Just a note, not sure what is / was required. You can of course get a palette from the image. Not in the order of the image, I wonder where that swatch came from ? You can sort a palette by color / luminosity .. but if you want something in the same order as the swatch image, then maybe some tedious hand editing 
That is a 16x16 grid, I did the top line, not going to do the remainder.
That is a 16x16 grid, I did the top line, not going to do the remainder.