matlab for loop vectorization

Question

I was wondering if anyone could help me vectorize these for loops I have attempt a few time but have not been able to thanks in advance.

pixel_depth = 16; 
pixel_range = 2^pixel_depth -1;

for i=1:height

    for j=1:width

        for k=1:gaussianComponents

           mean(i,j,k) = rand*pixel_range; 

           weights(i,j,k) = 1/gaussianComponents; 

           pixelDeviation(i,j,k) = diviationNew; 

       end

    end

 end

Thank you for any help....

Oliver Charlesworth · Accepted Answer · 2011-04-28 11:10:38Z

5

mean = rand(height, width, gaussianComponents) * pixel_range;

weights = 1/gaussianComponents * ones(height, width, gaussianComponents);

pixelDeviation = diviationNew * ones(height, width, gaussianComponents);

Note that mean is a bad name for a variable, as it will hide the mean function.

edited Apr 28, 2011 at 11:10

answered Apr 28, 2011 at 10:47

Oliver Charlesworth

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6 Comments

user101010101 Over a year ago

I am quite new to matlab so this may be a simple error, thank you for your answer I added this into matlab but it gives me an error saying repmat could have to many arguments, could you help with the error?

arne.b Over a year ago

It seems to mee you want to assign every entry of weight the same value, which weight=ones(height,width,gaussianComponents)*value will do (like for pixelDeviation). Note also that mean in the answer above is not yet scaled by pixelRange.

Oliver Charlesworth Over a year ago

@arne: You are absolutely right. Thank you. I've now fixed my answer (hopefully).

user101010101 Over a year ago

thank you that has fixed that, I still have a little problem I think it is from this line of code mean = rand(height, width, gaussianComponents); this does not seem to work I am not sure why I am finding it hard to debug compared to the original line as it is so different. I just wanted to check that it is doing the same idea? thank you again.

user101010101 Over a year ago

thanks arne.b I think the scaling issue it my current problem do you know how I could scale the mean by pixel range without a four loop? thank you.

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