Combined mask

Combined mask, a part of algorithm transparency, merges absolute contrast mask and relative contrast mask. It is computed during feature extraction. It is further refined into filtered mask before being used extensively to focus later algorithm stages on valid fingerprint area.

KeywordSuffixZip
combined-mask.json016-combined-mask.json
combined-mask.dat017-combined-mask.dat

Visualization

This visualization can be computed from this stage's binary data combined with block map and original fingerprint image. Visualization itself is not part of transparency data.

Combined absolute and relative contrast mask visualized as yellow masked out area around fingerprint image
Combined (absolute and relative) contrast mask. Yellow area consists of blocks excluded due to low contrast.

Binary data

Binary data has the same format as for absolute contrast mask.

Example: 017-combined-mask.dat

Json

Json data describes basic properties of the binary data, most importantly dimensions of the mask, which is the same as the number of primary blocks.

Example: 016-combined-mask.json

{
  "axes": [
    "y",
    "x"
  ],
  "dimensions": [
    25,
    26
  ],
  "scalar": "boolean",
  "bitness": 8,
  "format": "false as 0, true as 1"
}