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Image-In Node ​

Purpose & Use Cases ​

The image-in node is the primary entry point for loading images from the filesystem into Node-RED flows. It converts image files into the standardized image object format used throughout the Rosepetal Image Tools ecosystem.

Real-World Applications:

  • Photo Processing Workflows: Load photos for batch editing and enhancement
  • Computer Vision Pipelines: Import images for AI/ML analysis and object detection
  • Web Content Processing: Load user-uploaded images for processing before storage
  • Surveillance Systems: Import images from cameras or storage for analysis

/flows/node-red-contrib-rosepetal-image-tools/assets/nodes/io/image-in-demo.gif

Input/Output Specification ​

Inputs ​

  • (any): Input message that triggers the node (content ignored)

Outputs ​

The node outputs a standardized image object to the configured location:

javascript
{
  data: Buffer,        // Raw pixel data  
  width: number,       // Image width in pixels
  height: number,      // Image height in pixels
  channels: number,    // Channel count (1, 3, 4)
  colorSpace: string,  // "GRAY", "RGB", "RGBA", ...
  dtype: string        // "uint8" (standard)
}

Configuration Options ​

File Path ​

  • Type: String | msg | flow | global (required)
  • Description: Path to the image file on the server filesystem
  • Options:
    • String: Static absolute or relative path (e.g., /home/user/photos/image.jpg)
    • msg.*: Dynamic path from message properties (e.g., msg.imagePath)
    • flow.*: Dynamic path from flow context (e.g., flow.currentImageFile)
    • global.*: Dynamic path from global context (e.g., global.basePath)
  • Supported Formats: All formats supported by Sharp (JPEG, PNG, WebP, ...)

Output Location ​

  • Default: msg.payload
  • Options:
    • msg.* - Store in message property
    • flow.* - Store in flow context
    • global.* - Store in global context
  • Use Case: Choose based on how you want to access the image downstream

Debug Options ​

  • Show Loaded Image: Visual preview of loaded image in Node-RED editor
  • Debug Width: Preview image width in pixels (default: 200)
  • Dynamic Width: Can be resolved from msg, flow, or global context
  • Interactive: Preview appears in Node-RED editor with timing information

Performance Notes ​

Sharp (libvips) Backend Optimization ​

  • High-Speed Loading: Uses Sharp (libvips) for optimized image decoding
  • Async Processing: Non-blocking operation with performance timing display
  • Memory Efficient: Optimized for large images and batch processing
  • Metadata Extraction: Complete image properties extracted during load

Status Display ​

The node shows real-time progress and results:

  • Blue dot: Reading file
  • Green dot: Success with dimensions and timing info
  • Red ring: Error with file access or format issues

Real-World Examples ​

Basic Photo Import ​

[Inject] → [Image-In: /photos/vacation.jpg] → [Debug]

Load a single photo and inspect its properties.

Dynamic File Loading ​

[File List] → [Image-In: File Path from msg.imagePath] → [Resize] → [Save]

Process multiple files by configuring File Path to use msg.imagePath for dynamic file selection.

Computer Vision Pipeline ​

[Image-In] → [CropBB] → [Filter] → [Analysis]

Load images for object detection and post-processing.

Visual Development ​

[Image-In: Debug enabled] → [Transform] → [Output]

Enable debug preview to visually verify image loading and dimensions.

Batch Processing Setup ​

[Image-In] → [Array-In] → [Array-Out] → [Batch Transform]

Collect multiple images into arrays for parallel processing.

Common Issues & Troubleshooting ​

File Access Problems ​

  • Issue: "Cannot access file" warning
  • Solution: Verify file path exists and Node-RED has read permissions
  • Check: Use absolute paths to avoid relative path confusion

Unsupported Format ​

  • Issue: Node fails silently or errors
  • Solution: Ensure file is in supported format (JPEG, PNG, WebP, BMP)
  • Check: Verify file isn't corrupted using image viewer

Memory Issues ​

  • Issue: Large images cause performance problems
  • Solution: Process images in batches, consider resizing after load
  • Optimization: Use flow/global context for sharing large images

Path Configuration ​

  • Static Path: Set File Path to string type for fixed file locations
  • Dynamic Path: Configure File Path from msg, flow, or global context for runtime file selection
  • Best Practice: Validate dynamic path sources provide valid file paths

Debug Display Issues ​

  • Issue: Debug preview not appearing
  • Solution: Ensure debug checkbox is enabled and Node-RED editor is active
  • Performance: Large debug widths may impact editor performance