本文主要向大家介绍了Photoshop入门学习之利用Perlin nosie 完成（PS 滤镜—— 分成云彩），通过具体的内容向大家展现，希望对大家Photoshop入门学习有所帮助。

%%%% Cloud
%%%% 利用perlin noise生成云彩
 
clc;
clear all;
close all;
 
addpath('E:\PhotoShop Algortihm\Image Processing\PS Algorithm');
 
 
Image=imread('4.jpg');
Image=double(Image);
 
[row,col,layer]=size(Image);
 
baseNoise=rand(row,col);
 
persistance = 0.9;
totalAmplitude = 0.0;
 
octaveCount=10;
 
Cloud_texture=zeros(row,col);
 
for i=0:octaveCount
    amplitude=persistance.^(octaveCount-i);
    % amplitude=persistance.^i;
    totalAmplitude=totalAmplitude+amplitude;
    Cloud_texture=Cloud_texture+Generate_smoothnoise(baseNoise, i)*amplitude;
end
 
Cloud_texture=Cloud_texture/totalAmplitude;
 
imshow(Cloud_texture);
   
 
 
 
function SmoothNoise=Generate_smoothnoise(baseNoise, octave)
 
SmoothNoise=baseNoise;
 
[row, col]=size(baseNoise);
 
samplePeriod=2.^octave;
sampleFrequency=1/samplePeriod;
 
for i=1:row
    sample_i0=floor((i/samplePeriod))*samplePeriod;
    sample_i1=mod(sample_i0+samplePeriod,row);
    vertical_blend = (i - sample_i0) * sampleFrequency;
    for j=1:col
        sample_j0 = floor(j / samplePeriod) * samplePeriod;
        sample_j1 = mod(sample_j0 + samplePeriod,col);
        horizontal_blend = (j - sample_j0) * sampleFrequency;
        
        if(sample_i0<1)
            sample_i0=1;
        end
        
        if(sample_i1<1)
            sample_i1=1;
        end
        
        if(sample_j1<1)
            sample_j1=1;
        end
        
        if(sample_j0<1)
            sample_j0=1;
        end
        
        % blend the top two corners
        top = Cosine_Interpolate(baseNoise(sample_i0,sample_j0),...
        baseNoise(sample_i0,sample_j1), horizontal_blend);
 
        % blend the bottom two corners
        bottom = Cosine_Interpolate(baseNoise(sample_i1,sample_j0),...
        baseNoise(sample_i1,sample_j1), horizontal_blend);
 
        % final blend
        SmoothNoise(i,j) = Cosine_Interpolate(top, bottom, vertical_blend);
    end
end
function  y=Cosine_Interpolate(x1,x2,alpha)
ft = alpha * 3.1415927;
f = (1 - cos(ft)) * .5;
y=x1*(1-f)+x2*f;
   

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