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

import java.util.function.Function;

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 determines whether a pixel is closer to the
 * maximum or minimum pixel of a neighborhood.
 *
 * @author Jonathan Hale
 * @author Stefan Helfrich (University of Konstanz)
 * @implNote op names='threshold.localContrast'
 */
public class ComputeLocalContrastThreshold<T extends RealType<T>> implements
	Computers.Arity2<Iterable<T>, T, BitType>
{

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

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

	public static <T extends RealType<T>> void compute(
		final Iterable<T> inputNeighborhood, final T inputCenterPixel,
		final Function<Iterable<T>, Pair<T, T>> minMaxOp, final BitType output)
	{
		final var outputs = minMaxOp.apply(inputNeighborhood);

		final var centerValue = inputCenterPixel.getRealDouble();
		final var diffMin = centerValue - outputs.getA().getRealDouble();
		final var diffMax = outputs.getB().getRealDouble() - centerValue;

		// set to background (false) if pixel closer to min value,
		// and to foreground (true) if pixel closer to max value.
		// If diffMin and diffMax are equal, output will be set to fg.
		output.set(diffMin <= diffMax);
	}

}
