How Windows 11 Recall Captures and Indexes Snapshots

Windows 11 Recall is an AI-powered capability designed for Copilot+ PCs that acts as a searchable visual timeline of your digital activity. This article explains the technical workflow behind Recall, detailing how the system periodically captures encrypted snapshots of your screen, processes them locally using Neural Processing Units (NPUs), and creates a semantic search index that lets you retrieve past documents, websites, images, and conversations.

Periodic Snapshot Capture

Recall operates continuously in the background, capturing visual snapshots of your active desktop.

• Event-Driven Captures: Rather than taking a fixed-rate video stream, Recall captures a high-resolution snapshot every few seconds, specifically triggering when on-screen content changes.
• Storage and Filtering: Snapshots are saved locally on the device’s hard drive within an allocated storage limit. Users can configure storage sizes, pause recording, or exclude specific applications, websites, and private browsing sessions.
• Content Filtering: Protected content, such as DRM-restricted media and InPrivate browsing windows in supported browsers, is automatically excluded from capture.

Local AI Processing and Optical Character Recognition (OCR)

Once a snapshot is captured, it is processed entirely on-device without sending data to the cloud.

• NPU Acceleration: Recall relies on a dedicated Neural Processing Unit capable of at least 40 TOPS (trillion operations per second) to run small language models and computer vision algorithms in real time without degrading CPU or GPU performance.
• Text Extraction (OCR): An on-device OCR engine scans every pixel of the snapshot to extract written text in multiple languages, preserving the coordinates of where words appear on the screen.
• Visual Recognition: Multimodal AI models analyze graphical elements within the snapshot, identifying objects, user interface layouts, charts, and images.

Semantic and Relational Indexing

To make visual snapshots searchable, Recall converts raw visual and textual data into structured metadata.

• Vector Embeddings: The system generates vector embeddings—mathematical representations of the text and imagery—that capture the contextual meaning of what was on the screen rather than just exact keyword matches.
• Local Database Storage: The extracted text, visual tags, application metadata, timestamps, and embeddings are written to an encrypted local SQLite database.
• Contextual Association: The index correlates snapshots with the source application, window title, and exact point in time to maintain context.

Search and Retrieval

When a user searches within Recall, the feature queries the local index to find matching snapshots.

• Natural Language Queries: Users can enter descriptive phrases (such as “blue leather jacket” or “quarterly revenue chart”). The search engine compares the query’s vector embedding against the indexed embeddings to find semantically relevant snapshots.
• Timeline Scrubbing: Users can also navigate chronologically using a visual timeline slider to browse snapshots sequentially.
• Interactive Actions: When a snapshot is opened, the indexed text remains interactive, allowing users to highlight, copy, or reopen the original website or document directly via deep links.

Security and Encryption

All Recall snapshots and associated database entries are protected locally:

• Drive Encryption: The snapshot library and vector index are encrypted using BitLocker or Device Encryption.
• Isolated Access: Data is tied to the specific user profile and is only decrypted and accessed when the user authenticates through Windows Hello.