ImgurScreensaver/src/JpegReader.java

import java.awt.color.ColorSpace;
import java.awt.color.ICC_ColorSpace;
import java.awt.color.ICC_Profile;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Iterator;

import javax.imageio.IIOException;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

import org.apache.sanselan.ImageReadException;
import org.apache.sanselan.Sanselan;
import org.apache.sanselan.common.byteSources.ByteSource;
import org.apache.sanselan.common.byteSources.ByteSourceFile;
import org.apache.sanselan.formats.jpeg.JpegImageParser;
import org.apache.sanselan.formats.jpeg.segments.UnknownSegment;

public class JpegReader {

	public static final int COLOR_TYPE_RGB = 1;
	public static final int COLOR_TYPE_CMYK = 2;
	public static final int COLOR_TYPE_YCCK = 3;

	private int colorType = COLOR_TYPE_RGB;
	private boolean hasAdobeMarker = false;
	
	public BufferedImage readImage(File file) throws IOException,
			ImageReadException {
		colorType = COLOR_TYPE_RGB;
		hasAdobeMarker = false;

		ImageInputStream stream = ImageIO.createImageInputStream(file);
		Iterator<ImageReader> iter = ImageIO.getImageReaders(stream);
		while (iter.hasNext()) {
			ImageReader reader = iter.next();
			reader.setInput(stream);

			BufferedImage image;
			ICC_Profile profile = null;
			try {
				image = reader.read(0);
			} catch (IIOException e) {
				colorType = COLOR_TYPE_CMYK;
				checkAdobeMarker(file);
				profile = Sanselan.getICCProfile(file);
				WritableRaster raster = (WritableRaster) reader.readRaster(0,
						null);
				if (colorType == COLOR_TYPE_YCCK)
					convertYcckToCmyk(raster);
				if (hasAdobeMarker)
					convertInvertedColors(raster);
				image = convertCmykToRgb(raster, profile);
			}

			return image;
		}

		return null;
	}

	public void checkAdobeMarker(File file) throws IOException,
			ImageReadException {
		JpegImageParser parser = new JpegImageParser();
		ByteSource byteSource = new ByteSourceFile(file);
		@SuppressWarnings("rawtypes")
		ArrayList segments = parser.readSegments(byteSource,
				new int[] { 0xffee }, true);
		if (segments != null && segments.size() >= 1) {
			UnknownSegment app14Segment = (UnknownSegment) segments.get(0);
			byte[] data = app14Segment.bytes;
			if (data.length >= 12 && data[0] == 'A' && data[1] == 'd'
					&& data[2] == 'o' && data[3] == 'b' && data[4] == 'e') {
				hasAdobeMarker = true;
				int transform = app14Segment.bytes[11] & 0xff;
				if (transform == 2)
					colorType = COLOR_TYPE_YCCK;
			}
		}
	}

	public static void convertYcckToCmyk(WritableRaster raster) {
		int height = raster.getHeight();
		int width = raster.getWidth();
		int stride = width * 4;
		int[] pixelRow = new int[stride];
		for (int h = 0; h < height; h++) {
			raster.getPixels(0, h, width, 1, pixelRow);

			for (int x = 0; x < stride; x += 4) {
				int y = pixelRow[x];
				int cb = pixelRow[x + 1];
				int cr = pixelRow[x + 2];

				int c = (int) (y + 1.402 * cr - 178.956);
				int m = (int) (y - 0.34414 * cb - 0.71414 * cr + 135.95984);
				y = (int) (y + 1.772 * cb - 226.316);

				if (c < 0)
					c = 0;
				else if (c > 255)
					c = 255;
				if (m < 0)
					m = 0;
				else if (m > 255)
					m = 255;
				if (y < 0)
					y = 0;
				else if (y > 255)
					y = 255;

				pixelRow[x] = 255 - c;
				pixelRow[x + 1] = 255 - m;
				pixelRow[x + 2] = 255 - y;
			}

			raster.setPixels(0, h, width, 1, pixelRow);
		}
	}

	public static void convertInvertedColors(WritableRaster raster) {
		int height = raster.getHeight();
		int width = raster.getWidth();
		int stride = width * 4;
		int[] pixelRow = new int[stride];
		for (int h = 0; h < height; h++) {
			raster.getPixels(0, h, width, 1, pixelRow);
			for (int x = 0; x < stride; x++)
				pixelRow[x] = 255 - pixelRow[x];
			raster.setPixels(0, h, width, 1, pixelRow);
		}
	}

	public static BufferedImage convertCmykToRgb(Raster cmykRaster,
			ICC_Profile cmykProfile) throws IOException {
		if (cmykProfile == null)
			cmykProfile = ICC_Profile.getInstance(JpegReader.class
					.getResourceAsStream("/ISOcoated_v2_300_eci.icc"));

		if (cmykProfile.getProfileClass() != ICC_Profile.CLASS_DISPLAY) {
			byte[] profileData = cmykProfile.getData();

			if (profileData[ICC_Profile.icHdrRenderingIntent] == ICC_Profile.icPerceptual) {
				intToBigEndian(ICC_Profile.icSigDisplayClass, profileData,
						ICC_Profile.icHdrDeviceClass); // Header is first

				cmykProfile = ICC_Profile.getInstance(profileData);
			}
		}

		ICC_ColorSpace cmykCS = new ICC_ColorSpace(cmykProfile);
		BufferedImage rgbImage = new BufferedImage(cmykRaster.getWidth(),
				cmykRaster.getHeight(), BufferedImage.TYPE_INT_RGB);
		WritableRaster rgbRaster = rgbImage.getRaster();
		ColorSpace rgbCS = rgbImage.getColorModel().getColorSpace();
		ColorConvertOp cmykToRgb = new ColorConvertOp(cmykCS, rgbCS, null);
		cmykToRgb.filter(cmykRaster, rgbRaster);
		return rgbImage;
	}

	static void intToBigEndian(int value, byte[] array, int index) {
		array[index] = (byte) (value >> 24);
		array[index + 1] = (byte) (value >> 16);
		array[index + 2] = (byte) (value >> 8);
		array[index + 3] = (byte) (value);
	}
}