Grid Crop Coordinate Map

Map source grid coordinates into a half-open crop and retain excluded-coordinate evidence instead of silently clipping.

Description

Map source grid coordinates into a half-open crop and retain excluded-coordinate evidence instead of silently clipping.

A crop changes coordinate origin and excludes positions outside the selected rectangle.

When to use this tool

Map source grid coordinates into a half-open crop and retain excluded-coordinate evidence instead of silently clipping.

Prepare the supplied coordinates, cropTop, cropLeft, cropRows, cropColumns fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter coordinates, cropTop, cropLeft, cropRows, cropColumns. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.mapping. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Validate nonnegative integer source pairs, crop origin and positive crop dimensions. Subtract cropTop/cropLeft and test each result against zero-inclusive, size-exclusive bounds. Return inside with local row/column or null coordinates.^[1]

Input field	Meaning and representation	Accepted input
coordinates	coordinates.	Numeric rows; at most 128 rows and 128 values per row
cropTop	crop top.	Finite number
cropLeft	crop left.	Finite number
cropRows	crop rows.	Finite number
cropColumns	crop columns.	Finite number

Output field	Interpretation
result	Object containing the named outputs below.
result.mapping	The mapping list in the ordering and representation described above.

json

{
  "input": {
    "coordinates": [
      [
        2,
        3
      ],
      [
        0,
        0
      ]
    ],
    "cropTop": 1,
    "cropLeft": 2,
    "cropRows": 3,
    "cropColumns": 3
  },
  "output": {
    "result": {
      "mapping": [
        {
          "inside": true,
          "row": 1,
          "column": 1
        },
        {
          "inside": false,
          "row": null,
          "column": null
        }
      ]
    }
  }
}

Limitations and assumptions

Output records remain aligned with input pairs. No grid data is cropped or out-of-range source coordinate clamped.
Coordinate pairs use [row,column] where stated. Masks are nonempty rectangular zero/one matrices of at most 128 rows, 128 columns and 16,384 cells; outside-mask values are unset for the neighborhood operations.
Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
String lists have at most 128 entries of at most 128 code units; matrices have at most 128 rows and columns. Larger numeric lists and parsed JSON have separate bounded budgets. Nonfinite results and excessively large serialized outputs are rejected.
Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Keep row/column coordinates distinct from x/y pairs and byte offsets. Select the neighborhood metric, outside-mask rule and storage-order convention explicitly; these operations do not infer an image format.

References

Tool behavior and example: Grid Crop Coordinate Map — tool.io

Similar or alternative tools

Grid Padding Coordinate Map
Translate source grid coordinates after explicit top/left padding; no inferred original or padded dimensions.
Grid Diagonal Coordinate List
List coordinates on the grid diagonal column−row=offset in ascending row order; no square-grid assumption.