Reliable Image Compression for android

Reliable Image Compression for android

First, let's take a look at the quality compression method:

Private Bitmap compressImage (Bitmap image ){

ByteArrayOutputStream baos = new ByteArrayOutputStream ();

Image. compress (Bitmap. CompressFormat. JPEG, 100, baos); // quality compression method. Here, 100 indicates no compression. Store the compressed data in baos.

Int options = 100;

While (baos. toByteArray (). length/1024> 100) {// cyclically determine if the image is larger than kb after compression and greater than Continue compression

Baos. reset (); // reset baos to clear baos

Image. compress (Bitmap. CompressFormat. JPEG, options, baos); // compress options % to save the compressed data to baos.

Options-= 10; // reduce each time by 10

}

ByteArrayInputStream isBm = new ByteArrayInputStream (baos. toByteArray (); // store the compressed data baos in ByteArrayInputStream

Bitmap bitmap = BitmapFactory. decodeStream (isBm, null, null); // generates an image from ByteArrayInputStream

Return bitmap;

}

Second, the image is compressed proportionally (the image is obtained and compressed Based on the path ):

Private Bitmap getimage (String srcPath ){

BitmapFactory. Options newOpts = new BitmapFactory. Options ();

// Start reading the image, and set options. inJustDecodeBounds back to true.

NewOpts. inJustDecodeBounds = true;

Bitmap bitmap = BitmapFactory. decodeFile (srcPath, newOpts); // at this time, the returned bm is empty.

NewOpts. inJustDecodeBounds = false;

Int w = newOpts. outWidth;

Int h = newOpts. outHeight;

// Currently, most mainstream mobile phones have a resolution of 800*480, so we set the height and width

Float hh = 800f; // set the height to 800f.

Float ww = 480f; // set the width to 480f.

// Scale ratio. Because it is a fixed proportional scaling, only one of the data in the height or width can be calculated.

Int be = 1; // be = 1 indicates no Scaling

If (w> h & w> ww) {// if the width is large, scale it according to the fixed width.

Be = (int) (newOpts. outWidth/ww );

} Else if (w

Be = (int) (newOpts. outHeight/hh );

}

If (be <= 0)

Be = 1;

NewOpts. inSampleSize = be; // set the scaling ratio.

// Read the image again. Note that options. inJustDecodeBounds has been set back to false.

Bitmap = BitmapFactory. decodeFile (srcPath, newOpts );

Return compressImage (bitmap); // compress the proportion before performing quality compression.

}

Third: proportional image compression method (based on 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) {// determine if the image is larger than 1 MB, compress the image to avoid overflow when generating the image (BitmapFactory. decodeStream ).

Baos. reset (); // reset baos to clear baos

Image. compress (Bitmap. CompressFormat. JPEG, 50, baos); // compress 50% to save the compressed data to baos.

}

ByteArrayInputStream isBm = new ByteArrayInputStream (baos. toByteArray ());

BitmapFactory. Options newOpts = new BitmapFactory. Options ();

// Start reading the image, and set options. inJustDecodeBounds back to true.

NewOpts. inJustDecodeBounds = true;

Bitmap bitmap = BitmapFactory. decodeStream (isBm, null, newOpts );

NewOpts. inJustDecodeBounds = false;

Int w = newOpts. outWidth;

Int h = newOpts. outHeight;

// Currently, most mainstream mobile phones have a resolution of 800*480, so we set the height and width

Float hh = 800f; // set the height to 800f.

Float ww = 480f; // set the width to 480f.

// Scale ratio. Because it is a fixed proportional scaling, only one of the data in the height or width can be calculated.

Int be = 1; // be = 1 indicates no Scaling

If (w> h & w> ww) {// if the width is large, scale it according to the fixed width.

Be = (int) (newOpts. outWidth/ww );

} Else if (w

Be = (int) (newOpts. outHeight/hh );

}

If (be <= 0)

Be = 1;

NewOpts. inSampleSize = be; // set the scaling ratio.

// Read the image again. Note that options. inJustDecodeBounds has been set back to false.

IsBm = new ByteArrayInputStream (baos. toByteArray ());

Bitmap = BitmapFactory. decodeStream (isBm, null, newOpts );

Return compressImage (bitmap); // compress the proportion before performing quality compression.

}