Assignment 2 - Two questions

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Assignment 2 - Two questions

Beitrag von lustiz » 12. Jun 2013 17:22

Hi, I've got two questions about assignment two:

1) In problem 1 we have to implement a function upsample2 which should make use of a binomial filter after the upsample step. However, no treatment of boundaries is specified. I see two options here, either a standard convolution or a matlab image filtering method choosing one of the boundary treatment options. Should we just use the one which we find best? Either way, results may differ depending on the chosen method.

2) Subtasks of problem 1 and problem 2 involve the display of matrices in range [a, b] where a is negative and b is positive. Again, there are various options here. My preferred solution would be to normalize to the range [0, 1] such that the 0 in range [a, b] now corresponds to 0.5. If we ignore the zero, however, results look brighter. What do the teaching assistants prefer?

Thanks in advance!

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Registriert: 6. Apr 2009 20:22

Re: Assignment 2 - Two questions

Beitrag von franzel » 12. Jun 2013 17:41


1) Does it make sense to do "standard" convolution here? Elementwise matrix operations on differently sized matrices are going to be difficult, right? For boundary handling "symmetric" is a good choice, but in principle they all have different pros/cons.

2) You can set the range yourself by imshow(img,[a,b]) or let it decide based on the max/min vals of img with imshow(img,[]). If you want to visualize the difference more prominently you can set a different colormap, e.g. "colormap jet;"

The matlab online reference usually describes most of the essential use cases: ... #btp8vok-1

Kind Regards,


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