codec / predictor + mapping · 2D / lossless

med_zigzag

The fused version of MED + Zigzag.

MED: P = median(W, N, W + N − NW), r = sample − P
Zigzag: z = (r << 1) ^ (r >> (bits − 1))
Example: r = [0, −1, 1, −2, 2] → z = [0, 1, 2, 3, 4]

ctid

0x72D711

header

uint32 · row width in samples
+ uint32 · plane count, when above one

widths

8 · 16 · 32 · 64-bit integers

decode

inverse Zigzag folded into the MED reconstruction

next

an entropy stage, usually after a byte transpose