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lqshn

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[求助] 请教如何用matlab识别出一张曲线图上最高点对应的X,Y轴坐标已有14人参与

对于一张jpg图（例如下图），没有原始的数据，对于图中曲线，如何用matlab识别出最高点对应的X,Y轴坐标呢？我有很多这样的图，所以能编出程序或写出代码自动识别就好了，然后将坐标输出，请问谁有什么想法或者谁会吗？

ref.jpg

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Wormhole55

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【答案】应助回帖

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lqshn: 金币+1, ★有帮助 2015-06-16 13:16:18

试试泰勒公式，渐近线，高数课本里学过，可以模拟各种曲线的坐标，或者还有其他方法，具体的记不清了。这其实不仅是编程，更多的是对数学建模的理解和方法的选择，你可以找个学数学的专业人士讨论一下，肯定会有收获。
至于图像的扫描和像素的识别，编程方面没有什么大的难度，每个JPG 像素都是一个数值的形式储存的，对像素颜色数值进行分析就是了（个人想法，没试过）。windows 或c++ 或java 都有自己的类库专门做图像分析和处理的，是一些DLL 类库，直接拿来用就是了。一下是一个java例程，图片处理的，
Below is the syntax highlighted version of Picture.java from § Standard Libraries. Here is the Javadoc.

/*************************************************************************
* Compilation: javac Picture.java
* Execution: java Picture imagename
*
* Data type for manipulating individual pixels of an image. The original
* image can be read from a file in jpg, gif, or png format, or the
* user can create a blank image of a given size. Includes methods for
* displaying the image in a window on the screen or saving to a file.
*
* % java Picture mandrill.jpg
*
* Remarks
* -------
* - pixel (x, y) is column x and row y, where (0, 0) is upper left
*
* - see also GrayPicture.java for a grayscale version
*
*************************************************************************/

import java.awt.Color;
import java.awt.FileDialog;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.KeyStroke;

/**
* This class provides methods for manipulating individual pixels of
* an image. The original image can be read from a <tt>.jpg</tt>, <tt>.gif</tt>,
* or <tt>.png</tt> file or the user can create a blank image of a given size.
* This class includes methods for displaying the image in a window on
* the screen or saving it to a file.
* 
* Pixel (x, y

is column x and row y.
* By default, the origin (0, 0) is upper left, which is a common convention
* in image processing.
* The method <tt>setOriginLowerLeft()</tt> change the origin to the lower left.
* 
* For additional documentation, see
* <a href="http://introcs.cs.princeton.edu/31datatype">Section 3.1</a> of
* Introduction to Programming in Java: An Interdisciplinary Approach
* by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public final class Picture implements ActionListener {
private BufferedImage image; // the rasterized image
private JFrame frame; // on-screen view
private String filename; // name of file
private boolean isOriginUpperLeft = true; // location of origin
private final int width, height; // width and height

/**
 * Initializes a blank <tt>width</tt>-by-<tt>height</tt> picture, with <tt>width</tt> columns
 * and <tt>height</tt> rows, where each pixel is black.
 */
public Picture(int width, int height) {
 if (width < 0) throw new IllegalArgumentException("width must be nonnegative"

;
if (height < 0) throw new IllegalArgumentException("height must be nonnegative"

;
 this.width = width;
 this.height = height;
 image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
 // set to TYPE_INT_ARGB to support transparency
 filename = width + "-by-" + height;
}

/**
 * Initializes a new picture that is a deep copy of <tt>picture</tt>.
 */
public Picture(Picture picture) {
 width = picture.width();
 height = picture.height();
 image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
 filename = picture.filename;
 for (int col = 0; col < width(); col++)
 for (int row = 0; row < height(); row++)
 image.setRGB(col, row, picture.get(col, row).getRGB());
}

/**
 * Initializes a picture by reading in a .png, .gif, or .jpg from
 * the given filename or URL name.
 */
public Picture(String filename) {
 this.filename = filename;
 try {
 // try to read from file in working directory
 File file = new File(filename);
 if (file.isFile()) {
 image = ImageIO.read(file);
 }

 // now try to read from file in same directory as this .class file
 else {
 URL url = getClass().getResource(filename);
 if (url == null) { url = new URL(filename); }
 image = ImageIO.read(url);
 }
 width = image.getWidth(null);
 height = image.getHeight(null);
 }
 catch (IOException e) {
 // e.printStackTrace();
 throw new RuntimeException("Could not open file: " + filename);
 }
}

/**
 * Initializes a picture by reading in a .png, .gif, or .jpg from a File.
 */
public Picture(File file) {
 try { image = ImageIO.read(file); }
 catch (IOException e) {
 e.printStackTrace();
 throw new RuntimeException("Could not open file: " + file);
 }
 if (image == null) {
 throw new RuntimeException("Invalid image file: " + file);
 }
 width = image.getWidth(null);
 height = image.getHeight(null);
 filename = file.getName();
}

/**
 * Returns a JLabel containing this picture, for embedding in a JPanel,
 * JFrame or other GUI widget.
 * @return the <tt>JLabel</tt>
 */
public JLabel getJLabel() {
 if (image == null) { return null; } // no image available
 ImageIcon icon = new ImageIcon(image);
 return new JLabel(icon);
}

/**
 * Sets the origin to be the upper left pixel. This is the default.
 */
public void setOriginUpperLeft() {
 isOriginUpperLeft = true;
}

/**
 * Sets the origin to be the lower left pixel.
 */
public void setOriginLowerLeft() {
 isOriginUpperLeft = false;
}

/**
 * Displays the picture in a window on the screen.
 */
public void show() {

 // create the GUI for viewing the image if needed
 if (frame == null) {
 frame = new JFrame();

 JMenuBar menuBar = new JMenuBar();
 JMenu menu = new JMenu("File"

;
menuBar.add(menu);
JMenuItem menuItem1 = new JMenuItem(" Save... "

;
 menuItem1.addActionListener(this);
 menuItem1.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,
 Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
 menu.add(menuItem1);
 frame.setJMenuBar(menuBar);

 frame.setContentPane(getJLabel());
 // f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
 frame.setTitle(filename);
 frame.setResizable(false);
 frame.pack();
 frame.setVisible(true);
 }

 // draw
 frame.repaint();
}

/**
 * Returns the height of the picture.
 * @return the height of the picture (in pixels)
 */
public int height() {
 return height;
}

/**
 * Returns the width of the picture.
 * @return the width of the picture (in pixels)
 */
public int width() {
 return width;
}

/**
 * Returns the color of pixel (<tt>col</tt>, <tt>row</tt>

.
* @return the color of pixel (<tt>col</tt>, <tt>row</tt>

* @throws IndexOutOfBoundsException unless both 0 ≤ <tt>col</tt> < <tt>width</tt>
 * and 0 ≤ <tt>row</tt> < <tt>height</tt>
 */
public Color get(int col, int row) {
 if (col < 0 || col >= width()) throw new IndexOutOfBoundsException("col must be between 0 and " + (width()-1));
 if (row < 0 || row >= height()) throw new IndexOutOfBoundsException("row must be between 0 and " + (height()-1));
 if (isOriginUpperLeft) return new Color(image.getRGB(col, row));
 else return new Color(image.getRGB(col, height - row - 1));
}

/**
 * Sets the color of pixel (<tt>col</tt>, <tt>row</tt>

to given color.
 * @throws IndexOutOfBoundsException unless both 0 ≤ <tt>col</tt> < <tt>width</tt>
 * and 0 ≤ <tt>row</tt> < <tt>height</tt>
 * @throws NullPointerException if <tt>color</tt> is <tt>null</tt>
 */
public void set(int col, int row, Color color) {
 if (col < 0 || col >= width()) throw new IndexOutOfBoundsException("col must be between 0 and " + (width()-1));
 if (row < 0 || row >= height()) throw new IndexOutOfBoundsException("row must be between 0 and " + (height()-1));
 if (color == null) throw new NullPointerException("can't set Color to null"

;
 if (isOriginUpperLeft) image.setRGB(col, row, color.getRGB());
 else image.setRGB(col, height - row - 1, color.getRGB());
}

/**
 * Is this Picture equal to obj?
 * @return <tt>true</tt> if this picture is the same dimension as <tt>obj</tt>
 * and if all pixels have the same color
 */
public boolean equals(Object obj) {
 if (obj == this) return true;
 if (obj == null) return false;
 if (obj.getClass() != this.getClass()) return false;
 Picture that = (Picture) obj;
 if (this.width() != that.width()) return false;
 if (this.height() != that.height()) return false;
 for (int col = 0; col < width(); col++)
 for (int row = 0; row < height(); row++)
 if (!this.get(col, row).equals(that.get(col, row))) return false;
 return true;
}

/**
 * Saves the picture to a file in a standard image format.
 * The filetype must be .png or .jpg.
 */
public void save(String name) {
 save(new File(name));
}

/**
 * Saves the picture to a file in a standard image format.
 */
public void save(File file) {
 this.filename = file.getName();
 if (frame != null) { frame.setTitle(filename); }
 String suffix = filename.substring(filename.lastIndexOf('.') + 1);
 suffix = suffix.toLowerCase();
 if (suffix.equals("jpg"

|| suffix.equals("png"

) {
         try { ImageIO.write(image, suffix, file); }
         catch (IOException e) { e.printStackTrace(); }
      }
      else {
         System.out.println("Error: filename must end in .jpg or .png"

;
 }
}

/**
 * Opens a save dialog box when the user selects "Save As" from the menu.
 */
public void actionPerformed(ActionEvent e) {
 FileDialog chooser = new FileDialog(frame,
 "Use a .png or .jpg extension", FileDialog.SAVE);
 chooser.setVisible(true);
 if (chooser.getFile() != null) {
 save(chooser.getDirectory() + File.separator + chooser.getFile());
 }
}

/**
 * Tests this <tt>Picture</tt> data type. Reads a picture specified by the command-line argument,
 * and shows it in a window on the screen.
 */
public static void main(String[] args) {
 Picture picture = new Picture(args[0]);
 System.out.printf("%d-by-%d\n", picture.width(), picture.height());
 picture.show();
}

}