I have code for wavelet transform. Here they are using coif1 to decompose the signal. Can anybody explain what is the use of coif1? and what does it mean?
This is the code:
function wavelet = waveletTransform(image)
% input: image to process and extract wavelet coefficients from
% output: 1x20 feature vector containing the first 2 moments of wavelet
% coefficients
imgGray = double(rgb2gray(image))/255;
imgGray = imresize(imgGray, [256 256]);
coeff_1 = dwt2(imgGray', 'coif1');
coeff_2 = dwt2(coeff_1, 'coif1');
coeff_3 = dwt2(coeff_2, 'coif1');
coeff_4 = dwt2(coeff_3, 'coif1');
% construct the feaute vector
meanCoeff = mean(coeff_4);
stdCoeff = std(coeff_4);
wavelet = [meanCoeff stdCoeff];
end
Looking at the Matlab documentation here and there (documentation for the parameter wname), you will see that it means that the wavelet coif1 is the type of the wavelet, which is in this case from the coiflet family.
It is the wavelet used as filter for the decomposition of the image.