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RSpec.describe Magick::Image, '#channel_entropy' do
pixels = [[45, 9, 156], [45, 98, 156], [45, 74, 156], [45, 196, 156]]
it 'returns a channel entropy', unsupported_before('6.9.0') do
image = build_image(pixels: pixels)
result = image.channel_entropy
expect(result).to eq([0.3333333333333333])
end
it 'returns 0.0 when all pixels are the same', unsupported_before('6.9.0') do
image = build_image(pixels: pixels)
result = image.channel_entropy(Magick::RedChannel)
expect(result).to eq([0.0])
end
it 'returns 1.0 when all pixels are different', unsupported_before('6.9.0') do
image = build_image(pixels: pixels)
result = image.channel_entropy(Magick::GreenChannel)
expect(result).to eq([1.0])
end
it 'returns the entropy of multiple given channels', unsupported_before('6.9.0') do
image = build_image(pixels: pixels)
result = image.channel_entropy(Magick::GreenChannel, Magick::BlueChannel)
expect(result).to eq([0.5])
end
it 'raises an error on earlier versions', supported_before('6.9.0') do
image = build_image
expect { image.channel_entropy }.to raise_error(NotImplementedError)
end
end
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