PS 滤镜— — 镜头光晕

    clc;
    clear all;
    close all;

    addpath('E:\PhotoShop Algortihm\Image Processing\PS Algorithm');


    I=imread('4.jpg');
    Image=double(I)/255*0;

    [height, width, depth]=size(Image);

    rays = 200;
    radius=100;
    baseAmount = 1.0;
    ringAmount = 0.25;
    rayAmount = 0.15;
    color = [1.0, 1.0, 1.0];
    centreX = 0.7;
    centreY = 0.3;
    ringWidth = 1.5;    
    linear = 0.025;
    gauss = 0.005;
    mix = 0.50;
    falloff = 5.0;
    sigma=radius/6;

    icentreX = centreX*width;
    icentreY = centreY*height;

    [p, g1, g2, g3]=init_arr();

    Img_new=Image;

    for ii=1:height
        for jj=1:width

            dx = jj-icentreX;
            dy = ii-icentreY;
            distance=sqrt(dx*dx+dy*dy);

            a = exp(-distance*distance*gauss)*mix + exp(-distance*linear)*(1-mix);

            a=a*baseAmount;

            if (distance > radius + ringWidth)
                a =lerp((distance - (radius + ringWidth))/falloff, a, 0);
            end

            if (distance < radius - ringWidth || distance > radius + ringWidth)
                ring = 0;
            else 
                ring = abs(distance-radius)/ringWidth;
                ring = 1 - ring*ring*(3 - 2*ring);
                ring = ring*ringAmount;
            end

            a=a+ring;

            angle =atan2(dx, dy)+pi;
            angle = (mod(angle/pi*17 + 1.0 + Noise1(angle*10, p, g1), 1.0) - 0.5)*2;
            angle = abs(angle);
            angle = angle.^5;

            b = rayAmount * angle / (1 + distance*0.1);
            a = a + b;

            a=min(max(0,a),1);

            r=Image(ii, jj, 1);
            g=Image(ii, jj, 2);
            b=Image(ii, jj, 3);

            Img_new(ii, jj, 1)=lerp(a, r, color(1));
            Img_new(ii, jj, 2)=lerp(a, g, color(2));
            Img_new(ii, jj, 3)=lerp(a, b, color(3));

        end
    end

    imshow(Img_new);
    imwrite(Img_new, 'out.jpg');

参考来源：http://www.jhlabs.com/index.html

效果图：