Jsp实现动态验证码(由5个类组成的gif动验证码)

1、先将“gif验证码辅助类(4个)”，复制到src文件夹下(最好在该文件夹下建一个util包)
2、再在这个文件夹下添加一个类叫GifValidateCode。类它是用来在jsp页面直接调用GifValidateCode类的getValidateCode()方法来生成图片的。

3、用code.jsp页面来构造GIF图片。

4、在其他(登录或注册)页面以图片的形式引用code.jsp页面 。

 以下只是一个主要类(GifValidateCode类)、一个jsp页面和一个html页面。 

import java.awt.*; import java.io.*; import java.util.Date; import java.util.*; import java.awt.image.*; public class GifValidateCode { //定义验证码字符。去除了O和I等容易混淆的字母（也可写成） String[] s = {"A", "B", "C", "D", "E", "F", "G", "H", "G", "K","M", "N", "P", "Q", "R", "S", "T", "U", "V", "W","X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g","h", "i", "j", "k", "m", "n", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "1", "2", "3", "4", "5", "6", "7", "8", "9", "地", "在", "要", "工", "上", "是", "中", "国", "不", "这"}; //定义生成的验证码的宽度和高度 int width = 160; int height = 35; /** * 获得(生成)GIF验证码 * @param os * @return String 系统自动生成的验证码的内容 */ public String getValidateCode(OutputStream os) { BufferedImage frame = null; @SuppressWarnings("unused") Graphics2D teg = null; @SuppressWarnings("unused") AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1); AnimatedGifEncoder agf = new AnimatedGifEncoder(); agf.start(os); agf.setQuality(10); agf.setDelay(100); agf.setRepeat(0); // 生成6个随机字符 String rands[] = new String[6]; for (int i = 0; i < 6; i++) { rands[i] = s[this.randomInt(0, s.length)]; } //分别使用6种字体 Font[] font = new Font[6]; font[0] = new Font("Gungsuh", Font.BOLD, 24); font[1] = new Font("宋体", Font.BOLD, 24); font[2] = new Font("Times New Roman", Font.BOLD, 24); font[3] = new Font("隶书", Font.BOLD, 24); font[4] = new Font("Arial Unicode MS", Font.BOLD, 24); font[5] = new Font("方正舒体", Font.BOLD, 24); //生成各种颜色 Color bgcolor = new Color(255,255,255); Color linecolor = getRandColor(200, 250); Color fontcolor[] = new Color[6]; Random random = new Random(); for (int i = 0; i < 6; i++) { fontcolor[i] = new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)); } //生成Gif信息类 for (int i = 0; i < font.length; i++) { frame = this.getImage(bgcolor, linecolor, fontcolor, rands, font, i); agf.addFrame(frame); frame.flush(); } agf.finish(); String fonts = rands[0] + rands[1]+rands[2]+rands[3]+rands[4]+rands[5]; return fonts; } /* * // 随机产生150个干扰点 g.setColor(Color.gray); Random rand = new Random(); for (int i = 0; i < 150; i++) { g.setColor(new Color(0x123456));//设置干扰点的颜色 int x = rand.nextInt(width); int y = rand.nextInt(height); g.drawOval(x, y, 1, 1); //可以使用干扰线等其他的方式只是调用不同的方法而已 } Random rnd = new Random(new Date().getTime()); for(int i=0;i<10;i++){ // g.setColor(getRandomColor(100, 155)); //随机线条的颜色 int x1 = rnd.nextInt(width); //线条两端坐标值 int y1 = rnd.nextInt(height); int x2 = rnd.nextInt(width); int y2 = rnd.nextInt(height); g.drawLine(x1, y1, x2, y2); //画线条 } * */ //out.clear(); //out = pageContext.pushBody(); /** * 获得图片缓冲 * @param bgcolor 背景颜色 * @param linecolor 背景线的颜色 * @param fontcolor 字体颜色 * @param str * @param font 字体 * @param flag * @return BufferedImage */ private BufferedImage getImage(Color bgcolor, Color linecolor,Color[] fontcolor, String[] str, Font[] font,int flag) { BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //或得图形上下文 Graphics2D g2d = image.createGraphics(); //利用指定颜色填充背景 g2d.setColor(bgcolor); g2d.fillRect(0, 0, width, height); //画背景线 3*3 (数字越大格子越密) g2d.setColor(linecolor); for (int i = 0; i < height / 3; i++) g2d.drawLine(0, i * 3, width, i * 3); for (int i = 0; i < width / 3; i++) g2d.drawLine(i * 3, 0, i * 3, height); // 画背景LOGO /*AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.2f); g2d.setComposite(ac); g2d.setFont(new Font("隶书", Font.ITALIC + Font.BOLD, 26)); g2d.setColor(Color.red); g2d.drawString("HAHA小组", 19, 25);*/ //以下生成验证码 //透明度从0 循环到1 步长为0.2 。一共6个字母 //int[] height ={23,31,27,22,25,29}; int[] height = new int[6]; Random rand = new Random(); for(int i=0; i<6; i++){ height[i] = rand.nextInt(15) + 20; } AlphaComposite ac3 = null; for (int i = 0; i < str.length; i++) { g2d.setFont(font[i]); ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, getAlpha(flag, i)); g2d.setComposite(ac3); g2d.setColor(fontcolor[i]); g2d.drawString(str[i], 25 * i + 8, height[i]); } // 随机产生20个干扰点 for (int i = 0; i < 200; i++) { g2d.setColor(new Color(0x123456));//设置干扰点的随机颜色 int x = rand.nextInt(width); int y = rand.nextInt(this.height); g2d.drawOval(x, y, 1, 1); //可以使用干扰线等其他的方式只是调用不同的方法而已 } // 画15条干扰线 Random rnd = new Random(new Date().getTime()); for(int i=0;i<15;i++){ g2d.setColor(getRandColor(100, 155)); //设置干扰线的随机颜色 int x1 = rnd.nextInt(width); //线条两端坐标值 int y1 = rnd.nextInt(this.height); int x2 = rnd.nextInt(width); int y2 = rnd.nextInt(this.height); g2d.drawLine(x1, y1, x2, y2); //画线条 } g2d.dispose(); return image; } /** * 获得循环透明度，从0到1 步长为0.2 * @param i * @param j * @return float */ private float getAlpha(int i, int j) { if ((i + j) > 5) return ((i + j) * 0.2f - 1.2f); else return (i + j) * 0.2f; } /** * 获得随机颜色 * @param fc 给定范围获得随机颜色 * @param bc 给定范围获得随机颜色 * @return Color */ private Color getRandColor(int fc, int bc) { Random random = new Random(); if (fc > 255) fc = 255; if (bc > 255) bc = 255; int r = fc + random.nextInt(bc - fc); int g = fc + random.nextInt(bc - fc); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } /** * 产生随机数 * 返回[from,to)之间的一个随机整数 * @param from 起始值 * @param to 结束值 * @return [from,to)之间的一个随机整数 */ Random r = new Random(); private int randomInt(int from, int to) { return from + r.nextInt(to - from); } }

下面是一个code.jsp页面的全部代码

<%@ page contentType="text/html" pageEncoding="GBK" import="java.util.*,javax.imageio.*,java.io.*,java.awt.*, java.awt.image.*,com.accp.shi.validatecode.*"%> <% GifValidateCode gvc = new GifValidateCode(); OutputStream stream = response.getOutputStream(); // 获得输出流 String code = gvc.getValidateCode(stream); out.clear(); //释放在jsp中使用的对象 out = pageContext.pushBody(); //释放在jsp中使用的对象 %>

以下是一个html页面，是用于用户注册用的(根据实际情况可添加一些选项)
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <mce:script type="text/javascript"><!-- function changeValidateCode() { var imgCode = document.getElementById("imgCode"); imgCode.src = "code.jsp?s="+new Date().getTime(); //当点击换一张时可清空缓存中的原有页面，所以添加了一个时间作为参数传过去 } // --></mce:script> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <form action=""> 用户名：<input type="text" name="txtName"><br> 密　码：<input type="password" name="txtPassword"><br> <img alt="验证码" src="code.jsp" mce_src="code.jsp" id="imgCode"><a href="javascript:changeValidateCode()" mce_href="javascript:changeValidateCode()">看不清，换一张</a><br> <input type="submit" value="注 册"> </form> </body> </html>

下面是4个辅助类

之一：AnimatedGifEncoder.java类

package com.accp.bookshop.util; import java.io.*; import java.awt.*; import java.awt.image.*; /** * Class AnimatedGifEncoder - Encodes a GIF file consisting of one or * more frames. * <pre> * Example: * AnimatedGifEncoder e = new AnimatedGifEncoder(); * e.start(outputFileName); * e.setDelay(1000); // 1 frame per sec * e.addFrame(image1); * e.addFrame(image2); * e.finish(); * </pre> * No copyright asserted on the source code of this class. May be used * for any purpose, however, refer to the Unisys LZW patent for restrictions * on use of the associated LZWEncoder class. Please forward any corrections * to kweiner@fmsware.com. * * @author Kevin Weiner, FM Software * @version 1.03 November 2003 * */ public class AnimatedGifEncoder { protected int width; // image size protected int height; protected Color transparent = null; // transparent color if given protected int transIndex; // transparent index in color table protected int repeat = -1; // no repeat protected int delay = 0; // frame delay (hundredths) protected boolean started = false; // ready to output frames protected OutputStream out; protected BufferedImage image; // current frame protected byte[] pixels; // BGR byte array from frame protected byte[] indexedPixels; // converted frame indexed to palette protected int colorDepth; // number of bit planes protected byte[] colorTab; // RGB palette protected boolean[] usedEntry = new boolean[256]; // active palette entries protected int palSize = 7; // color table size (bits-1) protected int dispose = -1; // disposal code (-1 = use default) protected boolean closeStream = false; // close stream when finished protected boolean firstFrame = true; protected boolean sizeSet = false; // if false, get size from first frame protected int sample = 10; // default sample interval for quantizer /** * Sets the delay time between each frame, or changes it * for subsequent frames (applies to last frame added). * * @param ms int delay time in milliseconds */ public void setDelay(int ms) { delay = Math.round(ms / 10.0f); } /** * Sets the GIF frame disposal code for the last added frame * and any subsequent frames. Default is 0 if no transparent * color has been set, otherwise 2. * @param code int disposal code. */ public void setDispose(int code) { if (code >= 0) { dispose = code; } } /** * Sets the number of times the set of GIF frames * should be played. Default is 1; 0 means play * indefinitely. Must be invoked before the first * image is added. * * @param iter int number of iterations. * @return */ public void setRepeat(int iter) { if (iter >= 0) { repeat = iter; } } /** * Sets the transparent color for the last added frame * and any subsequent frames. * Since all colors are subject to modification * in the quantization process, the color in the final * palette for each frame closest to the given color * becomes the transparent color for that frame. * May be set to null to indicate no transparent color. * * @param c Color to be treated as transparent on display. */ public void setTransparent(Color c) { transparent = c; } /** * Adds next GIF frame. The frame is not written immediately, but is * actually deferred until the next frame is received so that timing * data can be inserted. Invoking <code>finish()</code> flushes all * frames. If <code>setSize</code> was not invoked, the size of the * first image is used for all subsequent frames. * * @param im BufferedImage containing frame to write. * @return true if successful. */ public boolean addFrame(BufferedImage im) { if ((im == null) || !started) { return false; } boolean ok = true; try { if (!sizeSet) { // use first frame's size setSize(im.getWidth(), im.getHeight()); } image = im; getImagePixels(); // convert to correct format if necessary analyzePixels(); // build color table & map pixels if (firstFrame) { writeLSD(); // logical screen descriptior writePalette(); // global color table if (repeat >= 0) { // use NS app extension to indicate reps writeNetscapeExt(); } } writeGraphicCtrlExt(); // write graphic control extension writeImageDesc(); // image descriptor if (!firstFrame) { writePalette(); // local color table } writePixels(); // encode and write pixel data firstFrame = false; } catch (IOException e) { ok = false; } return ok; } /** * Flushes any pending data and closes output file. * If writing to an OutputStream, the stream is not * closed. */ public boolean finish() { if (!started) return false; boolean ok = true; started = false; try { out.write(0x3b); // gif trailer out.flush(); if (closeStream) { out.close(); } } catch (IOException e) { ok = false; } // reset for subsequent use transIndex = 0; out = null; image = null; pixels = null; indexedPixels = null; colorTab = null; closeStream = false; firstFrame = true; return ok; } /** * Sets frame rate in frames per second. Equivalent to * <code>setDelay(1000/fps)</code>. * * @param fps float frame rate (frames per second) */ public void setFrameRate(float fps) { if (fps != 0f) { delay = Math.round(100f / fps); } } /** * Sets quality of color quantization (conversion of images * to the maximum 256 colors allowed by the GIF specification). * Lower values (minimum = 1) produce better colors, but slow * processing significantly. 10 is the default, and produces * good color mapping at reasonable speeds. Values greater * than 20 do not yield significant improvements in speed. * * @param quality int greater than 0. * @return */ public void setQuality(int quality) { if (quality < 1) quality = 1; sample = quality; } /** * Sets the GIF frame size. The default size is the * size of the first frame added if this method is * not invoked. * * @param w int frame width. * @param h int frame width. */ public void setSize(int w, int h) { if (started && !firstFrame) return; width = w; height = h; if (width < 1) width = 320; if (height < 1) height = 240; sizeSet = true; } /** * Initiates GIF file creation on the given stream. The stream * is not closed automatically. * * @param os OutputStream on which GIF images are written. * @return false if initial write failed. */ public boolean start(OutputStream os) { if (os == null) return false; boolean ok = true; closeStream = false; out = os; try { writeString("GIF89a"); // header } catch (IOException e) { ok = false; } return started = ok; } /** * Initiates writing of a GIF file with the specified name. * * @param file String containing output file name. * @return false if open or initial write failed. */ public boolean start(String file) { boolean ok = true; try { out = new BufferedOutputStream(new FileOutputStream(file)); ok = start(out); closeStream = true; } catch (IOException e) { ok = false; } return started = ok; } /** * Analyzes image colors and creates color map. */ protected void analyzePixels() { int len = pixels.length; int nPix = len / 3; indexedPixels = new byte[nPix]; NeuQuant nq = new NeuQuant(pixels, len, sample); // initialize quantizer colorTab = nq.process(); // create reduced palette // convert map from BGR to RGB for (int i = 0; i < colorTab.length; i += 3) { byte temp = colorTab[i]; colorTab[i] = colorTab[i + 2]; colorTab[i + 2] = temp; usedEntry[i / 3] = false; } // map image pixels to new palette int k = 0; for (int i = 0; i < nPix; i++) { int index = nq.map(pixels[k++] & 0xff, pixels[k++] & 0xff, pixels[k++] & 0xff); usedEntry[index] = true; indexedPixels[i] = (byte) index; } pixels = null; colorDepth = 8; palSize = 7; // get closest match to transparent color if specified if (transparent != null) { transIndex = findClosest(transparent); } } /** * Returns index of palette color closest to c * */ protected int findClosest(Color c) { if (colorTab == null) return -1; int r = c.getRed(); int g = c.getGreen(); int b = c.getBlue(); int minpos = 0; int dmin = 256 * 256 * 256; int len = colorTab.length; for (int i = 0; i < len;) { int dr = r - (colorTab[i++] & 0xff); int dg = g - (colorTab[i++] & 0xff); int db = b - (colorTab[i] & 0xff); int d = dr * dr + dg * dg + db * db; int index = i / 3; if (usedEntry[index] && (d < dmin)) { dmin = d; minpos = index; } i++; } return minpos; } /** * Extracts image pixels into byte array "pixels" */ protected void getImagePixels() { int w = image.getWidth(); int h = image.getHeight(); int type = image.getType(); if ((w != width) || (h != height) || (type != BufferedImage.TYPE_3BYTE_BGR)) { // create new image with right size/format BufferedImage temp = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR); Graphics2D g = temp.createGraphics(); g.drawImage(image, 0, 0, null); image = temp; } pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData(); } /** * Writes Graphic Control Extension */ protected void writeGraphicCtrlExt() throws IOException { out.write(0x21); // extension introducer out.write(0xf9); // GCE label out.write(4); // data block size int transp, disp; if (transparent == null) { transp = 0; disp = 0; // dispose = no action } else { transp = 1; disp = 2; // force clear if using transparent color } if (dispose >= 0) { disp = dispose & 7; // user override } disp <<= 2; // packed fields out.write(0 | // 1:3 reserved disp | // 4:6 disposal 0 | // 7 user input - 0 = none transp); // 8 transparency flag writeShort(delay); // delay x 1/100 sec out.write(transIndex); // transparent color index out.write(0); // block terminator } /** * Writes Image Descriptor */ protected void writeImageDesc() throws IOException { out.write(0x2c); // image separator writeShort(0); // image position x,y = 0,0 writeShort(0); writeShort(width); // image size writeShort(height); // packed fields if (firstFrame) { // no LCT - GCT is used for first (or only) frame out.write(0); } else { // specify normal LCT out.write(0x80 | // 1 local color table 1=yes 0 | // 2 interlace - 0=no 0 | // 3 sorted - 0=no 0 | // 4-5 reserved palSize); // 6-8 size of color table } } /** * Writes Logical Screen Descriptor */ protected void writeLSD() throws IOException { // logical screen size writeShort(width); writeShort(height); // packed fields out.write((0x80 | // 1 : global color table flag = 1 (gct used) 0x70 | // 2-4 : color resolution = 7 0x00 | // 5 : gct sort flag = 0 palSize)); // 6-8 : gct size out.write(0); // background color index out.write(0); // pixel aspect ratio - assume 1:1 } /** * Writes Netscape application extension to define * repeat count. */ protected void writeNetscapeExt() throws IOException { out.write(0x21); // extension introducer out.write(0xff); // app extension label out.write(11); // block size writeString("NETSCAPE" + "2.0"); // app id + auth code out.write(3); // sub-block size out.write(1); // loop sub-block id writeShort(repeat); // loop count (extra iterations, 0=repeat forever) out.write(0); // block terminator } /** * Writes color table */ protected void writePalette() throws IOException { out.write(colorTab, 0, colorTab.length); int n = (3 * 256) - colorTab.length; for (int i = 0; i < n; i++) { out.write(0); } } /** * Encodes and writes pixel data */ protected void writePixels() throws IOException { LZWEncoder encoder = new LZWEncoder(width, height, indexedPixels, colorDepth); encoder.encode(out); } /** * Write 16-bit value to output stream, LSB first */ protected void writeShort(int value) throws IOException { out.write(value & 0xff); out.write((value >> 8) & 0xff); } /** * Writes string to output stream */ protected void writeString(String s) throws IOException { for (int i = 0; i < s.length(); i++) { out.write((byte) s.charAt(i)); } } }

之二：GifDecoder.java类

package com.accp.bookshop.util; import java.net.*; import java.io.*; import java.util.*; import java.awt.*; import java.awt.image.*; /** * Class GifDecoder - Decodes a GIF file into one or more frames. * <br><pre> * Example: * GifDecoder d = new GifDecoder(); * d.read("sample.gif"); * int n = d.getFrameCount(); * for (int i = 0; i < n; i++) { * BufferedImage frame = d.getFrame(i); // frame i * int t = d.getDelay(i); // display duration of frame in milliseconds * // do something with frame * } * </pre> * No copyright asserted on the source code of this class. May be used for * any purpose, however, refer to the Unisys LZW patent for any additional * restrictions. Please forward any corrections to kweiner@fmsware.com. * * @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's ImageMagick. * @version 1.03 November 2003 * */ public class GifDecoder { /** * File read status: No errors. */ public static final int STATUS_OK = 0; /** * File read status: Error decoding file (may be partially decoded) */ public static final int STATUS_FORMAT_ERROR = 1; /** * File read status: Unable to open source. */ public static final int STATUS_OPEN_ERROR = 2; protected BufferedInputStream in; protected int status; protected int width; // full image width protected int height; // full image height protected boolean gctFlag; // global color table used protected int gctSize; // size of global color table protected int loopCount = 1; // iterations; 0 = repeat forever protected int[] gct; // global color table protected int[] lct; // local color table protected int[] act; // active color table protected int bgIndex; // background color index protected int bgColor; // background color protected int lastBgColor; // previous bg color protected int pixelAspect; // pixel aspect ratio protected boolean lctFlag; // local color table flag protected boolean interlace; // interlace flag protected int lctSize; // local color table size protected int ix, iy, iw, ih; // current image rectangle protected Rectangle lastRect; // last image rect protected BufferedImage image; // current frame protected BufferedImage lastImage; // previous frame protected byte[] block = new byte[256]; // current data block protected int blockSize = 0; // block size // last graphic control extension info protected int dispose = 0; // 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev protected int lastDispose = 0; protected boolean transparency = false; // use transparent color protected int delay = 0; // delay in milliseconds protected int transIndex; // transparent color index protected static final int MaxStackSize = 4096; // max decoder pixel stack size // LZW decoder working arrays protected short[] prefix; protected byte[] suffix; protected byte[] pixelStack; protected byte[] pixels; protected ArrayList frames; // frames read from current file protected int frameCount; static class GifFrame { public GifFrame(BufferedImage im, int del) { image = im; delay = del; } public BufferedImage image; public int delay; } /** * Gets display duration for specified frame. * * @param n int index of frame * @return delay in milliseconds */ public int getDelay(int n) { // delay = -1; if ((n >= 0) && (n < frameCount)) { delay = ((GifFrame) frames.get(n)).delay; } return delay; } /** * Gets the number of frames read from file. * @return frame count */ public int getFrameCount() { return frameCount; } /** * Gets the first (or only) image read. * * @return BufferedImage containing first frame, or null if none. */ public BufferedImage getImage() { return getFrame(0); } /** * Gets the "Netscape" iteration count, if any. * A count of 0 means repeat indefinitiely. * * @return iteration count if one was specified, else 1. */ public int getLoopCount() { return loopCount; } /** * Creates new frame image from current data (and previous * frames as specified by their disposition codes). */ protected void setPixels() { // expose destination image's pixels as int array int[] dest = ((DataBufferInt) image.getRaster().getDataBuffer()).getData(); // fill in starting image contents based on last image's dispose code if (lastDispose > 0) { if (lastDispose == 3) { // use image before last int n = frameCount - 2; if (n > 0) { lastImage = getFrame(n - 1); } else { lastImage = null; } } if (lastImage != null) { int[] prev = ((DataBufferInt) lastImage.getRaster().getDataBuffer()).getData(); System.arraycopy(prev, 0, dest, 0, width * height); // copy pixels if (lastDispose == 2) { // fill last image rect area with background color Graphics2D g = image.createGraphics(); Color c = null; if (transparency) { c = new Color(0, 0, 0, 0); // assume background is transparent } else { c = new Color(lastBgColor); // use given background color } g.setColor(c); g.setComposite(AlphaComposite.Src); // replace area g.fill(lastRect); g.dispose(); } } } // copy each source line to the appropriate place in the destination int pass = 1; int inc = 8; int iline = 0; for (int i = 0; i < ih; i++) { int line = i; if (interlace) { if (iline >= ih) { pass++; switch (pass) { case 2 : iline = 4; break; case 3 : iline = 2; inc = 4; break; case 4 : iline = 1; inc = 2; } } line = iline; iline += inc; } line += iy; if (line < height) { int k = line * width; int dx = k + ix; // start of line in dest int dlim = dx + iw; // end of dest line if ((k + width) < dlim) { dlim = k + width; // past dest edge } int sx = i * iw; // start of line in source while (dx < dlim) { // map color and insert in destination int index = ((int) pixels[sx++]) & 0xff; int c = act[index]; if (c != 0) { dest[dx] = c; } dx++; } } } } /** * Gets the image contents of frame n. * * @return BufferedImage representation of frame, or null if n is invalid. */ public BufferedImage getFrame(int n) { BufferedImage im = null; if ((n >= 0) && (n < frameCount)) { im = ((GifFrame) frames.get(n)).image; } return im; } /** * Gets image size. * * @return GIF image dimensions */ public Dimension getFrameSize() { return new Dimension(width, height); } /** * Reads GIF image from stream * * @param BufferedInputStream containing GIF file. * @return read status code (0 = no errors) */ public int read(BufferedInputStream is) { init(); if (is != null) { in = is; readHeader(); if (!err()) { readContents(); if (frameCount < 0) { status = STATUS_FORMAT_ERROR; } } } else { status = STATUS_OPEN_ERROR; } try { is.close(); } catch (IOException e) { } return status; } /** * Reads GIF image from stream * * @param InputStream containing GIF file. * @return read status code (0 = no errors) */ public int read(InputStream is) { init(); if (is != null) { if (!(is instanceof BufferedInputStream)) is = new BufferedInputStream(is); in = (BufferedInputStream) is; readHeader(); if (!err()) { readContents(); if (frameCount < 0) { status = STATUS_FORMAT_ERROR; } } } else { status = STATUS_OPEN_ERROR; } try { is.close(); } catch (IOException e) { } return status; } /** * Reads GIF file from specified file/URL source * (URL assumed if name contains ":/" or "file:") * * @param name String containing source * @return read status code (0 = no errors) */ public int read(String name) { status = STATUS_OK; try { name = name.trim().toLowerCase(); if ((name.indexOf("file:") >= 0) || (name.indexOf(":/") > 0)) { URL url = new URL(name); in = new BufferedInputStream(url.openStream()); } else { in = new BufferedInputStream(new FileInputStream(name)); } status = read(in); } catch (IOException e) { status = STATUS_OPEN_ERROR; } return status; } /** * Decodes LZW image data into pixel array. * Adapted from John Cristy's ImageMagick. */ protected void decodeImageData() { int NullCode = -1; int npix = iw * ih; int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi, pi; if ((pixels == null) || (pixels.length < npix)) { pixels = new byte[npix]; // allocate new pixel array } if (prefix == null) prefix = new short[MaxStackSize]; if (suffix == null) suffix = new byte[MaxStackSize]; if (pixelStack == null) pixelStack = new byte[MaxStackSize + 1]; // Initialize GIF data stream decoder. data_size = read(); clear = 1 << data_size; end_of_information = clear + 1; available = clear + 2; old_code = NullCode; code_size = data_size + 1; code_mask = (1 << code_size) - 1; for (code = 0; code < clear; code++) { prefix[code] = 0; suffix[code] = (byte) code; } // Decode GIF pixel stream. datum = bits = count = first = top = pi = bi = 0; for (i = 0; i < npix;) { if (top == 0) { if (bits < code_size) { // Load bytes until there are enough bits for a code. if (count == 0) { // Read a new data block. count = readBlock(); if (count <= 0) break; bi = 0; } datum += (((int) block[bi]) & 0xff) << bits; bits += 8; bi++; count--; continue; } // Get the next code. code = datum & code_mask; datum >>= code_size; bits -= code_size; // Interpret the code if ((code > available) || (code == end_of_information)) break; if (code == clear) { // Reset decoder. code_size = data_size + 1; code_mask = (1 << code_size) - 1; available = clear + 2; old_code = NullCode; continue; } if (old_code == NullCode) { pixelStack[top++] = suffix[code]; old_code = code; first = code; continue; } in_code = code; if (code == available) { pixelStack[top++] = (byte) first; code = old_code; } while (code > clear) { pixelStack[top++] = suffix[code]; code = prefix[code]; } first = ((int) suffix[code]) & 0xff; // Add a new string to the string table, if (available >= MaxStackSize) break; pixelStack[top++] = (byte) first; prefix[available] = (short) old_code; suffix[available] = (byte) first; available++; if (((available & code_mask) == 0) && (available < MaxStackSize)) { code_size++; code_mask += available; } old_code = in_code; } // Pop a pixel off the pixel stack. top--; pixels[pi++] = pixelStack[top]; i++; } for (i = pi; i < npix; i++) { pixels[i] = 0; // clear missing pixels } } /** * Returns true if an error was encountered during reading/decoding */ protected boolean err() { return status != STATUS_OK; } /** * Initializes or re-initializes reader */ protected void init() { status = STATUS_OK; frameCount = 0; frames = new ArrayList(); gct = null; lct = null; } /** * Reads a single byte from the input stream. */ protected int read() { int curByte = 0; try { curByte = in.read(); } catch (IOException e) { status = STATUS_FORMAT_ERROR; } return curByte; } /** * Reads next variable length block from input. * * @return number of bytes stored in "buffer" */ protected int readBlock() { blockSize = read(); int n = 0; if (blockSize > 0) { try { int count = 0; while (n < blockSize) { count = in.read(block, n, blockSize - n); if (count == -1) break; n += count; } } catch (IOException e) { } if (n < blockSize) { status = STATUS_FORMAT_ERROR; } } return n; } /** * Reads color table as 256 RGB integer values * * @param ncolors int number of colors to read * @return int array containing 256 colors (packed ARGB with full alpha) */ protected int[] readColorTable(int ncolors) { int nbytes = 3 * ncolors; int[] tab = null; byte[] c = new byte[nbytes]; int n = 0; try { n = in.read(c); } catch (IOException e) { } if (n < nbytes) { status = STATUS_FORMAT_ERROR; } else { tab = new int[256]; // max size to avoid bounds checks int i = 0; int j = 0; while (i < ncolors) { int r = ((int) c[j++]) & 0xff; int g = ((int) c[j++]) & 0xff; int b = ((int) c[j++]) & 0xff; tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b; } } return tab; } /** * Main file parser. Reads GIF content blocks. */ protected void readContents() { // read GIF file content blocks boolean done = false; while (!(done || err())) { int code = read(); switch (code) { case 0x2C : // image separator readImage(); break; case 0x21 : // extension code = read(); switch (code) { case 0xf9 : // graphics control extension readGraphicControlExt(); break; case 0xff : // application extension readBlock(); String app = ""; for (int i = 0; i < 11; i++) { app += (char) block[i]; } if (app.equals("NETSCAPE2.0")) { readNetscapeExt(); } else skip(); // don't care break; default : // uninteresting extension skip(); } break; case 0x3b : // terminator done = true; break; case 0x00 : // bad byte, but keep going and see what happens break; default : status = STATUS_FORMAT_ERROR; } } } /** * Reads Graphics Control Extension values */ protected void readGraphicControlExt() { read(); // block size int packed = read(); // packed fields dispose = (packed & 0x1c) >> 2; // disposal method if (dispose == 0) { dispose = 1; // elect to keep old image if discretionary } transparency = (packed & 1) != 0; delay = readShort() * 10; // delay in milliseconds transIndex = read(); // transparent color index read(); // block terminator } /** * Reads GIF file header information. */ protected void readHeader() { String id = ""; for (int i = 0; i < 6; i++) { id += (char) read(); } if (!id.startsWith("GIF")) { status = STATUS_FORMAT_ERROR; return; } readLSD(); if (gctFlag && !err()) { gct = readColorTable(gctSize); bgColor = gct[bgIndex]; } } /** * Reads next frame image */ protected void readImage() { ix = readShort(); // (sub)image position & size iy = readShort(); iw = readShort(); ih = readShort(); int packed = read(); lctFlag = (packed & 0x80) != 0; // 1 - local color table flag interlace = (packed & 0x40) != 0; // 2 - interlace flag // 3 - sort flag // 4-5 - reserved lctSize = 2 << (packed & 7); // 6-8 - local color table size if (lctFlag) { lct = readColorTable(lctSize); // read table act = lct; // make local table active } else { act = gct; // make global table active if (bgIndex == transIndex) bgColor = 0; } int save = 0; if (transparency) { save = act[transIndex]; act[transIndex] = 0; // set transparent color if specified } if (act == null) { status = STATUS_FORMAT_ERROR; // no color table defined } if (err()) return; decodeImageData(); // decode pixel data skip(); if (err()) return; frameCount++; // create new image to receive frame data image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB_PRE); setPixels(); // transfer pixel data to image frames.add(new GifFrame(image, delay)); // add image to frame list if (transparency) { act[transIndex] = save; } resetFrame(); } /** * Reads Logical Screen Descriptor */ protected void readLSD() { // logical screen size width = readShort(); height = readShort(); // packed fields int packed = read(); gctFlag = (packed & 0x80) != 0; // 1 : global color table flag // 2-4 : color resolution // 5 : gct sort flag gctSize = 2 << (packed & 7); // 6-8 : gct size bgIndex = read(); // background color index pixelAspect = read(); // pixel aspect ratio } /** * Reads Netscape extenstion to obtain iteration count */ protected void readNetscapeExt() { do { readBlock(); if (block[0] == 1) { // loop count sub-block int b1 = ((int) block[1]) & 0xff; int b2 = ((int) block[2]) & 0xff; loopCount = (b2 << 8) | b1; } } while ((blockSize > 0) && !err()); } /** * Reads next 16-bit value, LSB first */ protected int readShort() { // read 16-bit value, LSB first return read() | (read() << 8); } /** * Resets frame state for reading next image. */ protected void resetFrame() { lastDispose = dispose; lastRect = new Rectangle(ix, iy, iw, ih); lastImage = image; lastBgColor = bgColor; int dispose = 0; boolean transparency = false; int delay = 0; lct = null; } /** * Skips variable length blocks up to and including * next zero length block. */ protected void skip() { do { readBlock(); } while ((blockSize > 0) && !err()); } }

之三：LZWEncoder.java类

package com.accp.bookshop.util; import java.io.OutputStream; import java.io.IOException; //============================================================================== // Adapted from Jef Poskanzer's Java port by way of J. M. G. Elliott. // K Weiner 12/00 class LZWEncoder { private static final int EOF = -1; private int imgW, imgH; private byte[] pixAry; private int initCodeSize; private int remaining; private int curPixel; // GIFCOMPR.C - GIF Image compression routines // // Lempel-Ziv compression based on 'compress'. GIF modifications by // David Rowley (mgardi@watdcsu.waterloo.edu) // General DEFINEs static final int BITS = 12; static final int HSIZE = 5003; // 80% occupancy // GIF Image compression - modified 'compress' // // Based on: compress.c - File compression ala IEEE Computer, June 1984. // // By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas) // Jim McKie (decvax!mcvax!jim) // Steve Davies (decvax!vax135!petsd!peora!srd) // Ken Turkowski (decvax!decwrl!turtlevax!ken) // James A. Woods (decvax!ihnp4!ames!jaw) // Joe Orost (decvax!vax135!petsd!joe) int n_bits; // number of bits/code int maxbits = BITS; // user settable max # bits/code int maxcode; // maximum code, given n_bits int maxmaxcode = 1 << BITS; // should NEVER generate this code int[] htab = new int[HSIZE]; int[] codetab = new int[HSIZE]; int hsize = HSIZE; // for dynamic table sizing int free_ent = 0; // first unused entry // block compression parameters -- after all codes are used up, // and compression rate changes, start over. boolean clear_flg = false; // Algorithm: use open addressing double hashing (no chaining) on the // prefix code / next character combination. We do a variant of Knuth's // algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime // secondary probe. Here, the modular division first probe is gives way // to a faster exclusive-or manipulation. Also do block compression with // an adaptive reset, whereby the code table is cleared when the compression // ratio decreases, but after the table fills. The variable-length output // codes are re-sized at this point, and a special CLEAR code is generated // for the decompressor. Late addition: construct the table according to // file size for noticeable speed improvement on small files. Please direct // questions about this implementation to ames!jaw. int g_init_bits; int ClearCode; int EOFCode; // output // // Output the given code. // Inputs: // code: A n_bits-bit integer. If == -1, then EOF. This assumes // that n_bits =< wordsize - 1. // Outputs: // Outputs code to the file. // Assumptions: // Chars are 8 bits long. // Algorithm: // Maintain a BITS character long buffer (so that 8 codes will // fit in it exactly). Use the VAX insv instruction to insert each // code in turn. When the buffer fills up empty it and start over. int cur_accum = 0; int cur_bits = 0; int masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF }; // Number of characters so far in this 'packet' int a_count; // Define the storage for the packet accumulator byte[] accum = new byte[256]; //---------------------------------------------------------------------------- LZWEncoder(int width, int height, byte[] pixels, int color_depth) { imgW = width; imgH = height; pixAry = pixels; initCodeSize = Math.max(2, color_depth); } // Add a character to the end of the current packet, and if it is 254 // characters, flush the packet to disk. void char_out(byte c, OutputStream outs) throws IOException { accum[a_count++] = c; if (a_count >= 254) flush_char(outs); } // Clear out the hash table // table clear for block compress void cl_block(OutputStream outs) throws IOException { cl_hash(hsize); free_ent = ClearCode + 2; clear_flg = true; output(ClearCode, outs); } // reset code table void cl_hash(int hsize) { for (int i = 0; i < hsize; ++i) htab[i] = -1; } void compress(int init_bits, OutputStream outs) throws IOException { int fcode; int i /* = 0 */; int c; int ent; int disp; int hsize_reg; int hshift; // Set up the globals: g_init_bits - initial number of bits g_init_bits = init_bits; // Set up the necessary values clear_flg = false; n_bits = g_init_bits; maxcode = MAXCODE(n_bits); ClearCode = 1 << (init_bits - 1); EOFCode = ClearCode + 1; free_ent = ClearCode + 2; a_count = 0; // clear packet ent = nextPixel(); hshift = 0; for (fcode = hsize; fcode < 65536; fcode *= 2) ++hshift; hshift = 8 - hshift; // set hash code range bound hsize_reg = hsize; cl_hash(hsize_reg); // clear hash table output(ClearCode, outs); outer_loop : while ((c = nextPixel()) != EOF) { fcode = (c << maxbits) + ent; i = (c << hshift) ^ ent; // xor hashing if (htab[i] == fcode) { ent = codetab[i]; continue; } else if (htab[i] >= 0) // non-empty slot { disp = hsize_reg - i; // secondary hash (after G. Knott) if (i == 0) disp = 1; do { if ((i -= disp) < 0) i += hsize_reg; if (htab[i] == fcode) { ent = codetab[i]; continue outer_loop; } } while (htab[i] >= 0); } output(ent, outs); ent = c; if (free_ent < maxmaxcode) { codetab[i] = free_ent++; // code -> hashtable htab[i] = fcode; } else cl_block(outs); } // Put out the final code. output(ent, outs); output(EOFCode, outs); } //---------------------------------------------------------------------------- void encode(OutputStream os) throws IOException { os.write(initCodeSize); // write "initial code size" byte remaining = imgW * imgH; // reset navigation variables curPixel = 0; compress(initCodeSize + 1, os); // compress and write the pixel data os.write(0); // write block terminator } // Flush the packet to disk, and reset the accumulator void flush_char(OutputStream outs) throws IOException { if (a_count > 0) { outs.write(a_count); outs.write(accum, 0, a_count); a_count = 0; } } final int MAXCODE(int n_bits) { return (1 << n_bits) - 1; } //---------------------------------------------------------------------------- // Return the next pixel from the image //---------------------------------------------------------------------------- private int nextPixel() { if (remaining == 0) return EOF; --remaining; byte pix = pixAry[curPixel++]; return pix & 0xff; } void output(int code, OutputStream outs) throws IOException { cur_accum &= masks[cur_bits]; if (cur_bits > 0) cur_accum |= (code << cur_bits); else cur_accum = code; cur_bits += n_bits; while (cur_bits >= 8) { char_out((byte) (cur_accum & 0xff), outs); cur_accum >>= 8; cur_bits -= 8; } // If the next entry is going to be too big for the code size, // then increase it, if possible. if (free_ent > maxcode || clear_flg) { if (clear_flg) { maxcode = MAXCODE(n_bits = g_init_bits); clear_flg = false; } else { ++n_bits; if (n_bits == maxbits) maxcode = maxmaxcode; else maxcode = MAXCODE(n_bits); } } if (code == EOFCode) { // At EOF, write the rest of the buffer. while (cur_bits > 0) { char_out((byte) (cur_accum & 0xff), outs); cur_accum >>= 8; cur_bits -= 8; } flush_char(outs); } } }

之四：NeuQuant.java类

package com.accp.bookshop.util; /* NeuQuant Neural-Net Quantization Algorithm * ------------------------------------------ * * Copyright (c) 1994 Anthony Dekker * * NEUQUANT Neural-Net quantization algorithm by Anthony Dekker, 1994. * See "Kohonen neural networks for optimal colour quantization" * in "Network: Computation in Neural Systems" Vol. 5 (1994) pp 351-367. * for a discussion of the algorithm. * * Any party obtaining a copy of these files from the author, directly or * indirectly, is granted, free of charge, a full and unrestricted irrevocable, * world-wide, paid up, royalty-free, nonexclusive right and license to deal * in this software and documentation files (the "Software"), including without * limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons who receive * copies from any such party to do so, with the only requirement being * that this copyright notice remain intact. */ // Ported to Java 12/00 K Weiner public class NeuQuant { protected static final int netsize = 256; /* number of colours used */ /* four primes near 500 - assume no image has a length so large */ /* that it is divisible by all four primes */ protected static final int prime1 = 499; protected static final int prime2 = 491; protected static final int prime3 = 487; protected static final int prime4 = 503; protected static final int minpicturebytes = (3 * prime4); /* minimum size for input image */ /* Program Skeleton ---------------- [select samplefac in range 1..30] [read image from input file] pic = (unsigned char*) malloc(3*width*height); initnet(pic,3*width*height,samplefac); learn(); unbiasnet(); [write output image header, using writecolourmap(f)] inxbuild(); write output image using inxsearch(b,g,r) */ /* Network Definitions ------------------- */ protected static final int maxnetpos = (netsize - 1); protected static final int netbiasshift = 4; /* bias for colour values */ protected static final int ncycles = 100; /* no. of learning cycles */ /* defs for freq and bias */ protected static final int intbiasshift = 16; /* bias for fractions */ protected static final int intbias = (((int) 1) << intbiasshift); protected static final int gammashift = 10; /* gamma = 1024 */ protected static final int gamma = (((int) 1) << gammashift); protected static final int betashift = 10; protected static final int beta = (intbias >> betashift); /* beta = 1/1024 */ protected static final int betagamma = (intbias << (gammashift - betashift)); /* defs for decreasing radius factor */ protected static final int initrad = (netsize >> 3); /* for 256 cols, radius starts */ protected static final int radiusbiasshift = 6; /* at 32.0 biased by 6 bits */ protected static final int radiusbias = (((int) 1) << radiusbiasshift); protected static final int initradius = (initrad * radiusbias); /* and decreases by a */ protected static final int radiusdec = 30; /* factor of 1/30 each cycle */ /* defs for decreasing alpha factor */ protected static final int alphabiasshift = 10; /* alpha starts at 1.0 */ protected static final int initalpha = (((int) 1) << alphabiasshift); protected int alphadec; /* biased by 10 bits */ /* radbias and alpharadbias used for radpower calculation */ protected static final int radbiasshift = 8; protected static final int radbias = (((int) 1) << radbiasshift); protected static final int alpharadbshift = (alphabiasshift + radbiasshift); protected static final int alpharadbias = (((int) 1) << alpharadbshift); /* Types and Global Variables -------------------------- */ protected byte[] thepicture; /* the input image itself */ protected int lengthcount; /* lengthcount = H*W*3 */ protected int samplefac; /* sampling factor 1..30 */ // typedef int pixel[4]; /* BGRc */ protected int[][] network; /* the network itself - [netsize][4] */ protected int[] netindex = new int[256]; /* for network lookup - really 256 */ protected int[] bias = new int[netsize]; /* bias and freq arrays for learning */ protected int[] freq = new int[netsize]; protected int[] radpower = new int[initrad]; /* radpower for precomputation */ /* Initialise network in range (0,0,0) to (255,255,255) and set parameters ----------------------------------------------------------------------- */ public NeuQuant(byte[] thepic, int len, int sample) { int i; int[] p; thepicture = thepic; lengthcount = len; samplefac = sample; network = new int[netsize][]; for (i = 0; i < netsize; i++) { network[i] = new int[4]; p = network[i]; p[0] = p[1] = p[2] = (i << (netbiasshift + 8)) / netsize; freq[i] = intbias / netsize; /* 1/netsize */ bias[i] = 0; } } public byte[] colorMap() { byte[] map = new byte[3 * netsize]; int[] index = new int[netsize]; for (int i = 0; i < netsize; i++) index[network[i][3]] = i; int k = 0; for (int i = 0; i < netsize; i++) { int j = index[i]; map[k++] = (byte) (network[j][0]); map[k++] = (byte) (network[j][1]); map[k++] = (byte) (network[j][2]); } return map; } /* Insertion sort of network and building of netindex[0..255] (to do after unbias) ------------------------------------------------------------------------------- */ public void inxbuild() { int i, j, smallpos, smallval; int[] p; int[] q; int previouscol, startpos; previouscol = 0; startpos = 0; for (i = 0; i < netsize; i++) { p = network[i]; smallpos = i; smallval = p[1]; /* index on g */ /* find smallest in i..netsize-1 */ for (j = i + 1; j < netsize; j++) { q = network[j]; if (q[1] < smallval) { /* index on g */ smallpos = j; smallval = q[1]; /* index on g */ } } q = network[smallpos]; /* swap p (i) and q (smallpos) entries */ if (i != smallpos) { j = q[0]; q[0] = p[0]; p[0] = j; j = q[1]; q[1] = p[1]; p[1] = j; j = q[2]; q[2] = p[2]; p[2] = j; j = q[3]; q[3] = p[3]; p[3] = j; } /* smallval entry is now in position i */ if (smallval != previouscol) { netindex[previouscol] = (startpos + i) >> 1; for (j = previouscol + 1; j < smallval; j++) netindex[j] = i; previouscol = smallval; startpos = i; } } netindex[previouscol] = (startpos + maxnetpos) >> 1; for (j = previouscol + 1; j < 256; j++) netindex[j] = maxnetpos; /* really 256 */ } /* Main Learning Loop ------------------ */ public void learn() { int i, j, b, g, r; int radius, rad, alpha, step, delta, samplepixels; byte[] p; int pix, lim; if (lengthcount < minpicturebytes) samplefac = 1; alphadec = 30 + ((samplefac - 1) / 3); p = thepicture; pix = 0; lim = lengthcount; samplepixels = lengthcount / (3 * samplefac); delta = samplepixels / ncycles; alpha = initalpha; radius = initradius; rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (i = 0; i < rad; i++) radpower[i] = alpha * (((rad * rad - i * i) * radbias) / (rad * rad)); //fprintf(stderr,"beginning 1D learning: initial radius=%d/n", rad); if (lengthcount < minpicturebytes) step = 3; else if ((lengthcount % prime1) != 0) step = 3 * prime1; else { if ((lengthcount % prime2) != 0) step = 3 * prime2; else { if ((lengthcount % prime3) != 0) step = 3 * prime3; else step = 3 * prime4; } } i = 0; while (i < samplepixels) { b = (p[pix + 0] & 0xff) << netbiasshift; g = (p[pix + 1] & 0xff) << netbiasshift; r = (p[pix + 2] & 0xff) << netbiasshift; j = contest(b, g, r); altersingle(alpha, j, b, g, r); if (rad != 0) alterneigh(rad, j, b, g, r); /* alter neighbours */ pix += step; if (pix >= lim) pix -= lengthcount; i++; if (delta == 0) delta = 1; if (i % delta == 0) { alpha -= alpha / alphadec; radius -= radius / radiusdec; rad = radius >> radiusbiasshift; if (rad <= 1) rad = 0; for (j = 0; j < rad; j++) radpower[j] = alpha * (((rad * rad - j * j) * radbias) / (rad * rad)); } } //fprintf(stderr,"finished 1D learning: final alpha=%f !/n",((float)alpha)/initalpha); } /* Search for BGR values 0..255 (after net is unbiased) and return colour index ---------------------------------------------------------------------------- */ public int map(int b, int g, int r) { int i, j, dist, a, bestd; int[] p; int best; bestd = 1000; /* biggest possible dist is 256*3 */ best = -1; i = netindex[g]; /* index on g */ j = i - 1; /* start at netindex[g] and work outwards */ while ((i < netsize) || (j >= 0)) { if (i < netsize) { p = network[i]; dist = p[1] - g; /* inx key */ if (dist >= bestd) i = netsize; /* stop iter */ else { i++; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3]; } } } } if (j >= 0) { p = network[j]; dist = g - p[1]; /* inx key - reverse dif */ if (dist >= bestd) j = -1; /* stop iter */ else { j--; if (dist < 0) dist = -dist; a = p[0] - b; if (a < 0) a = -a; dist += a; if (dist < bestd) { a = p[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; best = p[3]; } } } } } return (best); } public byte[] process() { learn(); unbiasnet(); inxbuild(); return colorMap(); } /* Unbias network to give byte values 0..255 and record position i to prepare for sort ----------------------------------------------------------------------------------- */ public void unbiasnet() { int i, j; for (i = 0; i < netsize; i++) { network[i][0] >>= netbiasshift; network[i][1] >>= netbiasshift; network[i][2] >>= netbiasshift; network[i][3] = i; /* record colour no */ } } /* Move adjacent neurons by precomputed alpha*(1-((i-j)^2/[r]^2)) in radpower[|i-j|] --------------------------------------------------------------------------------- */ protected void alterneigh(int rad, int i, int b, int g, int r) { int j, k, lo, hi, a, m; int[] p; lo = i - rad; if (lo < -1) lo = -1; hi = i + rad; if (hi > netsize) hi = netsize; j = i + 1; k = i - 1; m = 1; while ((j < hi) || (k > lo)) { a = radpower[m++]; if (j < hi) { p = network[j++]; try { p[0] -= (a * (p[0] - b)) / alpharadbias; p[1] -= (a * (p[1] - g)) / alpharadbias; p[2] -= (a * (p[2] - r)) / alpharadbias; } catch (Exception e) { } // prevents 1.3 miscompilation } if (k > lo) { p = network[k--]; try { p[0] -= (a * (p[0] - b)) / alpharadbias; p[1] -= (a * (p[1] - g)) / alpharadbias; p[2] -= (a * (p[2] - r)) / alpharadbias; } catch (Exception e) { } } } } /* Move neuron i towards biased (b,g,r) by factor alpha ---------------------------------------------------- */ protected void altersingle(int alpha, int i, int b, int g, int r) { /* alter hit neuron */ int[] n = network[i]; n[0] -= (alpha * (n[0] - b)) / initalpha; n[1] -= (alpha * (n[1] - g)) / initalpha; n[2] -= (alpha * (n[2] - r)) / initalpha; } /* Search for biased BGR values ---------------------------- */ protected int contest(int b, int g, int r) { /* finds closest neuron (min dist) and updates freq */ /* finds best neuron (min dist-bias) and returns position */ /* for frequently chosen neurons, freq[i] is high and bias[i] is negative */ /* bias[i] = gamma*((1/netsize)-freq[i]) */ int i, dist, a, biasdist, betafreq; int bestpos, bestbiaspos, bestd, bestbiasd; int[] n; bestd = ~(((int) 1) << 31); bestbiasd = bestd; bestpos = -1; bestbiaspos = bestpos; for (i = 0; i < netsize; i++) { n = network[i]; dist = n[0] - b; if (dist < 0) dist = -dist; a = n[1] - g; if (a < 0) a = -a; dist += a; a = n[2] - r; if (a < 0) a = -a; dist += a; if (dist < bestd) { bestd = dist; bestpos = i; } biasdist = dist - ((bias[i]) >> (intbiasshift - netbiasshift)); if (biasdist < bestbiasd) { bestbiasd = biasdist; bestbiaspos = i; } betafreq = (freq[i] >> betashift); freq[i] -= betafreq; bias[i] += (betafreq << gammashift); } freq[bestpos] += beta; bias[bestpos] -= betagamma; return (bestbiaspos); } }