Contrast stretching transformation in Image Processing

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.

[Rooter Boy]

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

Answer 1

[Image Analyst]

Wow. Try this much easier way:

r = [70, 150]
s = [30, 230];
output = interp1(r, s, 110) % output is 130.

[Rooter Boy]

Sir, you are professional in matlab .Thanks you again.

[Rooter Boy]

Sir, i would be glad if you look at these questions when you are available.

https://www.mathworks.com/matlabcentral/answers/650893-code-block-of-operates-in-image-processing?s_tid=srchtitle

https://www.mathworks.com/matlabcentral/answers/650758-plotting-of-transfer-functions?s_tid=srchtitle

https://www.mathworks.com/matlabcentral/answers/650728-filters-main-function-in-image-processing?s_tid=srchtitle

[Image Analyst]

If this solved the question, can you "Accept this answer" unless you want to wait for possible other, better answers.

[Rooter Boy]

Excuse me,

Sir, i accepted your answer.

I sometimes forget it.