Using Handwritten Number Recognition by Yan Cheng, Cheok?

Question

I'm planning to use (Handwritten Number Recognition by Yan Cheng, Cheok) for a project I'm working on it,I should use their database for number recognition but the files are not on their website, I should use a file called "LRTBHVtrainingdata.txtI=96H=200LR=0.9M=0.1C=2000.snet" as they say in their tutorial,But what I found on their website (http://yann.lecun.com/exdb/mnist/) is four files and I don't know how to use them ? so any help on where to get their database or where or the files to use them ?

Answer 1

The files you're looking at are the correct files. They are normalized grey-scale images (0-white, 255-black) centered in a 20x20 box. The page explains the structure of the files (just scroll down towards the bottom).

Here's some code I wrote a while back in Java, that reads in the MNIST image and label files:

import net.vivin.digit.DigitImage;    
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Created by IntelliJ IDEA.
 * User: vivin
 * Date: 11/11/11
 * Time: 10:07 AM
 */
public class DigitImageLoadingService {

    private String labelFileName;
    private String imageFileName;

    /** the following constants are defined as per the values described at http://yann.lecun.com/exdb/mnist/ **/

    private static final int MAGIC_OFFSET = 0;
    private static final int OFFSET_SIZE = 4; //in bytes

    private static final int LABEL_MAGIC = 2049;
    private static final int IMAGE_MAGIC = 2051;

    private static final int NUMBER_ITEMS_OFFSET = 4;
    private static final int ITEMS_SIZE = 4;

    private static final int NUMBER_OF_ROWS_OFFSET = 8;
    private static final int ROWS_SIZE = 4;
    public static final int ROWS = 28;

    private static final int NUMBER_OF_COLUMNS_OFFSET = 12;
    private static final int COLUMNS_SIZE = 4;
    public static final int COLUMNS = 28;

    private static final int IMAGE_OFFSET = 16;
    private static final int IMAGE_SIZE = ROWS * COLUMNS;


    public DigitImageLoadingService(String labelFileName, String imageFileName) {
        this.labelFileName = labelFileName;
        this.imageFileName = imageFileName;
    }

    public List<DigitImage> loadDigitImages() throws IOException {
        List<DigitImage> images = new ArrayList<DigitImage>();

        ByteArrayOutputStream labelBuffer = new ByteArrayOutputStream();
        ByteArrayOutputStream imageBuffer = new ByteArrayOutputStream();

        InputStream labelInputStream = this.getClass().getResourceAsStream(labelFileName);
        InputStream imageInputStream = this.getClass().getResourceAsStream(imageFileName);

        int read;
        byte[] buffer = new byte[16384];

        while((read = labelInputStream.read(buffer, 0, buffer.length)) != -1) {
           labelBuffer.write(buffer, 0, read);
        }

        labelBuffer.flush();

        while((read = imageInputStream.read(buffer, 0, buffer.length)) != -1) {
            imageBuffer.write(buffer, 0, read);
        }

        imageBuffer.flush();

        byte[] labelBytes = labelBuffer.toByteArray();
        byte[] imageBytes = imageBuffer.toByteArray();

        byte[] labelMagic = Arrays.copyOfRange(labelBytes, 0, OFFSET_SIZE);
        byte[] imageMagic = Arrays.copyOfRange(imageBytes, 0, OFFSET_SIZE);

        if(ByteBuffer.wrap(labelMagic).getInt() != LABEL_MAGIC)  {
            throw new IOException("Bad magic number in label file!");
        }

        if(ByteBuffer.wrap(imageMagic).getInt() != IMAGE_MAGIC) {
            throw new IOException("Bad magic number in image file!");
        }

        int numberOfLabels = ByteBuffer.wrap(Arrays.copyOfRange(labelBytes, NUMBER_ITEMS_OFFSET, NUMBER_ITEMS_OFFSET + ITEMS_SIZE)).getInt();
        int numberOfImages = ByteBuffer.wrap(Arrays.copyOfRange(imageBytes, NUMBER_ITEMS_OFFSET, NUMBER_ITEMS_OFFSET + ITEMS_SIZE)).getInt();

        if(numberOfImages != numberOfLabels) {
            throw new IOException("The number of labels and images do not match!");
        }

        int numRows = ByteBuffer.wrap(Arrays.copyOfRange(imageBytes, NUMBER_OF_ROWS_OFFSET, NUMBER_OF_ROWS_OFFSET + ROWS_SIZE)).getInt();
        int numCols = ByteBuffer.wrap(Arrays.copyOfRange(imageBytes, NUMBER_OF_COLUMNS_OFFSET, NUMBER_OF_COLUMNS_OFFSET + COLUMNS_SIZE)).getInt();

        if(numRows != ROWS && numRows != COLUMNS) {
            throw new IOException("Bad image. Rows and columns do not equal " + ROWS + "x" + COLUMNS);
        }

        for(int i = 0; i < numberOfLabels; i++) {
            int label = labelBytes[OFFSET_SIZE + ITEMS_SIZE + i];
            byte[] imageData = Arrays.copyOfRange(imageBytes, (i * IMAGE_SIZE) + IMAGE_OFFSET, (i * IMAGE_SIZE) + IMAGE_OFFSET + IMAGE_SIZE);

            images.add(new DigitImage(label, imageData));
        }

        return images;
    }
}