void
lsm_filter_fast_blur (LsmFilterSurface *input,
LsmFilterSurface *output,
double sx, double sy)
{
gint kx, ky;
guchar *intermediate;
g_return_if_fail (input != NULL);
g_return_if_fail (output != NULL);
kx = floor (sx * 3 * sqrt (2 * M_PI) / 4 + 0.5);
ky = floor (sy * 3 * sqrt (2 * M_PI) / 4 + 0.5);
if (kx < 1 && ky < 1)
return;
intermediate = g_new (guchar, MAX (kx, ky));
box_blur (input, output, intermediate, kx, ky);
box_blur (output, output, intermediate, kx, ky);
box_blur (output, output, intermediate, kx, ky);
g_free (intermediate);
}
/** Requirements: img is SKRY_PIX_MONO8, box_radius < 2^11 */
struct SKRY_image *box_blur_img(const struct SKRY_image *img, unsigned box_radius, size_t iterations)
{
assert(SKRY_get_img_pix_fmt(img) == SKRY_PIX_MONO8);
SKRY_Image *blurred = SKRY_new_image(SKRY_get_img_width(img), SKRY_get_img_height(img), SKRY_PIX_MONO8, 0, 0);
if (blurred)
{
enum SKRY_result result = box_blur(SKRY_get_line(img, 0), SKRY_get_line(blurred, 0),
SKRY_get_img_width(img), SKRY_get_img_height(img),
SKRY_get_line_stride_in_bytes(img), SKRY_get_line_stride_in_bytes(blurred),
box_radius, iterations);
if (SKRY_SUCCESS == result)
return blurred;
else
{
SKRY_free_image(blurred);
return 0;
}
}
else
return 0;
}
/** Quality is the sum of differences between input image
and its blurred version. In other words, sum of values
of the high-frequency component. The sum is normalized
by dividing by the number of pixels. */
SKRY_quality_t estimate_quality(uint8_t *pixels, unsigned width, unsigned height, ptrdiff_t line_stride, unsigned box_blur_radius)
{
uint8_t *blurred = malloc(width*height);
box_blur(pixels, blurred, width, height, line_stride, width,
box_blur_radius, QUALITY_ESTIMATE_BOX_BLUR_ITERATIONS);
SKRY_quality_t quality = 0;
uint8_t * restrict src_line = pixels;
uint8_t * restrict blurred_line = blurred;
for (unsigned y = 0; y < height; y++)
{
for (unsigned x = 0; x < width; x++)
quality += abs(src_line[x] - blurred_line[x]);
src_line += line_stride;
blurred_line += width;
}
free(blurred);
return quality / (width*height);
}
