Appearance

Image-Out Node ​

Purpose & Use Cases ​

The image-out node is the primary output point for saving processed images to the filesystem from Node-RED flows. It features automatic timestamp-based naming, overwrite protection, and flexible format conversion, making it ideal for production workflows.

Real-World Applications:

  • Automated Image Processing: Save processed images with organized timestamp naming
  • Computer Vision Results: Export detected objects or processed frames
  • Batch Processing Workflows: Save multiple images without filename conflicts
  • Quality Control Systems: Archive inspection images with automatic naming
  • Web Application Backends: Save user-processed images with format optimization

Input/Output Specification ​

Inputs ​

The node accepts either:

  • Raw Image Object: Standard format with data, width, height, channels, colorSpace
  • Encoded Buffer: JPEG, PNG, or WebP buffer (automatically detected and handled)

Outputs ​

This is a terminal node with no outputs. It saves images to the filesystem and displays status information.

Button Control ​

  • Right-side button: Toggle node active/inactive state (similar to debug node)
  • Green: Active and saving images
  • Gray: Inactive (passes through without saving)

Configuration Options ​

Folder Path ​

  • Type: String | msg | flow | global (required)
  • Description: Directory where images will be saved
  • Options:
    • String: Static path (e.g., /home/user/output/)
    • msg.*: Dynamic path from message (e.g., msg.folder)
    • flow.*: Path from flow context
    • global.*: Path from global context
  • Auto-creation: Directory is created if it doesn't exist

Filename Prefix ​

  • Type: String (optional)
  • Default: "image"
  • Description: Custom prefix for generated filenames
  • Pattern: [prefix]_YYYYMMDD_HHMMSS.[ext]
  • Example: With prefix "webcam" → webcam_20240109_143022.jpg

Input From ​

  • Default: msg.payload
  • Options: Any message property, flow, or global variable
  • Accepts: Both raw image objects and encoded buffers

Output Format ​

  • Options: JPEG, PNG, WebP
  • Description: Target format for saved images
  • Conversion: Automatic conversion if input format differs

Quality ​

  • Type: Number (1-100)
  • Default: 90
  • Applies to: JPEG and WebP formats
  • Description: Higher values = better quality but larger files

PNG Optimize ​

  • Type: Boolean
  • Default: false
  • Description: Maximum compression for PNG files (slower but smaller)

Overwrite Protection ​

  • Type: Boolean
  • Default: true
  • Description: Automatically appends _2, _3, etc. to prevent overwriting
  • Example: If image_20240109_143022.jpg exists, saves as image_20240109_143022_2.jpg

Debug Preview ​

  • Type: Boolean
  • Default: false
  • Description: Shows saved image preview on the node

Performance & Technical Details ​

Timestamp Naming ​

Files are automatically named with timestamps:

  • Format: YYYYMMDD_HHMMSS
  • Example: image_20240109_143022.jpg
  • Benefits: Chronological ordering, no conflicts, easy sorting

Format Handling ​

The node intelligently handles format conversions:

  • Same Format: Direct save without re-encoding (fastest)
  • Different Format: Automatic conversion using Sharp
  • Raw to Encoded: Full processing with color space handling
  • Encoded to Encoded: Smart re-encoding only when needed

Status Indicators ​

  • Gray dot "inactive": Node disabled via button
  • Blue dot "saving...": Currently writing to disk
  • Green dot "saved: filename.jpg": Success with filename
  • Red dot "Error": Save failed (check debug panel)

Error Handling ​

Common errors and solutions:

  • "Folder path not configured": Ensure folder path is set
  • "Invalid image structure": Check input is valid image data
  • "Cannot create directory": Verify write permissions
  • "Too many file variations": Clean up old files (>1000 with same timestamp)

Examples ​

Basic Save with Timestamp ​

javascript
// Input: Processed image
// Config: Folder="/output", Format="jpg"
// Result: /output/image_20240109_143022.jpg

Custom Prefix for Source Identification ​

javascript
// Config: Prefix="camera1", Folder="/surveillance"
// Result: /surveillance/camera1_20240109_143022.jpg

Format Conversion ​

javascript
// Input: PNG buffer
// Config: Format="webp", Quality=80
// Result: Converts PNG to WebP with 80% quality

Dynamic Folder from Message ​

javascript
// msg.saveFolder = "/output/batch1"
// Config: Folder from msg.saveFolder
// Result: Saves to dynamic folder location

Overwrite Protection in Action ​

javascript
// First save: image_20240109_143022.jpg
// Second save (same second): image_20240109_143022_2.jpg
// Third save: image_20240109_143022_3.jpg

Tips & Best Practices ​

  1. Use Prefixes: Identify image sources with meaningful prefixes
  2. Enable Protection: Keep overwrite protection on to prevent data loss
  3. Choose Format Wisely:
    • JPEG for photos (smaller files)
    • PNG for graphics with transparency
    • WebP for web optimization
  4. Button Control: Disable during development to prevent unwanted saves
  5. Monitor Status: Check node status for save confirmations

Integration Examples ​

Computer Vision Pipeline ​

[Camera] → [Object Detection] → [Draw Boxes] → [Image-Out]

Save annotated detection results with timestamps.

Batch Processing ​

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

Process and save multiple images with automatic naming.

Quality Control ​

[Inspection Camera] → [Defect Detection] → [Image-Out (active/inactive)]

Conditionally save images based on detection results.

  • image-in: Load images from filesystem
  • array-out: Process multiple images before saving
  • filter: Apply enhancements before saving