spfilt.m

来自「Matlab數位影音處理 影像方面的處理」· M 代码 · 共 73 行

function f =spfilt(g, type, m, n, parameter)
    if nargin == 2
        m=3;n=3;Q=1.5;d=2;
    elseif nargin == 5
        Q=parameter;d=parameter;
    elseif nargin == 4
        Q=1.5;d=2;
    else 
        error('Wrong number of inputs.');
    end
    switch type
        case 'amean'
            w=fspecial('average',[m n]);
            f=imfilter(g, w, 'replicate');
        case 'gmean'
            f=gmean(g, m, n);
        case 'hmean'
            f=harmean(g, m, n);
        case 'chmean'
            f=charmean(g, m, n, Q);
        case 'median'
            f=medfilt2(g, [m n], 'symmetric');
        case 'max'
            f=ordfilt2(g, m*n, ones(m,n), 'symmetric'); 
        case 'min'
            f=ordfilt2(g, 1, ones(m,n), 'symmetric');
        case 'midpoint'
            f1=ordfilt2(g, 1, ones(m,n), 'symmetric');    
            f2=ordfilt2(g, m*n, ones(m,n), 'symmetric');
            f=imlincomb(0.5,f1,0.5,f2);
        case 'atrimmed'
            if (d<0) | (d/2 ~= round(d/2))
                error('d must be a nonnegative, even integer.')
            end
            f=alphatrim(g, m, n, d);
        otherwise
            error('Unknown filter type.')
    end
%-------------------------------------------------------------------------%
function f = gmean(g, m, n)
    inclass= class(g);
    g=im2double(g);
    warning off;
    f=exp(imfilter(log(g), ones(m, n), 'replicate')).^(1/m/n);
    warning on;
    f=changeclass(inclass, f);
%-------------------------------------------------------------------------%
function f = harmean(g, m, n)
    inclass= class(g);
    g=im2double(g);
    f=m*n./imfilter(1./(g + eps), ones(m,n), 'replicate');
    f=changeclass(inclass,f);
%-------------------------------------------------------------------------%
function f= charmean(g, m, n, q)
    inclass= class(g);
    g=im2double(g);
    f=imfilter(g.^(g+1), ones(m,n), 'replicate');
    f=f./ (imfilter(g.^q, ones(m,n), 'replicate') + eps);
    f = changeclass(inclass,f);
%-------------------------------------------------------------------------%
function f= alphatrim(g, m, n, d)
    inclass= class(g);
    g=im2double(g);
    f=imfilter(g, ones(m,n), 'symmetric');
    for k=1:d/2
        f=imsubtract(f, ordfilt2(g,k,ones(m,n), 'symmetric'));
    end
    for k=(m*n-(d/2)+1):m*n
        f=imsubtract(f, ordfilt2(g,k,ones(m,n), 'symmetric'));
    end
    f=f/(m8n-d);
    f=changeclass(inclass,f);