java - 使人脸检测器适用于任何文件格式

Question

由于人脸检测器仅适用于 jpg 文件，如何才能使其适用于所有格式？我让用户从 SD 卡中选择任何图像，因此图像可以是任何格式。我使用本文中提到的解码文件方法来缩小图像: Android: Resize a large bitmap file to scaled output file

我的问题是:
我们可以在decodefile方法中添加一些方法来首先将图像转换为jpg吗？
将图像转换为 jpg 以便面部检测器类检测面部的最佳且有效的方法是什么？

到目前为止我的代码:

public FaceView(Context context) {
            super(context);                         
            File photo = new File(selectedImagePath);                       
            sourceImage = decodeFile(photo);

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

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

            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();
                    Log.d("1st eye distance", "" + getFace.eyesDistance());
                    eyesMidPts[i] = eyesMP;                 
                }
                catch (Exception e)
                {
                    if (DEBUG) Log.e("Face", i + " is null");
                }
            }                   
        }

解码方法:

private Bitmap decodeFile(File f){
            Bitmap b = null;
            int screenWidth = 0;
            int screenHeight = 0;
            Point size = new Point();
            WindowManager w = getWindowManager();

            if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2)
            {
                w.getDefaultDisplay().getSize(size);
                screenWidth = size.x;
                screenHeight = size.y; 
            }
            else
            {
                Display d = w.getDefaultDisplay(); 
                screenWidth = d.getWidth(); 
                screenHeight = d.getHeight(); 
            }

            //Decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();      
            o.inJustDecodeBounds = true;

            FileInputStream fis = null;
            try{
                fis = new FileInputStream(f);
                BitmapFactory.decodeStream(fis, null, o);
                fis.close();

                // was > IMAGE_MAX_SIZE for both i changed it****
                int scale = 1;
                if (o.outHeight > screenHeight || o.outWidth > screenWidth) {
                    scale = (int)Math.pow(2, (int) Math.round(Math.log(screenHeight / 
                            (double) Math.max(o.outHeight, o.outWidth)) / Math.log(0.5)));
                }

                //Decode with inSampleSize
                BitmapFactory.Options o2 = new BitmapFactory.Options();
                o2.inSampleSize = scale;
                fis = new FileInputStream(f);
                b = BitmapFactory.decodeStream(fis, null, o2);
                fis.close();        
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            return b;
        }

Answer 1

在 decodeFile() 方法的末尾，您有一个位图。您可以轻松依靠 Android 将其转换为 JPEG，方法是使用

Bitmap.compress(Bitmap.CompressFormat format, int quality, OutputStream stream)

与Bitmap.compressFormat.JPEG

这里有更多信息:Conversion of bitmap into jpeg in android

您应该能够将其保存到文件，或压缩到内存中(也许使用ByteArrayOutputStream？)