A Fast Spectral Clustering Algorithm ... codes

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 2005-2006 %%% Input parsing %%% if nargin < 2, error('Not enough input arguments.'); end [SrcSpace,DestSpace] = parse(Conversion); if nargin == 2 Image = varargin{1}; elseif nargin >= 3 Image = cat(3,varargin{:}); else error('Invalid number of input arguments.'); end FlipDims = (size(Image,3) == 1); if FlipDims, Image = permute(Image,[1,3,2]); end if ~isa(Image,'double'), Image = double(Image)/255; end if size(Image,3) ~= 3, error('Invalid input size.'); end SrcT = 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 operation T = [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; else Image = feval(DestT,Image,SrcSpace); end %%% Output format %%% if nargout > 1 varargout = {Image(:,:,1),Image(:,:,2),Image(:,:,3)}; else if FlipDims, Image = permute(Image,[1,3,2]); end varargout = {Image}; end return; function [SrcSpace,DestSpace] = parse(Str) % Parse conversion argument if 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); else k = find(Str == '<'); if length(k) == 1 % Interpret the form 'dest<-src' DestSpace = Str(1:k-1); SrcSpace = Str(k+1:end); else error(['Invalid conversion, ''',Str,'''.']); end end SrcSpace = alias(SrcSpace); DestSpace = alias(DestSpace); else SrcSpace = 1; % No source pre-transform DestSpace = Conversion; if any(size(Conversion) ~= 3), error('Transformation matrix must be 3x3.'); end end return; function Space = alias(Space) Space = strrep(Space,'cie',''); if isempty(Space) Space = 'rgb'; end switch Space case {'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; end return; function T = gettransform(Space) % Get a colorspace transform: either a matrix describing an affine transform, % or a string referring to a conversion subroutine switch Space case '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: http://en.wikipedia.org/wiki/YUV T = [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: http://en.wikipedia.org/wiki/YDbDr T = [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: http://en.wikipedia.org/wiki/YIQ T = [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: http://en.wikipedia.org/wiki/YCbCr % Poynton, Equation 3, scaling of R'G'B to Y'PbPr conversion T = [65.481,128.553,24.966,16;-37.797,-74.203,112.0,128;112.0,-93.786,-18.214,128]; case 'jpegycbcr' % Wikipedia: http://en.wikipedia.org/wiki/YCbCr T = [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; otherwise error(['Unknown color space, ''',Space,'''.']); end return; function Image = rgb(Image,SrcSpace) % Convert to Rec. 709 R'G'B' from 'SrcSpace' switch SrcSpace case '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 XYZ Image = xyz(Image,SrcSpace); % Convert XYZ to RGB T = [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); % R G = T(2)*Image(:,:,1) + T(5)*Image(:,:,2) + T(8)*Image(:,:,3); % G B = 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 transform T = 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);