The $4$x$4$ pixel macroblock $($MB$)$ in Figure Q$8$a displays the output from the Discrete Cosine Transform $($DCT$)$ stage of a MPEG intra$-$frame video encoder.

Table one is:

$2421325829$

$115643323$

$7236268$

$172054$

If the following Q$-$table is used for quantising the DCT coefficients in this MB$,$ what will be the resulting compressed MB$?$ Include as part of your answer, showing clear workings, the calculations for the $4$ values in the first MB column.

$27181818$

$18181818$

$18181818$

$18181818$

If all Q$-$table values are now reduced by $1/3,$ what will be the impact on the visual quality of this compressed MB$?$