Canon MultiPASS C530 Service Manual page 135

MultiPASS C530/C560 Chapter 2: Technical Reference
d) The probability estimation table, published in the ITU-T T.82. Its contents are fixed, differing from
those of the study table.
NOTE
e) After the predicted value is found to be accurate/inaccurate by the actual pixel, the model template,
and the study table, that accuracy/inaccuracy is encoded in the arithmetic encoding section, and the
encoded image data is output.
f) In the encoding (mathematical encoding) done in the arithmetic encoding section, there is no
conversion table for encoding as is the case in encoding with conventional MH and MR. Using the
LSZ (probability estimation value of an inaccurate prediction: the form of a range) of the probability
estimation table and the accuracy/inaccuracy of the predicted value as a base, encoding is done by
showing the position of the progress of the prediction on an integer line (between 0~1.0). Encoding
shown as a position on this integer line, take a position under MPS in the case of accurate predictions,
and under LPS in the case of inaccurate predictions, as shown in the figure below.
Furthermore, there is a concept of range (A) in this arithmetic encoding. This range (A)
an MPS range in the case of accurate predictions and as an LPS range in the case of inaccurate
predictions for each pixel. When these ranges (A) are below a certain range
(which excludes the encoding "0". shown by the position on the integer line) shifts one position to the
left as encoded image data, and is output. At this time, the limit of this range (A) which was below the
certain range is narrow and it is difficult to show a position more detailed than this, so the range (A) is
magnified
is reset to a value above a certain range
This table shows probability of accuracy/inaccuracy in the form of a range, according to
the accurate/inaccurate results of a given status prediction value.
The plan of the probability estimation table is such that if the prediction is accurate, the
range of the next status number will be smaller than would be the case in an inaccurate
prediction.
The status number with this smaller range will be selected to be the next status number.
*4
to show it in more detail. This operation is called "Renormalization", and this range (A)
*3
.
2-56
*2
is shown as
*3
, the leading edge bit