effective image database search via dimensionality reduction
DESCRIPTION
Effective Image Database Search via Dimensionality Reduction. Anders Bjorholm Dahl and Henrik Aanæs IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshops. Outline. Introduction Methods LF-clustering Experiments and Results Discussion and Conclusion. - PowerPoint PPT PresentationTRANSCRIPT
Effective Image Database Search via Dimensionality Reduction
Anders Bjorholm Dahl and Henrik AanæsIEEE Computer Society Conference on
Computer Vision and Pattern Recognition Workshops
Outline
Introduction Methods
LF-clustering Experiments and Results Discussion and Conclusion
Introduction
The bag-of-words approach1. Feature extraction from the database
images2. Building the bag-of-words
representation3. Searching with a query image
Introduction
The Bag-of-word Model
Methods
Feature representation Clustering Feature assignment Image matching
Feature representation
PCA is applied to reduce the dimensionality of the feature vectors
The reduction of the SIFT descriptor is from 128 to between 3 and 12 dimensions
After dimension reduction we add color to our features the mean RGB value in a 10 × 10 pixels
patch around the localization of each feature
Feature representation
is the PCA reduced SIFT feature is the mean RGB values is a weighing parameter
( ) 1. normalized to unit length2. normalized
[ , (1 ) ]PCA RGBs s s
PCAs
RGBs
0.5 ,PCA RGBs s
s
Clustering
Similar but faster than Mean-shift clustering
Feature assignment
Similarity of images are found by comparing frequency vectors of a query image to images in the database
Give each visual words a weight[16]
log( )
: the weight of word
: the total number of images in the database
: the number of images where word occurs
ii
i
i
Nw
n
w i
N
n i
[16] D. Nister and H. Stewenius. Scalable recognition with a vocabulary tree. In IEEE Conference on Computer Vision and Pattern Recognition (CVPR), volume 2, pages 2161–2168, June 2006.
Image matching
Frequency vectors are compared using the norm which is found to be superior to the
euclidean distance[16]
norm gives equal weight to the overlapping and non-overlapping parts
Inverted files are used for fast image retrieval
1L
1L
Experiments and Results
Data set first 1400 images form [16]
a series of 4 images of the same scene Use three of the images from one scene
to train the model and the last for testing
The test result is the percentage of the correct images ranked in top 3
data set is relatively smallhttp://www.vis.uky.edu/~stewe/ukbench/
Experiments and Results
Data set:
Experiments and Results
Experiments Color added PCA SIFT
3, 8, and 12 dimensional PCA SIFT featuresadded features are 6, 11, and 15 dimensions
compare with SIFT features reduced with PCA to 6, 11 and 15 dimensions (without color)
Clustering experiments LF-clustering
from 8,000 to 12,000 clusters k-means
10 clusters in 4 levels resulting in 10,000 clusters
Experiments and Results
Results
Experiments and Results
Results
Discussion and Conclusion
did not apply LF-clustering to the 128 dimensional SIFT features, because it performed very poorly
for future work the model should be tested on a larger set of data
A problem of the design of the bag-of-words model is it static nature not designed for adding or removing
images from the database