Java: Color Image To Grayscale

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The following source code is an illustration of how to convert a color image to grayscale (black & white). This example shows usage of IO for images, file operations and RGB colors in java.

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package imageColor; import java.awt.image.BufferedImage; import java.awt.image.RenderedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; public class test { public static void main(String[] args){ BufferedImage image = null; try{ image = ImageIO.read(new File("File Location")); } catch(Exception e){ System.out.println(e); } convertToGrayscale(image); RenderedImage im = image; try{ ImageIO.write(im, "jpg", new File("save location")); } catch (IOException e){ System.out.println(e); } } private static void convertToGrayscale(final BufferedImage image){ for(int i=0; i<image.getWidth(); i++){ for(int j=0; j<image.getHeight(); j++){ int color = image.getRGB(i,j); int alpha = (color >> 24) & 255; int red = (color >> 16) & 255; int green = (color >> 8) & 255; int blue = (color) & 255; final int lum = (int)(0.2126 * red + 0.7152 * green + 0.0722 * blue); alpha = (alpha << 24); red = (lum << 16); green = (lum << 8); blue = lum; color = alpha + red + green + blue; image.setRGB(i,j,color); } } } }