Template Matcher

Quick Start

To get started:

• Provide main image path via msg.payload.image_path
• Provide template image path via msg.payload.template_path
• Set Minimum Features to be Matched (%) threshold
• Receive match locations in msg.payload

Configuration

Minimum Features to be Matched (%) (required)

Percentage of features (0-100) that must match for template detection. Default: 50

Note: Higher values require more precise matches, lower values are more tolerant.

Common Input Format

msg.payload.image_path (string)

Relative path of the main image on shared storage.

Example: "images/document.png"

msg.payload.template_path (string)

Relative path of the template image to find.

Example: "templates/logo.png"

Common Output Format

msg.payload (object | string)

Returns match details if found, or a "Match not found" message.

Example: {"matched_template": "document_crop.png", "number_of_features_matched": 87}

Example

Input (msg.payload)

{
  "image_path": "images/document.png",
  "template_path": "templates/logo.png"
}

Output (msg.payload)

{
  "matched_template": "document_crop.png",
  "number_of_features_matched": 87
}

Errors

When the block fails, it raises an error. Use a Catch block in your flow to handle failures and inspect the error payload.

Common mistakes

• Invalid image path: Main image or template image path is incorrect or file doesn't exist.
• Template larger than image: Template image dimensions exceed the main image dimensions.
• Invalid threshold: Feature match percentage must be between 0 and 100.
• No matches found: Try lowering the feature match threshold.
• Service unavailable: The service is unavailable or unreachable.

Best Practices

• Ensure template image is clear and well-defined
• Use templates that are roughly the same scale as they appear in the target image
• Start with 50% feature matching and adjust based on results
• Lower threshold (30-40%) for more matches with variations, higher (60-80%) for exact matches
• Template should be significantly smaller than the main image
• Use consistent image formats for both main and template images
• Test with sample images to determine optimal threshold for your use case
• Consider image quality and resolution when setting expectations