冈萨雷斯数字图像处理——彩色图像增强3实例
实例一：基于直方图均衡化的彩色图像增强
要处理的图片：fruit.jpgexample1.m:
clc;RGB=imread('fruit.jpg'); %输入彩色图像，得到三维数组R=RGB(:,:,1); %分别取三维数组的一维，得到红绿蓝三个分量G=RGB(:,:,2); %为R G BB=RGB(:,:,3);subplot(4,2,1),imshow(RGB); %绘制各分量的图像及其直方图title('原始真彩色图像');subplot(4,2,3),imshow(R);title('真彩色图像的红色分量');subplot(4,2,4), imhist(R);title('真彩色图像的红色分量直方图');subplot(4,2,5),imshow(G);title('真彩色图像的绿色分量');subplot(4,2,6), imhist(G);title('真彩色图像的绿色分量直方图');subplot(4,2,7),imshow(B);title('真彩色图像的蓝色分量');subplot(4,2,8), imhist(B);title('真彩色图像的蓝色分量直方图');r=histeq(R); %对个分量直方图均衡化，得到个分量均衡化图像 g=histeq(G); b=histeq(B); figure,subplot(3,2,1),imshow(r);title('红色分量均衡化后图像');subplot(3,2,2), imhist(r);title('红色分量均衡化后图像直方图');subplot(3,2,3),imshow(g);title('绿色分量均衡化后图像');subplot(3,2,4), imhist(g);title('绿色分量均衡化后图像直方图');subplot(3,2,5), imshow(b);title('蓝色分量均衡化后图像');subplot(3,2,6), imhist(b);title('蓝色分量均衡化后图像直方图');figure, %通过均衡化后的图像还原输出原图像newimg = cat(3,r,g,b);imshow(newimg,[]);title('均衡化后分量图像还原输出原图');
处理效果：
通过matlab仿真，比较均衡化后的还原图像与输入原始真彩色图像，输出图像轮廓更清晰，亮度明显增强。
实例二: 双边滤波(Bilateral Filtering)
双边滤波是一种非线性的滤波方法，是结合图像的空间邻近度和像素值相似度的一种折衷处理，同时考虑空域信息和灰度相似性，达到保边去噪的目的。具有简单、非迭代、局部的特点。双边滤波器的好处是可以做边缘保存（edge preserving），一般过去用的维纳滤波或者高斯滤波去降噪，都会较明显地模糊边缘，对于高频细节的保护效果并不明显。双边滤波器顾名思义比 高斯滤波 多了一个高斯方差sigma－d，它是基于空间分布的高斯滤波 函数 ，所以在边缘附近，离的较远的像素不会太多影响到边缘上的像素值，这样就保证了边缘附近像素值的保存。但是由于保存了过多的高频信息，对于彩色图像里的高频噪声，双边滤波器不能够干净的滤掉，只能够对于低频信息进行较好的滤波。测试用例图：
matlab代码： bfilter2.m
% BFILTER2 Two dimensional bilateral filtering.% This function implements 2-D bilateral filtering using% the method outlined in:%% C. Tomasi and R. Manduchi. Bilateral Filtering for % Gray and Color Images. In Proceedings of the IEEE % International Conference on Computer Vision, 1998. %% B = bfilter2(A,W,SIGMA) performs 2-D bilateral filtering% for the grayscale or color image A. A should be a double% precision matrix of size NxMx1 or NxMx3 (i.e., grayscale% or color images, respectively) with normalized values in% the closed interval [0,1]. The half-size of the Gaussian% bilateral filter window is defined by W. The standard% deviations of the bilateral filter are given by SIGMA,% where the spatial-domain standard deviation is given by% SIGMA(1) and the intensity-domain standard deviation is% given by SIGMA(2).%% Douglas R. Lanman, Brown University, September .% dlanman@brown.edu, http://mesh.brown.edu/dlanman%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Pre-process input and select appropriate filter.function B = bfilter2(A,w,sigma)% Verify that the input image exists and is valid.if ~exist('A','var') || isempty(A)error('Input image A is undefined or invalid.');endif ~isfloat(A) || ~sum([1,3] == size(A,3)) || ...min(A(:)) < 0 || max(A(:)) > 1error(['Input image A must be a double precision ',...'matrix of size NxMx1 or NxMx3 on the closed ',...'interval [0,1].']);end% Verify bilateral filter window size.if ~exist('w','var') || isempty(w) || ...numel(w) ~= 1 || w < 1w = 5;endw = ceil(w);% Verify bilateral filter standard deviations.if ~exist('sigma','var') || isempty(sigma) || ...numel(sigma) ~= 2 || sigma(1) <= 0 || sigma(2) <= 0sigma = [3 0.1];end% Apply either grayscale or color bilateral filtering.if size(A,3) == 1B = bfltGray(A,w,sigma(1),sigma(2));elseB = bfltColor(A,w,sigma(1),sigma(2));end%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Implements bilateral filtering for grayscale images.function B = bfltGray(A,w,sigma_d,sigma_r)% Pre-compute Gaussian distance weights.[X,Y] = meshgrid(-w:w,-w:w);G = exp(-(X.^2+Y.^2)/(2*sigma_d^2));% Create waitbar.h = waitbar(0,'Applying bilateral filter...');set(h,'Name','Bilateral Filter Progress');% Apply bilateral filter.dim = size(A);B = zeros(dim);for i = 1:dim(1)for j = 1:dim(2)% Extract local region.iMin = max(i-w,1);iMax = min(i+w,dim(1));jMin = max(j-w,1);jMax = min(j+w,dim(2));I = A(iMin:iMax,jMin:jMax);% Compute Gaussian intensity weights.H = exp(-(I-A(i,j)).^2/(2*sigma_r^2));% Calculate bilateral filter response.F = H.*G((iMin:iMax)-i+w+1,(jMin:jMax)-j+w+1);B(i,j) = sum(F(:).*I(:))/sum(F(:));endwaitbar(i/dim(1));end% Close waitbar.close(h);%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Implements bilateral filter for color images.function B = bfltColor(A,w,sigma_d,sigma_r)% Convert input sRGB image to CIELab color space.if exist('applycform','file')A = applycform(A,makecform('srgb2lab'));elseA = colorspace('Lab<-RGB',A);end% Pre-compute Gaussian domain weights.[X,Y] = meshgrid(-w:w,-w:w);G = exp(-(X.^2+Y.^2)/(2*sigma_d^2));% Rescale range variance (using maximum luminance).sigma_r = 100*sigma_r;% Create waitbar.h = waitbar(0,'Applying bilateral filter...');set(h,'Name','Bilateral Filter Progress');% Apply bilateral filter.dim = size(A);B = zeros(dim);for i = 1:dim(1)for j = 1:dim(2)% Extract local region.iMin = max(i-w,1);iMax = min(i+w,dim(1));jMin = max(j-w,1);jMax = min(j+w,dim(2));I = A(iMin:iMax,jMin:jMax,:);% Compute Gaussian range weights.dL = I(:,:,1)-A(i,j,1);da = I(:,:,2)-A(i,j,2);db = I(:,:,3)-A(i,j,3);H = exp(-(dL.^2+da.^2+db.^2)/(2*sigma_r^2));% Calculate bilateral filter response.F = H.*G((iMin:iMax)-i+w+1,(jMin:jMax)-j+w+1);norm_F = sum(F(:));B(i,j,1) = sum(sum(F.*I(:,:,1)))/norm_F;B(i,j,2) = sum(sum(F.*I(:,:,2)))/norm_F;B(i,j,3) = sum(sum(F.*I(:,:,3)))/norm_F;endwaitbar(i/dim(1));end% Convert filtered image back to sRGB color space.if exist('applycform','file')B = applycform(B,makecform('lab2srgb'));else B = colorspace('RGB<-Lab',B);end% Close waitbar.close(h);
cartoon.m
function C = cartoon(A)% CARTOON Image abstraction using bilateral filtering.% This function uses the bilateral filter to abstract% an image following the method outlined in:%% Holger Winnemoller, Sven C. Olsen, and Bruce Gooch.% Real-Time Video Abstraction. In Proceedings of ACM% SIGGRAPH, . %% C = cartoon(A) modifies the color image A to have a % cartoon-like appearance. A must be a double precision% matrix of size NxMx3 with normalized values in the % closed interval [0,1]. Default filtering parameters% are defined in CARTOON.M.%% Douglas R. Lanman, Brown University, September .% dlanman@brown.edu, http://mesh.brown.edu/dlanman%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Set the image abstraction parameters.% Set bilateral filter parameters.w= 5; % bilateral filter half-widthsigma = [3 0.1]; % bilateral filter standard deviations% Set image abstraction paramters.max_gradient= 0.2; % maximum gradient (for edges)sharpness_levels = [3 14]; % soft quantization sharpnessquant_levels= 8;% number of quantization levelsmin_edge_strength = 0.3; % minimum gradient (for edges)%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Verify that the input image exists and is valid.if ~exist('A','var') || isempty(A)error('Input image A is undefined or invalid.');endif ~isfloat(A) || size(A,3) ~= 3 || ...min(A(:)) < 0 || max(A(:)) > 1error(['Input image A must be a double precision ',...'matrix of size NxMx3 on the closed ',...'interval [0,1].']);end% Apply bilateral filter to input image.B = bfilter2(A,w,sigma);% Convert sRGB image to CIELab color space.if exist('applycform','file')B = applycform(B,makecform('srgb2lab'));elseB = colorspace('Lab<-RGB',B);end% Determine gradient magnitude of luminance.[GX,GY] = gradient(B(:,:,1)/100);G = sqrt(GX.^2+GY.^2);G(G>max_gradient) = max_gradient;G = G/max_gradient;% Create a simple edge map using the gradient magnitudes.E = G; E(E<min_edge_strength) = 0;% Determine per-pixel "sharpening" parameter.S = diff(sharpness_levels)*G+sharpness_levels(1);% Apply soft luminance quantization.qB = B; dq = 100/(quant_levels-1);qB(:,:,1) = (1/dq)*qB(:,:,1);qB(:,:,1) = dq*round(qB(:,:,1));qB(:,:,1) = qB(:,:,1)+(dq/2)*tanh(S.*(B(:,:,1)-qB(:,:,1)));% Transform back to sRGB color space.if exist('applycform','file')Q = applycform(qB,makecform('lab2srgb'));elseQ = colorspace('RGB<-Lab',qB);end% Add gradient edges to quantized bilaterally-filtered image.C = repmat(1-E,[1 1 3]).*Q;
colorspace.m
function varargout = colorspace(Conversion,varargin)%COLORSPACE Convert a color image between color representations.% B = COLORSPACE(S,A) converts the color representation of image A% where S is a string specifying the conversion. S tells the% source and destination color spaces, S = 'dest<-src', or% alternatively, S = 'src->dest'. Supported color spaces are%%'RGB' R'G'B' Red Green Blue (ITU-R BT.709 gamma-corrected)%'YPbPr' Luma (ITU-R BT.601) + Chroma %'YCbCr'/'YCC'Luma + Chroma ("digitized" version of Y'PbPr)%'YUV' NTSC PAL Y'UV Luma + Chroma%'YIQ' NTSC Y'IQ Luma + Chroma%'YDbDr' SECAM Y'DbDr Luma + Chroma%'JPEGYCbCr' JPEG-Y'CbCr Luma + Chroma%'HSV'/'HSB' Hue Saturation Value/Brightness%'HSL'/'HLS'/'HSI' Hue Saturation Luminance/Intensity%'XYZ' CIE XYZ%'Lab' CIE L*a*b* (CIELAB)%'Luv' CIE L*u*v* (CIELUV)%'Lch' CIE L*ch (CIELCH)%% All conversions assume 2 degree observer and D65 illuminant. Color% space names are case insensitive. When R'G'B' is the source or% destination, it can be omitted. For example 'yuv<-' is short for% 'yuv<-rgb'.%% MATLAB uses two standard data formats for R'G'B': double data with% intensities in the range 0 to 1, and uint8 data with integer-valued% intensities from 0 to 255. As MATLAB's native datatype, double data is% the natural choice, and the R'G'B' format used by colorspace. However,% for memory and computational performance, some functions also operate% with uint8 R'G'B'. Given uint8 R'G'B' color data, colorspace will% first cast it to double R'G'B' before processing.%% If A is an Mx3 array, like a colormap, B will also have size Mx3.%% [B1,B2,B3] = COLORSPACE(S,A) specifies separate output channels.% COLORSPACE(S,A1,A2,A3) specifies separate input channels.% Pascal Getreuer -%%% Input parsing %%%if nargin < 2, error('Not enough input arguments.'); end[SrcSpace,DestSpace] = parse(Conversion);if nargin == 2Image = varargin{1};elseif nargin >= 3Image = cat(3,varargin{:});elseerror('Invalid number of input arguments.');endFlipDims = (size(Image,3) == 1);if FlipDims, Image = permute(Image,[1,3,2]); endif ~isa(Image,'double'), Image = double(Image)/255; endif size(Image,3) ~= 3, error('Invalid input size.'); endSrcT = gettransform(SrcSpace);DestT = gettransform(DestSpace);if ~ischar(SrcT) & ~ischar(DestT)% Both source and destination transforms are affine, so they% can be composed into one affine operationT = [DestT(:,1:3)*SrcT(:,1:3),DestT(:,1:3)*SrcT(:,4)+DestT(:,4)];Temp = zeros(size(Image));Temp(:,:,1) = T(1)*Image(:,:,1) + T(4)*Image(:,:,2) + T(7)*Image(:,:,3) + T(10);Temp(:,:,2) = T(2)*Image(:,:,1) + T(5)*Image(:,:,2) + T(8)*Image(:,:,3) + T(11);Temp(:,:,3) = T(3)*Image(:,:,1) + T(6)*Image(:,:,2) + T(9)*Image(:,:,3) + T(12);Image = Temp;elseif ~ischar(DestT)Image = rgb(Image,SrcSpace);Temp = zeros(size(Image));Temp(:,:,1) = DestT(1)*Image(:,:,1) + DestT(4)*Image(:,:,2) + DestT(7)*Image(:,:,3) + DestT(10);Temp(:,:,2) = DestT(2)*Image(:,:,1) + DestT(5)*Image(:,:,2) + DestT(8)*Image(:,:,3) + DestT(11);Temp(:,:,3) = DestT(3)*Image(:,:,1) + DestT(6)*Image(:,:,2) + DestT(9)*Image(:,:,3) + DestT(12);Image = Temp;elseImage = feval(DestT,Image,SrcSpace);end%%% Output format %%%if nargout > 1varargout = {Image(:,:,1),Image(:,:,2),Image(:,:,3)};elseif FlipDims, Image = permute(Image,[1,3,2]); endvarargout = {Image};endreturn;function [SrcSpace,DestSpace] = parse(Str)% Parse conversion argumentif isstr(Str)Str = lower(strrep(strrep(Str,'-',''),' ',''));k = find(Str == '>');if length(k) == 1 % Interpret the form 'src->dest'SrcSpace = Str(1:k-1);DestSpace = Str(k+1:end);elsek = find(Str == '<');if length(k) == 1% Interpret the form 'dest<-src'DestSpace = Str(1:k-1);SrcSpace = Str(k+1:end);elseerror(['Invalid conversion, ''',Str,'''.']);end endSrcSpace = alias(SrcSpace);DestSpace = alias(DestSpace);elseSrcSpace = 1; % No source pre-transformDestSpace = Conversion;if any(size(Conversion) ~= 3), error('Transformation matrix must be 3x3.'); endendreturn;function Space = alias(Space)Space = strrep(Space,'cie','');if isempty(Space)Space = 'rgb';endswitch Spacecase {'ycbcr','ycc'}Space = 'ycbcr';case {'hsv','hsb'}Space = 'hsv';case {'hsl','hsi','hls'}Space = 'hsl';case {'rgb','yuv','yiq','ydbdr','ycbcr','jpegycbcr','xyz','lab','luv','lch'}return;endreturn;function T = gettransform(Space)% Get a colorspace transform: either a matrix describing an affine transform,% or a string referring to a conversion subroutineswitch Spacecase 'ypbpr'T = [0.299,0.587,0.114,0;-0.1687367,-0.331264,0.5,0;0.5,-0.418688,-0.081312,0];case 'yuv'% R'G'B' to NTSC/PAL YUV% Wikipedia: /wiki/YUVT = [0.299,0.587,0.114,0;-0.147,-0.289,0.436,0;0.615,-0.515,-0.100,0];case 'ydbdr'% R'G'B' to SECAM YDbDr% Wikipedia: /wiki/YDbDrT = [0.299,0.587,0.114,0;-0.450,-0.883,1.333,0;-1.333,1.116,0.217,0];case 'yiq'% R'G'B' in [0,1] to NTSC YIQ in [0,1];[-0.595716,0.595716];[-0.522591,0.522591];% Wikipedia: /wiki/YIQT = [0.299,0.587,0.114,0;0.595716,-0.274453,-0.321263,0;0.211456,-0.522591,0.311135,0];case 'ycbcr'% R'G'B' (range [0,1]) to ITU-R BRT.601 (CCIR 601) Y'CbCr% Wikipedia: /wiki/YCbCr% Poynton, Equation 3, scaling of R'G'B to Y'PbPr conversionT = [65.481,128.553,24.966,16;-37.797,-74.203,112.0,128;112.0,-93.786,-18.214,128];case 'jpegycbcr'% Wikipedia: /wiki/YCbCrT = [0.299,0.587,0.114,0;-0.168736,-0.331264,0.5,0.5;0.5,-0.418688,-0.081312,0.5]*255;case {'rgb','xyz','hsv','hsl','lab','luv','lch'}T = Space;otherwiseerror(['Unknown color space, ''',Space,'''.']);endreturn;function Image = rgb(Image,SrcSpace)% Convert to Rec. 709 R'G'B' from 'SrcSpace'switch SrcSpacecase 'rgb'return;case 'hsv'% Convert HSV to R'G'B'Image = huetorgb((1 - Image(:,:,2)).*Image(:,:,3),Image(:,:,3),Image(:,:,1));case 'hsl'% Convert HSL to R'G'B'L = Image(:,:,3);Delta = Image(:,:,2).*min(L,1-L);Image = huetorgb(L-Delta,L+Delta,Image(:,:,1));case {'xyz','lab','luv','lch'}% Convert to CIE XYZImage = xyz(Image,SrcSpace);% Convert XYZ to RGBT = [3.240479,-1.53715,-0.498535;-0.969256,1.875992,0.041556;0.055648,-0.204043,1.057311];R = T(1)*Image(:,:,1) + T(4)*Image(:,:,2) + T(7)*Image(:,:,3); % RG = T(2)*Image(:,:,1) + T(5)*Image(:,:,2) + T(8)*Image(:,:,3); % GB = T(3)*Image(:,:,1) + T(6)*Image(:,:,2) + T(9)*Image(:,:,3); % B% Desaturate and rescale to constrain resulting RGB values to [0,1] AddWhite = -min(min(min(R,G),B),0);Scale = max(max(max(R,G),B)+AddWhite,1);R = (R + AddWhite)./Scale;G = (G + AddWhite)./Scale;B = (B + AddWhite)./Scale; % Apply gamma correction to convert RGB to Rec. 709 R'G'B'Image(:,:,1) = gammacorrection(R); % R'Image(:,:,2) = gammacorrection(G); % G'Image(:,:,3) = gammacorrection(B); % B'otherwise % Conversion is through an affine transformT = gettransform(SrcSpace);temp = inv(T(:,1:3));T = [temp,-temp*T(:,4)];R = T(1)*Image(:,:,1) + T(4)*Image(:,:,2) + T(7)*Image(:,:,3) + T(10);G = T(2)*Image(:,:,1) + T(5)*Image(:,:,2) + T(8)*Image(:,:,3) + T(11);B = T(3)*Image(:,:,1) + T(6)*Image(:,:,2) + T(9)*Image(:,:,3) + T(12);AddWhite = -min(min(min(R,G),B),0);Scale = max(max(max(R,G),B)+AddWhite,1);R = (R + AddWhite)./Scale;G = (G + AddWhite)./Scale;B = (B + AddWhite)./Scale;Image(:,:,1) = R;Image(:,:,2) = G;Image(:,:,3) = B;end% Clip to [0,1]Image = min(max(Image,0),1);return;function Image = xyz(Image,SrcSpace)% Convert to CIE XYZ from 'SrcSpace'WhitePoint = [0.950456,1,1.088754]; switch SrcSpacecase 'xyz'return;case 'luv'% Convert CIE L*uv to XYZWhitePointU = (4*WhitePoint(1))./(WhitePoint(1) + 15*WhitePoint(2) + 3*WhitePoint(3));WhitePointV = (9*WhitePoint(2))./(WhitePoint(1) + 15*WhitePoint(2) + 3*WhitePoint(3));L = Image(:,:,1);Y = (L + 16)/116;Y = invf(Y)*WhitePoint(2);U = Image(:,:,2)./(13*L + 1e-6*(L==0)) + WhitePointU;V = Image(:,:,3)./(13*L + 1e-6*(L==0)) + WhitePointV;Image(:,:,1) = -(9*Y.*U)./((U-4).*V - U.*V); % XImage(:,:,2) = Y;% YImage(:,:,3) = (9*Y - (15*V.*Y) - (V.*Image(:,:,1)))./(3*V); % Zcase {'lab','lch'}Image = lab(Image,SrcSpace);% Convert CIE L*ab to XYZfY = (Image(:,:,1) + 16)/116;fX = fY + Image(:,:,2)/500;fZ = fY - Image(:,:,3)/200;Image(:,:,1) = WhitePoint(1)*invf(fX); % XImage(:,:,2) = WhitePoint(2)*invf(fY); % YImage(:,:,3) = WhitePoint(3)*invf(fZ); % Zotherwise % Convert from some gamma-corrected space% Convert to Rec. 701 R'G'B'Image = rgb(Image,SrcSpace);% Undo gamma correctionR = invgammacorrection(Image(:,:,1));G = invgammacorrection(Image(:,:,2));B = invgammacorrection(Image(:,:,3));% Convert RGB to XYZT = inv([3.240479,-1.53715,-0.498535;-0.969256,1.875992,0.041556;0.055648,-0.204043,1.057311]);Image(:,:,1) = T(1)*R + T(4)*G + T(7)*B; % X Image(:,:,2) = T(2)*R + T(5)*G + T(8)*B; % YImage(:,:,3) = T(3)*R + T(6)*G + T(9)*B; % Zendreturn;function Image = hsv(Image,SrcSpace)% Convert to HSVImage = rgb(Image,SrcSpace);V = max(Image,[],3);S = (V - min(Image,[],3))./(V + (V == 0));Image(:,:,1) = rgbtohue(Image);Image(:,:,2) = S;Image(:,:,3) = V;return;function Image = hsl(Image,SrcSpace)% Convert to HSL switch SrcSpacecase 'hsv'% Convert HSV to HSL MaxVal = Image(:,:,3);MinVal = (1 - Image(:,:,2)).*MaxVal;L = 0.5*(MaxVal + MinVal);temp = min(L,1-L);Image(:,:,2) = 0.5*(MaxVal - MinVal)./(temp + (temp == 0));Image(:,:,3) = L;otherwiseImage = rgb(Image,SrcSpace); % Convert to Rec. 701 R'G'B'% Convert R'G'B' to HSLMinVal = min(Image,[],3);MaxVal = max(Image,[],3);L = 0.5*(MaxVal + MinVal);temp = min(L,1-L);S = 0.5*(MaxVal - MinVal)./(temp + (temp == 0));Image(:,:,1) = rgbtohue(Image);Image(:,:,2) = S;Image(:,:,3) = L;endreturn;function Image = lab(Image,SrcSpace)% Convert to CIE L*a*b* (CIELAB)WhitePoint = [0.950456,1,1.088754];switch SrcSpacecase 'lab'return;case 'lch'% Convert CIE L*CH to CIE L*abC = Image(:,:,2);Image(:,:,2) = cos(Image(:,:,3)*pi/180).*C; % a*Image(:,:,3) = sin(Image(:,:,3)*pi/180).*C; % b*otherwiseImage = xyz(Image,SrcSpace); % Convert to XYZ% Convert XYZ to CIE L*a*b*X = Image(:,:,1)/WhitePoint(1);Y = Image(:,:,2)/WhitePoint(2);Z = Image(:,:,3)/WhitePoint(3);fX = f(X);fY = f(Y);fZ = f(Z);Image(:,:,1) = 116*fY - 16; % L*Image(:,:,2) = 500*(fX - fY); % a*Image(:,:,3) = 200*(fY - fZ); % b*endreturn;function Image = luv(Image,SrcSpace)% Convert to CIE L*u*v* (CIELUV)WhitePoint = [0.950456,1,1.088754];WhitePointU = (4*WhitePoint(1))./(WhitePoint(1) + 15*WhitePoint(2) + 3*WhitePoint(3));WhitePointV = (9*WhitePoint(2))./(WhitePoint(1) + 15*WhitePoint(2) + 3*WhitePoint(3));Image = xyz(Image,SrcSpace); % Convert to XYZU = (4*Image(:,:,1))./(Image(:,:,1) + 15*Image(:,:,2) + 3*Image(:,:,3));V = (9*Image(:,:,2))./(Image(:,:,1) + 15*Image(:,:,2) + 3*Image(:,:,3));Y = Image(:,:,2)/WhitePoint(2);L = 116*f(Y) - 16;Image(:,:,1) = L; % L*Image(:,:,2) = 13*L.*(U - WhitePointU); % u*Image(:,:,3) = 13*L.*(V - WhitePointV); % v*return; function Image = lch(Image,SrcSpace)% Convert to CIE L*chImage = lab(Image,SrcSpace); % Convert to CIE L*abH = atan2(Image(:,:,3),Image(:,:,2));H = H*180/pi + 360*(H < 0);Image(:,:,2) = sqrt(Image(:,:,2).^2 + Image(:,:,3).^2); % CImage(:,:,3) = H;% Hreturn;function Image = huetorgb(m0,m2,H)% Convert HSV or HSL hue to RGBN = size(H);H = min(max(H(:),0),360)/60;m0 = m0(:);m2 = m2(:);F = H - round(H/2)*2;M = [m0, m0 + (m2-m0).*abs(F), m2];Num = length(m0);j = [2 1 0;1 2 0;0 2 1;0 1 2;1 0 2;2 0 1;2 1 0]*Num;k = floor(H) + 1;Image = reshape([M(j(k,1)+(1:Num).'),M(j(k,2)+(1:Num).'),M(j(k,3)+(1:Num).')],[N,3]);return;function H = rgbtohue(Image)% Convert RGB to HSV or HSL hue[M,i] = sort(Image,3);i = i(:,:,3);Delta = M(:,:,3) - M(:,:,1);Delta = Delta + (Delta == 0);R = Image(:,:,1);G = Image(:,:,2);B = Image(:,:,3);H = zeros(size(R));k = (i == 1);H(k) = (G(k) - B(k))./Delta(k);k = (i == 2);H(k) = 2 + (B(k) - R(k))./Delta(k);k = (i == 3);H(k) = 4 + (R(k) - G(k))./Delta(k);H = 60*H + 360*(H < 0);H(Delta == 0) = nan;return;function Rp = gammacorrection(R)Rp = real(1.099*R.^0.45 - 0.099);i = (R < 0.018);Rp(i) = 4.5138*R(i);return;function R = invgammacorrection(Rp)R = real(((Rp + 0.099)/1.099).^(1/0.45));i = (R < 0.018);R(i) = Rp(i)/4.5138;return;function fY = f(Y)fY = real(Y.^(1/3));i = (Y < 0.008856);fY(i) = Y(i)*(841/108) + (4/29);return;function Y = invf(fY)Y = fY.^3;i = (Y < 0.008856);Y(i) = (fY(i) - 4/29)*(108/841);return;
runDemo.m
% RUNDEMO Illustrates the use of BFILTER2 and CARTOON.% This demo shows typical usage for the bilateral % filter implemented by BFILTER2. The application% of bilateral filtering to image abstraction is% demonstrated by the CARTOON function.%% Douglas R. Lanman, Brown University, September .% dlanman@brown.edu, http://mesh.brown.edu/dlanman% Load test images.% Note: Must be double precision in the interval [0,1].img1 = double(imread('einstein.jpg'))/255;img2 = double(imread('mandrill.jpg'))/255;img3 = double(imread('academy.jpg'))/255;% Introduce AWGN into test images.% Note: This will show the benefit of bilateral filtering.img1 = img1+0.03*randn(size(img1));img2 = img2+0.03*randn(size(img2));img1(img1<0) = 0; img1(img1>1) = 1;img2(img2<0) = 0; img2(img2>1) = 1;% Set bilateral filter parameters.w= 5; % bilateral filter half-widthsigma = [3 0.1]; % bilateral filter standard deviations% Apply bilateral filter to each image.bflt_img1 = bfilter2(img1,w,sigma);bflt_img2 = bfilter2(img2,w,sigma);% Display grayscale input image and filtered output.figure(1); clf;set(gcf,'Name','Grayscale Bilateral Filtering Results');subplot(1,2,1); imagesc(img1);axis image; colormap gray;title('Input Image');subplot(1,2,2); imagesc(bflt_img1);axis image; colormap gray;title('Result of Bilateral Filtering');% Display color input image and filtered output.figure(2); clf;set(gcf,'Name','Color Bilateral Filtering Results');subplot(1,2,1); imagesc(img2);axis image; colormap gray;title('Input Image');subplot(1,2,2); imagesc(bflt_img2);axis image; title('Result of Bilateral Filtering');drawnow;% Apply bilateral filter for a "cartoon" effect.cartoon_img3 = cartoon(img3);% Display color input image and abstracted output.figure(3); clf;set(gcf,'Name','Image Abstraction Input');imagesc(img3); axis image;title('Input Image');figure(4); clf;set(gcf,'Name','Result of Image Abstraction');imagesc(cartoon_img3); axis image;title('Abstracted Image');
实例三：图像的模糊增强
实例图片：matlab源码：mhzq01.m
%% 图像的模糊增强%% 准备工作%x=imread('lena.bmp');[M,N]=size(x);x1=double(x);%% 基本参数%Fd=0.8;FD=-1*Fd;% Fe=128;Fe=128;Xmax=255;%% 模糊特征平面%for i=1:Mfor j=1:NP(i,j)=(1+(Xmax-x1(i,j))/Fe)^FD;endend%% 模糊增强%times=1;for k=1:timesfor i=1:Mfor j=1:Nif P(i,j) <= 0.5000P1(i,j)=2*P(i,j)^2;elseP1(i,j)=1-2*(1-P(i,j))^2;endendendP=P1;end%% 反模糊化%for i=1:Mfor j=1:NI(i,j)=Xmax-Fe*((1/P(i,j))^(1/Fd)-1);endendX=uint8(I);figure,imshow(x);figure,imshow(X);
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