How to binarize an image

How to binarize an image

         The simple binarization method with a fixed threshold BinarizeFixed is using only one parameter - a threshold with value from 0 to 255. All pixels in this case that have an intensity greater than the defined threshold will be set as a black color, or if less than the threshold, then to a white color. You can use a more precise binarize method `Bradly` BinarizeBradley to improve binarization quality. Method `Bradly` use the threshold as an average estimation intensity of the surrounding area with size `s x s`. In this case, the resulting picture will have smooth edges. Also, you can use `Otsu` method BinarizeOtsu with automatic threshold:

import com.aspose.imaging.IMultipageImage;
import com.aspose.imaging.Image;
import com.aspose.imaging.RasterImage;
import com.aspose.imaging.imageoptions.PngOptions;
import java.io.File;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.function.Consumer;


binarizeFixed();


public static void binarizeOtsu()
{
	// https://apireference.aspose.com/imaging/java/com.aspose.imaging/RasterImage#binarizeOtsu--
	filterImages(RasterImage::binarizeOtsu, "binarizeotsu");
}


public static void binarizeBradley()
{
	filterImages(image ->
			{
					// https://apireference.aspose.com/imaging/java/com.aspose.imaging/RasterImage#binarizeBradley-double-
					image.binarizeBradley(0.5);
			}, "binarizebradley");
}


public static void binarizeFixed()
{
	filterImages(image ->
			{
					// https://apireference.aspose.com/imaging/java/com.aspose.imaging/RasterImage#binarizeFixed-byte-
					image.binarizeFixed((byte)70);
			}, "binarizefixed");
}

static String templatesFolder = "D:\\";

public static void filterImages(Consumer<RasterImage> doFilter, String filterName)
{
	List<String> rasterFormats = Arrays.asList("jpg", "png", "bmp", "apng", "dicom",
			"jp2", "j2k", "tga", "webp", "tif", "gif", "ico");
	List<String> vectorFormats = Arrays.asList("svg", "otg", "odg", "eps", "wmf", "emf", "wmz", "emz", "cmx", "cdr");

	List<String> allFormats = new LinkedList<>(rasterFormats);
	allFormats.addAll(vectorFormats);

	allFormats.forEach(
			formatExt ->
			{
				String inputFile = templatesFolder + "template." + formatExt;
				boolean isVectorFormat = vectorFormats.contains(formatExt);

				//Need to rasterize vector formats before background remove
				if (isVectorFormat)
				{
					inputFile = rasterizeVectorImage(formatExt, inputFile);
				}

				String outputFile = templatesFolder + String.format("%s_%s.png", filterName, formatExt);

				System.out.println("Processing " + formatExt);

				try (RasterImage image = (RasterImage) Image.load(inputFile))
				{
					doFilter.accept(image);

					//If image is multipage save each page to png to demonstrate results
					if (image instanceof IMultipageImage && ((IMultipageImage) image).getPageCount() > 1)
					{
						IMultipageImage multiPage = (IMultipageImage) image;
						final int pageCount = multiPage.getPageCount();
						final Image[] pages = multiPage.getPages();
						for (int pageIndex = 0; pageIndex < pageCount; pageIndex++)
						{
							String fileName = String.format("%s_page%d_%s.png", filterName, pageIndex, formatExt);
							pages[pageIndex].save(fileName, new PngOptions());
						}
					}
					else
					{
						image.save(outputFile, new PngOptions());
					}
				}

				//Remove rasterized vector image
				if (isVectorFormat)
				{
					new File(inputFile).delete();
				}
			}
	);
}

private static String rasterizeVectorImage(String formatExt, String inputFile)
{
	String outputFile = templatesFolder + "rasterized."+ formatExt + ".png";
	try (Image image = Image.load(inputFile))
	{
		image.save(outputFile, new PngOptions());
	}

	return outputFile;
}