Cropped ROI Endpoint (Classification Only)

Overview

The cropped_roi endpoint provides access to cropped Regions of Interest (ROIs) generated from classification results in Haystack running on the device.

Classification only

Haystack does not currently support segmentation results. This endpoint works only for classification-type results. If you need to process segmenter output programmatically, use the standard inspection results API instead.

The base URL format is:

http://{device-ip}/edge/haystack/cropped_roi/{classification_result_id}

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How It Works

When the camera completes a classification capture, The Node-RED flow dynamically constructs URLs for the cropped ROI images by pairing the device IP and classification result ID:

const imageUrl = `http://${baseUrl}/edge/haystack/cropped_roi/${result.id}`;

Each URL serves a cropped image corresponding to individual classification ROI, typically representing a single inspection.

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Node-RED Flow Summary

The ROI_Crop flow performs the following:

1. Extracts the Device IP

   • Parses the image_url field to find the IP (e.g., 192.168.0.101)
   • Stores it globally for reuse

2. Queries Latest Capture Data

   • Sends a GET request to the device’s PostgREST API:

     http://{device-ip}/postgrest/captures?select=...
     &order=id.desc&limit=1

   • Retrieves the most recent capture and all classification_result entries

3. Filters for Classification Results Only

   • Skips segmentation or alignment results

   • Iterates over each classification result:

     classificationResults.forEach(result => {
       const roiName = result.roi_result?.inspection_region?.name || `ROI_${result.id}`;
       const imageUrl = `http://${baseUrl}/edge/haystack/cropped_roi/${result.id}`;
       imageMap[roiName] = imageUrl;
     });

4. Outputs the Cropped ROI URLs

   • Saves all ROI image links to a global imageMap
   • Returns the list of latest cropped ROI image URLs

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Example Usage

Fetch a Cropped ROI Image

curl http://192.168.0.101/edge/haystack/cropped_roi/42 -o roi_42.jpg

Use in a Web Interface

<img src="http://192.168.0.101/edge/haystack/cropped_roi/42" alt="Cropped ROI 42">

Output Example

{
  "ROI_1": "http://192.168.0.101/edge/haystack/cropped_roi/1",
  "ROI_2": "http://192.168.0.101/edge/haystack/cropped_roi/2"
}

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Parameters

Parameter	Type	Description
device-ip	string	IP address of the camera (e.g. 192.168.0.101)

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Integration Flow

1. Acquire latest capture metadata via /postgrest/captures.
2. Identify available classification_result IDs.
3. Construct cropped ROI URLs for each result.
4. Display or download those images for analysis, training data, or QA inspection.

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Download Node-RED Flow

• ROI Crop Flow (JSON) - Complete Node-RED flow for extracting cropped ROI images
  • Import this flow directly into Node-RED to access cropped classification ROIs
  • Works with both OV20i and OV80i systems

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