Fast color texture recognition using chromaticity moments Pattern Recognition Letters 21 (2000) 837-841 Presented by Waseem Khatri

Existing approaches to texture analysis Statistical – Moments , Co-occurrence matrix Model Based – Fractal, Stochastic models Structural – Microtexture , Macrotexture , Morphology Transform – Fourier , Wavelet , Gabor transforms Limitations Computationally Intensive Cannot differentiate subtle variation in textures Scaling and Rotation

CIE xy chromaticity diagram of an image Proposed Method CIE xy chromaticity diagram of an image 2D and 3D moments to characterize a given color image. Classification using distance measure

CIE XYZ Color Space Chromaticity: The quality of a color as determined by its dominant wavelength Chromaticity diagram is a two dimensional representation of an image where each pixel produces a pair of (x,y) values Matlab: rgb2xyz

2D Shape and 2D distribution 2D Trace 2D Distribution

Moments Why moments ? Definition: If f(x,y) is piecewise continuous and has non zero values only in a finite part of the xy-plane, moments of all orders exist and the moment sequence (mpq) is uniquely determined by f(x,y). Why moments ? Moments uniquely capture the nature of both the 2D shape and the 2D distribution of chromaticities.

Procedure Given image is converted into CIE xyz color space The trace of the chromaticity diagram is computed The 2D distribution is computed using: D(x,y)= k , where k= #pixels producing (x,y) Moments are computed using: T(x,y) = 1 if exists (i,j) : I(i,j) produces (x,y) 0 otherwise; 0<i<Lx , 0<i<Ly

Classification Moments for all the classes in the database are computed Moments for the test sample is computed Minimum Distance measure d=|x-xi| where x is the feature vector of the class xi is the feature vector of the test image The given test sample is assigned to the class from which it has the minimum distance

Conclusion Advantages Simple Efficient Effective for a database with distinct texture Uses small number of chromaticity moment features Drawbacks Error rate is high if the database contains textures that are not significantly different