Android Image compression method:
First: Mass compression method:
private Bitmap Compressimage (Bitmap image) {
Bytearrayoutputstream BAOs = new Bytearrayoutputstream ();
image.compress (Bitmap.CompressFormat.JPEG, BAOs);//Quality compression method, here 100 means no compression, the compressed data stored in the BAOs
int options = +;
while (Baos.tobytearray (). length/1024>100) {//loop to determine if the picture is larger than 100kb after compression, greater than continue compression
Baos.reset ();//Reset BAOs is empty BAOs
Options-= 10;//each time it is reduced by ten
image.compress (Bitmap.CompressFormat.JPEG, Options, BAOs);//compress options% here and store the compressed data in BAOs
}
Bytearrayinputstream ISBM = new Bytearrayinputstream (Baos.tobytearray ());//Store compressed data BAOs into Bytearrayinputstream
Bitmap Bitmap = bitmapfactory.decodestream (ISBM, NULL, NULL);//Generate pictures of Bytearrayinputstream data
return bitmap;
}
Second: Picture by proportional size compression method (get picture according to Path and compress):
private Bitmap getimage (String srcpath) {
bitmapfactory.options newopts = new Bitmapfactory.options ();
///start reading the picture and set the Options.injustdecodebounds back to True
newopts.injustdecodebounds = true;
Bitmap Bitmap = Bitmapfactory.decodefile (srcpath,newopts);//return BM to empty at this time
newopts.injustdecodebounds = false;
int w = newopts.outwidth;
int h = newopts.outheight;
//Now the mainstream phone is more 800*480 resolution, so the height and width we set to
float hh = 800f;//Here Set the height to 800f
float ww = 480f;//here set width to 480f
//Zoom ratio. Because it is a fixed scale, only one of the data with high or wide is calculated
int be = 1;//be=1 means no scaling
If (W > H && w > ww) {//If the width is large, zoom according to the fixed width size
be = (int) (NEWOPTS.OUTWIDTH/WW);
} else if (W < h && h > hh) {//if height is scaled according to width fixed size
be = (int) (NEWOPTS.OUTHEIGHT/HH);
}
if (be <= 0)
be = 1;
newopts.insamplesize = be;//Setting the zoom ratio
//re-read the picture, note that the options.injustdecodebounds is now set back to False
bitmap = Bitmapfactory.decodefile (Srcpath, newopts);
return Compressimage (bitmap);//compress the proportions and then compress the mass
}
Picture proportional compression, I see an algorithm that says faster.
be = (int) ((w/standard_width + h/standard_height)/2);
Conclusion Two: Picture proportional compression multiplier is (width compression multiple + height compression multiple)/2.
Third: Image compression by proportional size (according to bitmap image compression):
Private Bitmap Comp (Bitmap image) {
Bytearrayoutputstream BAOs = new Bytearrayoutputstream ();
image.compress (Bitmap.CompressFormat.JPEG, BAOs);
if (Baos.tobytearray (). length/1024>1024) {//Judge if the picture is larger than 1M, compress to avoid overflow when generating the picture (Bitmapfactory.decodestream)
Baos.reset ();//Reset BAOs is empty BAOs
image.compress (Bitmap.CompressFormat.JPEG, 50%, BAOs);//compress the compressed data into BAOs .
}
Bytearrayinputstream ISBM = new Bytearrayinputstream (Baos.tobytearray ());
bitmapfactory.options newopts = new Bitmapfactory.options ();
///start reading the picture and set the 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;
//Now the mainstream phone is more 800*480 resolution, so the height and width we set to
float hh = 800f;//Here Set the height to 800f
float ww = 480f;//here set width to 480f
//Zoom ratio. Because it is a fixed scale, only one of the data with high or wide is calculated
int be = 1;//be=1 means no scaling
If (W > H && w > ww) {//If the width is large, zoom according to the fixed width size
be = (int) (NEWOPTS.OUTWIDTH/WW);
} else if (W < h && h > hh) {//if height is scaled according to width fixed size
be = (int) (NEWOPTS.OUTHEIGHT/HH);
}
if (be <= 0)
be = 1;
newopts.insamplesize = be;//Setting the zoom ratio
newopts.inpreferredconfig = config.rgb_565;//lower picture from ARGB888 to RGB565
//re-read the picture, note that the options.injustdecodebounds is now set back to False
ISBM = new Bytearrayinputstream (Baos.tobytearray ());
bitmap = Bitmapfactory.decodestream (ISBM, NULL, newopts);
return Compressimage (bitmap);//compress the proportions and then compress the mass
}
3 examples of how to compress Android images
