For example, consider the 3 X 3 pixel block
in Figure (2-a).
Khodaei and Faez  proposed a hybrid approach by combining LSB substitution and PVD in 1x3 pixel block
. It was further extended to 2x2 size block in  to achieve better performance.
The third is to use a pixel block
instead of a single pixel as the input signal.
Hence, a pixel block
smoothness measuring function needs to be constructed to select appropriate pixel blocks
The operation of LBP works on 3 x 3 pixel block
consisted of eight neighborhood pixels and converting their values into the binary 0 or 1 by comparing with the value of their center pixel of the pattern.
Cross-section of a white 10x10 pixel block
on black background before/after application of a 15x15 Gauss blur filter
LFSR engenders random sequence for user's given value to choose one M x N pixel block
among an N number of blocks.
The transformed coefficients are encoded using a zigzag sequence of each 8 x 8 pixel block
of the image and are thus represented by a stream (linear string of data) of numbers (eg, 19, 13, 13, 9, 11, 45, etc.) including several zeros.
Each pixel block
is classified into the regular group R, the singular group S, and the unusable group U by a flipping function and mask M.
In the calculation of the MB-LBP, the comparison between the pixel values of the LBP operator is replaced by the average gray value of the pixel block
. MBS-LBP represents an LBP operator with a pixel block
that measures SxS.