Method and apparatus for representing a group of images
A method of representing a group of images comprises determining the values of one or more dominant colors for the group of images and deriving a dominant color representation expressing the group of images in terms of one or more of said dominant color values.
1. A method of searching for a group of images using at least one processor to process signals corresponding to the images, the method comprising:
comparing, using a processor, a query dominant colour descriptor with a plurality of group descriptors for groups of images using a matching procedure; and
selecting one or more group of images for which the matching procedure indicates the closest match or matches,
wherein the group descriptors are derived using a method of representing a group of images, the method comprising determining the values of one or more dominant colours for the group of images and deriving a group dominant colour representation expressing the group of images in terms of one or more of said dominant colour values,
wherein at least some of the images in the group of images are represented by a respective image dominant colour representation in terms of one or more dominant colour values for the image, where each of the image dominant colour representations has one or more components including at least one dominant colour value, and for each dominant colour value, a variance indicating colour distribution variance of the image with respect to the dominant colour value, and a weight indicating the influence of the dominant colour in the image, said variance being calculated for each image dominant colour using
CV
j
=
1
N
∑
k
=
0
N
-
1
(
m
j
-
p
kj
)
2
where j indexes the color component, m j is j-th component of the image dominant color, p kj is j-th component of the k-th pixel value, and the summation is over N pixels corresponding to the image dominant color under consideration, and said group dominant colour representation is derived by combining a plurality of said image dominant colour representations, and
wherein for two dominant colours m 1 and m 2 , and respective weights W 1 and W 2 , the merged dominant colour m has the value:
m=w 1 m 1 +w 2 m 2 ,
where w i , w 2 are the relative weights, W 1 /W 1 +W 2 and W 2 /W 1 +W 2 respectively.
2. A method as claimed in claim 1 comprising combining one or more components of the image dominant colour representations based on proximity of dominant colours in colour space.
3. A method as claimed in claim 1 involving temporally or spatially subsampling the group of images.
4. A method as claimed in claim 3 wherein images are omitted or included depending on their similarity to other images in the group.
5. A method as claimed in claim 3 wherein the subsampling involves the step of combining one ore more components of the image dominant colour representations based on proximity of dominant colour space.
6. An apparatus for searching for a group of images comprising:
an image database storing images or groups of images;
a descriptor database storing descriptors for the images or groups of images in the image database; and
a processor configured to perform the method according to claim 1 .
7. A non-transitory computer-readable storage medium storing computer-executable process steps for implementing a method as claimed in claim 1 .
8. A computer system comprising:
an image database storing images or groups of images;
a descriptor database storing descriptors for the images or groups of images in the image database; and
a control unit, said control unit including a processor and a memory storing computer executable code for performing the method as claimed in claim 1 .