ADV601LCJSTZ datasheet(7/44 Pages) AD

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ADV601LC

–7–

REV. 0

THE PROGRAMMABLE QUANTIZER

This block quantizes the filtered image based on the response

profile of the human visual system. In general, the human eye

cannot resolve high frequencies in images to the same level of

accuracy as lower frequencies. Through intelligent “quantiza-

tion” of information contained within the filtered image, the

ADV601LC achieves compression without compromising the

visual quality of the image. Figure 7 shows the encode and de-

code data formats used by the quantizer.

Figure 8 shows how a typical quantization pattern applies over

Mallat block data. The high frequency blocks receive much

larger quantization (appear darker) than the low frequency

blocks (appear lighter). Looking at this figure, one sees some key

point concerning quantization: (1) quantization relates directly

to frequency in Mallat block data and (2) levels of quantization

range widely from high to low frequency block. (Note that the

fill is based on a log formula.) The relation between actual

ADV601LC bin width factors and the Mallat block fill pattern

in Figure 8 appears in Table II.

9.7

WAVELET

DATA

6.10 1/BW

15.17 DATA

0.5

15.0 BIN

NUMBER

QUANTIZER - ENCODE MODE

TRNC

SIGNED

UNSIGNED

1/BW

QUANTIZER - DECODE MODE

8.8 BW

23.8 DEQUANTIZED

WAVELET DATA

9.7

WAVELET

DATA

15.0 BIN

NUMBER

SIGNED

UNSIGNED

SAT

Figure 7. Programmable Quantizer Data Flow

Y COMPONENT

Cb COMPONENT

Cr COMPONENT

LOW

HIGH

QUANTIZATION OF MALLAT BLOCKS

Figure 8. Typical Quantization of Mallat Data Blocks (Graphed)

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