Description
Calculate image millimetres per pixel from a supplied calibration-marker diameter.
Orthopedic measurements distinguish side, reference origin, image scale, device lots and mechanical test geometry. A two-point load/displacement slope is structural stiffness rather than a material modulus. Supplied matches, offsets and calibration factors need verified anatomy, devices and test conditions before clinical or design interpretation.
Calculate image millimetres per pixel from a supplied calibration-marker diameter.
When to use this tool
Use Orthopedic Image Marker Diameter when you already have observedMarkerPixels, trueMarkerMillimeters and need to calculate image millimetres per pixel from a supplied calibration-marker diameter.
How to use the tool and how it works
- Enter observedMarkerPixels, trueMarkerMillimeters. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read millimetersPerPixel. Use the output convention below.
Require observedMarkerPixels>0 and trueMarkerMillimeters>0; return true/observed.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| observedMarkerPixels | Observed Marker Pixels | Required. Finite number; strictly above 0. |
| trueMarkerMillimeters | True Marker Millimeters | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| millimetersPerPixel | Millimeters Per Pixel | Required. Finite number. |
{
"input": {
"observedMarkerPixels": 100,
"trueMarkerMillimeters": 25
},
"output": {
"millimetersPerPixel": 0.25
}
}Limitations and assumptions
- Assumes matching marker geometry and scale; no image, perspective, projection plane or anatomical measurement is verified.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Inspect actual device specifications, calibrated images and the full measurement or test setup. Use complete geometry and material/test information when relating a local scale, side match or structural secant slope to a physical or clinical question.
References
Similar or alternative tools
- Model Scan Scale Factor
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- Orthopedic Implant Lot Label
Record explicit orthopedic implant and lot identifiers.