在Android上实现离散小波变换

Question

I'm writing an application to applying the Discrete Wavelet Transformation on an image and then inverse it the class for applying the algorithm works will in java but when i try to convert it to android platform the image dose not appear i don't know why here is the code for the class and the main activity :

wtc using haar class :

import android.graphics.Bitmap;

/**
 * @author the-e_000
 */
public class haar {

    private final double w0 = 0.5;
    private final double w1 = -0.5;
    private final double s0 = 0.5;
    private final double s1 = 0.5;

    /// <summary>
    ///   Discrete Haar Wavelet Transform
    /// </summary>
    ///
    public void FWT(double[] data) {
        double[] temp = new double[data.length];

        int h = data.length >> 1;
        for (int i = 0; i < h; i++) {
            int k = (i << 1);
            temp[i] = data[k] * s0 + data[k + 1] * s1;
            temp[i + h] = data[k] * w0 + data[k + 1] * w1;
        }

        for (int i = 0; i < data.length; i++)
            data[i] = temp[i];
    }

    /// <summary>
    ///   Discrete Haar Wavelet 2D Transform
    /// </summary>
    ///
    public void FWT(double[][] data, int iterations) {
        int rows = data.length;
        int cols = data[0].length;
        double[] row = new double[cols];
        double[] col = new double[rows];
        for (int k = 0; k < iterations; k++) {
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < row.length; j++)
                    row[j] = data[i][j];
                FWT(row);
                for (int j = 0; j < row.length; j++)
                    data[i][j] = row[j];
            }
            for (int j = 0; j < cols; j++) {
                for (int i = 0; i < col.length; i++)
                    col[i] = data[i][j];
                FWT(col);
                for (int i = 0; i < col.length; i++)
                    data[i][j] = col[i];
            }
        }
    }

    /// <summary>
    ///   Inverse Haar Wavelet Transform
    /// </summary>
    ///
    public void IWT(double[] data) {
        double[] temp = new double[data.length];

        int h = data.length >> 1;
        for (int i = 0; i < h; i++) {
            int k = (i << 1);
            temp[k] = (data[i] * s0 + data[i + h] * w0) / w0;
            temp[k + 1] = (data[i] * s1 + data[i + h] * w1) / s0;
        }

        for (int i = 0; i < data.length; i++)
            data[i] = temp[i];
    }

    /// <summary>
    ///   Inverse Haar Wavelet 2D Transform
    /// </summary>
    ///
    public void IWT(double[][] data, int iterations) {
        int rows = data.length;
        int cols = data[0].length;
        double[] col = new double[rows];
        double[] row = new double[cols];
        for (int l = 0; l < iterations; l++) {
            for (int j = 0; j < cols; j++) {
                for (int i = 0; i < row.length; i++)
                    col[i] = data[i][j];
                IWT(col);
                for (int i = 0; i < col.length; i++)
                    data[i][j] = col[i];
            }
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < row.length; j++)
                    row[j] = data[i][j];
                IWT(row);
                for (int j = 0; j < row.length; j++)
                    data[i][j] = row[j];
            }
        }
    }

    public double Scale(double fromMin, double fromMax, double toMin, double toMax, double x) {
        if (fromMax - fromMin == 0) {
            return 0;
        }
        double value = (toMax - toMin) * (x - fromMin) / (fromMax - fromMin) + toMin;
        if (value > toMax) {
            value = toMax;
        }
        if (value < toMin) {
            value = toMin;
        }
        return value;
    }

    public void ApplyHaarTransform(boolean Forward, Bitmap img) throws Exception {

        int Iterations = 1;
        double[][] Red = new double[img.getWidth()][img.getHeight()];
        double[][] Green = new double[img.getWidth()][img.getHeight()];
        double[][] Blue = new double[img.getWidth()][img.getHeight()];
        int c;
        for (int j = 0; j < img.getHeight(); j++) {
            for (int i = 0; i < img.getWidth(); i++) {
                c = img.getPixel(i, j);
                Red[i][j] = (double) Scale(0, 255, -1, 1, (c >> 16) & 0x000000FF);
                Green[i][j] = (double) Scale(0, 255, -1, 1, (c >> 8) & 0x000000FF);
                Blue[i][j] = (double) Scale(0, 255, -1, 1, (c) & 0x000000FF);
            }
        }
        if (Forward) {
            FWT(Red, Iterations);
            FWT(Green, Iterations);
            FWT(Blue, Iterations);
        } else {
            IWT(Red, Iterations);
            IWT(Green, Iterations);
            IWT(Blue, Iterations);
        }
        for (int j = 0; j < img.getHeight(); j++) {
            for (int i = 0; i < img.getWidth(); i++) {
                int r = (int) Scale(-1, 1, 0, 255, Red[i][j]);// red component 0...255
                int g = (int) Scale(-1, 1, 0, 255, Green[i][j]);// green component 0...255
                int b = (int) Scale(-1, 1, 0, 255, Blue[i][j]);// blue component 0...255
                int col = (r << 16) | (g << 8) | b;
                img.setPixel(i, j, col);
            }
        }
    }
}

main activity :

Bitmap img = BitmapFactory.decodeFile(imgDecodableString);
ImageView imgView = (ImageView) findViewById(R.id.imgView);
// take the image and add the transform
haar trans = new haar();
Bitmap img2 = null;
try {
    trans.ApplyHaarTransform(true, true, img);
} catch(Exception e) {
    Toast.makeText(this,e.getMessage(), Toast.LENGTH_LONG).show();
}
// Set the Image in ImageView after decoding the String
imgView.setImageBitmap(img2);

Answer 1

in your code u put a null image in imageview:

Bitmap img2 = null;

and after transformation your code

imgView.setImageBitmap(img2);

but

try {
    trans.ApplyHaarTransform(true, true, img);
} catch(Exception e) {
    Toast.makeText(this,e.getMessage(), Toast.LENGTH_LONG).show();
}

have no effect on img2 so instead u may make your method :

public void ApplyHaarTransform(boolean Forward, Bitmap img)

returns image and now it is

public Bitmap ApplyHaarTransform(boolean Forward, Bitmap img)

and before closing its parathesis add one line of code :

return img;

and now in your try catch code yourcode will be:

try {
    img2=trans.ApplyHaarTransform(true, true, img);
} catch(Exception e) {
    Toast.makeText(this,e.getMessage(), Toast.LENGTH_LONG).show();
}