stack_blur.h

stack_blur.h

#include "ofMain.h"

namespace stack_blur {
	
	template<class T> struct stack_blur_tables {
		static uint16_t const g_stack_blur8_mul[255];
		static uint8_t const g_stack_blur8_shr[255];
	};
	
	//------------------------------------------------------------------------
	template<class T>
	uint16_t const stack_blur_tables<T>::g_stack_blur8_mul[255] =
	{
		512,512,456,512,328,456,335,512,405,328,271,456,388,335,292,512,
		454,405,364,328,298,271,496,456,420,388,360,335,312,292,273,512,
		482,454,428,405,383,364,345,328,312,298,284,271,259,496,475,456,
		437,420,404,388,374,360,347,335,323,312,302,292,282,273,265,512,
		497,482,468,454,441,428,417,405,394,383,373,364,354,345,337,328,
		320,312,305,298,291,284,278,271,265,259,507,496,485,475,465,456,
		446,437,428,420,412,404,396,388,381,374,367,360,354,347,341,335,
		329,323,318,312,307,302,297,292,287,282,278,273,269,265,261,512,
		505,497,489,482,475,468,461,454,447,441,435,428,422,417,411,405,
		399,394,389,383,378,373,368,364,359,354,350,345,341,337,332,328,
		324,320,316,312,309,305,301,298,294,291,287,284,281,278,274,271,
		268,265,262,259,257,507,501,496,491,485,480,475,470,465,460,456,
		451,446,442,437,433,428,424,420,416,412,408,404,400,396,392,388,
		385,381,377,374,370,367,363,360,357,354,350,347,344,341,338,335,
		332,329,326,323,320,318,315,312,310,307,304,302,299,297,294,292,
		289,287,285,282,280,278,275,273,271,269,267,265,263,261,259
	};
	
	//------------------------------------------------------------------------
	template<class T>
	uint8_t const stack_blur_tables<T>::g_stack_blur8_shr[255] =
	{
		9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
		17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
		19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
		20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
		21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
		21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
		22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
		22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
		23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
		23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
		23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
		23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
		24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
		24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
		24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
		24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24
	};
	
	template <typename T>
	struct process_pixel_type {};
	
	template <>
	struct process_pixel_type<uint8_t> {
		typedef uint32_t value_type;
	};
	
	template <>
	struct process_pixel_type<float> {
		typedef float value_type;
	};
	
	template <typename T, int N>
	struct pixel_type {
		T data[N];
		
		inline pixel_type() {}
		
		template <typename V>
		inline pixel_type(const pixel_type<V, N>& copy) {
			for (int i = 0; i < N; i++)
				data[i] = copy.data[i];
		}
		
		template <typename V>
		inline pixel_type(V v) {
			for (int i = 0; i < N; i++)
				data[i] = v;
			return *this;
		}
		
		template <typename V>
		inline pixel_type operator*(const V v) const {
			pixel_type p;
			for (int i = 0; i < N; i++)
				p.data[i] = data[i] * v;
			return p;
		}
		
		template <typename V>
		inline pixel_type operator>>(const V v) const {
			pixel_type p;
			for (int i = 0; i < N; i++)
				p.data[i] = data[i] >> v;
			return p;
		}
		
		template <typename V>
		inline pixel_type& operator+=(const pixel_type<V, N>& v) {
			for (int i = 0; i < N; i++)
				data[i] += v.data[i];
			return *this;
		}
		
		template <typename V>
		inline pixel_type& operator-=(const pixel_type<V, N>& v) {
			for (int i = 0; i < N; i++)
				data[i] -= v.data[i];
			return *this;
		}
	};
	
	//
	
	template <typename T, int N>
	inline pixel_type<T, N>* get_pixel(T* data, int x, int y, int w)
	{
		return (pixel_type<T, N>*)(data + (x + (y * w)) * N);
	}
	
	template <typename T, int N>
	inline const pixel_type<T, N>* get_pixel(const T* data, int x, int y, int w)
	{
		return (pixel_type<T, N>*)(data + (x + (y * w)) * N);
	}
	
	template <typename T, int N>
	void stack_blur(const T* src, T* dst, int width, int height, int blur_width, int blur_height)
	{
		assert(src);
		assert(dst);
		
		typedef typename process_pixel_type<T>::value_type value_type;
		typedef pixel_type<T, N> pixel_ptr_type;
		typedef pixel_type<value_type, N> pixel_type;
		
		const int w = width;
		const int h = height;
		const int wm = w - 1;
		const int hm = h - 1;
		int rx = blur_width;
		int ry = blur_height;
		
		if(rx > 0)
		{
			if(rx > 254) rx = 254;
			
			const value_type div = rx * 2 + 1;
			const value_type mul_sum = stack_blur_tables<value_type>::g_stack_blur8_mul[rx];
			const value_type shr_sum = stack_blur_tables<value_type>::g_stack_blur8_shr[rx];
			
			vector<pixel_type> stack(div);
			
			for (int y = 0; y < h; y++)
			{
				pixel_type sum(0);
				pixel_type sum_in(0);
				pixel_type sum_out(0);
				
				const pixel_ptr_type* src_pix_ptr = get_pixel<T, N>(src, 0, y, w);
				pixel_ptr_type* dst_pix_ptr = NULL;
				
				pixel_type pix = *src_pix_ptr;
				
				for (int i = 0; i <= rx; i++)
					stack[i] = pix;
				
				for (int i = 0; i <= rx; i++)
					sum += pix * (i + 1);
				
				for (int i = 0; i <= rx; i++)
					sum_out += pix;
				
				for (int i = 1; i <= rx; i++)
				{
					if (i <= wm) src_pix_ptr++;
					pix = *src_pix_ptr;
					stack[i + rx] = pix;
					sum += pix * (rx + 1 - i);
					sum_in += pix;
				}
				
				unsigned int stack_ptr = rx;
				unsigned int xp = rx;
				unsigned int stack_start;
				
				if (xp > wm) xp = wm;
				
				src_pix_ptr = get_pixel<T, N>(src, xp, y, w);
				dst_pix_ptr = get_pixel<T, N>(dst, 0, y, w);
				
				for (int x = 0; x < w; x++)
				{
					*dst_pix_ptr = (sum * mul_sum) >> shr_sum;
					dst_pix_ptr++;
					
					sum -= sum_out;
					
					stack_start = stack_ptr + div - rx;
					
					if (stack_start >= div)
						stack_start -= div;
					
					sum_out -= stack[stack_start];
					
					if (xp < wm)
					{
						src_pix_ptr++;
						pix = *src_pix_ptr;
						++xp;
					}
					
					stack[stack_start] = pix;
					
					sum_in += pix;
					sum += sum_in;
					
					++stack_ptr;
					
					if (stack_ptr >= div) stack_ptr = 0;
					
					const pixel_type& stack_pix = stack[stack_ptr];
					sum_out += stack_pix;
					sum_in -= stack_pix;
				}
			}
		}
		
		if(ry > 0)
		{
			if(ry > 254) ry = 254;
			
			const value_type div = ry * 2 + 1;
			const value_type mul_sum = stack_blur_tables<value_type>::g_stack_blur8_mul[ry];
			const value_type shr_sum = stack_blur_tables<value_type>::g_stack_blur8_shr[ry];
			
			vector<pixel_type> stack(div);
			
			int stride = w;
			for(int x = 0; x < w; x++)
			{
				pixel_type sum(0);
				pixel_type sum_in(0);
				pixel_type sum_out(0);
				
				const pixel_ptr_type* src_pix_ptr = get_pixel<T, N>(dst, x, 0, w);
				pixel_ptr_type* dst_pix_ptr = NULL;
				pixel_type pix = *src_pix_ptr;
				
				for (int i = 0; i <= ry; i++)
					stack[i] = pix;
				
				for (int i = 0; i <= ry; i++)
					sum += pix * (i + 1);
				
				for (int i = 0; i <= ry; i++)
					sum_out += pix;
				
				for (int i = 1; i <= ry; i++)
				{
					if (i <= hm) src_pix_ptr += stride;
					pix = *src_pix_ptr;
					stack[i + ry] = pix;
					sum += pix * (ry + 1 - i);
					sum_in += pix;
				}
				
				unsigned int stack_ptr = ry;
				unsigned int yp = ry;
				unsigned int stack_start;
				
				if (yp > hm) yp = hm;
				
				src_pix_ptr = get_pixel<T, N>(dst, x, yp, w);
				dst_pix_ptr = get_pixel<T, N>(dst, x, 0, w);
				
				for (int y = 0; y < h; y++)
				{
					*dst_pix_ptr = (sum * mul_sum) >> shr_sum;
					dst_pix_ptr += stride;
					
					sum -= sum_out;
					
					stack_start = stack_ptr + div - ry;
					if (stack_start >= div) stack_start -= div;
					sum_out -= stack[stack_start];
					
					if (yp < hm)
					{
						src_pix_ptr += stride;
						pix = *src_pix_ptr;
						++yp;
					}
					
					stack[stack_start] = pix;
					
					sum_in += pix;
					sum += sum_in;
					
					++stack_ptr;
					if (stack_ptr >= div) stack_ptr = 0;
					
					const pixel_type& stack_pix = stack[stack_ptr];
					sum_out += stack_pix;
					sum_in -= stack_pix;
				}
			}
		}
	}
	
	void blur(const ofPixels& in, ofPixels& out, int radius)
	{
		assert(in.getNumChannels() == out.getNumChannels());
		
		switch (in.getNumChannels()) {
			case 1: {
				stack_blur<uint8_t, 1>(in.getPixels(), out.getPixels(), in.getWidth(), in.getHeight(), radius, radius);
				break;
			}
			case 3: {
				stack_blur<uint8_t, 3>(in.getPixels(), out.getPixels(), in.getWidth(), in.getHeight(), radius, radius);
				break;
			}
			case 4: {
				stack_blur<uint8_t, 4>(in.getPixels(), out.getPixels(), in.getWidth(), in.getHeight(), radius, radius);
				break;
			}
			default: throw;
		}
	}
	
}