Generate an image from a function in ImageJ

Generative_Image.groovy

#@ Long(value = 3000) size

import java.util.function.BiConsumer
import net.imglib2.img.display.imagej.ImageJFunctions
import net.imglib2.position.FunctionRandomAccessible
import net.imglib2.type.numeric.integer.UnsignedByteType
import net.imglib2.view.Views

// Define a function in 2-space.
ndim = 2
t = new UnsignedByteType()
typeSupplier = { -> t }
BiConsumer triangleFunction = { l, type ->
	x = l.getLongPosition(0)
	y = l.getLongPosition(1)
	foreground = 2 * x + y < size || 2 * (size - x) + y < size
	type.setReal(foreground ? 255 : 0)
}
ra = new FunctionRandomAccessible(ndim, triangleFunction, typeSupplier)

// Bound the function.
long[] min = [0, 0]
long[] max = [size - 1, size - 1]
rai = Views.interval(ra, min, max)

// Convert the ImgLib2 image to an ImageJ1 ImagePlus.
imp = ImageJFunctions.wrapUnsignedByte(rai, "Triangle")

Generative_Image.java

import java.util.function.BiConsumer;
import java.util.function.Supplier;

import ij.ImagePlus;

import net.imglib2.Localizable;
import net.imglib2.RandomAccessible;
import net.imglib2.RandomAccessibleInterval;
import net.imglib2.img.display.imagej.ImageJFunctions;
import net.imglib2.position.FunctionRandomAccessible;
import net.imglib2.type.numeric.integer.UnsignedByteType;
import net.imglib2.view.Views;

import org.scijava.ItemIO;
import org.scijava.command.Command;
import org.scijava.plugin.Parameter;
import org.scijava.plugin.Plugin;

@Plugin(type = Command.class)
public class Generative_Image implements Command {

	@Parameter
	private long size = 3000;

	@Parameter(type = ItemIO.OUTPUT)
	private ImagePlus imp;

	@Override
	public void run() {
		// Define a function in 2-space.
		int ndim = 2;
		UnsignedByteType t = new UnsignedByteType();
		Supplier<UnsignedByteType> typeSupplier = () -> t;
		BiConsumer<Localizable, UnsignedByteType> triangleFunction = (l, type) -> {
			long x = l.getLongPosition(0);
			long y = l.getLongPosition(1);
			boolean foreground = 2 * x + y < size || 2 * (size - x) + y < size;
			type.setReal(foreground ? 255 : 0);
		};
		FunctionRandomAccessible<UnsignedByteType> ra = new FunctionRandomAccessible<>(ndim, triangleFunction, typeSupplier);
		
		// Bound the function.
		long[] min = {0, 0};
		long[] max = {size - 1, size - 1};
		RandomAccessibleInterval<UnsignedByteType> rai = Views.interval(ra, min, max);
		
		// Convert the ImgLib2 image to an ImageJ1 ImagePlus.
		imp = ImageJFunctions.wrapUnsignedByte(rai, "Triangle");
	}
}

The Groovy script becomes very slow for large size, due to the lambda being interpreted every time. The Java command is much faster, on the order of seconds instead of minutes for a 30000 x 30000 image, thanks to Java's Just-in-Time compiler with type-safe lambda.

https://gist.github.com/ctrueden/fcdf93f0aef4db290f982d8df2e90b39#file-generative_image-java-L23 shows 3000 and not 30000. Typo?

Sorry for the confusion. I used 3000 to test it initially, then changed it to 30000 when I was confident it worked correctly. I think 3000 is a good default because it completes relatively quickly. But what I wrote above is correct: for a size of 30000, the Groovy script is much slower than the Java version.