Z rearrangement

    After DCT, it is necessary to convert the array (two-dimensional array) into a one-dimensional array according to the Z-shaped scanning rule for compression.

Schematic diagram of Z scan:

It can be seen from the figure that the Z shape starts from the upper left side and ends at the lower right side.

Implementation idea: Convert a two-dimensional array (array) to a one-dimensional array, take out the input array data through a two-dimensional loop, and transfer it to the address position of the one-dimensional array pointed to by the Z array.

The source program is as follows:

const unsigned char Zigzag[8][8] =
{
   0,  1,  5,  6, 14, 15, 27, 28,
   2,  4,  7, 13, 16, 26, 29, 42,
   3,  8, 12, 17, 25, 30, 41, 43,
   9, 11, 18, 24, 31, 40, 44, 53,
  10, 19, 23, 32, 39, 45, 52, 54,
  20, 22, 33, 38, 46, 51, 55, 60,
  21, 34, 37, 47, 50, 56, 59, 61,
  35, 36, 48, 49, 57, 58, 62, 63
};

void __fastcall ZigScan_8x8(int czOutPut[], int czInPut[][8])//Z变换
{
   for(int i = 0; i < 8; i++)
   for(int j = 0; j < 8; j++)
      {
         czOutPut[Zigzag[i][j]] = czInPut[i][j];
      }
}