Matlab HSL channel and RGB channel conversion HSL2RGB RGB2HSL

There is no image HSL channel support in Matlab, so it is necessary to implement rGB2HSL (R,G,B) and HSL2HSL (H,S,L) functions to convert BETWEEN HSL channel and RGB channel:

The content of the reference: zh.wikipedia.org/wiki/HSL

Color = (ColorR, ColorG, ColorB) = (r, g, b)

1. Hsl2rgb function: R, G, B two-dimensional matrix can be passed into the picture, or RGB single value

function [R,G,B] = hsl2rgb(H,S,L)
%HSL2RGB 
    [m,n]=size(H);
    % single-valued RGB
    if m==1&&n==1
        if S~=0
            if L<0.5
                q=L*(1+S);
            else
                q=L+S-(L*S);
            end
            p=2*L-q;
            hk=H/360;
            R_temp=hk+1/3;
            G_temp=hk;
            B_temp=hk- 1/3;
            R=hsl2rgb_subfun(R_temp,p,q);
            G=hsl2rgb_subfun(G_temp,p,q);
            B=hsl2rgb_subfun(B_temp,p,q);
        elseR=L; G=L; B=L;end
    % image RGB
    else
        R=zeros(m,n); G=zeros(m,n); B=zeros(m,n);
        for i=1:m
            for j=1:n
                s=S(i.j);   
                l=L(i.j);         
                if s~=0
                    h=H(i.j);      
                    if l<0.5
                        q=l*(1+s);
                    else
                        q=l+s-(l*s);
                    end
                    p=2*l-q;
                    hk=h/360;
                    R_temp=hk+1/3;
                    G_temp=hk;
                    B_temp=hk- 1/3;
                    
                    R(i.j)=hsl2rgb_subfun(R_temp,p,q);
                    G(i.j)=hsl2rgb_subfun(G_temp,p,q);
                    B(i.j)=hsl2rgb_subfun(B_temp,p,q);
                else
                    R(i.j)=l;
                    G(i.j)=l;
                    B(i.j)=l;
                end
            end
        end
    end
end

function re = hsl2rgb_subfun(t,p,q)
        if t<0
            t=t+1.0;
        elseif t>1
            t=t1.0;
        end
        if t<1/6
            re=p+((q-p)*6*t);
        elseif 1/6<=t && t<0.5
            re=q;
        elseif 0.5<=t && t<2/3
            re=p+((q-p)*6* (2/3-t));
        else
            re=p;
        end
    end    
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2. Rgb2hsl function: H, S, L two-dimensional matrix can be passed into the picture, or the single value of HSL

function [H,S,L] = rgb2hsl(R,G,B)
%RGB2HSL 
    [m,n]=size(R);
    % Single-value RGB
    if m==1&&n==1
        rgbMax=max([R,G,B]);
        rgbMin=min([R,G,B]);
        if rgbMax==rgbMin
            H=0;
        elseif rgbMax==R && G>=B
            H=60*(G-B)/(rgbMax-rgbMin);
        elseif rgbMax==R && G<B
            H=60*(G-B)/(rgbMax-rgbMin)+360;
        elseif rgbMax==G
            H=60*(B-R)/(rgbMax-rgbMin)+120;
        elseif rgbMax==B
            H=60*(R-G)/(rgbMax-rgbMin)+240;
        end
        L=(rgbMax+rgbMin)/2;
        if L==0 || rgbMax==rgbMin
            S=0;
        elseif L>0 && L<=0.5
            S=(rgbMax-rgbMin)/(2*L);
        elseif L>0.5
            S=(rgbMax-rgbMin)/(22 -*L);
        end
    % RGB of the picture
    else
        H=zeros(m,n);
        S=zeros(m,n);
        L=zeros(m,n);
        for i=1:m
            for j=1:n
               r=R(i.j);
               g=G(i.j);
               b=B(i.j);
               rgbMax=max([r,g,b]);
               rgbMin=min([r,g,b]);
               if rgbMax==rgbMin
                    H(i.j) =0;
               elseif rgbMax==r && g>=b
                    H(i.j) =60*(g-b)/(rgbMax-rgbMin);
               elseif rgbMax==r && g<b
                    H(i.j) =60*(g-b)/(rgbMax-rgbMin)+360;
               elseif rgbMax==g
                    H(i.j) =60*(b-r)/(rgbMax-rgbMin)+120;
               elseif rgbMax==b
                    H(i.j) =60*(r-g)/(rgbMax-rgbMin)+240;
               end
               L(i.j)=(rgbMax+rgbMin)/2;
               if L(i.j) = =0 || rgbMax==rgbMin
                    S(i.j) =0;
               elseif 0<L(i.j) && L(i.j) < =0.5
                    S(i.j)=(rgbMax-rgbMin)/(2*L(i.j));
               elseif L(i.j) >0.5
                    S(i.j)=(rgbMax-rgbMin)/(22 -*L(i.j));
               end
            end
        end
    end
end

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