180 lines
4.5 KiB
Matlab
180 lines
4.5 KiB
Matlab
% Create the color enhancement look-up table and write it to
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% file colorEnhancementTable.cpp. Copy contents of that file into
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% the source file for the color enhancement function.
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clear
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close all
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% First, define the color enhancement in a normalized domain
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% Compander function is defined in three radial zones.
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% 1. From 0 to radius r0, the compander function
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% is a second-order polynomial intersecting the points (0,0)
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% and (r0, r0), and with a slope B in (0,0).
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% 2. From r0 to r1, the compander is a third-order polynomial
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% intersecting the points (r0, r0) and (r1, r1), and with the
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% same slope as the first part in the point (r0, r0) and slope
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% equal to 1 in (r1, r1).
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% 3. For radii larger than r1, the compander function is the
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% unity scale function (no scaling at all).
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r0=0.07; % Dead zone radius (must be > 0)
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r1=0.6; % Enhancement zone radius (must be > r0 and < 1)
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B=0.2; % initial slope of compander function (between 0 and 1)
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x0=linspace(0,r0).'; % zone 1
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x1=linspace(r0,r1).'; % zone 2
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x2=linspace(r1,1).'; % zone 3
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A=(1-B)/r0;
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f0=A*x0.^2+B*x0; % compander function in zone 1
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% equation system for finding second zone parameters
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M=[r0^3 r0^2 r0 1;
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3*r0^2 2*r0 1 0;
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3*r1^2 2*r1 1 0;
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r1^3 r1^2 r1 1];
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m=[A*r0^2+B*r0; 2*A*r0+B; 1; r1];
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% solve equations
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theta=M\m;
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% compander function in zone 1
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f1=[x1.^3 x1.^2 x1 ones(size(x1))]*theta;
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x=[x0; x1; x2];
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f=[f0; f1; x2];
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% plot it
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figure(1)
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plot(x,f,x,x,':')
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xlabel('Normalized radius')
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ylabel('Modified radius')
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% Now, create the look-up table in the integer color space
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[U,V]=meshgrid(0:255, 0:255); % U-V space
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U0=U;
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V0=V;
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% Conversion matrix from normalized YUV to RGB
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T=[1 0 1.13983; 1 -0.39465 -0.58060; 1 2.03211 0];
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Ylum=0.5;
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figure(2)
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Z(:,:,1)=Ylum + (U-127)/256*T(1,2) + (V-127)/256*T(1,3);
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Z(:,:,2)=Ylum + (U-127)/256*T(2,2) + (V-127)/256*T(2,3);
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Z(:,:,3)=Ylum + (U-127)/256*T(3,2) + (V-127)/256*T(3,3);
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Z=max(Z,0);
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Z=min(Z,1);
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subplot(121)
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image(Z);
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axis square
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axis off
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set(gcf,'color','k')
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R = sqrt((U-127).^2 + (V-127).^2);
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Rnorm = R/127;
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RnormMod = Rnorm;
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RnormMod(RnormMod==0)=1; % avoid division with zero
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% find indices to pixels in dead-zone (zone 1)
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ix=find(Rnorm<=r0);
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scaleMatrix = (A*Rnorm(ix).^2 + B*Rnorm(ix))./RnormMod(ix);
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U(ix)=(U(ix)-127).*scaleMatrix+127;
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V(ix)=(V(ix)-127).*scaleMatrix+127;
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% find indices to pixels in zone 2
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ix=find(Rnorm>r0 & Rnorm<=r1);
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scaleMatrix = (theta(1)*Rnorm(ix).^3 + theta(2)*Rnorm(ix).^2 + ...
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theta(3)*Rnorm(ix) + theta(4)) ./ RnormMod(ix);
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U(ix)=(U(ix)-127).*scaleMatrix + 127;
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V(ix)=(V(ix)-127).*scaleMatrix + 127;
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% round to integer values and saturate
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U=round(U);
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V=round(V);
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U=max(min(U,255),0);
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V=max(min(V,255),0);
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Z(:,:,1)=Ylum + (U-127)/256*T(1,2) + (V-127)/256*T(1,3);
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Z(:,:,2)=Ylum + (U-127)/256*T(2,2) + (V-127)/256*T(2,3);
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Z(:,:,3)=Ylum + (U-127)/256*T(3,2) + (V-127)/256*T(3,3);
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Z=max(Z,0);
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Z=min(Z,1);
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subplot(122)
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image(Z);
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axis square
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axis off
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figure(3)
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subplot(121)
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mesh(U-U0)
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subplot(122)
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mesh(V-V0)
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% Last, write to file
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% Write only one matrix, since U=V'
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fid = fopen('../out/Debug/colorEnhancementTable.h','wt');
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if fid==-1
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error('Cannot open file colorEnhancementTable.cpp');
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end
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fprintf(fid,'//colorEnhancementTable.h\n\n');
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fprintf(fid,'//Copy the constant table to the appropriate header file.\n\n');
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fprintf(fid,'//Table created with Matlab script createTable.m\n\n');
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fprintf(fid,'//Usage:\n');
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fprintf(fid,'// Umod=colorTable[U][V]\n');
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fprintf(fid,'// Vmod=colorTable[V][U]\n');
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fprintf(fid,'static unsigned char colorTable[%i][%i] = {\n', size(U,1), size(U,2));
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for u=1:size(U,2)
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fprintf(fid,' {%i', U(1,u));
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for v=2:size(U,1)
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fprintf(fid,', %i', U(v,u));
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end
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fprintf(fid,'}');
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if u<size(U,2)
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fprintf(fid,',');
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end
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fprintf(fid,'\n');
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end
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fprintf(fid,'};\n\n');
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fclose(fid);
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fprintf('done');
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answ=input('Create test vector (takes some time...)? y/n : ','s');
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if answ ~= 'y'
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return
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end
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% Also, create test vectors
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% Read test file foreman.yuv
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fprintf('Reading test file...')
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[y,u,v]=readYUV420file('../out/Debug/testFiles/foreman_cif.yuv',352,288);
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fprintf(' done\n');
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unew=uint8(zeros(size(u)));
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vnew=uint8(zeros(size(v)));
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% traverse all frames
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for k=1:size(y,3)
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fprintf('Frame %i\n', k);
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for r=1:size(u,1)
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for c=1:size(u,2)
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unew(r,c,k) = uint8(U(double(v(r,c,k))+1, double(u(r,c,k))+1));
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vnew(r,c,k) = uint8(V(double(v(r,c,k))+1, double(u(r,c,k))+1));
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end
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end
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end
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fprintf('\nWriting modified test file...')
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writeYUV420file('../out/Debug/foremanColorEnhanced.yuv',y,unew,vnew);
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fprintf(' done\n');
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