TIFF 6.0 Specification
Final—June 3, 1992
Control Structure
Much of the control structure developed for the sequential DCT procedures is also
used for sequential lossless coding. Either interleaved or non-interleaved data
ordering may be used.
Coding Model
The coding model developed for coding the DC coefficients of the DCT is ex-
tended to allow a number of one-dimensional and two-dimensional predictors for
the lossless coding function. Each component uses an independent predictor.
Prediction
Figure 6 shows the relationship between the neighboring values used for predic-
tion and the sample being coded.
C
A
B
Y
Figure 6. Relationship between sample and prediction samples
Y is the sample to be coded and A, B, and C are the samples immediately to the
left, immediately above, and diagonally to the left and above.
The allowed predictors are listed in the following table.
Selection-value
0
1
2
3
4
5
6
7
Prediction
no prediction (differential coding)
A
B
C
A+B-C
A+((B-C)/2)
B+((A-C)/2)
(A+B)/2
Selection-value 0 shall only be used for differential coding in the hierarchical
mode. Selections 1, 2 and 3 are one-dimensional predictors and selections 4, 5, 6,
and 7 are two dimensional predictors. The divide by 2 in the prediction equations
is done by a arithmetic-right-shift of the integer values.
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