/*
    * ImageInfo.java
    *
    * Version 1.9
    *
    * A Java class to determine image width, height and color depth for
    * a number of image file formats.
    *
    * Written by Marco Schmidt 
   *
   * Contributed to the Public Domain.
   */
  package org.devlib.schmidt.imageinfo;
  
  import java.io.DataInput;
  import java.io.FileInputStream;
  import java.io.InputStream;
  import java.io.IOException;
  import java.net.URL;
  import java.util.Vector;
  
  /**
   * Get file format, image resolution, number of bits per pixel and optionally 
   * number of images, comments and physical resolution from 
   * JPEG, GIF, BMP, PCX, PNG, IFF, RAS, PBM, PGM, PPM and PSD files 
   * (or input streams).
   * <p>
   * Use the class like this:
   * <pre>
   * ImageInfo ii = new ImageInfo();
   * ii.setInput(in); // in can be InputStream or RandomAccessFile
   * ii.setDetermineImageNumber(true); // default is false
   * ii.setCollectComments(true); // default is false
   * if (!ii.check()) {
   *   System.err.println("Not a supported image file format.");
   *   return;
   * }
   * System.out.println(ii.getFormatName() + ", " + ii.getMimeType() + 
   *   ", " + ii.getWidth() + " x " + ii.getHeight() + " pixels, " + 
   *   ii.getBitsPerPixel() + " bits per pixel, " + ii.getNumberOfImages() +
   *   " image(s), " + ii.getNumberOfComments() + " comment(s).");
   *  // there are other properties, check out the API documentation
   * </pre>
   * You can also use this class as a command line program.
   * Call it with a number of image file names and URLs as parameters:
   * <pre>
   *   java ImageInfo *.jpg *.png *.gif http://somesite.tld/image.jpg
   * </pre>
   * or call it without parameters and pipe data to it:
   * <pre>
   *   java ImageInfo &lt; image.jpg  
   * </pre>
   * <p>
   * Known limitations:
   * <ul>
   * <li>When the determination of the number of images is turned off, GIF bits 
   *  per pixel are only read from the global header.
   *  For some GIFs, local palettes change this to a typically larger
   *  value. To be certain to get the correct color depth, call
   *  setDetermineImageNumber(true) before calling check().
   *  The complete scan over the GIF file will take additional time.</li>
   * <li>Transparency information is not included in the bits per pixel count.
   *  Actually, it was my decision not to include those bits, so it's a feature! ;-)</li>
   * </ul>
   * <p>
   * Requirements:
   * <ul>
   * <li>Java 1.1 or higher</li>
   * </ul>
   * <p>
   * The latest version can be found at <a href="http://schmidt.devlib.org/image-info/">http://schmidt.devlib.org/image-info/</a>.
   * <p>
   * Written by Marco Schmidt.
   * <p>
   * This class is contributed to the Public Domain.
   * Use it at your own risk.
   * <p>
   * <a name="history">History</a>:
   * <ul>
   * <li><strong>2001-08-24</strong> Initial version.</li>
   * <li><strong>2001-10-13</strong> Added support for the file formats BMP and PCX.</li>
   * <li><strong>2001-10-16</strong> Fixed bug in read(int[], int, int) that returned
   * <li><strong>2002-01-22</strong> Added support for file formats Amiga IFF and Sun Raster (RAS).</li>
   * <li><strong>2002-01-24</strong> Added support for file formats Portable Bitmap / Graymap / Pixmap (PBM, PGM, PPM) and Adobe Photoshop (PSD).
   *   Added new method getMimeType() to return the MIME type associated with a particular file format.</li>
   * <li><strong>2002-03-15</strong> Added support to recognize number of images in file. Only works with GIF.
   *   Use {@link #setDetermineImageNumber} with <code>true</code> as argument to identify animated GIFs
   *   ({@link #getNumberOfImages()} will return a value larger than <code>1</code>).</li>
   * <li><strong>2002-04-10</strong> Fixed a bug in the feature 'determine number of images in animated GIF' introduced with version 1.1.
   *   Thanks to Marcelo P. Lima for sending in the bug report. 
   *   Released as 1.1.1.</li>
   * <li><strong>2002-04-18</strong> Added {@link #setCollectComments(boolean)}. 
   *  That new method lets the user specify whether textual comments are to be  
   *  stored in an internal list when encountered in an input image file / stream.
   *  Added two methods to return the physical width and height of the image in dpi: 
   *   {@link #getPhysicalWidthDpi()} and {@link #getPhysicalHeightDpi()}.
   *  If the physical resolution could not be retrieved, these methods return <code>-1</code>.
   *  </li>
   * <li><strong>2002-04-23</strong> Added support for the new properties physical resolution and
  *   comments for some formats. Released as 1.2.</li>
  * <li><strong>2002-06-17</strong> Added support for SWF, sent in by Michael Aird.
  *  Changed checkJpeg() so that other APP markers than APP0 will not lead to a failure anymore.
  *  Released as 1.3.</li>
  * <li><strong>2003-07-28</strong> Bug fix - skip method now takes return values into consideration.
  *  Less bytes than necessary may have been skipped, leading to flaws in the retrieved information in some cases.
  *  Thanks to Bernard Bernstein for pointing that out.
  *  Released as 1.4.</li>
  * <li><strong>2004-02-29</strong> Added support for recognizing progressive JPEG and
  *  interlaced PNG and GIF. A new method {@link #isProgressive()} returns whether ImageInfo
  *  has found that the storage type is progressive (or interlaced). 
  *  Thanks to Joe Germuska for suggesting the feature.
  *  Bug fix: BMP physical resolution is now correctly determined.
  *  Released as 1.5.</li>
  * <li><strong>2004-11-30</strong> Bug fix: recognizing progressive GIFs 
  * (interlaced in GIF terminology) did not work (thanks to Franz Jeitler for 
  *   pointing this out). Now it should work, but only if the number of images is determined.
  *  This is because information on interlacing is stored in a local image header.
  *  In theory, different images could be stored interlaced and non-interlaced in one 
  *  file. However, I think  that's unlikely. Right now, the last image in the GIF file 
  *  that is examined by ImageInfo is used for the "progressive" status.</li>
  * <li><strong>2005-01-02</strong> Some code clean up (unused methods and variables
  *  commented out, missing javadoc comments, etc.). Thanks to George Sexton for a long list.
  *  Removed usage of Boolean.toString because
  *  it's a Java 1.4+ feature (thanks to Gregor Dupont).
  *  Changed delimiter character in compact output from semicolon to tabulator
  * (for better integration with cut(1) and other Unix tools).
  *  Added some points to the <a href="http://schmidt.devlib.org/image-info/index.html#knownissues">'Known
  *  issues' section of the website</a>. 
  *  Released as 1.6.</li>
  * <li><strong>2005-07-26</strong> Removed code to identify Flash (SWF) files.
  *  Has repeatedly led to problems and support requests, and I don't know the
  *  format and don't have the time and interest to fix it myself.
  *  I repeatedly included fixes by others which didn't work for some people.
  *  I give up on SWF. Please do not contact me about it anymore.
  *  Set package of ImageInfo class to org.devlib.schmidt.imageinfo (a package
  *  was repeatedly requested by some users).
  *  Released as 1.7.</li>
  *  <li><strong>2006-02-23</strong> Removed Flash helper methods which weren't used elsewhere.
  *   Updated skip method which tries "read" whenever "skip(Bytes)" returns a result of 0.
  *   The old method didn't work with certain input stream types on truncated data streams.
  *   Thanks to Martin Leidig for reporting this and sending in code.
  *   Released as 1.8.</li>
  *  </li>
  *  <li><strong>2006-11-13</strong> Removed check that made ImageInfo report JPEG APPx
  *   markers smaller than 14 bytes as files in unknown format. Such JPEGs seem to be
  *   generated by Google's Picasa application. First reported with fix by 
  *   Karl von Randow. Released as 1.9.</li>  
  * </ul>
  * @author Marco Schmidt
  */
 @SuppressWarnings("unchecked")
 public class ImageInfo {
 	/**
 	 * Return value of {@link #getFormat()} for JPEG streams.
 	 * ImageInfo can extract physical resolution and comments
 	 * from JPEGs (only from APP0 headers).
 	 * Only one image can be stored in a file.
 	 * It is determined whether the JPEG stream is progressive 
 	 * (see {@link #isProgressive()}).
 	 */
 	public static final int FORMAT_JPEG = 0;
 
 	/**
 	 * Return value of {@link #getFormat()} for GIF streams.
 	 * ImageInfo can extract comments from GIFs and count the number
 	 * of images (GIFs with more than one image are animations).
 	 * It is determined whether the GIF stream is interlaced (see {@link #isProgressive()}).
 	 */
 	public static final int FORMAT_GIF = 1;
 
 	/**
 	 * Return value of {@link #getFormat()} for PNG streams.
 	 * PNG only supports one image per file.
 	 * Both physical resolution and comments can be stored with PNG,
 	 * but ImageInfo is currently not able to extract those.
 	 * It is determined whether the PNG stream is interlaced (see {@link #isProgressive()}).
 	 */
 	public static final int FORMAT_PNG = 2;
 
 	/**
 	 * Return value of {@link #getFormat()} for BMP streams.
 	 * BMP only supports one image per file.
 	 * BMP does not allow for comments.
 	 * The physical resolution can be stored.
 	 */
 	public static final int FORMAT_BMP = 3;
 
 	/**
 	 * Return value of {@link #getFormat()} for PCX streams.
 	 * PCX does not allow for comments or more than one image per file.
 	 * However, the physical resolution can be stored.
 	 */
 	public static final int FORMAT_PCX = 4;
 
 	/**
 	 * Return value of {@link #getFormat()} for IFF streams.
 	 */
 	public static final int FORMAT_IFF = 5;
 
 	/**
 	 * Return value of {@link #getFormat()} for RAS streams.
 	 * Sun Raster allows for one image per file only and is not able to
 	 * store physical resolution or comments.
 	 */
 	public static final int FORMAT_RAS = 6;
 
 	/** Return value of {@link #getFormat()} for PBM streams. */
 	public static final int FORMAT_PBM = 7;
 
 	/** Return value of {@link #getFormat()} for PGM streams. */
 	public static final int FORMAT_PGM = 8;
 
 	/** Return value of {@link #getFormat()} for PPM streams. */
 	public static final int FORMAT_PPM = 9;
 
 	/** Return value of {@link #getFormat()} for PSD streams. */
 	public static final int FORMAT_PSD = 10;
 
 /*	public static final int COLOR_TYPE_UNKNOWN = -1;
 	public static final int COLOR_TYPE_TRUECOLOR_RGB = 0;
 	public static final int COLOR_TYPE_PALETTED = 1;
 	public static final int COLOR_TYPE_GRAYSCALE= 2;
 	public static final int COLOR_TYPE_BLACK_AND_WHITE = 3;*/
 
 	/**
 	 * The names of all supported file formats.
 	 * The FORMAT_xyz int constants can be used as index values for
 	 * this array.
 	 */
 	private static final String[] FORMAT_NAMES =
 		{"JPEG", "GIF", "PNG", "BMP", "PCX", 
 		 "IFF", "RAS", "PBM", "PGM", "PPM", 
 		 "PSD"};
 
 	/**
 	 * The names of the MIME types for all supported file formats.
 	 * The FORMAT_xyz int constants can be used as index values for
 	 * this array.
 	 */
 	private static final String[] MIME_TYPE_STRINGS =
 		{"image/jpeg", "image/gif", "image/png", "image/bmp", "image/pcx", 
 		 "image/iff", "image/ras", "image/x-portable-bitmap", "image/x-portable-graymap", "image/x-portable-pixmap", 
 		 "image/psd"};
 
 	private int width;
 	private int height;
 	private int bitsPerPixel;
 	//private int colorType = COLOR_TYPE_UNKNOWN;
 	private boolean progressive;
 	private int format;
 	private InputStream in;
 	private DataInput din;
 	private boolean collectComments = true;
 	private Vector comments;
 	private boolean determineNumberOfImages;
 	private int numberOfImages;
 	private int physicalHeightDpi;
 	private int physicalWidthDpi;
 
 	private void addComment(String s) {
 		if (comments == null) {
 			comments = new Vector();
 		}
 		comments.addElement(s);
 	}
 
 	/**
 	 * Call this method after you have provided an input stream or file
 	 * using {@link #setInput(InputStream)} or {@link #setInput(DataInput)}.
 	 * If true is returned, the file format was known and information
 	 * on the file's content can be retrieved using the various getXyz methods.
 	 * @return if information could be retrieved from input
 	 */
 	public boolean check() {
 		format = -1;
 		width = -1;
 		height = -1;
 		bitsPerPixel = -1;
 		numberOfImages = 1;
 		physicalHeightDpi = -1;
 		physicalWidthDpi = -1;
 		comments = null;
 		try {
 			int b1 = read() & 0xff;
 			int b2 = read() & 0xff;
 			if (b1 == 0x47 && b2 == 0x49) {
 				return checkGif();
 			}
 			else
 			if (b1 == 0x89 && b2 == 0x50) {
 				return checkPng();
 			}
 			else
 			if (b1 == 0xff && b2 == 0xd8) {
 				return checkJpeg();
 			}
 			else
 			if (b1 == 0x42 && b2 == 0x4d) {
 				return checkBmp();
 			}
 			else
 			if (b1 == 0x0a && b2 < 0x06) {
 				return checkPcx();
 			}
 			else
 			if (b1 == 0x46 && b2 == 0x4f) {
 				return checkIff();
 			}
 			else
 			if (b1 == 0x59 && b2 == 0xa6) {
 				return checkRas();
 			}
 			else
 			if (b1 == 0x50 && b2 >= 0x31 && b2 <= 0x36) {
 				return checkPnm(b2 - '0');
 			}
 			else
 			if (b1 == 0x38 && b2 == 0x42) {
 				return checkPsd();
 			}
 			else {
 				return false;
 			}
 		} catch (IOException ioe) {
 			return false;
 		}
 	}
 
 	private boolean checkBmp() throws IOException {
 		byte[] a = new byte[44];
 		if (read(a) != a.length) {
 			return false;
 		}
 		width = getIntLittleEndian(a, 16);
 		height = getIntLittleEndian(a, 20);
 		if (width < 1 || height < 1) {
 			return false;
 		}
 		bitsPerPixel = getShortLittleEndian(a, 26);
 		if (bitsPerPixel != 1 && bitsPerPixel != 4 &&
 		    bitsPerPixel != 8 && bitsPerPixel != 16 &&
 		    bitsPerPixel != 24 && bitsPerPixel != 32) {
 		    return false;
 		}
 		int x = (int)(getIntLittleEndian(a, 36) * 0.0254);
 		if (x > 0) {
 			setPhysicalWidthDpi(x);
 		}
 		int y = (int)(getIntLittleEndian(a, 40) * 0.0254);
 		if (y > 0) {
 			setPhysicalHeightDpi(y);
 		}
 		format = FORMAT_BMP;
 		return true;
 	}
 
 	private boolean checkGif() throws IOException {
 		final byte[] GIF_MAGIC_87A = {0x46, 0x38, 0x37, 0x61};
 		final byte[] GIF_MAGIC_89A = {0x46, 0x38, 0x39, 0x61};
 		byte[] a = new byte[11]; // 4 from the GIF signature + 7 from the global header
 		if (read(a) != 11) {
 			return false;
 		}
 		if ((!equals(a, 0, GIF_MAGIC_89A, 0, 4)) &&
 			(!equals(a, 0, GIF_MAGIC_87A, 0, 4))) {
 			return false;
 		}
 		format = FORMAT_GIF;
 		width = getShortLittleEndian(a, 4);
 		height = getShortLittleEndian(a, 6);
 		int flags = a[8] & 0xff;
 		bitsPerPixel = ((flags >> 4) & 0x07) + 1;
 		//progressive = (flags & 0x02) != 0;
 		if (!determineNumberOfImages) {
 			return true;
 		}
 		// skip global color palette
 		if ((flags & 0x80) != 0) {
 			int tableSize = (1 << ((flags & 7) + 1)) * 3;
 			skip(tableSize);
 		}
 		numberOfImages = 0;
 		int blockType;
 		do
 		{
 			blockType = read();
 			switch(blockType)
 			{
 				case(0x2c): // image separator
 				{
 					if (read(a, 0, 9) != 9) {
 						return false;
 					}
 					flags = a[8] & 0xff;
 					progressive = (flags & 0x40) != 0;
 					/*int locWidth = getShortLittleEndian(a, 4);
 					int locHeight = getShortLittleEndian(a, 6);
 					System.out.println("LOCAL: " + locWidth + " x " + locHeight);*/
 					int localBitsPerPixel = (flags & 0x07) + 1;
 					if (localBitsPerPixel > bitsPerPixel) {
 						bitsPerPixel = localBitsPerPixel;
 					}
 					if ((flags & 0x80) != 0) {
 						skip((1 << localBitsPerPixel) * 3);
 					}
 					skip(1); // initial code length
 					int n;
 					do
 					{
 						n = read();
 						if (n > 0) {
 							skip(n);
 						}
 						else
 						if (n == -1) {
 							return false;
 						}
 					}
 					while (n > 0);
 					numberOfImages++;
 					break;
 				}
 				case(0x21): // extension
 				{
 					int extensionType = read();
 					if (collectComments && extensionType == 0xfe) {
 						StringBuffer sb = new StringBuffer();
 						int n;
 						do
 						{
 							n = read();
 							if (n == -1) {
 								return false;
 							}
 							if (n > 0) {
 								for (int i = 0; i < n; i++) {
 									int ch = read();
 									if (ch == -1) {
 										return false;
 									}
 									sb.append((char)ch);
 								}
 							}
 						}
 						while (n > 0);
 					} else {
 						int n;
 						do
 						{
 							n = read();
 							if (n > 0) {
 								skip(n);
 							}
 							else
 							if (n == -1) {
 								return false;
 							}
 						}
 						while (n > 0);
 					}
 					break;
 				}
 				case(0x3b): // end of file
 				{
 					break;
 				}
 				default:
 				{
 					return false;
 				}
 			}
 		}
 		while (blockType != 0x3b);
 		return true;
 	}
 
 	private boolean checkIff() throws IOException {
 		byte[] a = new byte[10];
 		// read remaining 2 bytes of file id, 4 bytes file size 
 		// and 4 bytes IFF subformat
 		if (read(a, 0, 10) != 10) {
 			return false;
 		}
 		final byte[] IFF_RM = {0x52, 0x4d};
 		if (!equals(a, 0, IFF_RM, 0, 2)) {
 			return false;
 		}
 		int type = getIntBigEndian(a, 6);
 		if (type != 0x494c424d && // type must be ILBM...
 		    type != 0x50424d20) { // ...or PBM
 		    return false;
 		}
 		// loop chunks to find BMHD chunk
 		do {
 			if (read(a, 0, 8) != 8) {
 				return false;
 			}
 			int chunkId = getIntBigEndian(a, 0);
 			int size = getIntBigEndian(a, 4);
 			if ((size & 1) == 1) {
 				size++;
 			}
 			if (chunkId == 0x424d4844) { // BMHD chunk
 				if (read(a, 0, 9) != 9) {
 					return false;
 				}
 				format = FORMAT_IFF;
 				width = getShortBigEndian(a, 0);
 				height = getShortBigEndian(a, 2);
 				bitsPerPixel = a[8] & 0xff;
 				return (width > 0 && height > 0 && bitsPerPixel > 0 && bitsPerPixel < 33);
 			} else {
 				skip(size);
 			}
 		} while (true);
 	}
 
 	private boolean checkJpeg() throws IOException {
 		byte[] data = new byte[12];
 		while (true) {
 			if (read(data, 0, 4) != 4) {
 				return false;
 			}
 			int marker = getShortBigEndian(data, 0);
 			int size = getShortBigEndian(data, 2);
 			if ((marker & 0xff00) != 0xff00) {
 				return false; // not a valid marker
 			}
 			if (marker == 0xffe0) { // APPx 
 				if (size < 14) {
 					// not an APPx header as we know it, skip
 					skip(size - 2);
 					continue;
 				}
 				if (read(data, 0, 12) != 12) {
 					return false;
 				}
 				final byte[] APP0_ID = {0x4a, 0x46, 0x49, 0x46, 0x00};
 				if (equals(APP0_ID, 0, data, 0, 5)) {
 					//System.out.println("data 7=" + data[7]);
 					if (data[7] == 1) {
 						setPhysicalWidthDpi(getShortBigEndian(data, 8));
 						setPhysicalHeightDpi(getShortBigEndian(data, 10));
 					}
 					else
 					if (data[7] == 2) {
 						int x = getShortBigEndian(data, 8);
 						int y = getShortBigEndian(data, 10);
 						setPhysicalWidthDpi((int)(x * 2.54f));
 						setPhysicalHeightDpi((int)(y * 2.54f));
 					}
 				}
 				skip(size - 14);
 			}
 			else
 			if (collectComments && size > 2 && marker == 0xfffe) { // comment
 				size -= 2;
 				byte[] chars = new byte[size];
 				if (read(chars, 0, size) != size) {
 					return false;
 				}
 				String comment = new String(chars, "iso-8859-1");
 				comment = comment.trim();
 				addComment(comment);
 			}
 			else
 			if (marker >= 0xffc0 && marker <= 0xffcf && marker != 0xffc4 && marker != 0xffc8) {
 				if (read(data, 0, 6) != 6) {
 					return false;
 				}
 				format = FORMAT_JPEG;
 				bitsPerPixel = (data[0] & 0xff) * (data[5] & 0xff);
 				progressive = marker == 0xffc2 || marker == 0xffc6 ||
 					marker == 0xffca || marker == 0xffce;
 				width = getShortBigEndian(data, 3);
 				height = getShortBigEndian(data, 1);
 				return true;
 			} else {
 				skip(size - 2);
 			}
 		}
 	}
 
 	private boolean checkPcx() throws IOException {
 		byte[] a = new byte[64];
 		if (read(a) != a.length) {
 			return false;
 		}
 		if (a[0] != 1) { // encoding, 1=RLE is only valid value
 			return false;
 		}
 		// width / height
 		int x1 = getShortLittleEndian(a, 2);
 		int y1 = getShortLittleEndian(a, 4);
 		int x2 = getShortLittleEndian(a, 6);
 		int y2 = getShortLittleEndian(a, 8);
 		if (x1 < 0 || x2 < x1 || y1 < 0 || y2 < y1) {
 			return false;
 		}
 		width = x2 - x1 + 1;
 		height = y2 - y1 + 1;
 		// color depth
 		int bits = a[1];
 		int planes = a[63];
 		if (planes == 1 &&
 		    (bits == 1 || bits == 2 || bits == 4 || bits == 8)) {
 			// paletted
 			bitsPerPixel = bits;
 		} else
 		if (planes == 3 && bits == 8) {
 			// RGB truecolor
 			bitsPerPixel = 24;
 		} else {
 			return false;
 		}
 		setPhysicalWidthDpi(getShortLittleEndian(a, 10));
 		setPhysicalHeightDpi(getShortLittleEndian(a, 10));
 		format = FORMAT_PCX;
 		return true;
 	}
 
 	private boolean checkPng() throws IOException {
 		final byte[] PNG_MAGIC = {0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a};
 		byte[] a = new byte[27];
 		if (read(a) != 27) {
 			return false;
 		}
 		if (!equals(a, 0, PNG_MAGIC, 0, 6)) {
 			return false;
 		}
 		format = FORMAT_PNG;
 		width = getIntBigEndian(a, 14);
 		height = getIntBigEndian(a, 18);
 		bitsPerPixel = a[22] & 0xff;
 		int colorType = a[23] & 0xff;
 		if (colorType == 2 || colorType == 6) {
 			bitsPerPixel *= 3;
 		}
 		progressive = (a[26] & 0xff) != 0;
 		return true;
 	}
 
 	private boolean checkPnm(int id) throws IOException {
 		if (id < 1 || id > 6) {
 			return false;
 		}
 		final int[] PNM_FORMATS = {FORMAT_PBM, FORMAT_PGM, FORMAT_PPM};
 		format = PNM_FORMATS[(id - 1) % 3];
 		boolean hasPixelResolution = false;
 		String s;
 		while (true)
 		{
 			s = readLine();
 			if (s != null) {
 				s = s.trim();
 			}
 			if (s == null || s.length() < 1) {
 				continue;
 			}
 			if (s.charAt(0) == '#') { // comment
 				if (collectComments && s.length() > 1) {
 					addComment(s.substring(1));
 				}
 				continue;
 			}
 			if (!hasPixelResolution) { // split "343 966" into width=343, height=966
 				int spaceIndex = s.indexOf(' ');
 				if (spaceIndex == -1) {
 					return false;
 				}
 				String widthString = s.substring(0, spaceIndex);
 				spaceIndex = s.lastIndexOf(' ');
 				if (spaceIndex == -1) {
 					return false;
 				}
 				String heightString = s.substring(spaceIndex + 1);
 				try {
 					width = Integer.parseInt(widthString);
 					height = Integer.parseInt(heightString);
 				} catch (NumberFormatException nfe) {
 					return false;
 				}
 				if (width < 1 || height < 1) {
 					return false;
 				}
 				if (format == FORMAT_PBM) {
 					bitsPerPixel = 1;
 					return true;
 				}
 				hasPixelResolution = true;
 			}
 			else
 			{
 				int maxSample;
 				try {
 					maxSample = Integer.parseInt(s);
 				} catch (NumberFormatException nfe) {
 					return false;
 				}
 				if (maxSample < 0) {
 					return false;
 				}
 				for (int i = 0; i < 25; i++) {
 					if (maxSample < (1 << (i + 1))) {
 						bitsPerPixel = i + 1;
 						if (format == FORMAT_PPM) {
 							bitsPerPixel *= 3;
 						}
 						return true;
 					}
 				}
 				return false;
 			}
 		}
 	}
 
 	private boolean checkPsd() throws IOException {
 		byte[] a = new byte[24];
 		if (read(a) != a.length) {
 			return false;
 		}
 		final byte[] PSD_MAGIC = {0x50, 0x53};
 		if (!equals(a, 0, PSD_MAGIC, 0, 2)) {
 			return false;
 		}
 		format = FORMAT_PSD;
 		width = getIntBigEndian(a, 16);
 		height = getIntBigEndian(a, 12);
 		int channels = getShortBigEndian(a, 10);
 		int depth = getShortBigEndian(a, 20);
 		bitsPerPixel = channels * depth;
 		return (width > 0 && height > 0 && bitsPerPixel > 0 && bitsPerPixel <= 64);
 	}
 
 	private boolean checkRas() throws IOException {
 		byte[] a = new byte[14];
 		if (read(a) != a.length) {
 			return false;
 		}
 		final byte[] RAS_MAGIC = {0x6a, (byte)0x95};
 		if (!equals(a, 0, RAS_MAGIC, 0, 2)) {
 			return false;
 		}
 		format = FORMAT_RAS;
 		width = getIntBigEndian(a, 2);
 		height = getIntBigEndian(a, 6);
 		bitsPerPixel = getIntBigEndian(a, 10);
 		return (width > 0 && height > 0 && bitsPerPixel > 0 && bitsPerPixel <= 24);
 	}
 
 	/**
 	 * Run over String list, return false iff at least one of the arguments
 	 * equals <code>-c</code>.
 	 * @param args string list to check
 	 */
 	private static boolean determineVerbosity(String[] args) {
 		if (args != null && args.length > 0) {
 			for (int i = 0; i < args.length; i++) {
 				if ("-c".equals(args[i])) {
 					return false;
 				}
 			}
 		}
 		return true;
 	}
 
 	private static boolean equals(byte[] a1, int offs1, byte[] a2, int offs2, int num) {
 		while (num-- > 0) {
 			if (a1[offs1++] != a2[offs2++]) {
 				return false;
 			}
 		}
 		return true;
 	}
 
 	/** 
 	 * If {@link #check()} was successful, returns the image's number of bits per pixel.
 	 * Does not include transparency information like the alpha channel.
 	 * @return number of bits per image pixel
 	 */
 	public int getBitsPerPixel() {
 		return bitsPerPixel;
 	}
 
 	/**
 	 * Returns the index'th comment retrieved from the file.
 	 * @param index int index of comment to return
 	 * @throws IllegalArgumentException if index is smaller than 0 or larger than or equal
 	 * to the number of comments retrieved
 	 * @see #getNumberOfComments
 	 */
 	public String getComment(int index) {
 		if (comments == null || index < 0 || index >= comments.size()) {
 			throw new IllegalArgumentException("Not a valid comment index: " + index);
 		}
 		return (String)comments.elementAt(index);
 	}
 
 	/**
 	 * If {@link #check()} was successful, returns the image format as one
 	 * of the FORMAT_xyz constants from this class.
 	 * Use {@link #getFormatName()} to get a textual description of the file format.
 	 * @return file format as a FORMAT_xyz constant
 	 */
 	public int getFormat() {
 		return format;
 	}
 
 	/**
 	 * If {@link #check()} was successful, returns the image format's name.
 	 * Use {@link #getFormat()} to get a unique number.
 	 * @return file format name
 	 */
 	public String getFormatName() {
 		if (format >= 0 && format < FORMAT_NAMES.length) {
 			return FORMAT_NAMES[format];
 		} else {
 			return "?";
 		}
 	}
 
 	/** 
 	 * If {@link #check()} was successful, returns one the image's vertical
 	 * resolution in pixels.
 	 * @return image height in pixels
 	 */
 	public int getHeight() {
 		return height;
 	}
 
 	private static int getIntBigEndian(byte[] a, int offs) {
 		return
 			(a[offs] & 0xff) << 24 | 
 			(a[offs + 1] & 0xff) << 16 | 
 			(a[offs + 2] & 0xff) << 8 | 
 			a[offs + 3] & 0xff;
 	}
 
 	private static int getIntLittleEndian(byte[] a, int offs) {
 		return
 			(a[offs + 3] & 0xff) << 24 | 
 			(a[offs + 2] & 0xff) << 16 | 
 			(a[offs + 1] & 0xff) << 8 | 
 			a[offs] & 0xff;
 	}
 
 	/** 
 	 * If {@link #check()} was successful, returns a String with the
 	 * MIME type of the format.
 	 * @return MIME type, e.g. <code>image/jpeg</code>
 	 */
 	public String getMimeType() {
 		if (format >= 0 && format < MIME_TYPE_STRINGS.length) {
 			if (format == FORMAT_JPEG && progressive)
 			{
 				return "image/pjpeg";
 			}
 			return MIME_TYPE_STRINGS[format];
 		} else {
 			return null;
 		}
 	}
 
 	/**
 	 * If {@link #check()} was successful and {@link #setCollectComments(boolean)} was called with
 	 * <code>true</code> as argument, returns the number of comments retrieved 
 	 * from the input image stream / file.
 	 * Any number &gt;= 0 and smaller than this number of comments is then a
 	 * valid argument for the {@link #getComment(int)} method.
 	 * @return number of comments retrieved from input image
 	 */
 	public int getNumberOfComments()
 	{
 		if (comments == null) {
 			return 0;
 		} else {
 			return comments.size();
 		}
 	}
 
 	/**
 	 * Returns the number of images in the examined file.
 	 * Assumes that <code>setDetermineImageNumber(true);</code> was called before
 	 * a successful call to {@link #check()}.
 	 * This value can currently be only different from <code>1</code> for GIF images.
 	 * @return number of images in file
 	 */
 	public int getNumberOfImages()
 	{
 		return numberOfImages;
 	}
 
 	/**
 	 * Returns the physical height of this image in dots per inch (dpi).
 	 * Assumes that {@link #check()} was successful.
 	 * Returns <code>-1</code> on failure.
 	 * @return physical height (in dpi)
 	 * @see #getPhysicalWidthDpi()
 	 * @see #getPhysicalHeightInch()
 	 */
 	public int getPhysicalHeightDpi() {
 		return physicalHeightDpi;
 	}
 
 	/**
 	 * If {@link #check()} was successful, returns the physical width of this image in dpi (dots per inch)
 	 * or -1 if no value could be found.
 	 * @return physical height (in dpi)
 	 * @see #getPhysicalHeightDpi()
 	 * @see #getPhysicalWidthDpi()
 	 * @see #getPhysicalWidthInch()
 	 */
 	public float getPhysicalHeightInch() {
 		int h = getHeight();
 		int ph = getPhysicalHeightDpi();
 		if (h > 0 && ph > 0) {
 			return ((float)h) / ((float)ph);
 		} else {
 			return -1.0f;
 		}
 	}
 
 	/**
 	 * If {@link #check()} was successful, returns the physical width of this image in dpi (dots per inch)
 	 * or -1 if no value could be found.
 	 * @return physical width (in dpi)
 	 * @see #getPhysicalHeightDpi()
 	 * @see #getPhysicalWidthInch()
 	 * @see #getPhysicalHeightInch()
 	 */
 	public int getPhysicalWidthDpi() {
 		return physicalWidthDpi;
 	}
 
 	/**
 	 * Returns the physical width of an image in inches, or
 	 * <code>-1.0f</code> if width information is not available.
 	 * Assumes that {@link #check} has been called successfully.
 	 * @return physical width in inches or <code>-1.0f</code> on failure
 	 * @see #getPhysicalWidthDpi
 	 * @see #getPhysicalHeightInch
 	 */
 	public float getPhysicalWidthInch() {
 		int w = getWidth();
 		int pw = getPhysicalWidthDpi();
 		if (w > 0 && pw > 0) {
 			return ((float)w) / ((float)pw);
 		} else {
 			return -1.0f;
 		}
 	}
 
 	private static int getShortBigEndian(byte[] a, int offs) {
 		return
 			(a[offs] & 0xff) << 8 | 
 			(a[offs + 1] & 0xff);
 	}
 
 	private static int getShortLittleEndian(byte[] a, int offs) {
 		return (a[offs] & 0xff) | (a[offs + 1] & 0xff) << 8;
 	}
 
 	/** 
 	 * If {@link #check()} was successful, returns one the image's horizontal
 	 * resolution in pixels.
 	 * @return image width in pixels
 	 */
 	public int getWidth() {
 		return width;
 	}
 
 	/**
 	 * Returns whether the image is stored in a progressive (also called: interlaced) way.
 	 * @return true for progressive/interlaced, false otherwise
 	 */
 	public boolean isProgressive()
 	{
 		return progressive;
 	}
 
 	/**
 	 * To use this class as a command line application, give it either 
 	 * some file names as parameters (information on them will be
 	 * printed to standard output, one line per file) or call
 	 * it with no parameters. It will then check data given to it
 	 * via standard input.
 	 * @param args the program arguments which must be file names
 	 */
 	public static void main(String[] args) {
 		ImageInfo imageInfo = new ImageInfo();
 		imageInfo.setDetermineImageNumber(true);
 		boolean verbose = determineVerbosity(args);
 		if (args.length == 0) {
 			run(null, System.in, imageInfo, verbose);
 		} else {
 			int index = 0;
 			while (index < args.length) {
 				InputStream in = null;
 				try {
 					String name = args[index++];
 					System.out.print(name + ";");
 					if (name.startsWith("http://")) {
 						in = new URL(name).openConnection().getInputStream();
 					} else {
 						in = new FileInputStream(name);
 					}
 					run(name, in, imageInfo, verbose);
 					in.close();
 				} catch (IOException e) {
 					System.out.println(e);
 					try {
 						if (in != null) {
 							in.close();
 						}
 					} catch (IOException ee) {
 					}
 				}
 			}
 		}
 	}
 
 	private static void print(String sourceName, ImageInfo ii, boolean verbose) {
 		if (verbose) {
 			printVerbose(sourceName, ii);
 		} else {
 			printCompact(sourceName, ii);
 		}
 	}
 
 	private static void printCompact(String sourceName, ImageInfo imageInfo) {
 		final String SEP = "\t";
 		System.out.println(
 			sourceName + SEP + 
 			imageInfo.getFormatName() + SEP +
 			imageInfo.getMimeType() + SEP +
 			imageInfo.getWidth() + SEP +
 			imageInfo.getHeight() + SEP +
 			imageInfo.getBitsPerPixel() + SEP +
 			imageInfo.getNumberOfImages() + SEP +
 			imageInfo.getPhysicalWidthDpi() + SEP +
 			imageInfo.getPhysicalHeightDpi() + SEP +
 			imageInfo.getPhysicalWidthInch() + SEP +
 			imageInfo.getPhysicalHeightInch() + SEP +
 			imageInfo.isProgressive()
 		);
 	}
 
 	private static void printLine(int indentLevels, String text, float value, float minValidValue) {
 		if (value < minValidValue) {
 			return;
 		}
 		printLine(indentLevels, text, Float.toString(value));
 	}
 
 	private static void printLine(int indentLevels, String text, int value, int minValidValue) {
 		if (value >= minValidValue) {
 			printLine(indentLevels, text, Integer.toString(value));
 		}
 	}
 
 	private static void printLine(int indentLevels, String text, String value) {
 		if (value == null || value.length() == 0) {
 			return;
 		}
 		while (indentLevels-- > 0) {
 			System.out.print("\t");
 		}
 		if (text != null && text.length() > 0) {
 			System.out.print(text);
 			System.out.print(" ");
 		}
 		System.out.println(value);
 	}
 
 	private static void printVerbose(String sourceName, ImageInfo ii) {
 		printLine(0, null, sourceName);
 		printLine(1, "File format: ", ii.getFormatName());
 		printLine(1, "MIME type: ", ii.getMimeType());
 		printLine(1, "Width (pixels): ", ii.getWidth(), 1);
 		printLine(1, "Height (pixels): ", ii.getHeight(), 1);
 		printLine(1, "Bits per pixel: ", ii.getBitsPerPixel(), 1);
 		printLine(1, "Progressive: ", ii.isProgressive() ? "yes" : "no");
 		printLine(1, "Number of images: ", ii.getNumberOfImages(), 1);
 		printLine(1, "Physical width (dpi): ", ii.getPhysicalWidthDpi(), 1);
 		printLine(1, "Physical height (dpi): ", ii.getPhysicalHeightDpi(), 1);
 		printLine(1, "Physical width (inches): ", ii.getPhysicalWidthInch(), 1.0f);
 		printLine(1, "Physical height (inches): ", ii.getPhysicalHeightInch(), 1.0f);
 		int numComments = ii.getNumberOfComments();
 		printLine(1, "Number of textual comments: ", numComments, 1);
 		if (numComments > 0) {
 			for (int i = 0; i < numComments; i++) {
 				printLine(2, null, ii.getComment(i));
 			}
 		}
 	}
 
 	private int read() throws IOException {
 		if (in != null) {
 			return in.read();
 		} else {
 			return din.readByte();
 		}
 	}
 
 	private int read(byte[] a) throws IOException {
 		if (in != null) {
 			return in.read(a);
 		} else {
 			din.readFully(a);
 			return a.length;
 		}
 	}
 
 	private int read(byte[] a, int offset, int num) throws IOException {
 		if (in != null) {
 			return in.read(a, offset, num);
 		} else {
 			din.readFully(a, offset, num);
 			return num;
 		}
 	}
 
 	private String readLine() throws IOException {
 		return readLine(new StringBuffer());
 	}
 
 	private String readLine(StringBuffer sb) throws IOException {
 		boolean finished;
 		do {
 			int value = read();
 			finished = (value == -1 || value == 10);
 			if (!finished) {
 				sb.append((char)value);
 			}
 		} while (!finished);
 		return sb.toString();
 	}
 
 	private static void run(String sourceName, InputStream in, ImageInfo imageInfo, boolean verbose) {
 		imageInfo.setInput(in);
 		imageInfo.setDetermineImageNumber(true);
 		imageInfo.setCollectComments(verbose);
 		if (imageInfo.check()) {
 			print(sourceName, imageInfo, verbose);
 		}
 	}
 
 	/**
 	 * Specify whether textual comments are supposed to be extracted from input.
 	 * Default is <code>false</code>.
 	 * If enabled, comments will be added to an internal list.
 	 * @param newValue if <code>true</code>, this class will read comments
 	 * @see #getNumberOfComments
 	 * @see #getComment
 	 */
 	public void setCollectComments(boolean newValue)
 	{
 		collectComments = newValue;
 	}
 
 	/**
 	 * Specify whether the number of images in a file is to be
 	 * determined - default is <code>false</code>.
 	 * This is a special option because some file formats require running over
 	 * the entire file to find out the number of images, a rather time-consuming
 	 * task.
 	 * Not all file formats support more than one image.
 	 * If this method is called with <code>true</code> as argument,
 	 * the actual number of images can be queried via 
 	 * {@link #getNumberOfImages()} after a successful call to
 	 * {@link #check()}.
 	 * @param newValue will the number of images be determined?
 	 * @see #getNumberOfImages
 	 */
 	public void setDetermineImageNumber(boolean newValue)
 	{
 		determineNumberOfImages = newValue;
 	}
 
 	/**
 	 * Set the input stream to the argument stream (or file). 
 	 * Note that {@link java.io.RandomAccessFile} implements
 	 * {@link java.io.DataInput}.
 	 * @param dataInput the input stream to read from
 	 */
 	public void setInput(DataInput dataInput) {
 		din = dataInput;
 		in = null;
 	}
 
 	/**
 	 * Set the input stream to the argument stream (or file).
 	 * @param inputStream the input stream to read from
 	 */
 	public void setInput(InputStream inputStream) {
 		in = inputStream;
 		din = null;
 	}
 
 	private void setPhysicalHeightDpi(int newValue) {
 		physicalWidthDpi = newValue;
 	}
 
 	private void setPhysicalWidthDpi(int newValue) {
 		physicalHeightDpi = newValue;
 	}
 
     private void skip(int num) throws IOException {
         while (num > 0) {
             long result;
             if (in != null) {
                 result = in.skip(num);
             } else {
                 result = din.skipBytes(num);
             }
             if (result > 0) {
                 num -= result;
             } else {
                 if (in != null) {
                     result = in.read();
                 } else {
                     result = din.readByte();
                 }
                 if (result == -1) {
                 	throw new IOException("Premature end of input.");
                 } else {
                 	num--;
                 }
             }
         }
     }
 }