java - 使用 OpenCV 修改 Mat 对象的像素值

问题描述

我是 Android 编程的初学者。我正在构建一个用于图像隐写术的 Android 应用程序。我已经使用 Java 和 OpenCV 为桌面开发了这个应用程序，它运行良好。我正在尝试重新使用我拥有的代码.

我创建了一个Mat对象并将其传递给 Java 类（我已经拥有）。我能够读取Mat对象中的像素强度，但是，当我尝试修改这些值（通过使用put()）时，我的应用程序是崩溃。

抛出的异常是

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.hari.imagesteganography, PID: 8850
    java.lang.UnsupportedOperationException: Provided data element number (3) should be multiple of the Mat channels count (4)
        at org.opencv.core.Mat.put(Mat.java:954)
        at com.example.hari.imagesteganography.LSBImageStego.encodeOriginalMessageBinaryLength(LSBImageStego.java:101)
        at com.example.hari.imagesteganography.LSBImageStego.encodeImage(LSBImageStego.java:239)
        at com.example.hari.imagesteganography.EncodeActivity$1.onClick(EncodeActivity.java:98)
        at android.view.View.performClick(View.java:6302)
        at android.view.View$PerformClick.run(View.java:24782)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6518)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

同样的方法 ( put()) 在桌面上运行得非常好。

以下是我在 Android 应用程序中的代码。

private void encodeOriginalMessageBinaryLength(){

// LOGGING THIS,SHOWS THAT THE FUNCTION EXECUTION STARTED
        Log.i("URI" , "encodeOriginalMessageBinaryLength()");

        String binary_of_originalMessageBinaryLength = Integer.toBinaryString(this.originalMessageBinaryLength);
        if(binary_of_originalMessageBinaryLength.length()%2 !=0){
            binary_of_originalMessageBinaryLength = "0" + binary_of_originalMessageBinaryLength;
        }
        int remaining = binary_of_originalMessageBinaryLength.length();
        String newLsbBits;

        for(int col = this.coverImage_cols -1 ; col >=0 ; col--){
            if(remaining > 0){
                newLsbBits = binary_of_originalMessageBinaryLength.substring( remaining - NUMBER_OF_BITS_REPLACING , remaining );
                remaining -= NUMBER_OF_BITS_REPLACING;

            }else{
                newLsbBits = String.join("", Collections.nCopies(NUMBER_OF_BITS_REPLACING, "0"));
            }

            Log.i("URI","newLsbBits"+newLsbBits);
            String modifiedBinaryString = this.getBeautifiedBinaryString(this.coverImage.get( this.coverImage_rows -1,col )[0]).substring(0 , this.getBeautifiedBinaryString(this.coverImage.get( this.coverImage_rows -1,col )[0]).length() - NUMBER_OF_BITS_REPLACING) + newLsbBits;

            Log.i("URI","modifiedBianryString"+modifiedBinaryString);
            double[] data = new double[3];
            data[0] = Integer.parseInt(modifiedBinaryString , 2);
            data[1] = this.coverImage.get( this.coverImage_rows -1,col )[1];
            data[2] = this.coverImage.get( this.coverImage_rows -1,col )[2];
this.coverImage_rows -1,col )[0]);

//   LOGGING THE DIMENSIONS OF THE IMAGE CORRECTLY,SHOWS THAT THE Mat Object 
//   IS INITIALIZED CORRECTLY
            Log.i("URI" , new Integer(this.coverImage_rows).toString());
            Log.i("URI" , new Integer(this.coverImage_cols).toString());

//  EXECUTING BELOW LINE CAUSES THE APP TO CRASH
            this.coverImage.put( this.coverImage_rows -1,col  , data);


// BELOW MESSAGE IS NOT BEING LOGGED
           Log.i("URI" , "encodeOriginalMessageBinaryLength() END");

        }
}

对应的Logcat日志如下。

2019-02-08 12:30:37.019 1230-1230/com.example.hari.imagesteganography I/URI: encodeOriginalMessageBinaryLength()
2019-02-08 12:30:37.019 1230-1230/com.example.hari.imagesteganography I/URI: newLsbBits10
2019-02-08 12:30:37.019 1230-1230/com.example.hari.imagesteganography I/URI: modifiedBianryString10010110
2019-02-08 12:30:37.019 1230-1230/com.example.hari.imagesteganography I/URI: 1440
2019-02-08 12:30:37.019 1230-1230/com.example.hari.imagesteganography I/URI: 2560

对象和Mat其他属性设置如下

public LSBImageStego(Mat coverImage){
        this.coverImage = coverImage;
        this.coverImage_rows = (int)coverImage.size().height;
        this.coverImage_cols = (int)coverImage.size().width;
}

我的代码错了吗？如何Mat在 Android 中使用 OpenCV 和 Java 更改对象的像素强度值？

我相信，这个问题与Using get() and put() to access pixel values in OpenCV for Java OR opencv java modify pixel values不重复，因为它们不适用于 Android，并且put()这些问题中描述的方法有效即使在桌面上对我来说也很好。

标签： javaandroidopencvmat

java - 使用 OpenCV 修改 Mat 对象的像素值

问题描述

解决方案

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