Android 图片高斯模糊处理

原图：   效果图：

此效果是根据jhlabs 的Filters.jar 改写过来应用在android 平台上。

核心自然是高斯算法，这里没有深究其中的算法实现，只是项目实现而已。

引用代码：

/** 水平方向模糊度 */
private static float hRadius = 10;
/** 竖直方向模糊度 */
private static float vRadius = 10;
/** 模糊迭代度 */
private static int iterations = 7;

        /**
	 * 高斯模糊
	 */
	public static Drawable BoxBlurFilter(Bitmap bmp) {
		int width = bmp.getWidth();
		int height = bmp.getHeight();
		int[] inPixels = new int[width * height];
		int[] outPixels = new int[width * height];
		Bitmap bitmap = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);
		bmp.getPixels(inPixels, 0, width, 0, 0, width, height);
		for (int i = 0; i < iterations; i++) {
			blur(inPixels, outPixels, width, height, hRadius);
			blur(outPixels, inPixels, height, width, vRadius);
		}
		blurFractional(inPixels, outPixels, width, height, hRadius);
		blurFractional(outPixels, inPixels, height, width, vRadius);
		bitmap.setPixels(inPixels, 0, width, 0, 0, width, height);
		Drawable drawable = new BitmapDrawable(bitmap);
		return drawable;
	}

　　核心算法：

public static void blur(int[] in, int[] out, int width, int height,
			float radius) {
		int widthMinus1 = width - 1;
		int r = (int) radius;
		int tableSize = 2 * r + 1;
		int divide[] = new int[256 * tableSize];

		for (int i = 0; i < 256 * tableSize; i++)
			divide[i] = i / tableSize;

		int inIndex = 0;

		for (int y = 0; y < height; y++) {
			int outIndex = y;
			int ta = 0, tr = 0, tg = 0, tb = 0;

			for (int i = -r; i <= r; i++) {
				int rgb = in[inIndex + clamp(i, 0, width - 1)];
				ta += (rgb >> 24) & 0xff;
				tr += (rgb >> 16) & 0xff;
				tg += (rgb >> 8) & 0xff;
				tb += rgb & 0xff;
			}

			for (int x = 0; x < width; x++) {
				out[outIndex] = (divide[ta] << 24) | (divide[tr] << 16)
						| (divide[tg] << 8) | divide[tb];

				int i1 = x + r + 1;
				if (i1 > widthMinus1)
					i1 = widthMinus1;
				int i2 = x - r;
				if (i2 < 0)
					i2 = 0;
				int rgb1 = in[inIndex + i1];
				int rgb2 = in[inIndex + i2];

				ta += ((rgb1 >> 24) & 0xff) - ((rgb2 >> 24) & 0xff);
				tr += ((rgb1 & 0xff0000) - (rgb2 & 0xff0000)) >> 16;
				tg += ((rgb1 & 0xff00) - (rgb2 & 0xff00)) >> 8;
				tb += (rgb1 & 0xff) - (rgb2 & 0xff);
				outIndex += height;
			}
			inIndex += width;
		}
	}

	public static void blurFractional(int[] in, int[] out, int width,
			int height, float radius) {
		radius -= (int) radius;
		float f = 1.0f / (1 + 2 * radius);
		int inIndex = 0;

		for (int y = 0; y < height; y++) {
			int outIndex = y;

			out[outIndex] = in[0];
			outIndex += height;
			for (int x = 1; x < width - 1; x++) {
				int i = inIndex + x;
				int rgb1 = in[i - 1];
				int rgb2 = in[i];
				int rgb3 = in[i + 1];

				int a1 = (rgb1 >> 24) & 0xff;
				int r1 = (rgb1 >> 16) & 0xff;
				int g1 = (rgb1 >> 8) & 0xff;
				int b1 = rgb1 & 0xff;
				int a2 = (rgb2 >> 24) & 0xff;
				int r2 = (rgb2 >> 16) & 0xff;
				int g2 = (rgb2 >> 8) & 0xff;
				int b2 = rgb2 & 0xff;
				int a3 = (rgb3 >> 24) & 0xff;
				int r3 = (rgb3 >> 16) & 0xff;
				int g3 = (rgb3 >> 8) & 0xff;
				int b3 = rgb3 & 0xff;
				a1 = a2 + (int) ((a1 + a3) * radius);
				r1 = r2 + (int) ((r1 + r3) * radius);
				g1 = g2 + (int) ((g1 + g3) * radius);
				b1 = b2 + (int) ((b1 + b3) * radius);
				a1 *= f;
				r1 *= f;
				g1 *= f;
				b1 *= f;
				out[outIndex] = (a1 << 24) | (r1 << 16) | (g1 << 8) | b1;
				outIndex += height;
			}
			out[outIndex] = in[width - 1];
			inIndex += width;
		}
	}

	public static int clamp(int x, int a, int b) {
		return (x < a) ? a : (x > b) ? b : x;
	}

　　感谢Jhlabs 网站的开源！