Absolute contrast mask in SourceAFIS transparency data

SourceAFIS » Algorithm » Transparency » Absolute contrast mask

Absolute contrast mask, a part of algorithm transparency, is a set of primary blocks where contrast falls below some fixed threshold. It is computed during feature extraction. Absolute contrast mask contributes to combined mask.

KeyMIMEFilename in ZIP
absolute-contrast-maskapplication/cbor008-absolute-contrast-mask.cbor

Visualization

Absolute contrast visualization can be computed from this stage's binary data mapped onto blocks and the original fingerprint image. Visualization itself is not part of transparency data.

Absolute contrast mask visualized as yellow masked out area around fingerprint image
Absolute contrast mask. Yellow area consists of blocks excluded due to low contrast.

Format

Absolute contrast mask is a matrix (2-dimensional array) of boolean values. Every cell in the matrix corresponds to primary block. Cell value is true if the block has low contrast and false if it has high contrast. The mask is encoded in CBOR:

Example: 008-absolute-contrast-mask.cbor

{
  "width": 26,
  "height": 25,
  "cells": [
    true,
    true,
    "... skipped 646 items ...",
    true,
    true
  ]
}