Description
Subtract cropLeft/top from page coordinates, multiply by scale and return crop coordinates.
Forensic measurement calculations require a known calibration, geometric model and uncertainty convention. A converted length, ratio or residual describes the supplied measurements; it does not establish common origin, identity or evidentiary strength.
Subtract cropLeft/top from page coordinates, multiply by scale and return crop coordinates.
When to use this tool
Use Document Page Image Crop Offset when you need an explicit image or physical-measurement term.
How to use the tool and how it works
- Enter pageX, pageY, cropLeft, cropTop, scale. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read cropX, cropY. Use the output convention below.
Require positive scale. Subtract cropLeft/top from page coordinates, multiply by scale and return crop coordinates.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| pageX | Page X | Required. Finite number. |
| pageY | Page Y | Required. Finite number. |
| cropLeft | Crop Left | Required. Finite number. |
| cropTop | Crop Top | Required. Finite number. |
| scale | Scale | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| cropX | Crop X | Required. Finite number. |
| cropY | Crop Y | Required. Finite number. |
{
"input": {
"pageX": 120,
"pageY": 80,
"cropLeft": 20,
"cropTop": 30,
"scale": 2
},
"output": {
"cropX": 200,
"cropY": 100
}
}Limitations and assumptions
- The transform assumes aligned axes and uniform scale; it neither checks crop containment nor verifies image authenticity or perspective.
- 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
Use the validated measurement method and original evidence for interpretation. Include calibration, geometry, uncertainty and the full evidentiary context rather than turning a numerical match into an identification.
References
Similar or alternative tools
- Questioned Document Baseline Slope Term
Return Δy/Δx as slope and atan2(Δy,Δx) as directed angle in radians.
- Evidence Scale Perspective Length Factor
Return ruler-scaled length, then multiply it by objectDepth/rulerDepth.