Options opts = new Options(); //只请求图片宽高，不解析图片像素 opts.inJustDecodeBounds = true; //返回null，获取图片宽高，保存在opts对象中 BitmapFactory.decodeFile("sdcard/dog.jpg", opts); //获取图片宽高 int imageWidth = opts.outWidth; int imageHeight = opts.outHeight; //获取屏幕宽高 Display dp = getWindowManager().getDefaultDisplay(); int screenWidth = dp.getWidth(); int screenHeight = dp.getHeight(); //计算缩放比例 int scale = 1; int scaleWidth = imageWidth / screenWidth; int scaleHeight = imageHeight / screenHeight; //判断取哪个比例 if(scaleWidth >= scaleHeight && scaleWidth > 1){ scale = scaleWidth; } else if(scaleWidth < scaleHeight && scaleHeight > 1){ scale = scaleHeight; } //设置缩小比例 opts.inSampleSize = scale; opts.inJustDecodeBounds = false; //获取缩小后的图片的像素信息 Bitmap bm = BitmapFactory.decodeFile("sdcard/dog.jpg", opts); ImageView iv = (ImageView) findViewById(R.id.iv); iv.setImageBitmap(bm);原文：http://www.cnblogs.com/SoulCode/p/6393350.html