M65761FP Просмотр технического описания (PDF) - MITSUBISHI ELECTRIC

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M65761FP

QM-CODER

MITSUBISHI ELECTRIC  

MITSUBISHI ICs (LSI)

M65761FP

QM-CODER

9. CODING SPECIFICATION

(1) Coding Algorithm

• QM-Coder

XXX

(JBIG Standard Arithmetic Coding System)

XXXXA

(2) Context

(i) Built-in Context Mode

a) Template Model

• 2 or 3 line 10 pixel template (See Fig9. 1)

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

XX ?

XXXXXA

XX X X ?

Fig. 9. 1 Template (X, A)

(Top : 3line, Bottom : 2line)

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 127pixcels on the coding line.

XXX

(The position of ATgiven instruction by the MPU)

XXXX

Note:It is possible to improve the coding effeciency against the dither image

A

XX?

by the use of AT.

• It is posible to change the position of AT line by line in the middle of coding

MAX127

and decoding.

XXXXX

Note:It is not possible to change the template at the time when change the

A

XXXX ?

position of the AT pixels.

(ii) Extenal Context Mode

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

MAX127

Fig. 9. 2 Adaptive template (A)

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

(3) Typical Prediction

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

The pseudo-pixcel (SLNTP) is geneated by the symbol LNTPwhich 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 extenal circuits during the external context mode.

(5) Coding Data Format

• The Stripe Data Entity (SDE)

(=Stripe coded data with byte stuffing (PSCD) + end marker (SDNORM/ SDRST)) Coding/decoding of one stripe portion os

perfformed.In case of the multi-striped (construct the multi stripes) stripes are activated one at a time.

(6) Marker Code

• The SDE end marker is supported.(SDNORM=02h, SDRST=03h, ABORT=04h)

(During coding the marker code previously set in the register is outputted.During decoding ,the marker code detected by requesting an

interrupt to MPU when the marker is detected is read out od register.)

(7) Rough Estimate of Coding and Decoding Time(T1:M65761FP as a whole,T2;Processing Time of the arithmetic coding section alone)

• The total number of clocks needed for coding and decoding 1 page (stripe)is calculates roughly using the following equations.

T1= (p ∗ Lp) + (9/8 ∗ C) + (α ∗ Lp)

- S ∗ ((1 - β) ∗ p ∗ Ltp - Lp) [clock]

T2= (p ∗ Lp) + (9/8 ∗ C)

- S ∗ ((p ∗ Ltp) - Lp)) [clock]

p : Number of pixcels/line

Lp : Number of lines/page

β : about 0.3

Ltp : Number of TP line /page

C : Number of coded data bits/page

S= 1: TP exists 0: No TP α : about 10

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