How to change pixels to a different colour with a greyscale image?

Hi everyone,

I want to change all the pixels with the intensity less than 8000 to the colour red. However, I am struggling with this as the image is greyscale and not sure how to change this. As I want to clearly differentiate the metal clip from the tissue and to make sure that no pixels of the tissue are being identified with the metal clip. The metal clip in the image uploaded can be seen as the thick black line within the tube connected to the tissue.

Answer 1

[Tom Holz]

Here's a hacky approach that does the job:

I = imread('CTimagem.png');

mask = I < 8000;

Ired = I;
Igreen = I;
Iblue = I;

Ired(mask) = max(I, [], 'all');
Igreen(mask) = 0;
Iblue(mask) = 0;

img = cat(3, Ired, Igreen, Iblue);

figure
imagesc(img)