Options options1 = new Options();
options1.inJustDecodeBounds = true;  
BitmapFactory.decodeFile(filePath, options1);  
options1.inSampleSize = RegisterTool.calculateInSampleSize(options1, 110, 160);  //110,160：轉換後的寬和高，具體值會有些出入
options1.inJustDecodeBounds = false;  
Bitmap bitmap = BitmapFactory.decodeFile(filePath, options1);       //filePath:檔案路徑
 

public static int calculateInSampleSize(BitmapFactory.Options options,
			int reqWidth, int reqHeight) {
		
		final int height = options.outHeight;
		final int width = options.outWidth;
		int inSampleSize = 1;

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

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

			inSampleSize = heightRatio < widthRatio ? widthRatio : heightRatio;
		}

		return inSampleSize;
	}
 

//壓縮圖片並將Bitmap儲存到本地
FileOutputStream out = new FileOutputStream(new File(filePath));
saveBitmap.compress(Bitmap.CompressFormat.JPEG, 60, out);   //60代表壓縮40%