Android Bitmap Compress (image compression)

With the development of mobile hardware, the camera function of Android bitmap compressandroid is becoming more and more powerful and able to find high resolution images. Some scenes, need to take photos and upload to the service, but because the size of the picture is too large, then the upload will be very slow (in some network conditions), and very consumption of traffic, to speed up, then you need to reduce the size of the picture. There are two ways to reduce the size of a picture, 1. Take a small picture; 2. Compress large pictures. Take pictures of small images generally do not meet the requirements, because the clarity of the picture will be very poor, but this situation has a benefit is that the application speed will be faster; compress the picture, is to compress the large picture, reduce the quality of the picture, in a certain range, reduce the size of the picture, and meet the needs (picture is still clear). The following group should describe the compression of the picture: 1. For photos, see http://blog.csdn.net/luhuajcdd/article/details/8826587 To save a picture to a directory, you need to specify a file when you start the camera app2. Compression process: 2.1 Read the picture from the picture path (the picture is very large, can not be all added to the memory processing, if all loaded into memory memory overflow) [Java]View Plaincopy

2. Final Bitmapfactory.options Options = new Bitmapfactory.options ();
4. Options.injustdecodebounds = true;
6. Bitmapfactory.decodefile (FilePath, Options);
10. //Calculate insamplesize
12. Options.insamplesize = calculateinsamplesize (options, 480, 800);
16. //Decode bitmap with Insamplesize set
18. Options.injustdecodebounds = false;
22. Bitmap BM = Bitmapfactory.decodefile (FilePath, Options);

2.2 Handling Picture Rotation [Java]View Plaincopy

1. int degree = Readpicturedegree (FilePath);
2. BM = Rotatebitmap (bm,degree);

[Java]View Plaincopy

2. Private static int readpicturedegree (String path) {
4. int degree = 0;
6. try {
8. Exifinterface exifinterface = new Exifinterface (path);
10. int orientation = Exifinterface.getattributeint (Exifinterface.tag_orientation, Exifinterface.orientation_    NORMAL);
12. switch (orientation) {
14. Case exifinterface.orientation_rotate_90:
16. degree = 90;
18. Break ;
20. Case exifinterface.orientation_rotate_180:
22. degree = 180;
24. Break ;
26. Case exifinterface.orientation_rotate_270:
28. degree = 270;
30. Break ;
32. }
34. } catch (IOException e) {
36. E.printstacktrace ();
38. }
40. return degree;
42. }

[Java]View Plaincopy

2. Private static Bitmap Rotatebitmap (Bitmap Bitmap, int rotate) {
4. if (bitmap = = null)
6. return null;
10. int w = bitmap.getwidth ();
12. int h = bitmap.getheight ();
16. //Setting post rotate to
18. Matrix MTX = new Matrix ();
20. Mtx.postrotate (rotate);
22. return Bitmap.createbitmap (Bitmap, 0, 0, W, H, MTX, true);
24. }

2.3 Compressing pictures [Java]View Plaincopy

1. Bm.compress (Bitmap.CompressFormat.JPEG, BAOs);  30 is the compression ratio, which means compression 70%; If no compression is 100, it indicates a compression rate of 0

The Complete method code: [Java]View Plaincopy

2. Public static Bitmap Getsmallbitmap (String filePath) {
6. final Bitmapfactory.options Options = new Bitmapfactory.options ();
8. Options.injustdecodebounds = true;
10. Bitmapfactory.decodefile (FilePath, Options);
14. //Calculate insamplesize
16. Options.insamplesize = calculateinsamplesize (options, 480, 800);
20. //Decode bitmap with Insamplesize set
22. Options.injustdecodebounds = false;
26. Bitmap BM = Bitmapfactory.decodefile (FilePath, Options);
28. if (BM = = null) {
30. return null;
32. }
34. int degree = Readpicturedegree (FilePath);
36. BM = Rotatebitmap (bm,degree);
38. Bytearrayoutputstream BAOs = null;
40. try{
42. BAOs = new Bytearrayoutputstream ();
44. Bm.compress (Bitmap.CompressFormat.JPEG, BAOs);
48. }finally{
50. try {
52. if (BAOs! = null)
54. Baos.close ();
56. } catch (IOException e) {
58. E.printstacktrace ();
60. }
62. }
64. return BM;
68. }

[Java]View Plaincopy

2. Private static int calculateinsamplesize (bitmapfactory.options Options,
4. int reqwidth, int reqheight) {
6. //Raw height and width of image
8. final int height = options.outheight;
10. final int width = options.outwidth;
12. int insamplesize = 1;
16. if (height > Reqheight | | width > reqwidth) {
20. //Calculate ratios of height and width to requested height and
22. //Width
24. final int heightratio = Math.Round ((float) height
26. /(float) reqheight);
28. final int widthRatio = Math.Round ((float) width/(float) reqwidth);
32. //Choose the smallest ratio as insamplesize value, this would
34. //Guarantee
36. //A final image with both dimensions larger than or equal to the
38. //requested height and width.
40. Insamplesize = HeightRatio < WidthRatio? Widthratio:heightratio;
42. }
46. return insamplesize;
48. }

Android Bitmap Compress (image compression)