How do i figure out the size of the matrices for a and g?

[Star Strider]

What is ‘SanDiego.jpg’?

[per isakson]

There is a function named, size

Answer 1

[Image Analyst]

Try this

[rows, columns, numberOfColorChannels] = size(a);

Similar for g. You can also use whos

whos a
whos g

I really suggest strongly that you use more descriptive variable names. You don't want your program to become an alphabet soup mess of a code.