add image converter for DL4JConverter extension point

org.knime.knip.dl4j/plugin.xml

@@ -19,5 +19,11 @@
             path="/labs/deeplearning/">
       </category>
    </extension>
+   <extension
+         point="org.knime.ext.dl4j.base.DL4JConverter">
+      <DL4JConverter
+            converterClass="org.knime.knip.dl4j.data.convert.ImgPlusValueToDoubleArrayConverter">
+      </DL4JConverter>
+   </extension>
 
 </plugin>

org.knime.knip.dl4j/src/org/knime/knip/dl4j/data/convert/ImgPlusValueToDoubleArrayConverter.java

@@ -0,0 +1,54 @@
+package org.knime.knip.dl4j.data.convert;
+
+import java.util.Iterator;
+
+import org.knime.ext.dl4j.base.data.convert.extension.BaseDL4JConverter;
+import org.knime.knip.base.data.img.ImgPlusValue;
+
+import net.imglib2.img.Img;
+import net.imglib2.type.numeric.RealType;
+
+/**
+ * DL4JConverter that converts a ImgPlusValue to double[].
+ * 
+ * @author David Kolb, KNIME.com GmbH
+ *
+ * @param <T>
+ */
+@SuppressWarnings("rawtypes")
+public class ImgPlusValueToDoubleArrayConverter<T extends RealType<T>>
+		extends BaseDL4JConverter<ImgPlusValue, double[]> {
+
+	/**
+	 * Constructor for class ImgPlusValueToDoubleArrayConverter.
+	 */
+	public ImgPlusValueToDoubleArrayConverter() {
+		super(ImgPlusValue.class, double[].class, BaseDL4JConverter.DEFAULT_PRIORITY);
+	}
+
+	/**
+	 * {@inheritDoc} Flattens the image and copies the pixel values to double[].
+	 */
+	@Override
+	@SuppressWarnings("unchecked")
+	public double[] convert(ImgPlusValue source) throws Exception {
+		Img<T> img = source.getImgPlus();
+		Iterator<T> imgIter = img.iterator();
+		double[] flattenedImg = new double[(int) calcNumPixels(source.getDimensions())];
+		int i = 0;
+		while (imgIter.hasNext()) {
+			flattenedImg[i] = imgIter.next().getRealDouble();
+			i++;
+		}
+		return flattenedImg;
+	}
+
+	private long calcNumPixels(long[] dims) {
+		long numPix = 1;
+		for (long dim : dims) {
+			numPix *= dim;
+		}
+		return numPix;
+	}
+
+}