Decoded image

Decoded image, a part of algorithm transparency, is the original fingerprint image used for feature extraction (template construction). Decoded image contains unchanged pixels as deserialized by SourceAFIS except that pixel values are mapped to floating-point range between 0 and 1. It is an input to image scaling.

Visualization

The following fingerprint image can be reconstructed from this stage's binary data. Visualization itself is not part of transparency data.

Format

Decoded image is a matrix (2-dimensional array) of floating-point numbers, each representing pixel darkness in range 0 (white) to 1 (black). It is encoded in CBOR:

• width - Image width in pixels.
• height - Image height in pixels.
• cells - Array of width * height 64-bit floating-point numbers representing image pixels. The 2-dimensional pixel space is mapped into 1-dimensional array by sorting pixels by Y position top to bottom and then by X position left to right.

Example: 002-decoded-image.cbor

{
  "width": 388,
  "height": 374,
  "cells": [
    0.0039215686274510775,
    0.0039215686274510775,
    "... skipped 145,108 items in range 0.00392 to 0.996 ...",
    0.0039215686274510775,
    0.07058823529411773
  ]
}