Surface roughness determined from a depth map.

Hi,

I would like to determine the surface rougness of a microscopic picture.

I have code that creates a depth map:

File_Name='CPTi_D2_75_right_off_centre.tif';

% micron/pixel

% this is the spatial resolution of the input

Resolution=0.459;

% Number of intensity levels in the image,

% if you think that the result porosity is overestimated,

% just increase this number and vice versa, it accepts integers

N=18;

A = imread(File_Name);

if ndims(A) == 3

B = rgb2gray(A);

end

level = multithresh(B ,N);

C= imquantize(B,level);

RGB1 = label2rgb(B);

imwrite(RGB1,[File_Name(1:end-4) '_Depth Map.png']);

P=zeros(size(C));

for I=1:size(C,1)

for J=1:size(C,2)

if C(I,J)==1

P(I,J)=1;

end

end

end

P=1-P;

P=bwmorph(P,'majority',1);

figure;

imshow(RGB1); title('Depth Map')

I would like to use to create a 2D graph of the various distances and then use that to calculate the surface roughness.

Can anyone help me with this? Would it be possible? If not, any other suggestions?

Thank you for taking the time to assist me.

Kind Regards,

Andri

Answer 1

[Image Analyst]

Looks like youi're assuming that your brightness corresponds to depth. Assuming that's true there are several definitions of roughness. In fact whole books have been written about them. Perhaps the most common are Sa and Sq. Sa is the average absolute deviation from the mean surface, in other words

Sa = mean2(abs(C - mean2(C)));

and Sq is the rms of the deviations.

[Andri de Waal]

Thank you very much for taking the time to answer my question.