--- title: "Speeding up first ICR operation by predownloading models | Nutrient Java SDK" canonical_url: "https://www.nutrient.io/guides/java/extraction/speed-up-first-icr-by-downloading-requirements/" md_url: "https://www.nutrient.io/guides/java/extraction/speed-up-first-icr-by-downloading-requirements.md" last_updated: "2026-06-10T14:59:56.779Z" description: "Predownload vision API models to eliminate first-request latency using Nutrient Java SDK." --- # Speeding up first ICR operation by predownloading models Use warmup to pre-download vision models before processing documents. Common use cases include: - Removing first-request latency in user-facing apps - Preparing batch jobs before processing starts - Marking containers ready only after dependencies are available - Preloading models before offline operation - Meeting latency targets for production APIs This guide shows how to warm up ICR models so `extractContent()` runs without initial download delays. [Download sample](https://www.nutrient.io/downloads/samples/java/speed-up-first-icr-by-downloading-requirements.zip) ## How Nutrient helps Nutrient Java SDK handles model download orchestration and cache management. The SDK handles: - AI model downloads, storage locations, and cache invalidation strategies - Model requirements for specific vision engine configurations (ICR, OCR, VLM) - Network failures during model downloads and retry behavior - Model availability checks with readiness probes and health endpoints ## Complete implementation This example warms up ICR models and then runs extraction: ```java package io.nutrient.Sample; ``` Import required classes from the SDK: ```java import io.nutrient.sdk.Document; import io.nutrient.sdk.Vision; import io.nutrient.sdk.enums.VisionEngine; import io.nutrient.sdk.exceptions.NutrientException; import java.io.FileWriter; import java.io.IOException; public class SpeedUpFirstIcrByDownloadingRequirements { ``` Create the main method and declare thrown exceptions: ```java public static void main(String[] args) throws NutrientException, IOException { ``` ## Warming up Vision API Open a document in try-with-resources, set `VisionEngine.Icr`, create a vision instance, and call `warmup()`. In this sample: - `setEngine(VisionEngine.Icr)` selects ICR mode. - `vision.warmup()` downloads required models. - Models are cached for subsequent requests. - The console output shows progress. ```java try (Document document = Document.open("input.png")) { // Configure ICR engine document.getSettings().getVisionSettings().setEngine(VisionEngine.Icr); // Create Vision instance Vision vision = Vision.set(document); // Pre-download all required models // This ensures subsequent extractContent() calls are fast System.out.println("Downloading Vision models..."); vision.warmup(); System.out.println("Models ready!"); ``` ## Processing documents after warmup After warmup, run `extractContent()` without download latency. In this sample: - `extractContent()` returns a JSON string. - The JSON output is written to `output.json`. - File handling uses try-with-resources. ```java // Now extractContent() won't need to download anything String contentJson = vision.extractContent(); try (FileWriter writer = new FileWriter("output.json")) { writer.write(contentJson); } } } } ``` ## Best practices Apply these patterns for using warmup effectively in production environments: - **Application startup** — Run warmup before accepting requests. - **Background thread** — Run warmup asynchronously during initialization. - **Health checks** — Expose warmup status in readiness probes. - **Deployment pipelines** — Validate model availability during deployment. - **Offline environments** — Download models while connected, then process offline. ## What gets downloaded? Warmup downloads model sets based on `VisionSettings.engine`: - **ICR mode** (`VisionEngine.Icr`) — Layout, text, tables, equations, and key-value detection models - **OCR mode** (`VisionEngine.AdaptiveOcr`) — OCR language and text recognition resources - **VLM-enhanced mode** (`VisionEngine.VlmEnhancedIcr`) — ICR resources plus VLM-related resources Downloaded models are cached locally and reused across restarts until the cache is cleared or models are updated. ## Conclusion Use this workflow to pre-download ICR requirements: 1. Open a document using try-with-resources for automatic resource cleanup after warmup and processing complete. 2. The SDK supports multiple document formats, including PNG, JPEG, PDF, and TIFF for vision operations. 3. Retrieve the vision settings with `document.getSettings().getVisionSettings()` to configure the vision engine. 4. Set the engine to ICR with `setEngine(VisionEngine.Icr)` to enable advanced document understanding with layout detection, text recognition, table extraction, equation recognition, and key-value pair detection. 5. Alternative engines include OCR mode for basic text extraction and VLM-enhanced mode for semantic understanding with vision language models. 6. Create a vision instance with `Vision.set()` bound to the document with configured engine settings. 7. Call `vision.warmup()` to trigger pre-download of all AI models required for the configured vision engine, fetching models from the SDK’s model repository and caching them locally. 8. Warmup downloads different model sets based on engine configuration — ICR downloads comprehensive document understanding models, OCR downloads text recognition models, and VLM downloads ICR models plus semantic understanding resources. 9. Console output provides feedback during model downloads, informing users about download progress and completion status for potentially multi-second operations. 10. After warmup completes, call `vision.extractContent()` to perform ICR operations without model download delays, ensuring predictable and fast processing for all subsequent requests. 11. The `extractContent()` method returns extracted content as JSON, including document structure (headings, paragraphs, tables, lists), textual content, table structures, equations, and key-value pairs. 12. Write the extracted JSON to a file using try-with-resources with `FileWriter` for automatic resource cleanup after writing completes. 13. Handle `NutrientException` for vision processing failures, including model download errors, processing failures, or configuration issues. 14. Handle `IOException` for file operations, including read failures or write errors when saving extracted content. For related image extraction workflows, refer to the [Java SDK guides](https://www.nutrient.io/guides/java.md). Download [this ready-to-use sample package](https://www.nutrient.io/downloads/samples/java/speed-up-first-icr-by-downloading-requirements.zip) to integrate warmup into application startup. --- ## Related pages - [Applying OCR to a PDF page](/guides/java/extraction/apply-ocr-to-pdf-page.md) - [Applying OCR to a PDF document](/guides/java/extraction/apply-ocr-to-pdf.md) - [Generating image descriptions using local AI](/guides/java/extraction/describe-image-with-local-ai.md) - [Generating image descriptions using Claude](/guides/java/extraction/describe-image-with-claude.md) - [Generating image descriptions using OpenAI](/guides/java/extraction/describe-image-with-openai.md) - [Extracting data from images using ICR](/guides/java/extraction/extract-data-from-image-icr.md) - [Extracting data from images using OCR](/guides/java/extraction/extract-data-from-image-ocr.md) - [Extracting data from images using vision language models](/guides/java/extraction/extract-data-from-image-vlm.md) - [Nutrient Java SDK extraction guides](/guides/java/extraction.md) - [Extracting structured data from documents](/guides/java/extraction/extract-structured-data.md) - [Extracting form fields from images](/guides/java/extraction/extract-form-fields-from-image.md) - [Labeling form fields with a vision language model](/guides/java/extraction/label-form-fields-with-vlm.md) - [Extracting JSON data from a PDF document](/guides/java/extraction/json-data-extraction.md) - [Extracting text from multilingual images](/guides/java/extraction/read-text-from-image-multi-language.md) - [Extracting text from images](/guides/java/extraction/read-text-from-image.md) - [Extracting text from PDF documents](/guides/java/extraction/pdf-to-text.md)