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Alternate Backdrop Calibration

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In this tutorial, we’ll demonstrate how to calibrate a linear distance using a known reference measurement within the patient’s photo. This method represents a legacy calibration approach and is generally not required with current versions of PostureScreen.

Modern versions of PostureScreen automatically crop based on the patient’s entered height—so it is essential that their height is input accurately. This legacy calibration method should only be used in exceptional cases, such as when assessing a seated or wheelchair-bound individual.

Important:
If you’re unsure whether this setting applies to your scenario, please contact our support team before enabling it. If you’re being prompted to mark a calibration line and do not wish to use this method, the video will guide you through how to disable it.

Video link: https://youtu.be/qu0u9wmk-AY

Overview

This tutorial outlines how to manually calibrate a PostureScreen assessment using a known linear distance (instead of patient height). This feature is intended for exceptional clinical use cases—such as patients with severe postural deformities, infants, or individuals who cannot stand upright. In nearly all cases, the default calibration using the patient’s known height is recommended.

🔧 Step-by-Step Instructions

Step 1: Understand When to Use This Feature

  • Use this method only in rare scenarios such as:
    • A patient with severe spinal deformity that alters true standing height.
    • Non-ambulatory children or infants assessed lying down.
    • Cases where a background calibration marker (e.g., ruler) is positioned close to the subject.

Important: Do not use this method for routine posture assessments. Default height-based calibration is preferred.

Step 2: Enable Background Calibration

  1. Open the PostureScreen app.
  2. Tap on the Settings.
  3. Go to Images and Video.
  4. Toggle “Use Backdrop Calibration” to ON.
  5. Confirm the warning prompt—only proceed if you understand the use case.

Step 3: Set the Known Calibration Distance

  1. After enabling, you’ll be prompted to enter a known distance.
  2. The default is 10 inches. Change this to match your marker (e.g., 12 inches or 30 cm).
  3. Ensure your calibration object (e.g., measuring tape or known-length item) is placed adjacent to the subject during photo capture.

Step 4: Disable Background Removal (if applicable)

  • Background calibration requires seeing the surrounding area in the image.
  • If PostureScreen automatically removed the background:
    1. Go to Settings.
    2. Turn ON “Keep Original Background” to restore visibility of calibration markers.

Step 5: Capture or Import Image

  • Capture a photo or import an image that includes the calibration marker clearly visible next to the subject.
  • If necessary, use the image rotation tools during import to orient the image properly.

Step 6: Mark Calibration Points

  • Begin the assessment and follow prompts to:
    1. Digitally mark the start and end points of the known distance.
    2. Continue with digitization as normal.

Step 7: Complete Assessment

  • The app will now calculate linear distances based on the manually defined calibration marker, not on the patient’s height.

Step 8: Disable the Feature After Use

  • After your specialized use, return to:
    1. Settings > Images and Video
    2. Toggle “Use Backdrop Calibration” OFF
  • This resets the app to default behavior using known patient height and automatic background removal.
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