How do I convert a large array of 8 bit binary values in MATLAB?

Question

This is a follow-up question to another SO question of mine.

I have a large array of 8 bit binary values that I want to convert back to uint8.

I have used Amro's lookupTable solution from the previous question. Now I want to do the reverse. I wanted to do a lookup table but sadly I am unable to.

What I managed to do is the following:

temp = ones([(TotalPixel),1], 'uint8');

for iter2 = 1 : TotalPixel,
     temp(iter2,1) = sum(Data(iter2,1:8).*2.^(7:-1:0));   
end

But the for loop is too slow as it takes 2 seconds to convert a [76800 x 1] array. Is there a better/faster way to do this?

Answer 1

Try this:

temp = uint8(Data*(2.^(7:-1:0))');

Note that this answer is basically the same as an edit I made to an answer I gave to a previous question you asked. You had asked there about just converting a single row of 12-bit values, but I had added an extra discussion of how you would extend it to converting multiple values at once using a matrix multiply. The difference between that answer and this is simply the number of bits and the inclusion of UINT8 to change the variable type.