MATLAB: How to make white regions in red color

colorpixelsregion

how to make the white regions in this image to red color

I = imread('Capturefffffff.png') ;
I(:,:,2:3) = 0 ;
imshow(I)

yellow = red == 255 & green == 255;

if you are using a uint8 image or replace 255 with whatever the data maximum is otherwise.

(Edited to reflect Guillaume's comment below!)

k is the image(RGB) array

j=k(:,:,1);
l=k(:,:,2);
m=k(:,:,3);
l((j>=40))=0;
m(j>=40)=0;
k(:,:,1)=j;k(:,:,2)=l;k(:,:,3)=m;
imshow(k)