Android 人脸检测仅适用于绘图，不适用于 SD 卡中的图像

所以我有代码可以在任何给定的图像文件中检测最多 10 张面孔，并向我返回信息，例如眼睛的位置和其他类似信息。因此，当我告诉它使用存储在我的项目资源的可绘制文件夹中的图像文件时，它效果很好。但是当我尝试从 SD 卡导入的位图中查找面孔时，它不会找到任何面孔。但这些都是完全相同的图像。有任何想法吗？我的代码如下：

编辑： 经过进一步检查我发现当我插入这行代码时System.out.println("Row Bytes: " + sourceImage.getRowBytes());我得到的可绘制对象是 352，而 SD 卡映像是 704。我认为这意味着可绘制对象被压缩在 .apk 文件中，但 SD 卡映像显然没有被压缩。不确定这是否会产生任何影响。

 public class FaceView extends View {
           private static final int NUM_FACES = 10; // max is 64
           private static final boolean DEBUG = true;

           private FaceDetector arrayFaces;
           private FaceDetector.Face getAllFaces[] = new FaceDetector.Face[NUM_FACES];
           private FaceDetector.Face getFace = null;

           private PointF eyesMidPts[] = new PointF[NUM_FACES];
           private float  eyesDistance[] = new float[NUM_FACES];

           private Bitmap sourceImage;

           private Paint tmpPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
           private Paint pOuterBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);
           private Paint pInnerBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);

           private int picWidth, picHeight;
           private float xRatio, yRatio;

           public FaceView(Context context) {
                   super(context);

                   pInnerBullsEye.setStyle(Paint.Style.FILL);
                   pInnerBullsEye.setColor(Color.RED);

                   pOuterBullsEye.setStyle(Paint.Style.STROKE);
                   pOuterBullsEye.setColor(Color.RED);

                   tmpPaint.setStyle(Paint.Style.STROKE);
                   tmpPaint.setTextAlign(Paint.Align.CENTER);

                   BitmapFactory.Options bfo = new BitmapFactory.Options();
                   bfo.inPreferredConfig = Bitmap.Config.RGB_565;

                   //********This code imports the image from the SD card which does not work
                   String imageInSD = Environment.getExternalStorageDirectory()
                        .getAbsolutePath() + "/testfolder/" + "face1" + ".png";

                   Bitmap sourceImage = BitmapFactory.decodeFile(imageInSD,bfo);

                   //**********This code uses an image in the projects drawable folder, this code works.
                   sourceImage = BitmapFactory.decodeResource( getResources() ,R.drawable.face1, bfo);

                   picWidth = sourceImage.getWidth();
                   picHeight = sourceImage.getHeight();

                   arrayFaces = new FaceDetector( picWidth, picHeight, NUM_FACES );
                   arrayFaces.findFaces(sourceImage, getAllFaces);

                   for (int i = 0; i < getAllFaces.length; i++)
                   {
                           getFace = getAllFaces[i];
                           try {
                                   PointF eyesMP = new PointF();
                                   getFace.getMidPoint(eyesMP);
                                   eyesDistance[i] = getFace.eyesDistance();
                                   eyesMidPts[i] = eyesMP;

                                   if (DEBUG)
                                   {
                                           Log.i("Face",
                                                   i +  " " + getFace.confidence() + " " + getFace.eyesDistance() + " "
                                                   + "Pose: ("+ getFace.pose(FaceDetector.Face.EULER_X) + ","
                                                   + getFace.pose(FaceDetector.Face.EULER_Y) + ","
                                                   + getFace.pose(FaceDetector.Face.EULER_Z) + ")"
                                                   + "Eyes Midpoint: ("+eyesMidPts[i].x + "," + eyesMidPts[i].y +")"
                                           );
                                   }
                           }
                           catch (Exception e)
                           {
                                   if (DEBUG) Log.e("Face", i + " is null");
                           }

                   }


           }

           @Override
           protected void onDraw(Canvas canvas)
           {
                   xRatio = getWidth()*1.0f / picWidth;
                   yRatio = getHeight()*1.0f / picHeight;
                   canvas.drawBitmap( sourceImage, null , new Rect(0,0,getWidth(),getHeight()),tmpPaint);
                   for (int i = 0; i < eyesMidPts.length; i++)
                   {
                           if (eyesMidPts[i] != null)
                           {
                                   pOuterBullsEye.setStrokeWidth(eyesDistance[i] /6);
                                   canvas.drawCircle(eyesMidPts[i].x*xRatio, eyesMidPts[i].y*yRatio, eyesDistance[i] / 2 , pOuterBullsEye);
                                   canvas.drawCircle(eyesMidPts[i].x*xRatio, eyesMidPts[i].y*yRatio, eyesDistance[i] / 6 , pInnerBullsEye);
                           }
                   }


           }  

}

好吧，我相信我知道你的问题是什么。由于图像位于外部存储器中，因此设备无法将图像渲染为位图图像。人脸识别正在工作，只是没有出现在画布上。所有设备对我的 xoom (2048x2048) 都有渲染限制 我发现here http://groups.google.com/group/android-developers/browse_thread/thread/2352c776651b6f99。当您将图像添加为资源时它起作用的原因是因为您的文件在构建 .apk 时缩小了（说实话，我不确定它为什么这样做，但我留下了一些 println 进行测试，其他人可以更好地回答这个问题）。不管怎样，我只是在代码查找面孔之后、尝试将位图渲染到画布之前，通过除以 2 来缩放位图。现在一切似乎都运行良好。您可能想调整脸部指示器，但它很实用。我希望这有帮助。

public class FaceView extends View {
private static final int NUM_FACES = 1; // max is 64
private static final boolean DEBUG = true;

private FaceDetector arrayFaces;
private FaceDetector.Face getAllFaces[] = new FaceDetector.Face[NUM_FACES];
private FaceDetector.Face getFace = null;

private PointF eyesMidPts[] = new PointF[NUM_FACES];
private float  eyesDistance[] = new float[NUM_FACES];

private Bitmap sourceImage;

private Paint tmpPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private Paint pOuterBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);
private Paint pInnerBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);

private int picWidth, picHeight;
private float xRatio, yRatio;

public FaceView(Context context) {
        super(context);

        pInnerBullsEye.setStyle(Paint.Style.FILL);
        pInnerBullsEye.setColor(Color.RED);

        pOuterBullsEye.setStyle(Paint.Style.STROKE);
        pOuterBullsEye.setColor(Color.RED);

        tmpPaint.setStyle(Paint.Style.STROKE);
        tmpPaint.setTextAlign(Paint.Align.CENTER);

        BitmapFactory.Options bfo = new BitmapFactory.Options();
        bfo.inPreferredConfig = Bitmap.Config.RGB_565;

        //********This code imports the image from the SD card which does not work
        String imageInSD = Environment.getExternalStorageDirectory().getAbsolutePath() + "/face1" + ".jpg";

        System.out.println(imageInSD);

        sourceImage = BitmapFactory.decodeFile(imageInSD, bfo);

        //Bitmap sourceImage;// = BitmapFactory.decodeFile(imageInSD,bfo);


        //**********This code uses an image in the projects drawable folder, this code works.
        //sourceImage = BitmapFactory.decodeResource( getResources() ,R.drawable.face1, bfo);

        picWidth = sourceImage.getWidth();
        picHeight = sourceImage.getHeight(); 

        System.out.println(picWidth + "x" + picHeight);

        arrayFaces = new FaceDetector( picWidth, picHeight, NUM_FACES );
        arrayFaces.findFaces(sourceImage, getAllFaces);

        sourceImage = Bitmap.createScaledBitmap (sourceImage, picWidth/2, picHeight/2, false);

        for (int i = 0; i < getAllFaces.length; i++)
        {
                getFace = getAllFaces[i];
                try {
                        PointF eyesMP = new PointF();
                        getFace.getMidPoint(eyesMP);
                        eyesDistance[i] = getFace.eyesDistance();
                        eyesMidPts[i] = eyesMP;

                        if (DEBUG)
                        {
                                Log.i("Face",
                                        i +  " " + getFace.confidence() + " " + getFace.eyesDistance() + " "
                                        + "Pose: ("+ getFace.pose(FaceDetector.Face.EULER_X) + ","
                                        + getFace.pose(FaceDetector.Face.EULER_Y) + ","
                                        + getFace.pose(FaceDetector.Face.EULER_Z) + ")"
                                        + "Eyes Midpoint: ("+eyesMidPts[i].x + "," + eyesMidPts[i].y +")"
                                );
                        }
                }
                catch (Exception e)
                {
                        if (DEBUG) Log.e("Face", i + " is null");
                }

        }


}

@Override
protected void onDraw(Canvas canvas)
{
        xRatio = getWidth()*1.0f / picWidth; 
        yRatio = getHeight()*1.0f / picHeight;
        canvas.drawBitmap( sourceImage, null , new Rect(0,0,getWidth(),getHeight()),tmpPaint);
        for (int i = 0; i < eyesMidPts.length; i++)
        {
                if (eyesMidPts[i] != null)
                {
                        pOuterBullsEye.setStrokeWidth(eyesDistance[i] /6);
                        canvas.drawCircle(eyesMidPts[i].x*xRatio, eyesMidPts[i].y*yRatio, eyesDistance[i] / 2 , pOuterBullsEye);
                        canvas.drawCircle(eyesMidPts[i].x*xRatio, eyesMidPts[i].y*yRatio, eyesDistance[i] / 6 , pInnerBullsEye);
                }
        }


}

}