How to grayscale an image

How to grayscale an image

         If you need to transform your color photo to its grayscale representation you can apply Grayscale method of the RasterImage class to them. Vector images can be converted to grayscale as well by rasterizing them to `png` format:

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;
grayscale();
public static void grayscale()
{
filterImages(RasterImage::grayscale, "grayscale");
}
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;
}