How would I go about running trough an RGB image and turning all pixels with R >200 to white?

Fairly new to working with images and I have been scrounging the net but can't seem to find anything simple to understand. All I want to do is remove the background of an image which is all a singular color from and image and just either make it black or white.

I really just don't understand how to move through step by step of a 3d array when the third element is 3 values on its own...

Answer 1

[Arun Mathamkode]

You can use logical indexing. First, find a logical map to find the pixels locations (R>200) and use this logical map for logical indexing. if I is 3D matrix representing the image,

map=I(:,:,1)>200;
I(map(:,:,[1,1,1]))=0;