Question about Quantization in the DCT domain

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#96

From: Saad Bedros 625 7542
Date: Fri, 06 Nov 1992 15:11

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working in quantization for the DCT coefficients, I know I can apply
MAX quantizer for the ac coefficients with a laplacian source,
But for the DC term, a uniform quantization is best.
What is the best approach for quantizing the DC term:
 1- calculate the min and max, then quantizing using 8 bits after
     normalization. in this case, the min and max should be transmitted.
 2- find a global max for the DC, normalize then quantize. I know in JPEG
    they use 16 as a quantization level.

What is the advantage to set the range between -128,128 instead 0,255
before taking the DCT ? ( I think that is what they do in JPEG)

By the way, I was looking for a DCT in matlab, and I got one, not fast
but not slow if somebody is intersted.

Saad Bedros
U of Minnesota

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From: bedros@loon.cs.umn.edu (Saad Bedros 625 7542)
Subject: Question about Quantization in the DCT domain
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Date: Fri, 6 Nov 1992 15:11:48 GMT
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