Splitting an image into matrix based on color?

Hi i have an low res image and i want to extract the color information from this into a cell-matrix.

I already know the 8 colours contained in this image. It is stored in an 8x3 array,

0 0 0; //black

255 0 0; //red

240 220 0; 50 0 255; etc

now all i want to do is search the image for these colours (including small variations), and if a match is found put this region in a matching cell array.

So if in the image 0,0 to 10,25 consists of colour black then in the matrix the first element will be a cell with dimension {10 x 25 x 1} where 10 and 25 are the dimensions and the 1 dimension holds the colour information.

The value of this cell will be 1 since black is uindex 1 in the predefined colour array.

How do i convert this logic into code? Thanks for helping,