package ij.io;
import java.io.*;
import java.net.*;
import ij.*;  //??

/** Reads raw 8-bit, 16-bit or 32-bit (float or RGB)
	images from a stream or URL. */
public class ImageReader {

	private static final int CLEAR_CODE = 256;
	private static final int EOI_CODE = 257;

    private FileInfo fi;
    private int width, height;
    private long skipCount;
    private int bytesPerPixel, bufferSize, byteCount, nPixels;
	private boolean showProgressBar=true;
	private int eofErrorCount;
	private long startTime;
	public double min, max; // readRGB48() calculates min/max pixel values

	/**
	Constructs a new ImageReader using a FileInfo object to describe the file to be read.
	@see ij.io.FileInfo
	*/
	public ImageReader (FileInfo fi) {
		this.fi = fi;
	    width = fi.width;
	    height = fi.height;
	    skipCount = fi.longOffset>0?fi.longOffset:fi.offset;
	}
	
	void eofError() {
		eofErrorCount++;
	}
	
	byte[] read8bitImage(InputStream in) throws IOException {
		if (fi.compression == FileInfo.LZW || fi.compression == FileInfo.LZW_WITH_DIFFERENCING)
			return readCompressed8bitImage(in);
		byte[] pixels = new byte[nPixels];
		// assume contiguous strips
		int count, actuallyRead;
		int totalRead = 0;
	  	while (totalRead<byteCount) {
	  		if (totalRead+bufferSize>byteCount)
	  			count = byteCount-totalRead;
  			else
  				count = bufferSize;
  			actuallyRead = in.read(pixels, totalRead, count);
  			if (actuallyRead==-1) {eofError(); break;}
  			totalRead += actuallyRead;
  			showProgress(totalRead, byteCount);
  		}
		return pixels;
	}
	
	byte[] readCompressed8bitImage(InputStream in) throws IOException {
		byte[] pixels = new byte[nPixels];
		int current = 0;
		byte last = 0;
		for (int i=0; i<fi.stripOffsets.length; i++) {
			if (in instanceof RandomAccessStream)
				((RandomAccessStream)in).seek(fi.stripOffsets[i]);
			else if (i > 0) {
				int skip = fi.stripOffsets[i] - fi.stripOffsets[i-1] - fi.stripLengths[i-1];
				if (skip > 0) in.skip(skip);
			}
			byte[] byteArray = new byte[fi.stripLengths[i]];
			int read = 0, left = byteArray.length;
			while (left > 0) {
				int r = in.read(byteArray, read, left);
				if (r == -1) {eofError(); break;}
				read += r;
				left -= r;
			}
			byteArray = lzwUncompress(byteArray);
			if (fi.compression == FileInfo.LZW_WITH_DIFFERENCING)
				for (int b=0; b<byteArray.length; b++) {
					byteArray[b] += last;
					last = b % fi.width == fi.width - 1 ? 0 : byteArray[b];
				}
			int length = byteArray.length;
			if (current+length>pixels.length) length = pixels.length-current;
			System.arraycopy(byteArray, 0, pixels, current, length);
			current += byteArray.length;
			showProgress(i+1, fi.stripOffsets.length);
		}
		return pixels;
	}
	
	/** Reads a 16-bit image. Signed pixels are converted to unsigned by adding 32768. */
	short[] read16bitImage(InputStream in) throws IOException {
		if (fi.compression == FileInfo.LZW)
			return readCompressed16bitImage(in);
		int pixelsRead;
		byte[] buffer = new byte[bufferSize];
		short[] pixels = new short[nPixels];
		int totalRead = 0;
		int base = 0;
		int count, value;
		int bufferCount;
		
		while (totalRead<byteCount) {
			if ((totalRead+bufferSize)>byteCount)
				bufferSize = byteCount-totalRead;
			bufferCount = 0;
			while (bufferCount<bufferSize) { // fill the buffer
				count = in.read(buffer, bufferCount, bufferSize-bufferCount);
				if (count==-1) {
					if (bufferCount>0)
						for (int i=bufferCount; i<bufferSize; i++) buffer[i] = 0;
					totalRead = byteCount;
					eofError();
					break;
				}
				bufferCount += count;
			}
			totalRead += bufferSize;
			showProgress(totalRead, byteCount);
			pixelsRead = bufferSize/bytesPerPixel;
			if (fi.intelByteOrder) {
				if (fi.fileType==FileInfo.GRAY16_SIGNED)
					for (int i=base,j=0; i<(base+pixelsRead); i++,j+=2)
						pixels[i] = (short)((((buffer[j+1]&0xff)<<8) | (buffer[j]&0xff))+32768);
				else
					for (int i=base,j=0; i<(base+pixelsRead); i++,j+=2)
						pixels[i] = (short)(((buffer[j+1]&0xff)<<8) | (buffer[j]&0xff));
			} else {
				if (fi.fileType==FileInfo.GRAY16_SIGNED)
					for (int i=base,j=0; i<(base+pixelsRead); i++,j+=2)
						pixels[i] = (short)((((buffer[j]&0xff)<<8) | (buffer[j+1]&0xff))+32768);
				else
					for (int i=base,j=0; i<(base+pixelsRead); i++,j+=2)
						pixels[i] = (short)(((buffer[j]&0xff)<<8) | (buffer[j+1]&0xff));
			}
			base += pixelsRead;
		}
		return pixels;
	}
	
	short[] readCompressed16bitImage(InputStream in) throws IOException {
		short[] pixels = new short[nPixels];
		int base = 0;
		short last = 0;
		for (int k=0; k<fi.stripOffsets.length; k++) {
			if (k > 0) {
				int skip = fi.stripOffsets[k] - fi.stripOffsets[k-1] - fi.stripLengths[k-1];
				if (skip > 0) in.skip(skip);
			}
			byte[] byteArray = new byte[fi.stripLengths[k]];
			int read = 0, left = byteArray.length;
			while (left > 0) {
				int r = in.read(byteArray, read, left);
				if (r == -1) {eofError(); break;}
				read += r;
				left -= r;
			}
			byteArray = lzwUncompress(byteArray);
			int pixelsRead = byteArray.length/bytesPerPixel;
			int pmax = base+pixelsRead;
			if (pmax > nPixels) pmax = nPixels;
			if (fi.intelByteOrder) {
				if (fi.fileType==FileInfo.GRAY16_SIGNED)
					for (int i=base,j=0; i<pmax; i++,j+=2)
						pixels[i] = (short)((((byteArray[j+1]&0xff)<<8) | (byteArray[j]&0xff))+32768);
				else
					for (int i=base,j=0; i<pmax; i++,j+=2)
						pixels[i] = (short)(((byteArray[j+1]&0xff)<<8) | (byteArray[j]&0xff));
			} else {
				if (fi.fileType==FileInfo.GRAY16_SIGNED)
					for (int i=base,j=0; i<pmax; i++,j+=2)
						pixels[i] = (short)((((byteArray[j]&0xff)<<8) | (byteArray[j+1]&0xff))+32768);
				else
					for (int i=base,j=0; i<pmax; i++,j+=2)
						pixels[i] = (short)(((byteArray[j]&0xff)<<8) | (byteArray[j+1]&0xff));
			}
			base += pixelsRead;
			showProgress(k+1, fi.stripOffsets.length);
		}
		return pixels;
	}

	float[] read32bitImage(InputStream in) throws IOException {
		int pixelsRead;
		byte[] buffer = new byte[bufferSize];
		float[] pixels = new float[nPixels];
		int totalRead = 0;
		int base = 0;
		int count, value;
		int bufferCount;
		int tmp;
		
		while (totalRead<byteCount) {
			if ((totalRead+bufferSize)>byteCount)
				bufferSize = byteCount-totalRead;
			bufferCount = 0;
			while (bufferCount<bufferSize) { // fill the buffer
				count = in.read(buffer, bufferCount, bufferSize-bufferCount);
				if (count==-1) {
					if (bufferCount>0)
						for (int i=bufferCount; i<bufferSize; i++) buffer[i] = 0;
					totalRead = byteCount;
					eofError();
					break;
				}
				bufferCount += count;
			}
			totalRead += bufferSize;
			showProgress(totalRead, byteCount);
			pixelsRead = bufferSize/bytesPerPixel;
			int j = 0;
			if (fi.intelByteOrder)
				for (int i=base; i < (base+pixelsRead); i++) {
					tmp = (int)(((buffer[j+3]&0xff)<<24) | ((buffer[j+2]&0xff)<<16) | ((buffer[j+1]&0xff)<<8) | (buffer[j]&0xff));
					if (fi.fileType==FileInfo.GRAY32_FLOAT)
						pixels[i] = Float.intBitsToFloat(tmp);
					else if (fi.fileType==FileInfo.GRAY32_UNSIGNED)
						pixels[i] = (float)(tmp&0xffffffffL);
					else
						pixels[i] = tmp;
					j += 4;
				}
			else
				for (int i=base; i < (base+pixelsRead); i++) {
					tmp = (int)(((buffer[j]&0xff)<<24) | ((buffer[j+1]&0xff)<<16) | ((buffer[j+2]&0xff)<<8) | (buffer[j+3]&0xff));
					if (fi.fileType==FileInfo.GRAY32_FLOAT)
						pixels[i] = Float.intBitsToFloat(tmp);
					else if (fi.fileType==FileInfo.GRAY32_UNSIGNED)
						pixels[i] = (float)(tmp&0xffffffffL);
					else
						pixels[i] = tmp;
					j += 4;
				}
			base += pixelsRead;
		}
		return pixels;
	}
	
	float[] read64bitImage(InputStream in) throws IOException {
		int pixelsRead;
		byte[] buffer = new byte[bufferSize];
		float[] pixels = new float[nPixels];
		int totalRead = 0;
		int base = 0;
		int count, value;
		int bufferCount;
		long tmp;
		long b1, b2, b3, b4, b5, b6, b7, b8;
		
		while (totalRead<byteCount) {
			if ((totalRead+bufferSize)>byteCount)
				bufferSize = byteCount-totalRead;
			bufferCount = 0;
			while (bufferCount<bufferSize) { // fill the buffer
				count = in.read(buffer, bufferCount, bufferSize-bufferCount);
				if (count==-1) {
					if (bufferCount>0)
						for (int i=bufferCount; i<bufferSize; i++) buffer[i] = 0;
					totalRead = byteCount;
					eofError();
					break;
				}
				bufferCount += count;
			}
			totalRead += bufferSize;
			showProgress(totalRead, byteCount);
			pixelsRead = bufferSize/bytesPerPixel;
			int j = 0;
			for (int i=base; i < (base+pixelsRead); i++) {
				b1 = buffer[j+7]&0xff;  b2 = buffer[j+6]&0xff;  b3 = buffer[j+5]&0xff;  b4 = buffer[j+4]&0xff; 
				b5 = buffer[j+3]&0xff;  b6 = buffer[j+2]&0xff;  b7 = buffer[j+1]&0xff;  b8 = buffer[j]&0xff; 
				if (fi.intelByteOrder)
					tmp = (long)((b1<<56)|(b2<<48)|(b3<<40)|(b4<<32)|(b5<<24)|(b6<<16)|(b7<<8)|b8);
				else
					tmp = (long)((b8<<56)|(b7<<48)|(b6<<40)|(b5<<32)|(b4<<24)|(b3<<16)|(b2<<8)|b1);
				pixels[i] = (float)Double.longBitsToDouble(tmp);
				j += 8;
			}
			base += pixelsRead;
		}
		return pixels;
	}

	int[] readChunkyRGB(InputStream in) throws IOException {
		if (fi.compression == FileInfo.LZW || fi.compression == FileInfo.LZW_WITH_DIFFERENCING)
			return readCompressedChunkyRGB(in);
		int pixelsRead;
		bufferSize = 24*width;
		byte[] buffer = new byte[bufferSize];
		int[] pixels = new int[nPixels];
		int totalRead = 0;
		int base = 0;
		int count, value;
		int bufferCount;
		int r, g, b;
		
		while (totalRead<byteCount) {
			if ((totalRead+bufferSize)>byteCount)
				bufferSize = byteCount-totalRead;
			bufferCount = 0;
			while (bufferCount<bufferSize) { // fill the buffer
				count = in.read(buffer, bufferCount, bufferSize-bufferCount);
				if (count==-1) {
					if (bufferCount>0)
						for (int i=bufferCount; i<bufferSize; i++) buffer[i] = 0;
					totalRead = byteCount;
					eofError();
					break;
				}
				bufferCount += count;
			}
			totalRead += bufferSize;
			showProgress(totalRead, byteCount);
			pixelsRead = bufferSize/bytesPerPixel;
			boolean bgr = fi.fileType==FileInfo.BGR;
			int j = 0;
			for (int i=base; i<(base+pixelsRead); i++) {
				if (bytesPerPixel==4) {
					if (fi.fileType==FileInfo.BARG) {  // MCID
						b = buffer[j++]&0xff;
						j++; // ignore alfa byte
						r = buffer[j++]&0xff;
						g = buffer[j++]&0xff;
					} else if (fi.intelByteOrder) {
						b = buffer[j++]&0xff;
						g = buffer[j++]&0xff;
						r = buffer[j++]&0xff;
						j++; // ignore alfa byte
					} else {
						j++; // ignore alfa byte
						r = buffer[j++]&0xff;
						g = buffer[j++]&0xff;
						b = buffer[j++]&0xff;
					}
				} else {
					r = buffer[j++]&0xff;
					g = buffer[j++]&0xff;
					b = buffer[j++]&0xff;
				}
				if (bgr)
					pixels[i] = 0xff000000 | (b<<16) | (g<<8) | r;
				else
					pixels[i] = 0xff000000 | (r<<16) | (g<<8) | b;
			}
			base += pixelsRead;
		}
		return pixels;
	}

	int[] readCompressedChunkyRGB(InputStream in) throws IOException {
		int[] pixels = new int[nPixels];
		int base = 0;
		int lastRed=0, lastGreen=0, lastBlue=0;
		int nextByte;
		int red=0, green=0, blue=0;
		boolean bgr = fi.fileType==FileInfo.BGR;
		boolean differencing = fi.compression == FileInfo.LZW_WITH_DIFFERENCING;
		for (int i=0; i<fi.stripOffsets.length; i++) {
			if (i > 0) {
				int skip = fi.stripOffsets[i] - fi.stripOffsets[i-1] - fi.stripLengths[i-1];
				if (skip > 0) in.skip(skip);
			}
			byte[] byteArray = new byte[fi.stripLengths[i]];
			int read = 0, left = byteArray.length;
			while (left > 0) {
				int r = in.read(byteArray, read, left);
				if (r == -1) {eofError(); break;}
				read += r;
				left -= r;
			}
			byteArray = lzwUncompress(byteArray);
			if (differencing) {
				for (int b=0; b<byteArray.length; b++) {
					if (b / bytesPerPixel % fi.width == 0) continue;
					byteArray[b] += byteArray[b - bytesPerPixel];
				}
			}
			int k = 0;
			int pixelsRead = byteArray.length/bytesPerPixel;
			int pmax = base+pixelsRead;
			if (pmax > nPixels) pmax = nPixels;
			for (int j=base; j<pmax; j++) {
				if (bytesPerPixel==4) k++; // ignore alfa byte
				red = byteArray[k++]&0xff;
				green = byteArray[k++]&0xff;
				blue = byteArray[k++]&0xff;
				if (bgr)
					pixels[j] = 0xff000000 | (blue<<16) | (green<<8) | red;
				else
					pixels[j] = 0xff000000 | (red<<16) | (green<<8) | blue;
			}
			base += pixelsRead;
			showProgress(i+1, fi.stripOffsets.length);
		}
		return pixels;
	}

	int[] readPlanarRGB(InputStream in) throws IOException {
		if (fi.compression == FileInfo.LZW || fi.compression == FileInfo.LZW_WITH_DIFFERENCING)
			return readCompressedPlanarRGBImage(in);
		DataInputStream dis = new DataInputStream(in);
		int planeSize = nPixels; // 1/3 image size
		byte[] buffer = new byte[planeSize];
		int[] pixels = new int[nPixels];
		int r, g, b;

		startTime = 0L;
		showProgress(10, 100);
		dis.readFully(buffer);
		for (int i=0; i < planeSize; i++) {
			r = buffer[i]&0xff;
			pixels[i] = 0xff000000 | (r<<16);
		}
		
		showProgress(40, 100);
		dis.readFully(buffer);
		for (int i=0; i < planeSize; i++) {
			g = buffer[i]&0xff;
			pixels[i] |= g<<8;
		}

		showProgress(70, 100);
		dis.readFully(buffer);
		for (int i=0; i < planeSize; i++) {
			b = buffer[i]&0xff;
			pixels[i] |= b;
		}

		showProgress(90, 100);
		return pixels;
	}

	int[] readCompressedPlanarRGBImage(InputStream in) throws IOException {
		int[] pixels = new int[nPixels];
		int r, g, b;
		nPixels *= 3; // read all 3 planes
		byte[] buffer = readCompressed8bitImage(in);
		nPixels /= 3;
		for (int i=0; i<nPixels; i++) {
			r = buffer[i]&0xff;
			pixels[i] = 0xff000000 | (r<<16);
		}
		for (int i=0; i<nPixels; i++) {
			g = buffer[nPixels+i]&0xff;
			pixels[i] |= g<<8;
		}
		for (int i=0; i<nPixels; i++) {
			b = buffer[nPixels*2+i]&0xff;
			pixels[i] |= b;
		}
		return pixels;
	}

	private void showProgress(int current, int last) {
		if (showProgressBar && (System.currentTimeMillis()-startTime)>500L)
			IJ.showProgress(current, last);
	}
	
	Object readRGB48(InputStream in) throws IOException {
		int channels = 3;
		short[][] stack = new short[channels][nPixels];
		DataInputStream dis = new DataInputStream(in);
		int pixel = 0;
		int min=65535, max=0;
		for (int i=0; i<fi.stripOffsets.length; i++) {
			if (i>0) {
				int skip = fi.stripOffsets[i] - fi.stripOffsets[i-1] - fi.stripLengths[i-1];
				if (skip>0) dis.skip(skip);
			}
			int len = fi.stripLengths[i];
			byte[] buffer = new byte[len];
			dis.readFully(buffer);
			int value;
			int channel=0;
			boolean intel = fi.intelByteOrder;
			for (int base=0; base<len; base+=2) {
				if (intel)
					value = ((buffer[base+1]&0xff)<<8) | (buffer[base]&0xff);
				else
					value = ((buffer[base]&0xff)<<8) | (buffer[base+1]&0xff);
				if (value<min) min = value;
				if (value>max) max = value;
				stack[channel][pixel] = (short)(value);
				channel++;
				if (channel==channels) {
					channel = 0;
					pixel++;
				}
			}
			showProgress(i+1, fi.stripOffsets.length);
		}
		this.min=min; this.max=max;
		return stack;
	}

	Object readRGB48Planar(InputStream in) throws IOException {
		short[] red = read16bitImage(in);
		short[] green = read16bitImage(in);
		short[] blue = read16bitImage(in);
		Object[] stack = new Object[3];
		stack[0] = red;
		stack[1] = green;
		stack[2] = blue;
		return stack;
	}

	short[] read12bitImage(InputStream in) throws IOException {
		int nBytes = (int)(nPixels*1.5);
		if ((nPixels&1)==1) nBytes++; // add 1 if odd
		byte[] buffer = new byte[nBytes];
		short[] pixels = new short[nPixels];
		DataInputStream dis = new DataInputStream(in);
		dis.readFully(buffer);
		int i = 0;
		int j = 0;
		for (int index=0; index<buffer.length/3; index++) {
			pixels[j++] = (short)(((buffer[i]&0xff)*16) + ((buffer[i+1]>>4)&0xf));
			pixels[j++] = (short)(((buffer[i+1]&0xf)*256) + (buffer[i+2]&0xff));
			i += 3;
		}
		return pixels;
	}

	float[] read24bitImage(InputStream in) throws IOException {
		byte[] buffer = new byte[width*3];
		float[] pixels = new float[nPixels];
		int b1, b2, b3;
		DataInputStream dis = new DataInputStream(in);
		for (int y=0; y<height; y++) {
			//IJ.log("read24bitImage: ");
			dis.readFully(buffer);
			int b = 0;
			for (int x=0; x<width; x++) {
				b1 = buffer[b++]&0xff;
				b2 = buffer[b++]&0xff;
				b3 = buffer[b++]&0xff;
				pixels[x+y*width] = (b3<<16) | (b2<<8) | b1;
			}
		}
		return pixels;
	}

	byte[] read1bitImage(InputStream in) throws IOException {
 		int scan=(int)Math.ceil(width/8.0);
		int len = scan*height;
		byte[] buffer = new byte[len];
		byte[] pixels = new byte[nPixels];
		DataInputStream dis = new DataInputStream(in);
		dis.readFully(buffer);
		int value1,value2, offset, index;
		for (int y=0; y<height; y++) {
			offset = y*scan;
			index = y*width;
			for (int x=0; x<scan; x++) {
				value1 = buffer[offset+x]&0xff;
				for (int i=7; i>=0; i--) {
					value2 = (value1&(1<<i))!=0?255:0;
					if (index<pixels.length)
						pixels[index++] = (byte)value2;
				}
			}
		}
		return pixels;
	}

	void skip(InputStream in) throws IOException {
		if (skipCount>0) {
			long bytesRead = 0;
			int skipAttempts = 0;
			long count;
			while (bytesRead<skipCount) {
				count = in.skip(skipCount-bytesRead);
				skipAttempts++;
				if (count==-1 || skipAttempts>5) break;
				bytesRead += count;
				//IJ.log("skip: "+skipCount+" "+count+" "+bytesRead+" "+skipAttempts);
			}
		}
		byteCount = width*height*bytesPerPixel;
		if (fi.fileType==FileInfo.BITMAP) {
 			int scan=width/8, pad = width%8;
			if (pad>0) scan++;
			byteCount = scan*height;
		}
		nPixels = width*height;
		bufferSize = byteCount/25;
		if (bufferSize<8192)
			bufferSize = 8192;
		else
			bufferSize = (bufferSize/8192)*8192;
	}
	
	/** 
	Reads the image from the InputStream and returns the pixel
	array (byte, short, int or float). Returns null if there
	was an IO exception. Does not close the InputStream.
	*/
	public Object readPixels(InputStream in) {
		Object pixels;
		startTime = System.currentTimeMillis();
		try {
			switch (fi.fileType) {
				case FileInfo.GRAY8:
				case FileInfo.COLOR8:
					bytesPerPixel = 1;
					skip(in);
					pixels = (Object)read8bitImage(in);
					break;
				case FileInfo.GRAY16_SIGNED:
				case FileInfo.GRAY16_UNSIGNED:
					bytesPerPixel = 2;
					skip(in);
					pixels = (Object)read16bitImage(in);
					break;
				case FileInfo.GRAY32_INT:
				case FileInfo.GRAY32_UNSIGNED:
				case FileInfo.GRAY32_FLOAT:
					bytesPerPixel = 4;
					skip(in);
					pixels = (Object)read32bitImage(in);
					break;
				case FileInfo.GRAY64_FLOAT:
					bytesPerPixel = 8;
					skip(in);
					pixels = (Object)read64bitImage(in);
					break;
				case FileInfo.RGB:
				case FileInfo.BGR:
				case FileInfo.ARGB:
				case FileInfo.BARG:
					bytesPerPixel = fi.getBytesPerPixel();
					skip(in);
					pixels = (Object)readChunkyRGB(in);
					break;
				case FileInfo.RGB_PLANAR:
					bytesPerPixel = 3;
					skip(in);
					pixels = (Object)readPlanarRGB(in);
					break;
				case FileInfo.BITMAP:
					bytesPerPixel = 1;
					skip(in);
					pixels = (Object)read1bitImage(in);
					break;
				case FileInfo.RGB48:
					bytesPerPixel = 6;
					skip(in);
					pixels = (Object)readRGB48(in);
					break;
				case FileInfo.RGB48_PLANAR:
					bytesPerPixel = 2;
					skip(in);
					pixels = (Object)readRGB48Planar(in);
					break;
				case FileInfo.GRAY12_UNSIGNED:
					skip(in);
					short[] data = read12bitImage(in);
					pixels = (Object)data;
					break;
				case FileInfo.GRAY24_UNSIGNED:
					skip(in);
					pixels = (Object)read24bitImage(in);
					break;
				default:
					pixels = null;
			}
			showProgress(1, 1);
			return pixels;
		}
		catch (IOException e) {
			IJ.log("" + e);
			return null;
		}
	}
	
	/** 
	Skips the specified number of bytes, then reads an image and 
	returns the pixel array (byte, short, int or float). Returns
	null if there was an IO exception. Does not close the InputStream.
	*/
	public Object readPixels(InputStream in, long skipCount) {
		this.skipCount = skipCount;
		showProgressBar = false;
		Object pixels = readPixels(in);
		if (eofErrorCount>0)
			return null;
		else
			return pixels;
	}
	
	/** 
	Reads the image from a URL and returns the pixel array (byte, 
	short, int or float). Returns null if there was an IO exception.
	*/
	public Object readPixels(String url) {
		java.net.URL theURL;
		InputStream is;
		try {theURL = new URL(url);}
		catch (MalformedURLException e) {IJ.log(""+e); return null;}
		try {is = theURL.openStream();}
		catch (IOException e) {IJ.log(""+e); return null;}
		return readPixels(is);
	}
	
  /**
 * Utility method for decoding an LZW-compressed image strip. 
 * Adapted from the TIFF 6.0 Specification:
 * http://partners.adobe.com/asn/developer/pdfs/tn/TIFF6.pdf (page 61)
 * @author Curtis Rueden (ctrueden at wisc.edu)
 */
	public byte[] lzwUncompress(byte[] input) {
		if (input == null || input.length == 0)
			return input;
		byte[][] symbolTable = new byte[4096][1];
		int bitsToRead = 9;
		int nextSymbol = 258;
		int code;
		int oldCode = -1;
		ByteVector out = new ByteVector(8192);
		BitBuffer bb = new BitBuffer(input);
		byte[] byteBuffer1 = new byte[16];
		byte[] byteBuffer2 = new byte[16];
		
		while (true) {
			code = bb.getBits(bitsToRead);
			if (code == EOI_CODE || code == -1)
				break;
			if (code == CLEAR_CODE) {
				// initialize symbol table
				for (int i = 0; i < 256; i++)
					symbolTable[i][0] = (byte)i;
				nextSymbol = 258;
				bitsToRead = 9;
				code = bb.getBits(bitsToRead);
				if (code == EOI_CODE || code == -1)
					break;
				out.add(symbolTable[code]);
				oldCode = code;
			} else {
				if (code < nextSymbol) {
					// code is in table
					out.add(symbolTable[code]);
					// add string to table
					ByteVector symbol = new ByteVector(byteBuffer1);
					symbol.add(symbolTable[oldCode]);
					symbol.add(symbolTable[code][0]);
					symbolTable[nextSymbol] = symbol.toByteArray(); //**
					oldCode = code;
					nextSymbol++;
				} else {
					// out of table
					ByteVector symbol = new ByteVector(byteBuffer2);
					symbol.add(symbolTable[oldCode]);
					symbol.add(symbolTable[oldCode][0]);
					byte[] outString = symbol.toByteArray();
					out.add(outString);
					symbolTable[nextSymbol] = outString; //**
					oldCode = code;
					nextSymbol++;
				}
				if (nextSymbol == 511) { bitsToRead = 10; }
				if (nextSymbol == 1023) { bitsToRead = 11; }
				if (nextSymbol == 2047) { bitsToRead = 12; }
			}
		}
		return out.toByteArray();
	}
 
}

/** A growable array of bytes. */
class ByteVector {
	private byte[] data;
	private int size;

	public ByteVector() {
		data = new byte[10];
		size = 0;
	}

	public ByteVector(int initialSize) {
		data = new byte[initialSize];
		size = 0;
	}

	public ByteVector(byte[] byteBuffer) {
		data = byteBuffer;
		size = 0;
	}

	public void add(byte x) {
		if (size>=data.length) {
			doubleCapacity();
			add(x);
		} else
			data[size++] = x;
	}

	public int size() {
		return size;
	}

	public void add(byte[] array) {
		int length = array.length;
		while (data.length-size<length)
	    	doubleCapacity();
		System.arraycopy(array, 0, data, size, length);
		size += length;
    }

	void doubleCapacity() {
		//IJ.log("double: "+data.length*2);
		byte[] tmp = new byte[data.length*2 + 1];
		System.arraycopy(data, 0, tmp, 0, data.length);
		data = tmp;
	}

	public void clear() {
		size = 0;
	}

	public byte[] toByteArray() {
		byte[] bytes = new byte[size];
		System.arraycopy(data, 0, bytes, 0, size);
		return bytes;
	}

}

