- Addition of new class to select the channel for the surface extraction

src/main/java/fr/pasteur/ida/zellige/steps/ChannelImageSelection.java

+package fr.pasteur.ida.zellige.steps;
+
+import net.imagej.Dataset;
+import net.imagej.ImgPlus;
+import net.imglib2.RandomAccess;
+import net.imglib2.img.Img;
+import net.imglib2.type.NativeType;
+import net.imglib2.type.numeric.RealType;
+
+public class ChannelImageSelection< T extends RealType< T > & NativeType< T > >
+{
+
+    private final int targetChannel;
+    private final Dataset dataset;
+
+    public static< T extends RealType< T > & NativeType< T > > Img< T > run(Dataset input, int targetChannel)
+    {
+        ChannelImageSelection<T> channelImageSelection = new ChannelImageSelection<>( input, targetChannel );
+        return channelImageSelection.run();
+    }
+
+    public ChannelImageSelection( Dataset dataset, int targetChannel )
+    {
+        this.targetChannel = targetChannel;
+        this.dataset = dataset;
+    }
+
+    public Img< T > run()
+    {
+        Img< T > input = ( ImgPlus< T > ) this.dataset.getImgPlus();
+        if (getTargetChannel() == 0)
+        {
+            return  input;
+        }
+        else
+        {
+            Img< T > output = input.factory().create( input.dimension( 0 ), input.dimension( 1 ), input.dimension( 3 ) );
+            RandomAccess< T > randomAccess = input.randomAccess();
+            RandomAccess< T > randomAccess1 = output.randomAccess();
+            for ( int x = 0; x < ( int ) input.dimension( 0 ); x++ )
+            {
+                for ( int y = 0; y < ( int ) input.dimension( 1 ); y++ )
+                {
+                    for ( int z = 0; z < ( int ) input.dimension( 3 ); z++ )
+                    {
+                        randomAccess.setPositionAndGet( x, y, getTargetChannel()-1, z );
+                        randomAccess1.setPosition( new int[]{ x, y, z } );
+                        randomAccess1.get().set( randomAccess.get() );
+                    }
+                }
+            }
+            return output;
+        }
+    }
+    public int getTargetChannel()
+    {
+        return targetChannel;
+    }
+}