Android 下压缩图片—微弱失真

Android下压缩图片的方法：

大概能将3M左右的图片压缩到100K左右， 几乎不失真。 代码如下：

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.OutputStream;



import android.graphics.Bitmap;

import android.graphics.BitmapFactory;



public class BitmapUtil {

    /**

     * 压缩图片之后保存为文件

     * 

     * @param filePath

     *            原始图片的完整路径

     * @param storeImgPath

     *            压缩之后要存储的图片的完整路径

     * @return boolean

     * @author Doraemon

     * @time 2014年6月27日下午5:10:19

     */

    public static boolean saveCompressImg(String filePath, String storeImgPath) {

        Bitmap bm = getSmallBitmap(filePath);

        OutputStream stream = null;

        try {

            stream = new FileOutputStream(storeImgPath);

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        }



        return bm.compress(Bitmap.CompressFormat.JPEG, 40, stream);

    }



    /**

     * 根据路径获得突破并压缩返回bitmap用于显示

     * 

     * @param imagesrc

     * @return

     */

    private static Bitmap getSmallBitmap(String filePath) {

        final BitmapFactory.Options options = new BitmapFactory.Options();

        options.inJustDecodeBounds = true;

        BitmapFactory.decodeFile(filePath, options);



        // Calculate inSampleSize

        options.inSampleSize = calculateInSampleSize(options, 480, 800);



        // Decode bitmap with inSampleSize set

        options.inJustDecodeBounds = false;



        return BitmapFactory.decodeFile(filePath, options);

    }



    /**

     * 计算图片的缩放值

     * 

     * @param options

     * @param reqWidth

     * @param reqHeight

     * @return

     */

    private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {

        // Raw height and width of image

        final int height = options.outHeight;

        final int width = options.outWidth;

        int inSampleSize = 1;



        if (height > reqHeight || width > reqWidth) {



            // Calculate ratios of height and width to requested height and

            // width

            final int heightRatio = Math.round((float) height / (float) reqHeight);

            final int widthRatio = Math.round((float) width / (float) reqWidth);



            // Choose the smallest ratio as inSampleSize value, this will

            // guarantee

            // a final image with both dimensions larger than or equal to the

            // requested height and width.

            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;

        }



        return inSampleSize;

    }

}