Smoothed histogram

SourceAFIS » Algorithm » Transparency » Smoothed histogram

Smoothed histogram, a part of algorithm transparency, is computed during feature extraction for every secondary block by summing histograms of four overlapping primary blocks from histogram data. It is used to compute contrast and equalized image.

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Histogram visualization can be created from this stage's binary data mapped onto blocks. Visualization itself is not part of transparency data.

Array of histograms, one per block
Histogram is shown separately for every secondary block on the image. Secondary blocks are smaller next to image borders. Vertical axis of histograms is logarithmic.


Smoothed histogram has the same format as unsmoothed block histogram except that its size matches secondary blocks instead of primary blocks and pixels count is gathered from 4 primary blocks overlapping given secondary block.

Example: 006-smoothed-histogram.cbor

  "width": 27,
  "height": 26,
  "bins": 256,
  "counts": [
    "... skipped 179,708 items in range 0 to 900 ...",