Examples of three methods of android image compression

android image compression method:

1. Mass compression method:

private Bitmap compressImage(Bitmap image) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        image.compress(Bitmap.CompressFormat.JPEG, 100, baos);// Mass compression method, here 100 Is not compressed, the compressed data stored in baos In the 
        int options = 100;
        while ( baos.toByteArray().length / 1024>100) {    // Loop to determine if the image is larger than if compressed 100kb, Greater than continue to compress         
            baos.reset();// reset baos The empty baos
            options -= 10;// It goes down every time 10
            image.compress(Bitmap.CompressFormat.JPEG, options, baos);// This compression options% , to store the compressed data into baos In the 

        }
        ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());// You compress the data baos Deposit to ByteArrayInputStream In the 
        Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);// the ByteArrayInputStream Data generation picture 
        return bitmap;
    }

2. Image compression method (get the image according to the path and compress it) :

private Bitmap getimage(String srcPath) {
        BitmapFactory.Options newOpts = new BitmapFactory.Options();
        // Start reading in the picture options.inJustDecodeBounds  Set back true the 
        newOpts.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeFile(srcPath,newOpts);// At this time back bm Is empty 

        newOpts.inJustDecodeBounds = false;
        int w = newOpts.outWidth;
        int h = newOpts.outHeight;
        // Now the mainstream mobile phone is more 800*480 The resolution, so the height and the width are set to zero 
        float hh = 800f;// I'm going to set the height to zero 800f
        float ww = 480f;// I'm going to set the width to zero 480f
        // Zoom ratio. Since the scale is fixed, only the height or width is used 1 The data can be calculated 
        int be = 1;//be=1 Means no scaling 
        if (w > h && w > ww) {// If the width is large, it will scale according to the width 
            be = (int) (newOpts.outWidth / ww);
        } else if (w < h && h > hh) {// If the height is high, it will scale according to the width 
            be = (int) (newOpts.outHeight / hh);
        }
        if (be <= 0)
            be = 1;
        newOpts.inSampleSize = be;// Set the scale 
        // Read in the picture again and notice that it is already there options.inJustDecodeBounds  Set back false the 
        bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
        return compressImage(bitmap);// After the compression of a good proportion of the size of the mass compression 
    }

Picture proportion compression, I saw 1 algorithm, said relatively fast.
be = (int) ((w / STANDARD_WIDTH + h/ STANDARD_HEIGHT) / 2);
Conclusion 2: the compression ratio of the picture is (width compression ratio + height compression ratio) /2..

3. Image compression by proportional size (according to Bitmap image compression) :

private Bitmap comp(Bitmap image) {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();        
        image.compress(Bitmap.CompressFormat.JPEG, 100, baos);
        if( baos.toByteArray().length / 1024>1024) {// Judge if the picture is greater than 1M, Compress to avoid generating images ( BitmapFactory.decodeStream When the overflow     
            baos.reset();// reset baos The empty baos
            image.compress(Bitmap.CompressFormat.JPEG, 50, baos);// This compression 50% , to store the compressed data into baos In the 
        }
        ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());
        BitmapFactory.Options newOpts = new BitmapFactory.Options();
        // Start reading in the picture options.inJustDecodeBounds  Set back true the 
        newOpts.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, newOpts);
        newOpts.inJustDecodeBounds = false;
        int w = newOpts.outWidth;
        int h = newOpts.outHeight;
        // Now the mainstream mobile phone is more 800*480 The resolution, so the height and the width are set to zero 
        float hh = 800f;// I'm going to set the height to zero 800f
        float ww = 480f;// I'm going to set the width to zero 480f
        // Zoom ratio. Since the scale is fixed, only the height or width is used 1 The data can be calculated 
        int be = 1;//be=1 Means no scaling 
        if (w > h && w > ww) {// If the width is large, it will scale according to the width 
            be = (int) (newOpts.outWidth / ww);
        } else if (w < h && h > hh) {// If the height is high, it will scale according to the width 
            be = (int) (newOpts.outHeight / hh);
        }
        if (be <= 0)
            be = 1;
        newOpts.inSampleSize = be;// Set the scale 
        newOpts.inPreferredConfig = Config.RGB_565;// Lower the image from ARGB888 to RGB565
        // Read in the picture again and notice that it is already there options.inJustDecodeBounds  Set back false the 
        isBm = new ByteArrayInputStream(baos.toByteArray());
        bitmap = BitmapFactory.decodeStream(isBm, null, newOpts);
        return compressImage(bitmap);// After the compression of a good proportion of the size of the mass compression 
    }