M65761FP Просмотр технического описания (PDF) - Renesas Electronics

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M65761FP

QM-Coder

Renesas Electronics 

M65761FP

Coding Specification

(1) Coding Algorithm

• QM-Coder

(JBIG standard arithmetic coding system)

(2) Context

(i) Built-in context mode

a) Template model

• 2 or 3 line 10 pixel template (see figure 1)

(This agrees with the template used with the minimum resolution of JBIG)

Note: The coding efficiency of the 3-line template is better than that of the 2-line template by several %.

b) Adaptive template (AT)

• It is possible to move up to 127 pixels on the coding line.

(The position of AT given instruction by the MPU)

Note: It is possible to improve the coding efficiency against the dither image by the use of AT.

• It is possible to change the position of AT line by line in the middle of coding and decoding.

Note: It is not possible to change the template at the time when change the position of the AT pixels.

(ii) External context mode

• It is possible to input any context up to 12 bits.

(It is possible to interface with JBIG Progressive Coding and the Arithmatic Coding of JPEG Option

Function)

X XX

X X XX A

XX ?

XX X XXA

XXXX ?

Figure 1 Template (X, A) (Top: 3-line, Bottom: 2-line)

XXX

XXXX

A

XX ?

Max 127

XX XXX

A

XXX X?

Max 127

Figure 2 Adaptive Template (A)

(3) Typical Prediction

• Agreement with the Typical Prediction of the lowest resolution of JBIG.

The pseudo-pixel (SLNTP) is generated by the symbol LNTP which shows whether the coding/decoding

process agree with the directly before line. If they agree, the line is not coding/decoding.

This makes it possible to shorten the time of process and rejection of the code data.

SLNTPy =! (LNTPy ⊕ LNTPy – 1)

(y: line number, LNTPy = 1; LNTPy – 1 = 1)

(4) Deterministic Prediction

• This LSI is not equipped with the Typical Prediction. However, the DP function is realized when the DP

pixels are identified and eliminated by the external circuits during the external context mode.

REJ03F0234-0200 Rev.2.00 Sep 14, 2007

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