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What is CBIR ?
• Content-based image retrieval, a technique which uses visual contents to search images from large scale image databases according to users interests, has been an active and fast advancing research area since the 1990s.
• In our project we concentrated on histogram and Texture features to retrieve the images according to an example query image supplied by the user.
Block Diagram
Original Image
RGB
RGB HSV
Conversion
Histogram
Dist and Diff
Color Feature
Extract
RGB Gray
Conversion
2D-DWT
Transform
Higher
Component
Extraction
Texture
Feature Extract
Input Image
Color Feature Texture Feature
Pre-Processing
Feature Extract
Extracted Feature
Image Retrieval /
Similarity
Result Image
Histogram is a measure used to describe the image. In simple words it means the distribution of color brightness across the image. The brightness values range in [0..255].
What is Histogram
The histogram of a digital image with gray values 110 ,,, Lrrr is the discrete function
n
nrp kk )(
nk: Number of pixels with gray value rk n: total Number of pixels in the image
The function p(rk) represents the fraction of the total
number of pixels with gray value rk.
What is the histogram of a digital image?
Histogram provides a global description of the appearance of the
image.
If we consider the gray values in the image as realizations of a
random variable R, with some probability density, histogram provides
an approximation to this probability density. In other words,
)()Pr( kk rprR
0 1 1 2 4
2 1 0 0 2
5 2 0 0 4
1 1 2 4 1
The (intensity or brightness) histogram shows how many times a
particular grey level (intensity) appears in an image.
For example, 0 - black, 255 – white
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6
Some Typical Histograms
The shape of a histogram provides useful information for
contrast enhancement.
Dark image
N
i
nmnm iimHiimHimHimHd1
),(),())(),((
N
i
nmnm iimHiimHimHimHd1
)),(),(min())(),((
Histogram Difference :
Histogram Intersection Distance :
Texture
Edge Density and Direction :
• Use an edge detector as the first step in texture analysis.
• The number of edge pixels in a fixed-size region tells us how
busy that region is.
• The directions of the edges also help characterize the texture
Two Edge-based Texture
Measures
1. Edge-ness per unit area
2. Edge magnitude and direction histograms
Fedgeness = |{ p / gradient_magnitude(p) threshold}| / N
where N is the size of the unit area
Fmagdir = ( Hmagnitude, Hdirection )
where these are the normalized histograms of gradient magnitudes
and gradient directions, respectively.
Local Binary Pattern Measure
100 101 103
40 50 80
50 60 90
• For each pixel p, create an 8-bit number b1 b2 b3 b4 b5 b6 b7 b8,
where bi = 0 if neighbor i has value less than or equal to p’s
value and 1 otherwise.
• Represent the texture in the image (or a region) by the
histogram of these numbers.
1 1 1 1 1 1 0 0
1 2 3
4
5
7 6
8
Discrete Wavelet Transform
• The wavelet transform (WT) has gained widespread acceptance in
signal processing and image compression.
• Because of their inherent multi-resolution nature, wavelet-coding
schemes are especially suitable for applications where scalability
and tolerable degradation are important
• Recently the JPEG committee has released its new image coding
standard, JPEG-2000, which has been based upon DWT.
• Wavelet transform decomposes a signal into a set of basis functions.
• These basis functions are called wavelets
• Wavelets are obtained from a single prototype wavelet y(t) called mother wavelet by dilations and shifting:
• where a is the scaling parameter and b is the shifting parameter
)(1
)(,a
bt
atba
Simulation and Results
• Here as per the flow of the system mentioned in
the block, the input image is applied for both the
feature extraction Methods.
• The Combined results of the methods is applied
to the database images and features are compared.
• Resultant Image will be displayed as matched and
in the otherwise condition the access is denied.
Conclusion and Future
Color information on some of information by image makes
usefulness but, as weakness of color information is that can search
the similar color range, different image. In present method image DB
retrieval by Image information, which combines the info about
Texture along with Color, in order to overcome the weakness of
color.
In Future In order to increase accuracy to more extent, test are
been applied for the Surf Algorithm to match with point wise
determination, in combination with color and texture.