Module: JXL::Filter::EPF

Defined in:
lib/jxl/filter/epf.rb

Constant Summary collapse

INV_SIGMA_NUM = 
-1.17157287525381
MIN_SIGMA = 
-3.9052429175127
PLUS = 
[[0, 0], [-1, 0], [0, -1], [1, 0], [0, 1]].freeze
CROSS = 
[[-1, 0], [0, -1], [0, 1], [1, 0]].freeze
WIDE = 
[[-2, 0], [-1, -1], [-1, 0], [-1, 1], [0, -2], [0, -1],
[0, 1], [0, 2], [1, -1], [1, 0], [1, 1], [2, 0]].freeze

Class Method Summary collapse

Class Method Details

.apply(channels, loop_filter, global, lf_group) ⇒ Object 



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# File 'lib/jxl/filter/epf.rb', line 15

def apply(channels, loop_filter, global, lf_group)
  return channels if loop_filter.epf_iterations.zero?

  sigma = sigma_map(loop_filter, global, lf_group)
  apply_filter(channels, sigma, loop_filter)
end

.apply_modular(channels, loop_filter) ⇒ Object 



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# File 'lib/jxl/filter/epf.rb', line 22

def apply_modular(channels, loop_filter)
  return channels if loop_filter.epf_iterations.zero?

  sigma = Plane.new(Num.ceil_div(channels.first.width, 8), Num.ceil_div(channels.first.height, 8),
                    INV_SIGMA_NUM / loop_filter.epf_sigma_for_modular)
  apply_filter(channels, sigma, loop_filter)
end

.sigma_map(loop_filter, global, lf_group) ⇒ Object 



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# File 'lib/jxl/filter/epf.rb', line 42

def sigma_map(loop_filter, global, lf_group)
  width = lf_group.quant_field.width
  height = lf_group.quant_field.height
  output = Plane.new(width, height)
  height.times do |y|
    width.times do |x|
      index = (y * width) + x
      next unless lf_group.strategy_first[index]

      strategy = lf_group.strategies[index]
      quant = lf_group.quant_field[x, y]
      base = loop_filter.epf_quant_mul / (global.quantizer.scale * quant * INV_SIGMA_NUM)
      strategy.blocks_y.times do |dy|
        strategy.blocks_x.times do |dx|
          sharpness = lf_group.sharpness[x + dx, y + dy]
          value = [base * loop_filter.epf_sharpness[sharpness], -1e-4].min
          output[x + dx, y + dy] = 1.0 / value
        end
      end
    end
  end
  output
end