matlab图像风格化

close all;
clear all;
clc;
f=imread('th.jpg');
[VG,A,PPG]=colorgrad(f);
ppg=im2uint8(PPG);
ppgf=255-ppg;
[M,N]=size(ppgf);
T=200;
ppgf1=zeros(M,N);
for ii=1:M
for jj=1:N
if ppgf(ii,jj)<T
ppgf1(ii,jj)=0;
else
ppgf1(ii,jj)=235/(255-T)*(ppgf(ii,jj)-T);
	end
end
end
ppgf1=uint8(ppgf1);
figure;
subplot(221);imshow(ppgf);
subplot(222);imshow(ppgf1);
subplot(223);imhist(ppgf);
subplot(224);imhist(ppgf1);

figure;imshow(ppgf1);

function [VG,A,PPG]=colorgrad(f,T)
if (ndims(f)~=3)||(size(f,3)~=3)
error('Input?image?must?be?RGB');
end
sh=fspecial('sobel');
sv=sh';
Rx=imfilter(double(f(:,:,1)),sh,'replicate');
Ry=imfilter(double(f(:,:,1)),sv,'replicate');
Gx=imfilter(double(f(:,:,2)),sh,'replicate');
Gy=imfilter(double(f(:,:,2)),sv,'replicate');
Bx=imfilter(double(f(:,:,3)),sh,'replicate');
By=imfilter(double(f(:,:,3)),sv,'replicate');

gxx=Rx.^2+Gx.^2+Bx.^2;
gyy=Ry.^2+Gy.^2+By.^2;
gxy=Rx.*Ry+Gx.*Gy+Bx.*By;
A=0.5*(atan(2*gxy./(gxx-gyy+eps)));
G1=0.5*((gxx+gyy)+(gxx-gyy).*cos(2*A)+2*gxy.*sin(2*A));

A=A+pi/2;
G2=0.5*((gxx+gyy)+(gxx-gyy).*cos(2*A)+2*gxy.*sin(2*A));
G1=G1.^0.5;
G2=G2.^0.5;
VG=mat2gray(max(G1,G2));

RG=sqrt(Rx.^2+Ry.^2);
GG=sqrt(Gx.^2+Gy.^2);
BG=sqrt(Bx.^2+By.^2);

PPG=mat2gray(RG+GG+BG);

if nargin==2
VG=(VG>T).*VG;
PPG=(PPG>T).*PPG;
end
endclose all;
clear all;
clc;
f=imread('th.jpg');