Contrast stretching transformation in Image Processing

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Rooter Boy
Rooter Boy 2020-11-12
评论： Rooter Boy 2020-11-17
I tried to solve for question but i didn't do.
I tried this code for solving.
p1=[0,0];
p2=[75,5];
p3=[140,250];
p4=[255,255];
m1=(p1(1,2)-p2(1,2))/(p1(1,1)-p2(1,1));
m2=(p2(1,2)-p3(1,2))/(p2(1,1)-p3(1,1));
m3=(p3(1,2)-p4(1,2))/(p3(1,1)-p4(1,1));
c1=p1(1,2)-m1*p1(1,1);
c2=p2(1,2)-m2*p2(1,1);
c3=p3(1,2)-m3*p3(1,1);
%% Transformation function
t=[];
for x=0:255
if(x<=p2(1,1))
t=[t (m1*x+c1)];
end
if(x>p2(1,1) && x<=p3(1,1))
t=[t (m2*x+c2)];
end
if(x>p3(1,1) && x<=p4(1,1))
t=[t (m3*x+c3)];
end
end
for n=1:s(1,1)
for m=1:s(1,2)
ot(n,m)=t(a(n,m)+1);
end
end
I don't know how to find answer of this question. I will be glad if you help.
  1 个评论
Rooter Boy
Rooter Boy 2020-11-15
I found answer is 130 but i'm not sure.
I tried this:
r = input("Please input the intensity value, r: ");
fprintf("\n");
r1 = 70;
r2 = 150;
s1 = 30;
s2 = 230;
Point_1 = [0 0];
Point_2 = [r1 s1];
Point_3 = [r2 s2];
Point_4 = [255 255];
x = 1;
y = 2;
%Slope of region 1%
Rise = Point_2(y) - Point_1(y);
Run = Point_2(x) - Point_1(x);
Slope_1 = Rise/Run;
%Slope of region 2%
Rise = Point_3(y) - Point_2(y);
Run = Point_3(x) - Point_2(x);
Slope_2 = Rise/Run;
%Slope of region 3%
Rise = Point_4(y) - Point_3(y);
Run = Point_4(x) - Point_3(x);
Slope_3 = Rise/Run;
if r <= r1
fprintf("Region 1\n");
s = Slope_1*r;
fprintf("The output intensity, s = T(r) is: %.2f\n",s);
elseif (r1 < r) && (r < r2)
fprintf("Region 2\n");
Constant_Offset = s1;
Relative_Run = (r - r1);
s = Slope_2*Relative_Run + Constant_Offset;
fprintf("The output intensity, s = T(r) is: %.2f\n",s);
elseif r >= r2
fprintf("Region 3\n");
Constant_Offset = s2;
Relative_Run = (r - r2);
s = Slope_3*Relative_Run + Constant_Offset;
fprintf("The output intensity, s = T(r) is: %.2f\n",s);
end

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采纳的回答

Image Analyst
Image Analyst 2020-11-16
Wow. Try this much easier way:
r = [70, 150]
s = [30, 230];
output = interp1(r, s, 110) % output is 130.
  4 个评论
显示 2更早的评论
Image Analyst
Image Analyst 2020-11-17
If this solved the question, can you "Accept this answer" unless you want to wait for possible other, better answers.
Rooter Boy
Rooter Boy 2020-11-17
Excuse me,
Sir, i accepted your answer.
I sometimes forget it.

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