Intensity and Symmetry

[carto]

May I know precisely how to obtain the features intensity and symmetry from a 16 by 16 binary matrix so that I can apply the classifiers in Homework 8?

I thought intensity is the number of 1's divided by 16^2. However, the entries in the intensity column (from the file features.train) multiplied by 16^2 are not integers. Also, why are the symmetry features negative numbers?

I am asking this question because I want to hand write a digit and see if the program can recognize it right.

Thanks in advance!

[rainbow]

There is matlab code http://amlbook.com/support.html. I haven't had a look at it myself.

[magdon]

You are correct about the definition of intensity. You can see the support matlab code at

http://www.amlbook.com/support.html

which gives the details of the computation. The images actually contain grayscale values not binary 1,0 which is why the intensity features multiplied by 16^2 are not integers.

Caveat: The images are preprocessed using image processing and normalization algorithms to remove slant and make sure the digits are of comparable size (at least one pixel on the horizontal boundary and one on the vertical boundary are non-white). If you want to apply to your own handwritten digits, you will have to take this into account if you build a classifier from the data on the site.

Originally Posted by carto

May I know precisely how to obtain the features intensity and symmetry from a 16 by 16 binary matrix so that I can apply the classifiers in Homework 8?

I thought intensity is the number of 1's divided by 16^2. However, the entries in the intensity column (from the file features.train) multiplied by 16^2 are not integers. Also, why are the symmetry features negative numbers?

I am asking this question because I want to hand write a digit and see if the program can recognize it right.

Thanks in advance!

[carto]

Thank you for the useful responses.