Binary Mask Four Connected Component Labels

Description

Label four-connected foreground components and return their cell coordinates in deterministic traversal order.

A binary grid represents foreground as numeric one and background as zero. A stencil is a set of integer [rowOffset,columnOffset] positions relative to a cell. Connectivity describes allowed neighbor steps: four-neighbor connectivity uses orthogonal steps, while eight-neighbor connectivity also includes diagonals. Finite image borders and asymmetric stencils affect the result.

Label four-connected foreground components and return their cell coordinates in deterministic traversal order.

When to use this tool

Use orthogonal component labels to distinguish regions that touch only at corners.

How to use the tool and how it works

Enter mask using the definitions below.
Run the operation. Resolve input-format errors before interpreting an output.
Read result.labels, result.components, using the stated boundary, ordering, sign and absence conventions.

Scan foreground cells row first, assigning the next positive label to each previously unseen component and exploring its orthogonal neighbors. Return the label image and component cell lists.^[1]

Input field	Meaning and units	Accepted input
mask	Rectangular numeric 0/1 rows, up to 64×64; row is the first coordinate and column the second.	Dense numeric rows, each dimension at most 128; the stated shape rules also apply.

Output field	Interpretation
result	Object containing the fields below.
result.labels	Grid of positive foreground component labels; background cells are zero.
result.components	Component records with positive label and traversal-order cells as [row,column] coordinates.

json

{
  "input": {
    "mask": [
      [
        1,
        0
      ],
      [
        0,
        1
      ]
    ]
  },
  "output": {
    "result": {
      "labels": [
        [
          1,
          0
        ],
        [
          0,
          2
        ]
      ],
      "components": [
        {
          "label": 1,
          "cells": [
            [
              0,
              0
            ]
          ]
        },
        {
          "label": 2,
          "cells": [
            [
              1,
              1
            ]
          ]
        }
      ]
    }
  }
}

Limitations and assumptions

Only up/down/left/right steps connect foreground. Background labels remain zero; diagonal contact alone does not connect two components.
Masks are rectangular dense arrays of numeric 0/1 cells, with at most 64 rows and 64 columns. Empty frames are allowed where no in-bounds seed is required. Stencils are nonempty lists of distinct integer [rowOffset,columnOffset] pairs, each coordinate between -16 and 16. Outside-frame samples are zero at every stage.
Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
Numeric outputs must remain finite and within safe-integer magnitude. Original record indexes and cell coordinates are zero-based; stated half-open ranges exclude their end.

Alternative or Complementary methods

Choose a component operation for connected regions and an explicit stencil for local shape tests. Fix connectivity and border policy before comparing masks; convert cell counts to physical area separately when pixel spacing is known.

References

Tool behavior and example: Binary Mask Four Connected Component Labels — tool.io

Similar or alternative tools

Binary Mask Eight Connected Component Labels
Label eight-connected foreground components and return their cell coordinates in deterministic traversal order.
Binary Mask Component Cell Area Table
Report foreground component areas as cell counts under the chosen connectivity.