Image processing method and image processing device

1. An image processing method for detecting visual saliency of an image based on regional contrast, the method comprising:

segmenting an input image into a plurality of regions by using an automatic segmentation algorithm; and

calculating a saliency value of one region of the plurality of segmented regions by using a weighted sum of color differences between the one region and all other regions and by using spatial distances between the one region and all other regions,

wherein, in the segmenting, a saliency S(r k ) of a region r k of the plurality of segmented regions is defined by the following expression:

S

⁡

(

r

k

)

=

∑

r

k

≠

r

i

⁢

exp

⁡

(

-

D

s

⁡

(

r

k

,

r

i

)

σ

s

2

)

⁢

w

⁡

(

r

i

)

⁢

D

c

⁡

(

r

k

,

r

i

)

,

and

wherein D s (r k ,r i ) and D c (r k ,r i ) are respectively a sMatial distance and a color difference between the region r k and a region r i , and k are natural numbers, w(r i ) is a weighted value of the region r i and σ s 2 is a parameter for controlling the effect of a distance factor.

2. The image processing method according to claim 1 , wherein the parameter σ s 2 is a value in a range from 0.1 to 1.0 when spatial coordinates of a pixel in the image are normalized to values in a range from 0 to 1.

3. The image processing method according to claim 1 , wherein a number of pixels included in the region r, is deemed as the weighted value w(r i ) of the region r i .

4. The image processing method according to claim 1 ,

wherein the color difference D c (r k ,r i ) between the region r k and the region r i is defined by the following expression: D c (r k ,r i )=Σ i=1 n 1 Σ j=1 n 2 f (c 1 ,i)f(c 2 ,j)D(c 1,i ,c 2,j ), and

wherein f(c k ,i) is an appearance frequency of i-th c k of n k types of colors contained in the region r k , D(c 1,i ,c 2,j ) is an Euclidean distance between two colors c 1,i and c 2,j in a color space, and k={1,2}.

5. The image processing method according to claim 4 , wherein the calculating is performed with 8 to 128 classes of colors in each color channel.

6. An image processing device for detecting visual saliency of an image based on regional contrast, the device comprising:

a segmentation processor that segments an input image into a plurality of regions by using an automatic segmentation algorithm; and

a computation processor that calculates a saliency value of one region of the plurality of segmented regions by using a weighted sum of color differences between the one region and all other regions and by spatial distances between the one region and all other regions,

wherein a saliency S(r k ) of a region r k of the plurality of segmented regions is defined by the following expression:

S

⁡

(

r

k

)

=

∑

r

k

≠

r

i

⁢

exp

⁡

(

-

D

s

⁡

(

r

k

,

r

i

)

σ

s

2

)

⁢

w

⁡

(

r

i

)

⁢

D

c

⁡

(

r

k

,

r

i

)

,

and

wherein D s (r k ,r i ) and D c (r k ,r i ) are respectively a spatial distance and a color difference between the region r k and a region r i , i, and k are natural numbers, w(r i ) is a weighted value of the region r i and σ s 2 is a parameter for controlling the effect of a distance factor.

7. The image processing device according to claim 6 , wherein the parameter σ s 2 is a value in a range from 0.1 to 1.0 when spatial coordinates of a pixel in the image are normalized to values in a range from 0 to 1.

8. The image processing device according to claim 6 , wherein a number of pixels included in the region r, is deemed as the weighted value w(r i ) of the region r i .

9. The image processing device according to claim 6 ,

wherein the color difference D c (r k ,r i ) between the region r k and the region r i is defined by the following expression: D c (r k ,r i )=Σ i=1 n 1 Σ j=1 n 2 f(c 1 ,i)f(c 2 ,j)D(c 1,i ,c 2,j ), and

wherein f(c k ,i) is an appearance frequency of i-th c k of n k types of colors contained in region r k , D(c 1,i ,c 2,j ) is an Euclidean distance between two colors c 1,i and c 2,j in a color space, and k={1,2}.

10. The image processing device according to claim 9 , wherein the computation processor calculates with 8 to 128 classes of colors in each color channel.

11. The image processing method according to claim 1 , further comprising at least one of:

outputting the calculated saliency value;

displaying the calculated saliency value; and

storing the calculated saliency value.

12. The image processing method according to claim 2 , further comprising at least one of:

outputting the calculated saliency value;

displaying the calculated saliency value; and

storing the calculated saliency value.

13. The image processing method according to claim 3 , further comprising at least one of:

outputting the calculated saliency value;

displaying the calculated saliency value; and

storing the calculated saliency value.

14. The image processing method according to claim 4 , further comprising at least one of:

outputting the calculated saliency value;

displaying the calculated saliency value; and

storing the calculated saliency value.

15. The image processing method according to claim 5 , further comprising at least one of:

outputting the calculated saliency value;

displaying the calculated saliency value; and

storing the calculated saliency value.

16. The image processing device according to claim 6 , further comprising at least one of:

an output processor that outputs the calculated saliency value;

a display processor that displays the calculated saliency value; and

a storage processor that stores the calculated saliency value.