1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
% 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<size(U,2)
fprintf(fid,',');
end
fprintf(fid,'\n');
end
fprintf(fid,'};\n\n');
fclose(fid);
fprintf('done');
answ=input('Create test vector (takes some time...)? y/n : ','s');
if answ ~= 'y'
return
end
% Also, create test vectors
% Read test file foreman.yuv
fprintf('Reading test file...')
[y,u,v]=readYUV420file('../out/Debug/testFiles/foreman_cif.yuv',352,288);
fprintf(' done\n');
unew=uint8(zeros(size(u)));
vnew=uint8(zeros(size(v)));
% traverse all frames
for k=1:size(y,3)
fprintf('Frame %i\n', k);
for r=1:size(u,1)
for c=1:size(u,2)
unew(r,c,k) = uint8(U(double(v(r,c,k))+1, double(u(r,c,k))+1));
vnew(r,c,k) = uint8(V(double(v(r,c,k))+1, double(u(r,c,k))+1));
end
end
end
fprintf('\nWriting modified test file...')
writeYUV420file('../out/Debug/foremanColorEnhanced.yuv',y,unew,vnew);
fprintf(' done\n');
|
