Android Image Compression Tips

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http://blog.csdn.net/fengyuzhengfan/article/details/41759835

When the Android client needs to upload pictures to the server, often need to compress the picture, about the image compression method, small series to share several common ways:

The first way: cut to achieve the purpose of compression

I have described in detail how to crop a photo in the article "cropped photos of Android development," and interested friends can go and see it.

The second way: To reduce the quality of the image processing (that is, reducing the image of the mass) to achieve the purpose of compression

This way is also a more common way, the following for you to describe how to reduce the quality of the picture:

To reduce the quality of the picture we can use this method of Bitmap: Boolean android.graphics.Bitmap.compress (compressformat format, int quality, OutputStream Stream

Where the parameter format represents the compressed format, quality the compressed picture quality (0 for the lowest, 100 for non-compression), and the stream represents the output stream to which the compressed picture will be saved.

Here is the detailed code:

/** * Multi-threaded compressed picture quality * @author JPH * @param bitmap in-memory picture * @param the save path of Imgpath picture * @date 2014-12-5 pm 11:30:43 */public Static void Compressimagebyquality (Final Bitmap bitmap,final String imgpath) {new Thread (new Runnable () {// Turn on multithreading for compression processing @overridepublic void Run () {//TODO auto-generated method Stubbytearrayoutputstream BAOs = new Bytearrayoutput Stream (); options = 100;bitmap.compress (Bitmap.CompressFormat.JPEG, Options, BAOs);//Quality compression method, the compressed data stored in the BAOs ( 100 means no compression, 0 is compressed to a minimum) while (Baos.tobytearray (). length/1024 > 100) {//cycle to determine if the image is larger than 100kb after compression, greater than the continued compression baos.reset ();// Reset BAOs to let the next write overwrite the contents of the options-= 10;//picture quality is reduced by 10if (options<0) options=0;//If the picture quality is less than 10, The quality of the picture is compressed to the minimum bitmap.compress (Bitmap.CompressFormat.JPEG, Options, BAOs);//Save the compressed picture to BAOs if (options==0) break;// If the quality of the picture has been minimized, it is no longer compressed}try {fileoutputstream fos = new FileOutputStream (new File (Imgpath));// Save the compressed picture locally on the specified path in Fos.write (Baos.tobytearray ()); Fos.flush (); Fos.close ();} catch (Exception e) {e.printstacktrace ();}}}). Start ();}

Method parsing:

Because I/O operations and recursive calls are time-consuming in this method, I use multithreading to handle them.

The Third way: proportionally reduce the pixels of the picture to achieve the purpose of compression

This method is mainly used android.graphics. bitmapfactory . Options . The options () method loads the picture into memory at the specified adoption rate and then outputs it locally to achieve the purpose of compressing the pixels.

Detailed code:

/** * Proportionally reduces the pixels of the image for compression purposes * @author JPH * @param imgpath * @date 2014-12-5 pm 11:30:59 */public static void Compressimagebypi Xel (String imgpath) {bitmapfactory.options newopts = new Bitmapfactory.options (); newopts.injustdecodebounds = true;// Read-only edge, unread content bitmap bitmap = Bitmapfactory.decodefile (Imgpath, newopts); newopts.injustdecodebounds = false;int width = Newopts.outwidth;int height = newopts.outheight;float maxSize = 1000f;//default 1000pxint be = 1;if (width > Height &&amp ; Width > MaxSize) {//zoom ratio, compute be = (int) (newopts.outwidth/maxsize) with a high or wide one of the larger data,} else if (Width < height &&am P Height > maxSize) {be = (int) (newopts.outheight/maxsize);} Be++;newopts.insamplesize = be;//Set Sample rate Newopts.inpreferredconfig = config.argb_8888;//The mode is the default, Newopts.inpurgeable = true;//is not set to be valid newopts.ininputshareable = true;//. When the system memory is not enough, the picture is automatically recycled bitmap = Bitmapfactory.decodefile (Imgpath, newopts); Bytearrayoutputstream BAOs = new Bytearrayoutputstream (); Bitmap.compress (Bitmap.CompressFormat.JPEG, BAOs); try {fileoutputstream fos = new FileOutputStream (new File (Imgpath)); Fos.write (Baos.tobytearray ()); Fos.flush (); Fos.close ();} catch (Exception e) {e.printstacktrace ();}}

The Fourth way: compress the picture first and then drop the quality

This approach is mainly combined with the second and third methods the following is the detailed code:

/** * Multi-threaded compressed picture quality * @author JPH * @param bitmap in-memory picture * @param the save path of Imgpath picture * @date 2014-12-5 pm 11:30:43 */public Static void Compressimagebyquality (Final Bitmap bitmap,final String imgpath) {new Thread (new Runnable () {// Turn on multithreading for compression processing @overridepublic void Run () {//TODO auto-generated method Stubbytearrayoutputstream BAOs = new Bytearrayoutput Stream (); options = 100;bitmap.compress (Bitmap.CompressFormat.JPEG, Options, BAOs);//Quality compression method, the compressed data stored in the BAOs ( 100 means no compression, 0 is compressed to a minimum) while (Baos.tobytearray (). length/1024 > 100) {//cycle to determine if the image is larger than 100kb after compression, greater than the continued compression baos.reset ();// Reset BAOs to let the next write overwrite the contents of the options-= 10;//picture quality is reduced by 10if (options<0) options=0;//If the picture quality is less than 10, The quality of the picture is compressed to the minimum bitmap.compress (Bitmap.CompressFormat.JPEG, Options, BAOs);//Save the compressed picture to BAOs if (options==0) break;// If the quality of the picture has been minimized, it is no longer compressed}try {fileoutputstream fos = new FileOutputStream (new File (Imgpath));// Save the compressed picture locally on the specified path in Fos.write (Baos.tobytearray ()); Fos.flush (); Fos.close ();} catch (Exception e) {e.printstacktrace ();}}}). Start ();} /** * ProportionallyReduce the pixels of the image for compression purposes * @author JPH * @param imgpath * @date 2014-12-5 pm 11:30:59 */public static void Compressimagebypixel (Strin G Imgpath) {bitmapfactory.options newopts = new Bitmapfactory.options (); newopts.injustdecodebounds = true;//read-only Edge, Unread content Bitmap bitmap = Bitmapfactory.decodefile (Imgpath, newopts); newopts.injustdecodebounds = false;int width = Newopts.outwidth;int height = newopts.outheight;float maxSize = 1000f;//default 1000pxint be = 1;if (width > Height &&amp ; Width > MaxSize) {//zoom ratio, compute be = (int) (newopts.outwidth/maxsize) with a high or wide one of the larger data,} else if (Width < height &&am P Height > maxSize) {be = (int) (newopts.outheight/maxsize);} Be++;newopts.insamplesize = be;//Set Sample rate Newopts.inpreferredconfig = config.argb_8888;//The mode is the default, Newopts.inpurgeable = true;//is not set to be valid newopts.ininputshareable = true;//. When the system memory is not enough, the picture is automatically recycled bitmap = Bitmapfactory.decodefile (Imgpath, newopts); compressimagebyquality (Bitmap,imgpath);// Compress the scale size and then mass compress}

Android Image Compression Tips