Grey levels	0	1	2	3	4	5	6	7
No of pixels	100	90	50	20	0	0	0	0

Histogram Equalization Transformation function is defined as:

$S_k =\sum_{j=0}^k P_r r_j$

where $r_k$ and $s_k$ are normalized input and output gray values

Input gray value	Normalized input	Frequency $N_{rk}$	PDF $P_r = N_{rk}/N$	CDF $S_k = \sum P_r$	Output gray value,$S_k$(CDFx7)
0	0	100	0.384	0.84	0.2688=3
1	1/7	90 …