[Java] Picture compression

There are two ways to compress images built into Java:

1. The image size is compressed by the getScaledInstance method of image, and its compression strategy is:

   Scale_default	Default image Scaling algorithm
   Scale_fast	Zoom Speed First
   Scale_smooth	Image Smoothing Priority

   It is the advantage of the image can not affect the quality of a certain compression of the picture, the disadvantage is that the compression effect has limitations.
2. Using Imagewriteparam's Setcompressionquality method to set the image quality generated when the image is imagewrite output, it has the advantage of compressing the size of the picture without changing the size of the picture, and the compression efficiency is higher.

The following code is used together to control the size and size of the compressed picture.

Package Test;import Java.awt.image;import Java.awt.image.bufferedimage;import java.awt.image.colormodel;import Java.io.bytearrayinputstream;import Java.io.bytearrayoutputstream;import Java.io.file;import Java.util.Iterator; Import Javax.imageio.iioimage;import Javax.imageio.imageio;import Javax.imageio.imagetypespecifier;import Javax.imageio.imagewriteparam;import Javax.imageio.imagewriter;import Javax.imageio.stream.ImageOutputStream; public class Compresspicutil {public image cmopresspic (image image) throws Exception {int Newwidth;int newheight;//specifies the generated drawing width High if (Image.getwidth (NULL) > 1024) {//Here you can specify the conditions for scaling double rate = (double) image.getwidth (null)/1024;newwidth = 1024; Newheight = (int) (Image.getheight (null)/rate);} else {newwidth = Image.getwidth (null); newheight = Image.getheight (null);} BufferedImage compression compression policy by scaling to image.scale_fast speed first bufferedimage buffer = new BufferedImage (Newwidth, Newheight, BUFFEREDIMAGE.TYPE_INT_BGR); Buffer.getgraphics (). DrawImage (Image.getscaledinstance (NewwidtH, Newheight,image.scale_fast), 0, 0, NULL);//Get a ImageWriter output stream imagewriter writer = Null;imagetypespecifier type = Imag Etypespecifier.createfromrenderedimage (buffer); Iterator iter = Imageio.getimagewriters (type, "JPG"); if ( Iter.hasnext ()) {writer = (ImageWriter) iter.next ();} if (writer = = null) {return null;} Iioimage iioimage = new Iioimage (buffer, NULL, NULL);//Specify compression mode compression degree color mode imagewriteparam param = Writer.getdefaultwritepara M ();p Aram.setcompressionmode (imagewriteparam.mode_explicit);p aram.setcompressionquality (0.4F);//You can specify the degree of compression here 0-1.0colormodel ColorModel = Colormodel.getrgbdefault ();p Aram.setdestinationtype (new  Javax.imageio.ImageTypeSpecifier (ColorModel, ColorModel Createcompatiblesamplemodel (16, 16)); Prints the picture in the cache to the byte array as specified in the configuration Bytearrayoutputstream bytearrayoutputstream = new Bytearrayoutputstream (); Mageoutputstream outputstream = Imageio.createimageoutputstream (Bytearrayoutputstream); Writer.setOutput ( OutputStream); Writer.write (null, iioimage, param);//From the wordReading a picture in a section array bytearrayinputstream bytearrayinputstream = new Bytearrayinputstream (Bytearrayoutputstream.tobytearray ()) ; Image smallimage = Imageio.read (Bytearrayinputstream); return smallimage;}}

Its compression effect is (the compression time has been planed to read the file time):

File 1----Compressed before size 3378KB compression size 44KB compression time 639 ms Picture width 1024 picture height 640
File 2----Compressed before size 2240KB compression size 60KB compression time 295 ms Picture width 1024 picture height 640
File 3----Compressed before size 1161KB compression size 37KB compression time 224 ms Picture width 1024 picture height 640
File 4----Compressed before size 1309KB compression size 50KB compression time 194 ms Picture width 1024 picture height 576
File 5----Compressed before size 872KB compression size 26KB compression time 223 ms Picture width 1024 picture height 576

[Java] Picture compression