How do I reduce image brightness and increase image contrast?

I have images with small ROI that are overexposed. Is there any way I can run this image editing as part of the code?

Answer 1

[Sajad Sadeghkhani]

You should map it with a transform.

I2 = histeq(I);
imshow(I2) %contrast enhancing

to reduce brightness:

I=double(I);
a=min(min(I));
b=max(max(I));
t=150;
[m1,m2]=size(I);
I2=zeros(m1,m2);
for i=1:m1
 for j=1:m2
  I2(i,j)=(t/(b-a))*(I(i,j)-a);
 end
end
I2=uint8(I2);
imshow(I2);

as you decrease 't', the output image will become darker.

[Vishal Rajput]

Can you please tell us the name of this transform.