Module: Okmain::Scorer

Defined in:
lib/okmain/scorer.rb

Constant Summary collapse

MAX_SRGB_OKLAB_CHROMA = 
0.32

Class Method Summary collapse

Class Method Details

.score(centroids, assignments, mask, config) ⇒ Object

Returns Array of [r, g, b] (0..255) sorted by score descending.



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# File 'lib/okmain/scorer.rb', line 10

def score(centroids, assignments, mask, config)
  k = centroids.size
  n = assignments.size
  mask_w = config.mask_weighted_counts_weight
  chroma_w = config.chroma_weight

  # Weighted counts per centroid
  weighted_counts = Array.new(k, 0.0)
  i = 0
  while i < n
    c = assignments[i]
    w = 1.0 - mask_w * (1.0 - mask[i])
    weighted_counts[c] += w
    i += 1
  end

  # Normalize to sum to 1.0
  total = weighted_counts.sum
  if total > 0
    inv = 1.0 / total
    j = 0
    while j < k
      weighted_counts[j] *= inv
      j += 1
    end
  end

  # Score each centroid
  scored = centroids.each_with_index.map do |centroid, idx|
    chroma = Math.sqrt(centroid[1] * centroid[1] + centroid[2] * centroid[2]) / MAX_SRGB_OKLAB_CHROMA
    score = (1.0 - chroma_w) * weighted_counts[idx] + chroma_w * chroma
    [score, centroid]
  end

  scored.sort_by! { |s, _| -s }
  scored.map { |_, centroid| Oklab.oklab_to_srgb8(centroid[0], centroid[1], centroid[2]) }
end