Surface roughness and gaussian filtering

I'm trying to measure surface roughness from an image. I want to carry out gaussian filtering and according to literature, gaussian filtering gives the waviness profile and subtracting the waviness from the primary profile would give the roughness profile.

Does imgaussfilt work in the same way? I obtained a filtered image and then going on to subtract gives me a black image.

function gauss
I = imread('/Users/doyindav/Desktop/qualitymap.bmp');
sigma = 1;
%cutoff = 0.08;
h = imgaussfilt(I,'Filtersize',sigma);
new_image = imsubtract(I,h);
montage([I,new_image])
end

Answer 1

[Image Analyst]

Your blur wasn't big enough, plus your difference values were all zero because you didn't blur it enough. This works:

% grayImage = imread('/Users/doyindav/Desktop/qualitymap.bmp');
grayImage = imread('moon.tif'); % Demo image.
subplot(1, 3, 1);
imshow(grayImage);
[blurredImage, subtractedImage] = gauss(grayImage);
subplot(1, 3, 2);
imshow(blurredImage);
subplot(1, 3, 3);
imshow(subtractedImage, []);

function [blurredImage, new_image] = gauss(grayImage)
sigma = 15;
%cutoff = 0.08;
blurredImage = imgaussfilt(grayImage,'Filtersize', sigma);
new_image = imsubtract(grayImage, blurredImage);
end

[Doyinsola Oduwole]

Thank you.

[Image Analyst]

Did that solve the problem? If so, can you "Accept this answer"? Thanks in advance.

[NGUEUKO Francis Darryl]

when i do this i get

Undefined function or variable 'gauss'.

please why is this

[Image Analyst]

@NGUEUKO Francis Darryl Because you most likely altered the code I posted. I just copied and pasted it into an m-file in the editor and it ran perfectly fine. Attach your m-file with the paper clip icon so I can see how you altered it if you still need more help.

[NGUEUKO Francis Darryl]

[NGUEUKO Francis Darryl]

@Image Analysti still need more help sir, thanks.

couldnot attach my m.file

[Image Analyst]

Why not? Did you use the paperclip icon? It should let you attach the m-file.

Why does the code appear in the command window also? Did you have "echo on" or did you paste it there?

How did you try to run demo.m? Did you click the green run triangle on the toolbar? That should run and have no errors.