小波分解中参数coif1是什么意思？

Question

我有小波变换的代码。他们在这里使用 coif1 来分解信号。谁能解释一下 coif1 有什么用？这是什么意思？

这是代码：

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

Answer 1

看Matlab文档here and there（参数wname的文档），你会看到意思是小波coif1是小波的类型，即在这种情况下来自 coiflet 家族。

它是用作图像分解滤波器的小波。