preprocess.py

import cv2
import numpy as np
import os
import logging

def read_image(image_path, is_uploaded=False):
    if is_uploaded:
        img_bytes = image_path.read()
        img = cv2.imdecode(np.frombuffer(img_bytes, np.uint8), cv2.IMREAD_COLOR)
        return img
    return cv2.imread(image_path)

def extract_id_card(img):
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    blur = cv2.GaussianBlur(gray, (5,5), 0)
    thresh = cv2.adaptiveThreshold(
        blur, 255,
        cv2.ADAPTIVE_THRESH_MEAN_C,
        cv2.THRESH_BINARY, 11, 2
    )

    contours, _ = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
    largest = max(contours, key=cv2.contourArea)

    x, y, w, h = cv2.boundingRect(largest)
    roi = img[y:y+h, x:x+w]

    path = "data/intermediate/id_roi.jpg"
    cv2.imwrite(path, roi)
    return roi, path

def save_image(image, filename, path):
    full_path = os.path.join(path, filename)
    cv2.imwrite(full_path, image)
    return full_path