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 * Image processing operations for SciJava Ops.
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package org.scijava.ops.image.threshold.localBernsen;

import java.util.function.Function;

import org.scijava.ops.image.threshold.localMidGrey.ComputeLocalMidGreyThreshold;
import net.imglib2.type.logic.BitType;
import net.imglib2.type.numeric.RealType;
import net.imglib2.util.Pair;

import org.scijava.function.Computers;
import org.scijava.ops.spi.OpDependency;

/**
 * Local threshold method which is similar to
 * {@link ComputeLocalMidGreyThreshold}, but uses a constant value rather than
 * the value of the input pixel when the contrast in the neighborhood of that
 * pixel is too small.
 *
 * @author Jonathan Hale
 * @author Stefan Helfrich (University of Konstanz)
 * @param <T> input type
 * @implNote op names='threshold.localBernsen'
 */
public class ComputeLocalBernsenThreshold<T extends RealType<T>> implements
	Computers.Arity4<Iterable<T>, T, Double, Double, BitType>
{

	@OpDependency(name = "stats.minMax")
	private Function<Iterable<T>, Pair<T, T>> minMaxOp;

	/**
	 * TODO
	 *
	 * @param inputNeighborhood
	 * @param inputCenterPixel
	 * @param contrastThreshold
	 * @param halfMaxValue
	 * @param output
	 */
	@Override
	public void compute(final Iterable<T> inputNeighborhood,
		final T inputCenterPixel, final Double contrastThreshold,
		final Double halfMaxValue, final BitType output)
	{
		compute(inputNeighborhood, inputCenterPixel, contrastThreshold,
			halfMaxValue, minMaxOp, output);
	}

	public static <T extends RealType<T>> void compute(
		final Iterable<T> inputNeighborhood, final T inputCenterPixel,
		final Double contrastThreshold, final Double halfMaxValue,
		final Function<Iterable<T>, Pair<T, T>> minMaxOp, final BitType output)
	{
		final var outputs = minMaxOp.apply(inputNeighborhood);
		final var minValue = outputs.getA().getRealDouble();
		final var maxValue = outputs.getB().getRealDouble();
		final var midGrey = (maxValue + minValue) / 2.0;

		if ((maxValue - minValue) < contrastThreshold) {
			output.set(midGrey >= halfMaxValue);
		}
		else {
			output.set(inputCenterPixel.getRealDouble() >= midGrey);
		}
	}

}
