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

import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;

import net.imglib2.Dimensions;
import net.imglib2.RandomAccessibleInterval;
import net.imglib2.img.Img;
import net.imglib2.loops.LoopBuilder;
import net.imglib2.type.numeric.ComplexType;
import net.imglib2.type.numeric.RealType;
import net.imglib2.util.Util;

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

/**
 * Computes Richardson Lucy correction factor for (@link
 * RandomAccessibleInterval) (Lucy, L. B. (1974). "An iterative technique for
 * the rectification of observed distributions".)
 *
 * @author Brian Northan
 * @param <I>
 * @param <O>
 * @param <C>
 * @implNote op names='deconvolve.richardsonLucyCorrection', priority='100.'
 */
public class RichardsonLucyCorrection<I extends RealType<I>, O extends RealType<O>, C extends ComplexType<C>>
	implements
	Computers.Arity4<RandomAccessibleInterval<I>, RandomAccessibleInterval<O>, RandomAccessibleInterval<C>, RandomAccessibleInterval<C>, RandomAccessibleInterval<O>>
{

	/** fft of reblurred (will be computed) **/
	private RandomAccessibleInterval<C> fftBuffer;

	/** fft of kernel (needs to be previously computed) **/
	private RandomAccessibleInterval<C> fftKernel;

	@OpDependency(name = "create.img")
	private BiFunction<Dimensions, O, Img<O>> create;

	@OpDependency(name = "copy.rai")
	private Function<RandomAccessibleInterval<O>, RandomAccessibleInterval<O>> copy;

//	@OpDependency(name = "math.divide") TODO: match an Op here?
	private BiConsumer<RandomAccessibleInterval<O>, RandomAccessibleInterval<I>> divide =
		(denomResult, numer) -> {
			LoopBuilder.setImages(denomResult, numer).multiThreaded().forEachChunk(
				chunk -> {
					final var tmp = Util.getTypeFromInterval(denomResult).createVariable();
					chunk.forEachPixel((d, n) -> {
						if (d.getRealFloat() > 0) {
							tmp.setReal(n.getRealFloat());
							tmp.div(d);
							d.set(tmp);
						}
						else d.setZero();
					});
					return null;
				});
		};

	@OpDependency(name = "filter.correlate")
	private Computers.Arity6<RandomAccessibleInterval<O>, RandomAccessibleInterval<O>, //
			RandomAccessibleInterval<C>, RandomAccessibleInterval<C>, Boolean, //
			Boolean, RandomAccessibleInterval<O>> correlateOp;

	/**
	 * computes the correction factor of the Richardson Lucy Algorithm
	 *
	 * @param observed
	 * @param reblurred
	 * @param fftBuffer
	 * @param fftKernel
	 * @param correction
	 */
	@Override
	public void compute(RandomAccessibleInterval<I> observed,
		RandomAccessibleInterval<O> reblurred,
		RandomAccessibleInterval<C> fftBuffer,
		RandomAccessibleInterval<C> fftKernel,
		RandomAccessibleInterval<O> correction)
	{
		// divide observed image by reblurred
		// reblurred = observed / reblurred
		divide.accept(reblurred, observed);

		// correlate with psf to compute the correction factor
		// Note: FFT of psf is pre-computed and set as an input parameter of the op
		correlateOp.compute(reblurred, null, fftBuffer, fftKernel, true, false,
			correction);

	}

}
