How does image search work in e-commerce?

Image search in e-commerce enables users to find products by uploading or taking a photo instead of using text queries. The process typically involves three stages: image processing, feature extraction, and database matching. When a user submits an image, the system first analyzes it to identify key visual attributes like color, shape, texture, or patterns. For example, a photo of a striped shirt might be broken down into its dominant colors, the orientation of stripes, and the fabric texture. These features are converted into numerical vectors (embeddings) using machine learning models like convolutional neural networks (CNNs). Tools like ResNet or pre-trained vision models from frameworks like TensorFlow or PyTorch are often used here to generate embeddings that represent the image in a high-dimensional space.

Next, the system compares the extracted feature vector against a database of product images indexed with similar embeddings. This is done using approximate nearest neighbor (ANN) algorithms, such as FAISS or Annoy, which efficiently search large datasets for vectors that closely match the query. For instance, if a user uploads a shoe image, the system retrieves products with embeddings closest to the query, prioritizing similarities in sole design, color blocks, or logo placement. Indexing strategies, like hierarchical navigable small world (HNSW) graphs, optimize search speed and accuracy, even when dealing with millions of product images. Some platforms also incorporate metadata (e.g., product categories) to filter results, ensuring a striped shirt query doesn’t return unrelated items like shoes.

Finally, the ranked results are returned to the user, often with additional relevance scoring. Backend systems might use REST APIs to connect the image search pipeline to the frontend, while caching mechanisms handle high traffic. For example, an e-commerce app might use AWS S3 for image storage, PyTorch for feature extraction, and Elasticsearch with a vector plugin for matching. Challenges include handling low-quality images, scaling for real-time performance, and minimizing false positives. Some platforms refine results using user feedback—like click-through rates—to retrain models and improve future searches. Overall, the technical stack balances accuracy, latency, and scalability to deliver a seamless shopping experience.