quantiz

Produce quantization index and quantized output value

Syntax

index = quantiz(sig,partition)
[index,quants] = quantiz(sig,partition,codebook)
[index,quants,distor] = quantiz(sig,partition,codebook)

Description

index = quantiz(sig,partition) returns the quantization levels in the real vector signal sig using the parameter partition. partition is a real vector whose entries are in strictly ascending order. If partition has length n, index is a vector whose kth entry is

  • 0 if sig(k) ≤ partition(1)

  • m if partition(m) < sig(k) ≤ partition(m+1)

  • n if partition(n) < sig(k)

[index,quants] = quantiz(sig,partition,codebook) is the same as the syntax above, except that codebook prescribes a value for each partition in the quantization and quants contains the quantization of sig based on the quantization levels and prescribed values. codebook is a vector whose length exceeds the length of partition by one. quants is a row vector whose length is the same as the length of sig. quants is related to codebook and index by

quants(ii) = codebook(index(ii)+1); 

where ii is an integer between 1 and length(sig).

[index,quants,distor] = quantiz(sig,partition,codebook) is the same as the syntax above, except that distor estimates the mean square distortion of this quantization data set.

Examples

The command below rounds several numbers between 1 and 100 up to the nearest multiple of 10. quants contains the rounded numbers, and index tells which quantization level each number is in.

[index,quants] = quantiz([3 34 84 40 23],10:10:90,10:10:100)

The output is below.

index =

     0    3    8    3    2


quants =

    10    40    90    40    30

See Also

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