blob: 2c7fb522f6e57494267a576581e5720ea1f2568d [file] [log] [blame]
 % Create the color enhancement look-up table and write it to % file colorEnhancementTable.cpp. Copy contents of that file into % the source file for the color enhancement function. clear close all % First, define the color enhancement in a normalized domain % Compander function is defined in three radial zones. % 1. From 0 to radius r0, the compander function % is a second-order polynomial intersecting the points (0,0) % and (r0, r0), and with a slope B in (0,0). % 2. From r0 to r1, the compander is a third-order polynomial % intersecting the points (r0, r0) and (r1, r1), and with the % same slope as the first part in the point (r0, r0) and slope % equal to 1 in (r1, r1). % 3. For radii larger than r1, the compander function is the % unity scale function (no scaling at all). r0=0.07; % Dead zone radius (must be > 0) r1=0.6; % Enhancement zone radius (must be > r0 and < 1) B=0.2; % initial slope of compander function (between 0 and 1) x0=linspace(0,r0).'; % zone 1 x1=linspace(r0,r1).'; % zone 2 x2=linspace(r1,1).'; % zone 3 A=(1-B)/r0; f0=A*x0.^2+B*x0; % compander function in zone 1 % equation system for finding second zone parameters M=[r0^3 r0^2 r0 1; 3*r0^2 2*r0 1 0; 3*r1^2 2*r1 1 0; r1^3 r1^2 r1 1]; m=[A*r0^2+B*r0; 2*A*r0+B; 1; r1]; % solve equations theta=M\m; % compander function in zone 1 f1=[x1.^3 x1.^2 x1 ones(size(x1))]*theta; x=[x0; x1; x2]; f=[f0; f1; x2]; % plot it figure(1) plot(x,f,x,x,':') xlabel('Normalized radius') ylabel('Modified radius') % Now, create the look-up table in the integer color space [U,V]=meshgrid(0:255, 0:255); % U-V space U0=U; V0=V; % Conversion matrix from normalized YUV to RGB T=[1 0 1.13983; 1 -0.39465 -0.58060; 1 2.03211 0]; Ylum=0.5; figure(2) Z(:,:,1)=Ylum + (U-127)/256*T(1,2) + (V-127)/256*T(1,3); Z(:,:,2)=Ylum + (U-127)/256*T(2,2) + (V-127)/256*T(2,3); Z(:,:,3)=Ylum + (U-127)/256*T(3,2) + (V-127)/256*T(3,3); Z=max(Z,0); Z=min(Z,1); subplot(121) image(Z); axis square axis off set(gcf,'color','k') R = sqrt((U-127).^2 + (V-127).^2); Rnorm = R/127; RnormMod = Rnorm; RnormMod(RnormMod==0)=1; % avoid division with zero % find indices to pixels in dead-zone (zone 1) ix=find(Rnorm<=r0); scaleMatrix = (A*Rnorm(ix).^2 + B*Rnorm(ix))./RnormMod(ix); U(ix)=(U(ix)-127).*scaleMatrix+127; V(ix)=(V(ix)-127).*scaleMatrix+127; % find indices to pixels in zone 2 ix=find(Rnorm>r0 & Rnorm<=r1); scaleMatrix = (theta(1)*Rnorm(ix).^3 + theta(2)*Rnorm(ix).^2 + ... theta(3)*Rnorm(ix) + theta(4)) ./ RnormMod(ix); U(ix)=(U(ix)-127).*scaleMatrix + 127; V(ix)=(V(ix)-127).*scaleMatrix + 127; % round to integer values and saturate U=round(U); V=round(V); U=max(min(U,255),0); V=max(min(V,255),0); Z(:,:,1)=Ylum + (U-127)/256*T(1,2) + (V-127)/256*T(1,3); Z(:,:,2)=Ylum + (U-127)/256*T(2,2) + (V-127)/256*T(2,3); Z(:,:,3)=Ylum + (U-127)/256*T(3,2) + (V-127)/256*T(3,3); Z=max(Z,0); Z=min(Z,1); subplot(122) image(Z); axis square axis off figure(3) subplot(121) mesh(U-U0) subplot(122) mesh(V-V0) % Last, write to file % Write only one matrix, since U=V' fid = fopen('../out/Debug/colorEnhancementTable.h','wt'); if fid==-1 error('Cannot open file colorEnhancementTable.cpp'); end fprintf(fid,'//colorEnhancementTable.h\n\n'); fprintf(fid,'//Copy the constant table to the appropriate header file.\n\n'); fprintf(fid,'//Table created with Matlab script createTable.m\n\n'); fprintf(fid,'//Usage:\n'); fprintf(fid,'// Umod=colorTable[U][V]\n'); fprintf(fid,'// Vmod=colorTable[V][U]\n'); fprintf(fid,'static unsigned char colorTable[%i][%i] = {\n', size(U,1), size(U,2)); for u=1:size(U,2) fprintf(fid,' {%i', U(1,u)); for v=2:size(U,1) fprintf(fid,', %i', U(v,u)); end fprintf(fid,'}'); if u