Pixel mask

Pixel mask, a part of algorithm transparency, is an expansion of filtered mask from primary blocks of the block map to individual pixels. It is constructed during feature extraction. It is used to compute inner mask and to create binarized skeleton for valleys.

KeywordSuffixZip
pixel-mask.json036-pixel-mask.json
pixel-mask.dat037-pixel-mask.dat

Visualization

The following visualization was created from this stage's binary data overlaid on top of the original fingerprint image. Visualization itself is not part of transparency data.

Fingerprint image with valid fingerprint area highlighted in yellow color
Valid fingerprint area is shown as light yellow.

Binary data

Binary data is a 2D array with dimensions that can be found in the associated json data, height first, or in block map's pixels field. Binary data consists of rows of pixels ordered from top to bottom. Every row is a sequence of pixels from left to right. Every pixel is a single byte with value 1 (valid fingerprint area) or 0 (surrounding area).

Example: 037-pixel-mask.dat

Json

Json data describes basic properties of the binary data, most importantly dimensions of the image.

Example: 036-pixel-mask.json

{
  "axes": [
    "y",
    "x"
  ],
  "dimensions": [
    374,
    388
  ],
  "scalar": "boolean",
  "bitness": 8,
  "format": "false as 0, true as 1"
}