        img = read_image(img_path)

    if not prompt_usr and device_id is not None:
        img = take_picture(device_id)

        if img is None:
            print("Please capture another image or provide a valid image path. \n")
            return None

    # rotate the image by 90 degree CCW if image width > image height
    if img.shape[0] < img.shape[1]:
        img = rotate_bound(img, -90)

    return img