Topic: Python – Reading Images from Datasets and Organizing Them

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1. Reading Images from Folder Structure

Assuming your dataset folder looks like this:

dataset/
   class1/
      img1.jpg
      img2.jpg
   class2/
      img3.jpg
      img4.jpg

You can use Python libraries like os, OpenCV, or PIL to read and organize images by their classes.

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2. Code Example Using OpenCV

import os
import cv2

dataset_path = "dataset"
data = []
labels = []

for class_name in os.listdir(dataset_path):
    class_dir = os.path.join(dataset_path, class_name)
    if os.path.isdir(class_dir):
        for img_name in os.listdir(class_dir):
            img_path = os.path.join(class_dir, img_name)
            img = cv2.imread(img_path)
            if img is not None:
                data.append(img)
                labels.append(class_name)

print(f"Total images: {len(data)}")
print(f"Total labels: {len(labels)}")

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3. Optional: Resize Images for Uniformity

target_size = (128, 128)
resized_img = cv2.resize(img, target_size)

Use this inside the loop before appending img to data.

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4. Using PIL (Pillow) Instead of OpenCV

from PIL import Image

img = Image.open(img_path)
img = img.resize((128, 128))
img_array = np.array(img)

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5. Organizing Images in a Dictionary

dataset_dict = {}

for class_name in os.listdir(dataset_path):
    class_dir = os.path.join(dataset_path, class_name)
    if os.path.isdir(class_dir):
        dataset_dict[class_name] = []
        for img_name in os.listdir(class_dir):
            img_path = os.path.join(class_dir, img_name)
            img = cv2.imread(img_path)
            if img is not None:
                dataset_dict[class_name].append(img)

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6. Summary

• Use os.listdir() to iterate dataset directories.

• Read images with cv2.imread() or PIL.Image.open().

• Resize images to a uniform shape for model input.

• Store images and labels in lists or dictionaries for easy access.

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Exercise

• Extend the code to save the loaded images and labels as numpy arrays for faster loading in the future.

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#Python #ImageProcessing #DatasetHandling #OpenCV #PIL

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