Android 下压缩图片—微弱失真

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;
}
}