**ISO/IEC 10918-1 : 1993(E)**

0

0

0

4

8

12

16

+S

+L

+S

S

+L

L

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

92

96

TISO1690-93/d107

S

L

Difference to left

(position a)

Difference above (position b)

**Figure H.2 5 × 5 Conditioning array for two-dimensional statistical model**

Figure H.2 [D107] = 7 cm = 273 %

**H.1.2.3.2**

**Assignment of statistical bins to the DC binary **

**decision tree**

Each statistics area for lossless coding consists of a contiguous set of 158 statistics bins. The first 100 bins consist of

25 sets of four bins selected by a context-index S0. The value of S0 is given by L_Context(Da,Db), which provides a

value of 0, 4,..., 92 or 96, depending on the difference classifications of Da and Db (see H.1.2.3.1). The value for S0

provided by L_Context(Da,Db) is from the array in Figure H.2.

The remaining 58 bins consist of two sets of 29 bins, X1, ..., X15, M2, ..., M15, which are used to code magnitude

category decisions and magnitude bits. The value of X1 is given by X1_Context(Db), which provides a value of 100 when

Db is in the zero, small positive or small negative categories and a value of 129 when Db is in the large positive or large

negative categories.

The assignment of statistical bins to the binary decision tree used for coding the difference is given in Table H.3.

**Table H.3 Statistical model for lossless coding**

Context-index

Value

Coding decision

S0

L_Context(Da,Db)

V

=

0

SS

S0

+

1

Sign

SP

S0

+

2

Sz < 1 if V > 0

SN

S0

+

3

Sz < 1 if V < 0

X1

X1_Context(Db)

Sz < 2

X2

X1

+

1

Sz < 4

X3

X1

+

2

Sz < 8

.

.

.

.

.

.

X15

X1

+

14

Sz < 2

15

M2

X2

+

14

Magnitude bits if Sz < 4

M3

X3

+

14

Magnitude bits if Sz < 8

.

.

.

.

.

.

M15

X15

+

14

Magnitude bits if Sz < 2

15

**CCITT Rec. T.81 (1992 E)**

**135**