Can anyone please explain waveletTransform coding

I have a code for waveletTransform to find the feature vector containing the first 2 moments of wavelet coefficients.Can anybody please explain me this code?I don't understand what is coif1 and coeff_1 in this 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

[Pavan Kumar]

Where did you get this code

Answer 1

[anita jasmine]

Coiflet is derived from daubechies wavelet.

1. the coiflet wavelet of order 1 is computed for image.

coeff_1 = dwt2(imgGray', 'coif1');

2. Applying 4 levels of 2DWT

coeff_2 = dwt2(coeff_1, 'coif1');

coeff_3 = dwt2(coeff_2, 'coif1');

coeff_4 = dwt2(coeff_3, 'coif1');

3.computing the first 2 moments mean and std