Description
Calculate questioned-document line spacing from supplied image geometry.
Forensic records distinguish exhibit identity, container links, declared conclusions, timestamp resolution and measurement bases. A matching seal string or recorded certificate is not authentication or proof of custody. Redacted display text and salt-version labels also do not by themselves establish sufficient de-identification or lawful disclosure.
Calculate questioned-document line spacing from supplied image geometry.
When to use this tool
Use Questioned Document Line Spacing when checking the stated exhibit record, measurement, time or display-policy convention.
How to use the tool and how it works
- Enter firstBaseline, secondBaseline, scaleUnitsPerPixel. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read signedSpacing, absoluteSpacing. Use the output convention below.
Require scaleUnitsPerPixel>0. Multiply secondBaseline-firstBaseline by that scale for signedSpacing; use the absolute baseline difference for absoluteSpacing.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstBaseline | First Baseline | Required. Finite number. |
| secondBaseline | Second Baseline | Required. Finite number. |
| scaleUnitsPerPixel | Scale Units Per Pixel | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| signedSpacing | Signed Spacing | Required. Finite number. |
| absoluteSpacing | Absolute Spacing | Required. Finite number. |
{
"input": {
"firstBaseline": 120,
"secondBaseline": 150,
"scaleUnitsPerPixel": 0.1
},
"output": {
"signedSpacing": 3,
"absoluteSpacing": 3
}
}Limitations and assumptions
- The image scale and baselines are supplied; no document image, perspective, authorship, alteration or evidential conclusion is assessed.
- 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
Review verified original evidence and custody records using qualified forensic and legal assessment for actual interpretation, disclosure and evidential decisions.
References
Similar or alternative tools
- Forensic Photo Scale Perspective Label
Attach a supplied scale-perspective label to a forensic photograph.
- Blood Film Field Area Calibration
Convert blood-film pixel area to physical area using the square of a supplied linear scale.