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Changed the behavior of gaussian_blur() to make it a little more user friendly.

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This commit is contained in:
Davis King 2011-09-29 19:19:32 -04:00
parent 128cc0cb51
commit 3c04d06abb
2 changed files with 26 additions and 17 deletions
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32
dlib/image_transforms/spatial_filtering.h
View File

@ -369,33 +369,41 @@ namespace dlib
>
matrix<T,0,1> create_gaussian_filter (
double sigma,
int size
int max_size
)
/*!
requires
- sigma > 0
- size > 0
- size is an odd number
- max_size > 0
- max_size is an odd number
ensures
- returns a separable Gaussian filter F such that:
- is_vector(F) == true
- F.size() == size
- F.size() <= max_size
- F is suitable for use with the spatially_filter_image_separable() routine
and its use with this function corresponds to running a Gaussian filter
of sigma width over an image.
!*/
{
DLIB_ASSERT(sigma > 0 && size > 0 && (size%2)==1,
DLIB_ASSERT(sigma > 0 && max_size > 0 && (max_size%2)==1,
"\t matrix<T,0,1> create_gaussian_filter()"
<< "\n\t Invalid inputs were given to this function."
<< "\n\t sigma: " << sigma
<< "\n\t size: " << size
<< "\n\t max_size: " << max_size
);
matrix<double,0,1> f(size);
// Adjust the size so that the ratio of the gaussian values isn't huge.
// This only matters when T is an integer type. However, we do it for
// all types so that the behavior of this function is always relatively
// the same.
while (gaussian(0,sigma)/gaussian(max_size/2,sigma) > 50)
--max_size;
matrix<double,0,1> f(max_size);
for (long i = 0; i < f.size(); ++i)
{
f(i) = gaussian(i-size/2, sigma);
f(i) = gaussian(i-max_size/2, sigma);
}
if (is_float_type<T>::value == false)
@ -419,22 +427,22 @@ namespace dlib
const in_image_type& in_img,
out_image_type& out_img,
double sigma = 1,
int size = 7
int max_size = 1001
)
{
DLIB_ASSERT(sigma > 0 && size > 0 && (size%2)==1 &&
DLIB_ASSERT(sigma > 0 && max_size > 0 && (max_size%2)==1 &&
is_same_object(in_img, out_img) == false,
"\t void gaussian_blur()"
<< "\n\t Invalid inputs were given to this function."
<< "\n\t sigma: " << sigma
<< "\n\t size: " << size
<< "\n\t max_size: " << max_size
<< "\n\t is_same_object(in_img,out_img): " << is_same_object(in_img,out_img)
);
typedef typename pixel_traits<typename out_image_type::type>::basic_pixel_type type;
typedef typename promote<type>::type ptype;
const matrix<ptype,0,1>& filt = create_gaussian_filter<ptype>(sigma, size);
const matrix<ptype,0,1>& filt = create_gaussian_filter<ptype>(sigma, max_size);
ptype scale = sum(filt);
scale = scale*scale;

11
dlib/image_transforms/spatial_filtering_abstract.h
View File

@ -225,7 +225,7 @@ namespace dlib
const in_image_type& in_img,
out_image_type& out_img,
double sigma = 1,
int size = 7
int max_size = 1001
);
/*!
requires
@ -235,12 +235,13 @@ namespace dlib
- pixel_traits<typename out_image_type::type>::has_alpha == false
- is_same_object(in_img, out_img) == false
- sigma > 0
- size > 0
- size is an odd number
- max_size > 0
- max_size is an odd number
ensures
- Filters in_img with a Gaussian filter of sigma width. The actual spatial filter will
be applied to pixel blocks that are size wide and size tall. The results are stored
into #out_img.
be applied to pixel blocks that are at most max_size wide and max_size tall (note that
this function will automatically select a smaller block size as appropriate). The
results are stored into #out_img.
- Pixel values are stored into out_img using the assign_pixel() function and therefore
any applicable color space conversion or value saturation is performed.
- if (pixel_traits<typename in_image_type::type>::grayscale == false) then