Scaled image

SourceAFIS » Algorithm » Transparency » Scaled image

Scaled image, a part of algorithm transparency, is computed from decoded image during feature extraction by scaling it to 500dpi. If decoded image is at (or almost at) 500dpi, no scaling is performed and scaled image is identical to decoded image.

All other parts of the algorithm assume they work with 500dpi images. Scaled image coordinate space is used to measure all pixel positions and distances in all other transparency data, especially blocks. Scaled image itself is used to compute contrast and equalized image.

Key	MIME	Filename in ZIP
`scaled-image`	`application/cbor`	`003-scaled-image.cbor`

Visualization

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

Black fingerprint image on white background — Fingerprint image scaled to 500dpi.

Format

Scaled image is stored in the same format as decoded image.

Example: 003-scaled-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
  ]
}