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i3lock-color
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Implement generic box blur

This commit is contained in:
Sebastian Frysztak 2017-02-15 11:22:06 +01:00
parent 6029c8e0b5
commit 3598cf19e8
3 changed files with 77 additions and 110 deletions
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145
blur.c
View File

@ -24,15 +24,12 @@
#include <math.h>
#include "blur.h"
#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
/* Performs a simple 2D Gaussian blur of radius @radius on surface @surface. */
void
blur_image_surface (cairo_surface_t *surface, int radius)
{
cairo_surface_t *tmp;
int width, height;
int src_stride, dst_stride;
uint32_t *src, *dst;
if (cairo_surface_status (surface))
@ -64,89 +61,87 @@ blur_image_surface (cairo_surface_t *surface, int radius)
return;
src = (uint32_t*)cairo_image_surface_get_data (surface);
src_stride = cairo_image_surface_get_stride (surface);
dst = (uint32_t*)cairo_image_surface_get_data (tmp);
dst_stride = cairo_image_surface_get_stride (tmp);
//blur_impl_naive(src, dst, width, height, src_stride, dst_stride, 10000);
//blur_impl_sse2(src, dst, width, height, 4.5);
blur_impl_ssse3(src, dst, width, height, 4.5);
// according to a paper by Peter Kovesi [1], box filter of width w, equals to Gaussian blur of following sigma:
// σ_av = sqrt((w*w-1)/12)
// for our 7x7 filter we have σ_av = 2.0.
// applying the same Gaussian filter n times results in σ_n = sqrt(n*σ_av*σ_av) [2]
// after some trivial math, we arrive at n = ((σ_d)/(σ_av))^2
// since it's a box blur filter, n >= 3
//
// [1]: http://www.peterkovesi.com/papers/FastGaussianSmoothing.pdf
// [2]: https://en.wikipedia.org/wiki/Gaussian_blur#Mathematics
float sigma = 5;
int n = lrintf((sigma*sigma)/(SIGMA_AV*SIGMA_AV));
if (n < 3) n = 3;
for (int i = 0; i < n; i++)
{
// horizontal pass includes image transposition:
// instead of writing pixel src[x] to dst[x],
// we write it to transposed location.
// (to be exact: dst[height * current_column + current_row])
#ifdef __x86_64__
blur_impl_horizontal_pass_sse2(src, dst, width, height);
blur_impl_horizontal_pass_sse2(dst, src, height, width);
#else
blur_impl_horizontal_pass_generic(src, dst, width, height);
blur_impl_horizontal_pass_generic(dst, src, height, width);
#endif
}
cairo_surface_destroy (tmp);
cairo_surface_flush (surface);
cairo_surface_mark_dirty (surface);
}
void blur_impl_naive(uint32_t* _src, uint32_t* _dst, int width, int height, int src_stride, int dst_stride, int radius)
{
int x, y, z, w;
uint32_t *s, *d, a, p;
int i, j, k;
uint8_t kernel[17];
const int size = ARRAY_LENGTH (kernel);
const int half = size / 2;
void blur_impl_horizontal_pass_generic(uint32_t *src, uint32_t *dst, int width, int height) {
for (int row = 0; row < height; row++) {
for (int column = 0; column < width; column++, src++) {
uint32_t rgbaIn[KERNEL_SIZE];
uint8_t *src = (uint8_t*)_src;
uint8_t *dst = (uint8_t*)_dst;
// handle borders
int leftBorder = column < HALF_KERNEL;
int rightBorder = column > width - HALF_KERNEL;
int i = 0;
if (leftBorder) {
// for kernel size 7x7 and column == 0, we have:
// x x x P0 P1 P2 P3
// first loop mirrors P{0..3} to fill x's,
// second one loads P{0..3}
for (; i < HALF_KERNEL - column; i++)
rgbaIn[i] = *(src + (HALF_KERNEL - i));
for (; i < KERNEL_SIZE; i++)
rgbaIn[i] = *(src - (HALF_KERNEL - i));
} else if (rightBorder) {
for (; i < width - column; i++)
rgbaIn[i] = *(src + i);
for (int k = 0; i < KERNEL_SIZE; i++, k++)
rgbaIn[i] = *(src - k);
} else {
for (; i < KERNEL_SIZE; i++)
rgbaIn[i] = *(src + i - HALF_KERNEL);
}
a = 0;
for (i = 0; i < size; i++) {
double f = i - half;
a += kernel[i] = exp (- f * f / 30.0) * 80;
}
uint32_t acc[4] = {0};
/* Horizontally blur from surface -> tmp */
for (i = 0; i < height; i++) {
s = (uint32_t *) (src + i * src_stride);
d = (uint32_t *) (dst + i * dst_stride);
for (j = 0; j < width; j++) {
if (radius < j && j < width - radius) {
d[j] = s[j];
continue;
for (i = 0; i < KERNEL_SIZE; i++) {
acc[0] += (rgbaIn[i] & 0xFF000000) >> 24;
acc[1] += (rgbaIn[i] & 0x00FF0000) >> 16;
acc[2] += (rgbaIn[i] & 0x0000FF00) >> 8;
acc[3] += (rgbaIn[i] & 0x000000FF) >> 0;
}
for(i = 0; i < 4; i++)
acc[i] *= 1.0/KERNEL_SIZE;
*(dst + height * column + row) = (acc[0] << 24) |
(acc[1] << 16) |
(acc[2] << 8 ) |
(acc[3] << 0);
}
x = y = z = w = 0;
for (k = 0; k < size; k++) {
if (j - half + k < 0 || j - half + k >= width)
continue;
p = s[j - half + k];
x += ((p >> 24) & 0xff) * kernel[k];
y += ((p >> 16) & 0xff) * kernel[k];
z += ((p >> 8) & 0xff) * kernel[k];
w += ((p >> 0) & 0xff) * kernel[k];
}
d[j] = (x / a << 24) | (y / a << 16) | (z / a << 8) | w / a;
}
}
/* Then vertically blur from tmp -> surface */
for (i = 0; i < height; i++) {
s = (uint32_t *) (dst + i * dst_stride);
d = (uint32_t *) (src + i * src_stride);
for (j = 0; j < width; j++) {
if (radius <= i && i < height - radius) {
d[j] = s[j];
continue;
}
x = y = z = w = 0;
for (k = 0; k < size; k++) {
if (i - half + k < 0 || i - half + k >= height)
continue;
s = (uint32_t *) (dst + (i - half + k) * dst_stride);
p = s[j];
x += ((p >> 24) & 0xff) * kernel[k];
y += ((p >> 16) & 0xff) * kernel[k];
z += ((p >> 8) & 0xff) * kernel[k];
w += ((p >> 0) & 0xff) * kernel[k];
}
d[j] = (x / a << 24) | (y / a << 16) | (z / a << 8) | w / a;
}
}
}

9
blur.h
View File

@ -4,11 +4,14 @@
#include <stdint.h>
#include <cairo.h>
void blur_image_surface (cairo_surface_t *surface, int radius);
void blur_impl_naive(uint32_t* src, uint32_t* dst, int width, int height, int src_stride, int dst_stride, int radius);
#define KERNEL_SIZE 7
#define SIGMA_AV 2
#define HALF_KERNEL KERNEL_SIZE / 2
void blur_image_surface (cairo_surface_t *surface, int radius);
void blur_impl_sse2(uint32_t* src, uint32_t* dst, int width, int height, float sigma);
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, int width, int height);
void blur_impl_horizontal_pass_generic(uint32_t *src, uint32_t *dst, int width, int height);
#endif

33
blur_simd.c
View File

@ -8,43 +8,12 @@
*/
#include "blur.h"
#include <math.h>
#include <xmmintrin.h>
#define ALIGN16 __attribute__((aligned(16)))
#define KERNEL_SIZE 7
#define SIGMA_AV 2
#define HALF_KERNEL KERNEL_SIZE / 2
// number of xmm registers needed to store
// input pixels for given kernel size
// number of xmm registers needed to store input pixels for given kernel size
#define REGISTERS_CNT (KERNEL_SIZE + 4/2) / 4
void blur_impl_sse2(uint32_t *src, uint32_t *dst, int width, int height, float sigma) {
// according to a paper by Peter Kovesi [1], box filter of width w, equals to Gaussian blur of following sigma:
// σ_av = sqrt((w*w-1)/12)
// for our 7x7 filter we have σ_av = 2.0.
// applying the same Gaussian filter n times results in σ_n = sqrt(n*σ_av*σ_av) [2]
// after some trivial math, we arrive at n = ((σ_d)/(σ_av))^2
// since it's a box blur filter, n >= 3
//
// [1]: http://www.peterkovesi.com/papers/FastGaussianSmoothing.pdf
// [2]: https://en.wikipedia.org/wiki/Gaussian_blur#Mathematics
int n = lrintf((sigma*sigma)/(SIGMA_AV*SIGMA_AV));
if (n < 3) n = 3;
for (int i = 0; i < n; i++)
{
// horizontal pass includes image transposition:
// instead of writing pixel src[x] to dst[x],
// we write it to transposed location.
// (to be exact: dst[height * current_column + current_row])
blur_impl_horizontal_pass_sse2(src, dst, width, height);
blur_impl_horizontal_pass_sse2(dst, src, height, width);
}
}
void blur_impl_horizontal_pass_sse2(uint32_t *src, uint32_t *dst, int width, int height) {
for (int row = 0; row < height; row++) {
for (int column = 0; column < width; column++, src++) {