Java tutorial
/* * @author Jon Deering Copyright 2011 Saint Louis University. Licensed under the Educational Community License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.osedu.org/licenses/ECL-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ package imageLines; import com.sun.media.jai.codec.ImageCodec; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Transparency; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.awt.image.renderable.ParameterBlock; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.logging.Level; import java.util.logging.Logger; import javax.imageio.ImageIO; import javax.media.jai.Histogram; import javax.media.jai.JAI; import javax.media.jai.PlanarImage; import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.auth.AuthScope; import org.apache.http.auth.UsernamePasswordCredentials; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.ResponseHandler; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpHead; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.DefaultHttpClient; /**Provides a bunch of helper functions for dealing with bufferedimages*/ public class ImageHelpers { /**Scale an image to the specified width and height*/ public static BufferedImage scale(BufferedImage img, int height, int width) { BufferedImage bdest = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g = bdest.createGraphics(); AffineTransform at = AffineTransform.getScaleInstance((double) width / img.getWidth(), (double) height / img.getHeight()); g.drawRenderedImage(img, at); return bdest; } public static BufferedImage getScaledInstance(BufferedImage img, int targetWidth, int targetHeight, Object hint, boolean higherQuality) { int type = (img.getTransparency() == Transparency.OPAQUE) ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB; BufferedImage ret = (BufferedImage) img; int w, h; if (higherQuality) { // Use multi-step technique: start with original size, then // scale down in multiple passes with drawImage() // until the target size is reached w = img.getWidth(); h = img.getHeight(); } else { // Use one-step technique: scale directly from original // size to target size with a single drawImage() call w = targetWidth; h = targetHeight; } do { if (higherQuality && w > targetWidth) { w /= 2; if (w < targetWidth) { w = targetWidth; } } if (higherQuality && h > targetHeight) { h /= 2; if (h < targetHeight) { h = targetHeight; } } BufferedImage tmp = new BufferedImage(w, h, type); Graphics2D g2 = tmp.createGraphics(); g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint); g2.drawImage(ret, 0, 0, w, h, null); g2.dispose(); ret = tmp; } while (w != targetWidth || h != targetHeight); return ret; } /**Perform a binary thresholding on the image using 1 of 5 methods 0-IterativeThreshold 1-MaxEntropyThreshold 2-Maximum Variance 3-Minimum Error 4-Minimum Fuzziness */ public static BufferedImage binaryThreshold(BufferedImage img, int method) { PlanarImage j = PlanarImage.wrapRenderedImage(img); //JAI.create("fileload", imageFile.getPath()); //double[][] matrix = {{ 0.114, 0.587, 0.299, 0 }}; double[][] matrix = { { 0.114, 0.587, 0.299, 0 } }; ParameterBlock pb = new ParameterBlock(); pb.addSource(j); pb.add(matrix); try { j = JAI.create("bandcombine", pb); } catch (IllegalArgumentException e) { } pb = new ParameterBlock(); pb.addSource(j); pb.add(null); // The ROI pb.add(1); pb.add(1); pb.add(new int[] { 256 }); pb.add(new double[] { 0 }); pb.add(new double[] { 256 }); // Calculate the histogram of the image. PlanarImage dummyImage = JAI.create("histogram", pb); Histogram h = (Histogram) dummyImage.getProperty("histogram"); // Calculate the thresholds based on the selected method. double[] thresholds = null; switch (method) { case 0: // Iterative Bisection thresholds = h.getIterativeThreshold(); break; case 1: // Maximum Entropy thresholds = h.getMaxEntropyThreshold(); break; case 2: // Maximum Variance thresholds = h.getMaxVarianceThreshold(); break; case 3: // Minimum Error thresholds = h.getMinErrorThreshold(); break; case 4: // Minimum Fuzziness thresholds = h.getMinFuzzinessThreshold(); break; } int threshold = (int) thresholds[0]; BufferedImage bin = (binarize(threshold, j)); return bin; } /**Binarize a planar image. Only used internally.*/ private static BufferedImage binarize(int threshold, PlanarImage image) { // Binarizes the original image. if (threshold > 5) threshold -= 3; ParameterBlock pb = new ParameterBlock(); pb.addSource(image); pb.add(1.0 * threshold); // Creates a new, thresholded image and uses it on the DisplayJAI component PlanarImage thresholdedImage = JAI.create("binarize", pb); return thresholdedImage.getAsBufferedImage(); } /**Read an image from a file into a BufferedImage*/ public static BufferedImage readAsBufferedImage(String filename) { FileInputStream fis = null; try { fis = new FileInputStream(filename); BufferedImage bi = ImageIO.read(fis); return bi; } catch (Exception e) { System.out.println(e); return null; } finally { try { if (fis != null) fis.close(); } catch (IOException ex) { } } } public static BufferedImage readAsBufferedImage(FileInputStream i) { try { //FileInputStream fis = new FileInputStream(filename); BufferedImage bi = ImageIO.read(i); return bi; } catch (Exception e) { System.out.println(e); return null; } } /**Read a jpeg image from a url into a BufferedImage*/ public static BufferedImage readAsBufferedImage(URL imageURL) { InputStream i = null; try { URLConnection u = imageURL.openConnection(); u.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.151 Safari/535.19"); if (u instanceof HttpURLConnection) { HttpURLConnection h = (HttpURLConnection) u; if (h.getResponseCode() == 403) throw new Exception("403 forbidden"); } i = u.getInputStream(); BufferedImage bi = ImageIO.read(i); return bi; } catch (Exception e) { System.out.println(e + " for " + imageURL.toString() + "\n"); return null; } finally { try { i.close(); } catch (IOException ex) { } } } /**Read a jpeg image from a url into a BufferedImage*/ public static BufferedImage readAsBufferedImage(URL imageURL, String cookieVal) { InputStream i = null; try { HttpURLConnection conn = (HttpURLConnection) imageURL.openConnection(); conn.setRequestProperty("Cookie", cookieVal); int responseCode = conn.getResponseCode(); if (responseCode == 200 || responseCode == 304) { System.out.print("good response" + responseCode + "\n"); } else { System.out.print("bad response " + responseCode + "\n"); } i = conn.getInputStream(); //JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(i); BufferedImage bi = ImageIO.read(i);//decoder.decodeAsBufferedImage(); return bi; } catch (Exception e) { System.out.println(e); return null; } finally { try { if (i != null) i.close(); } catch (IOException ex) { } } } public static Boolean checkImageHeader(String imageURLString, String uname, String pass) throws ClientProtocolException { /* URLConnection conn=imageURL.openConnection(); String userPassword=user+":"+ pass; String encoding = new sun.misc.BASE64Encoder().encode (userPassword.getBytes()); conn.setRequestProperty ("Authorization", "Basic " + encoding);*/ DefaultHttpClient httpclient = new DefaultHttpClient(); ResponseHandler<String> responseHandler = new BasicResponseHandler(); httpclient.getCredentialsProvider().setCredentials(new AuthScope(AuthScope.ANY), new UsernamePasswordCredentials(uname, pass)); HttpHead head = new HttpHead(imageURLString); //HttpGet httpget = new HttpGet(imageURLString); System.out.println("executing head request" + head.getRequestLine()); HttpResponse response; try { response = httpclient.execute(head); int code = response.getStatusLine().getStatusCode(); if (code == 200 || code == 304) return true; } catch (IOException ex) { Logger.getLogger(ImageHelpers.class.getName()).log(Level.SEVERE, null, ex); } return false; } /**Read a jpeg image from a url into a BufferedImage*/ public static BufferedImage readAsBufferedImage(String imageURLString, String user, String pass) { InputStream i = null; try { /* URLConnection conn=imageURL.openConnection(); String userPassword=user+":"+ pass; String encoding = new sun.misc.BASE64Encoder().encode (userPassword.getBytes()); conn.setRequestProperty ("Authorization", "Basic " + encoding);*/ DefaultHttpClient httpclient = new DefaultHttpClient(); ResponseHandler<String> responseHandler = new BasicResponseHandler(); httpclient.getCredentialsProvider().setCredentials(new AuthScope(AuthScope.ANY), new UsernamePasswordCredentials(user, pass)); HttpGet httpget = new HttpGet(imageURLString); System.out.println("executing request" + httpget.getRequestLine()); HttpResponse response = httpclient.execute(httpget); HttpEntity en = response.getEntity(); Header[] h = response.getAllHeaders(); for (int c = 0; c < h.length; c++) System.out.print(h[c].getName() + ":" + h[c].getValue() + "\n"); i = response.getEntity().getContent(); //JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(i); BufferedImage bi = ImageIO.read(i);//decoder.decodeAsBufferedImage(); return bi; } catch (Exception e) { System.out.println(e); return null; } finally { try { if (i != null) i.close(); } catch (IOException ex) { } } } public static void main(String[] args) { ImageHelpers.readAsBufferedImage("http://stacks.stanford.edu/image/app/kn454rb6080/asn0048-M", "dms-access", "5cripts4u"); } //Save a bufferedimage as a jpg public static void writeImage(BufferedImage img, String filename) { try { ImageIO.write(img, "jpg", new File(filename)); } catch (IOException e) { System.out.println(e); } } /**reflect the image over the horizontal axis. This is useful when the border around the image is on the right side and very dark, as this can cause issues when detecting lines.*/ public static BufferedImage flipHorizontal(BufferedImage image) { PlanarImage j = PlanarImage.wrapRenderedImage(image); j = (PlanarImage) JAI.create("transpose", j, javax.media.jai.operator.TransposeDescriptor.FLIP_HORIZONTAL); return j.getAsBufferedImage(); } public static String getCookie(String urlString) throws MalformedURLException, IOException { URL url = new URL(urlString); URLConnection conn = url.openConnection(); conn.connect(); Map<String, List<String>> headers = conn.getHeaderFields(); List<String> values = headers.get("Set-Cookie"); String cookieValue = null; for (Iterator iter = values.iterator(); iter.hasNext();) { String v = iter.next().toString(); return v; } return ""; } }