03 Image Classifier
Simple Image Classifier
This notebook shows you how to classify images using a pre-trained neural network.
What you'll learn:
- How to load and use a pre-trained model
- Image preprocessing
- Making predictions on images
- Understanding confidence scores
Use case: Identify objects in images (like "cat", "dog", "car", etc.)
Step 1: Import Required Libraries
Let's import the tools we need. Don't worry if you don't understand all of these yet!
Step 2: Load Pre-trained Model
We'll use MobileNetV2, a neural network already trained on millions of images.
This is called Transfer Learning - using a model someone else trained!
Step 3: Helper Functions
Let's create functions to load and prepare images for our model.
Step 4: Test on Sample Images
Let's try classifying some images from the internet!
Classify Each Image
Step 5: Try Your Own Images!
Replace the URL below with any image URL you want to classify.
๐ก What Just Happened?
- We loaded a pre-trained model - MobileNetV2 was trained on millions of images
- We preprocessed images - Resized and formatted them for the model
- The model made predictions - It output probabilities for 1000 object classes
- We decoded the results - Converted numbers to human-readable labels
Understanding Confidence Scores
- 90-100%: Very confident (almost certainly correct)
- 70-90%: Confident (probably correct)
- 50-70%: Somewhat confident (might be correct)
- Below 50%: Not very confident (uncertain)
Why might predictions be wrong?
- Unusual angle or lighting - Model was trained on typical photos
- Multiple objects - Model expects one main object
- Rare objects - Model only knows 1000 categories
- Low quality image - Blurry or pixelated images are harder
๐ Next Steps
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Try different images:
- Find images on Unsplash
- Right-click โ "Copy image address" to get URL
-
Experiment:
- What happens with abstract art?
- Can it recognize objects from different angles?
- How does it handle multiple objects?
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Learn more:
- Explore Computer Vision lessons
- Learn to train your own image classifier
- Understand how CNNs (Convolutional Neural Networks) work
๐ Congratulations!
You just built an image classifier using a state-of-the-art neural network!
This same technique powers:
- Google Photos (organizing your photos)
- Self-driving cars (recognizing objects)
- Medical diagnosis (analyzing X-rays)
- Quality control (detecting defects)
Keep exploring and learning! ๐