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A class of anisotropic multiple multiresolution analysis Mariantonia - - PowerPoint PPT Presentation

A class of anisotropic multiple multiresolution analysis Mariantonia Cotronei University of Reggio Calabria, Italy MAIA 2013, Erice, September 2013 Jointly with: Mira Bozzini, Milvia Rossini, Tomas Sauer Multiple multiresolution analysis


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SLIDE 1

A class of anisotropic multiple multiresolution analysis

Mariantonia Cotronei University of Reggio Calabria, Italy MAIA 2013, Erice, September 2013

Jointly with: Mira Bozzini, Milvia Rossini, Tomas Sauer

Multiple multiresolution analysis

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SLIDE 2

Description of expanding matrices and related

  • bjects

Multiple multiresolution analysis

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SLIDE 3

Description of expanding matrices and related

  • bjects

Inside filterbanks and subdivisions

Multiple multiresolution analysis

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SLIDE 4

Description of expanding matrices and related

  • bjects

Inside filterbanks and subdivisions Remarks of their multiple counterparts

Multiple multiresolution analysis

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SLIDE 5

Description of expanding matrices and related

  • bjects

Inside filterbanks and subdivisions Remarks of their multiple counterparts An efficient strategy to construct (multiple) filterbanks

Multiple multiresolution analysis

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SLIDE 6

Description of expanding matrices and related

  • bjects

Inside filterbanks and subdivisions Remarks of their multiple counterparts An efficient strategy to construct (multiple) filterbanks Case study

Multiple multiresolution analysis

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SLIDE 7

Description of expanding matrices and related

  • bjects

Inside filterbanks and subdivisions Remarks of their multiple counterparts An efficient strategy to construct (multiple) filterbanks Case study

Multiple multiresolution analysis

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SLIDE 8

Expanding matrices

Let ▼ ∈ Zs×s be an expanding matrix, i.e. all its its eigenvalues are larger than one in modulus ▼−♥ → ✵ ⇓ as ♥ increases, ▼−♥Zs → Rs ▼ ❞ ❞❡t ▼

Multiple multiresolution analysis

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SLIDE 9

Expanding matrices

Let ▼ ∈ Zs×s be an expanding matrix, i.e. all its its eigenvalues are larger than one in modulus ▼−♥ → ✵ ⇓ as ♥ increases, ▼−♥Zs → Rs ▼ defines a sampling lattice ❞ = | ❞❡t(▼)| is the number of cosets

Multiple multiresolution analysis

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SLIDE 10

The cosets have the form ▼Zs + ξ❥, ❥ = ✵, . . . , ❞ − ✶ where ξ❥ ∈ ▼[✵, ✶)s Zs are the coset representatives. It is well known that Zs =

❞−✶

  • ❥=✵

(ξ❥ + ▼Zs)

Multiple multiresolution analysis

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SLIDE 11

Separable/Nonseparable

▼ = ✷ ✵ ✵ ✷

  • ▼ =

✶ −✶ ✶

  • Multiple multiresolution analysis
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SLIDE 12

Isotropy/Anisotropy

▼ =

✶ −✶ ✶

  • ▼ =

✶ ✶ ✶ −✷

  • Multiple multiresolution analysis
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SLIDE 13

Down/upsampling

Let ❝ ∈ ℓ(Zs) be a given signal.

▼ ❝

❝ ▼

▼ ❝

❝ ▼

s

Multiple multiresolution analysis

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SLIDE 14

Down/upsampling

Let ❝ ∈ ℓ(Zs) be a given signal. Downsampling operator ↓▼ associated to ▼: ↓▼ ❝ = ❝(▼·)

▼ ❝

❝ ▼

s

Multiple multiresolution analysis

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SLIDE 15

Down/upsampling

Let ❝ ∈ ℓ(Zs) be a given signal. Downsampling operator ↓▼ associated to ▼: ↓▼ ❝ = ❝(▼·) Upsampling operator ↑▼ associated to ▼: ↑▼ ❝(α) =

  • ❝(▼−✶α)

if α ∈ ▼Zs ✵

  • therwise

Multiple multiresolution analysis

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SLIDE 16

Filtering

Filter operator ❋: ❋❝ = ❢ ∗ ❝ =

  • α∈Zs

❢ (· − α)❝(α) where ❢ = ❋δ = (❢ (α) : α ∈ Zs) is the impulse response of ❋

Multiple multiresolution analysis

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SLIDE 17

❞-channel filter bank

Critically sampled: ❞ = | ❞❡t ▼| ❋

s ❞ s

❋❝

▼ ❋❥❝

❥ ✵ ❞ ✶

s s

  • ❝❥

❥ ✵ ❞ ✶

❞ ❥ ✵

▼ ❝❥

Multiple multiresolution analysis

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SLIDE 18

❞-channel filter bank

Critically sampled: ❞ = | ❞❡t ▼| Analysis filter: ❋ : ℓ(Zs) → ℓ❞(Zs) ❋❝ = [↓▼ ❋❥❝ : ❥ = ✵, . . . , ❞ − ✶] Synthesis filter:

  • : ℓ❞(Zs) → ℓ(Zs)
  • [❝❥ : ❥ = ✵, . . . , ❞ − ✶] =

  • ❥=✵
  • ❥ ↑▼ ❝❥,

Multiple multiresolution analysis

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SLIDE 19

❞-channel filter bank

Critically sampled: ❞ = | ❞❡t ▼| Analysis filter: ❋ : ℓ(Zs) → ℓ❞(Zs) ❋❝ = [↓▼ ❋❥❝ : ❥ = ✵, . . . , ❞ − ✶] Synthesis filter:

  • : ℓ❞(Zs) → ℓ(Zs)
  • [❝❥ : ❥ = ✵, . . . , ❞ − ✶] =

  • ❥=✵
  • ❥ ↑▼ ❝❥,

Perfect reconstruction:

  • ❋ = ■

Multiple multiresolution analysis

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SLIDE 20

❞-channel filter bank

By perfect reconstruction: ❝

→      ❝✶

❝✶

. . . ❝✶

❞−✶

     = ❝✶ ❞ ✶

  • → ❝

❋✵, ●✵ − → low-pass ❋❥, ●❥, ❥ > ✵ − → high-pass Multiresolution decomposition . . .

Multiple multiresolution analysis

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SLIDE 21

Iterated filter bank

MRA structure... ❝ ❝✶ ❝✷ ❝✸ ❞ ✸ ❞ ✷ ❞ ✶

Multiple multiresolution analysis

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SLIDE 22

Observe that

  • ❥ ↑ ❝ = ❣❥∗ ↑▼ ❝ =
  • α∈Zs

❣❥(· − ▼α) ❝(α), i.e. all reconstruction filters act as stationary subdivision

  • perators with dilation matrix ▼.

Multiple multiresolution analysis

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SLIDE 23

Stationary subdivision

Subdivision operator: ❙ := ❙❛,▼ : ℓ(Zs) → ℓ(Zs) defined by ❝(♥+✶) := ❙❝(♥) =

  • α∈Zs

❛(· − ▼α)❝(♥)(α) where ▼ ∈ Zs×s is expanding

Multiple multiresolution analysis

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SLIDE 24

Multiple subdivision

Consider a set of a finite number of dilation matrices (▼❥ : ❥ ∈ Z♠) where Z♠ = {✵, . . . , ♠ − ✶} for ♠ ∈ N. ▼❥ ❛❥

s

❛❥ ▼❥ ♠ ❙❥ ❙❛❥ ▼❥

Multiple multiresolution analysis

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SLIDE 25

Multiple subdivision

Consider a set of a finite number of dilation matrices (▼❥ : ❥ ∈ Z♠) where Z♠ = {✵, . . . , ♠ − ✶} for ♠ ∈ N. Associate a mask to each ▼❥: ❛❥ ∈ ℓ (Zs) , ❥ ∈ Z♠ . ❛❥ ▼❥ ♠ ❙❥ ❙❛❥ ▼❥

Multiple multiresolution analysis

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SLIDE 26

Multiple subdivision

Consider a set of a finite number of dilation matrices (▼❥ : ❥ ∈ Z♠) where Z♠ = {✵, . . . , ♠ − ✶} for ♠ ∈ N. Associate a mask to each ▼❥: ❛❥ ∈ ℓ (Zs) , ❥ ∈ Z♠ . Together, ❛❥ and ▼❥ define ♠ stationary subdivision

  • perators

❙❥ := ❙❛❥,▼❥

Multiple multiresolution analysis

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SLIDE 27

Multiple subdivision

Call ǫ = (ǫ✶, . . . , ǫ♥) ∈ Z♥

a digit sequence of length ♥ =: |ǫ|.

♠ ♥ ♥ ♠ ♠

Multiple multiresolution analysis

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SLIDE 28

Multiple subdivision

Call ǫ = (ǫ✶, . . . , ǫ♥) ∈ Z♥

a digit sequence of length ♥ =: |ǫ|. We collect all finite digit sequences in Z∗

♠ :=

  • ♥∈N

Z♥

and extend |ǫ| canonically to ǫ ∈ Z∗

♠.

Multiple multiresolution analysis

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SLIDE 29

Multiple subdivision

Consider the subdivision operator: ❙ǫ = ❙ǫ♥ · · · ❙ǫ✶.

❛ ❙ ❙ ❝

s

❛ ▼ ❝ ❝

s

▼ ▼ ♥ ▼ ✶ ♥

Multiple multiresolution analysis

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SLIDE 30

Multiple subdivision

Consider the subdivision operator: ❙ǫ = ❙ǫ♥ · · · ❙ǫ✶. For any ǫ ∈ Z∗

♠ there exists a mask

❛ǫ = ❙ǫδ such that ❙ǫ❝ =

  • α∈Zs

❛ǫ (· − ▼ǫα) ❝(α), ❝ ∈ ℓ(Zs), where ▼ǫ := ▼ǫ♥ · · · ▼ǫ✶, ♥ = |ǫ|.

Multiple multiresolution analysis

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SLIDE 31

Multiple subdivision

Values of ❙ǫ❝ = approximations to a function on ▼−✶

ǫ Zs.

✶ s s

▼❥ ▼ ▼ ❧✐♠ ▼

✵ ▼

✶ ❥

Multiple multiresolution analysis

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SLIDE 32

Multiple subdivision

Values of ❙ǫ❝ = approximations to a function on ▼−✶

ǫ Zs.

In order for ▼−✶

ǫ Zs to tend to Rs:

▼❥ ▼ ▼ ❧✐♠ ▼

✵ ▼

✶ ❥

Multiple multiresolution analysis

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SLIDE 33

Multiple subdivision

Values of ❙ǫ❝ = approximations to a function on ▼−✶

ǫ Zs.

In order for ▼−✶

ǫ Zs to tend to Rs:

each matrix ▼❥ must be expanding, ▼ ▼ ❧✐♠ ▼

✵ ▼

✶ ❥

Multiple multiresolution analysis

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SLIDE 34

Multiple subdivision

Values of ❙ǫ❝ = approximations to a function on ▼−✶

ǫ Zs.

In order for ▼−✶

ǫ Zs to tend to Rs:

each matrix ▼❥ must be expanding, all the matrices ▼ǫ must be expanding ▼ ❧✐♠ ▼

✵ ▼

✶ ❥

Multiple multiresolution analysis

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SLIDE 35

Multiple subdivision

Values of ❙ǫ❝ = approximations to a function on ▼−✶

ǫ Zs.

In order for ▼−✶

ǫ Zs to tend to Rs:

each matrix ▼❥ must be expanding, all the matrices ▼ǫ must be expanding ⇓ The matrices ▼ǫ must all be jointly expanding i.e. ❧✐♠

|ǫ|→∞

  • ▼−✶

ǫ

  • = ✵,

(1)

  • r, equivalently,

ρ

  • ▼−✶

: ❥ ∈ Z♠

  • < ✶

(joint spectral radius condition)

Multiple multiresolution analysis

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SLIDE 36

Multiple subdivision

Example: adaptive subdivision/discrete shearlets Based on: ✷ ✹ ✶ ✶ ✶

Multiple multiresolution analysis

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SLIDE 37

Multiple subdivision

Example: adaptive subdivision/discrete shearlets Based on: parabolic scaling ✷ ✹

✶ ✶

Multiple multiresolution analysis

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SLIDE 38

Multiple subdivision

Example: adaptive subdivision/discrete shearlets Based on: parabolic scaling ✷ ✹

  • shear

✶ ✶ ✶

  • Multiple multiresolution analysis
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SLIDE 39

Multiple subdivision

Example: adaptive subdivision/discrete shearlets Based on: parabolic scaling ✷ ✹

  • shear

✶ ✶ ✶

  • What about other choices?

Case study . . .

Multiple multiresolution analysis

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SLIDE 40

Multiple ❞-channel filter bank

For each ❦ ∈ Z♠ Analysis filters: ❋❦ : ℓ(Zs) → ℓ❞(Zs) acting as ❋❦❝ = [↓▼❦ ❋❦,❥❝ : ❥ = ✵, . . . , ❞ − ✶]

❞ s s

  • ❦ ❝❥

❥ ✵ ❞ ✶

❞ ❥ ✵

  • ❦ ❥

▼❦ ❝❥

  • ❦❋❦

■ ❦

Multiple multiresolution analysis

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SLIDE 41

Multiple ❞-channel filter bank

For each ❦ ∈ Z♠ Analysis filters: ❋❦ : ℓ(Zs) → ℓ❞(Zs) acting as ❋❦❝ = [↓▼❦ ❋❦,❥❝ : ❥ = ✵, . . . , ❞ − ✶] Synthesis filters: ●❦ : ℓ❞(Zs) → ℓ(Zs), acting as

  • ❦ [❝❥ : ❥ = ✵, . . . , ❞ − ✶] =

  • ❥=✵
  • ❦,❥ ↑▼❦ ❝❥,
  • ❦❋❦

■ ❦

Multiple multiresolution analysis

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SLIDE 42

Multiple ❞-channel filter bank

For each ❦ ∈ Z♠ Analysis filters: ❋❦ : ℓ(Zs) → ℓ❞(Zs) acting as ❋❦❝ = [↓▼❦ ❋❦,❥❝ : ❥ = ✵, . . . , ❞ − ✶] Synthesis filters: ●❦ : ℓ❞(Zs) → ℓ(Zs), acting as

  • ❦ [❝❥ : ❥ = ✵, . . . , ❞ − ✶] =

  • ❥=✵
  • ❦,❥ ↑▼❦ ❝❥,

Perfect reconstruction:

  • ❦❋❦ = ■,

❦ ∈ Z♠

Multiple multiresolution analysis

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SLIDE 43

▼✵

❝✶

✵ ▼✵

❝✷

✵✵

❞ ✷

✵✵ ▼✶

❝✷

✵✶

❞ ✷

✵✶

❞ ✶

✵ ▼✶

❝✶

✶ ▼✵

❝✷

✶✵

❞ ✷

✶✵ ▼✶

❝✷

✶✶

❞ ✷

✶✶

❞ ✶

Multiple multiresolution analysis

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SLIDE 44

Symbol notation

Given a finitely supported ❛ Symbol: ❛♯(③) :=

  • α∈Zs

❛(α)③α ❛ ❥ ③

s

❛ ▼

❥ ③

❥ ✵ ❞ ✶

Multiple multiresolution analysis

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SLIDE 45

Symbol notation

Given a finitely supported ❛ Symbol: ❛♯(③) :=

  • α∈Zs

❛(α)③α Subsymbols: ❛♯

ξ❥(③) :=

  • α∈Zs

❛(▼α + ξ❥)③α, ❥ = ✵, . . . , ❞ − ✶

Multiple multiresolution analysis

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SLIDE 46

Filter bank construction

Start from the lowpass reconstruction filter ●✵ associated to a mask ❛.

❛ ❛ ③ ❛ ③

Multiple multiresolution analysis

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SLIDE 47

Filter bank construction

Start from the lowpass reconstruction filter ●✵ associated to a mask ❛.

  • ✵ can be completed to a perfect reconstruction filter

bank if and only if ❛ is unimodular: algebraic property involved in general simple for interpolatory schemes ❛ ③ ❛ ③

Multiple multiresolution analysis

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SLIDE 48

Filter bank construction

Start from the lowpass reconstruction filter ●✵ associated to a mask ❛.

  • ✵ can be completed to a perfect reconstruction filter

bank if and only if ❛ is unimodular: algebraic property involved in general simple for interpolatory schemes In 1D − → ❛♯(③) and ❛♯(−③) have no common zeros.

Multiple multiresolution analysis

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SLIDE 49

Filter bank construction

Simplest filter bank − → lazy filters: translation operators τξ✐, ✐ = ✵, . . . , ❞ − ✶ In fact ■ =

❞−✶

  • ✐=✵

τξ✐ ↑ ↓ τ−ξ✐, ▼

Multiple multiresolution analysis

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SLIDE 50

Filter bank construction

Simplest filter bank − → lazy filters: translation operators τξ✐, ✐ = ✵, . . . , ❞ − ✶ In fact ■ =

❞−✶

  • ✐=✵

τξ✐ ↑ ↓ τ−ξ✐, It: decomposes a signal modulo ▼ in the analysis recombines the components in the synthesis

Multiple multiresolution analysis

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SLIDE 51

Filter bank construction

If ❛ defines an interpolatory subdivision scheme, then ●✵ can be easily completed to a perfect reconstruction filter bank. ❙❛ ▼ ❙❛❝ ▼ ❝ ❝

s

Multiple multiresolution analysis

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SLIDE 52

Filter bank construction

If ❛ defines an interpolatory subdivision scheme, then ●✵ can be easily completed to a perfect reconstruction filter bank. A subdivision operator ❙❛ with dilation matrix ▼ is called interpolatory if ❙❛❝(▼·) = ❝, for any ❝ ∈ ℓ(Zs)

Multiple multiresolution analysis

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SLIDE 53

Prediction–correction scheme

The completion of an interpolatory ❛ yields the prediction–correction scheme ❋✵ ■ ❋❥

❥ ■

❙❛

❥ ✶ ❞ ✶

❥ ✶ ❞ ✶

Multiple multiresolution analysis

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SLIDE 54

Prediction–correction scheme

The completion of an interpolatory ❛ yields the prediction–correction scheme Analysis part: ❋✵ = ■, ❋❥ = τ−ξ❥ (■ − ❙❛ ↓▼) , ❥ = ✶, . . . , ❞ − ✶, Synthesis part:

and

  • ❥ = τξ❥,

❥ = ✶, . . . , ❞ − ✶.

Multiple multiresolution analysis

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SLIDE 55

Prediction–correction scheme

In terms of symbols: ❋ ♯

✵(③) = ✶,

❋ ♯

❥ (③) = ③ξ❥ − ❛♯ ξ❥(③−▼),

❥ = ✶, . . . , ❞ − ✶

✵(③) = ❛♯(③),

❋ ♯

❥ (③) = ③ξ❥,

❥ = ✶, . . . , ❞ − ✶

Multiple multiresolution analysis

slide-56
SLIDE 56

A special construction of s-variate interpolatory schemes

Let ▼ = ΘΣΘ′ be a Smith factorization of the expanding matrix ▼, where Σ =      σ✶ σ✷ ... σs      and Θ, Θ′ unimodular

Multiple multiresolution analysis

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SLIDE 57

A special construction of s-variate interpolatory schemes

1 Find s univariate interpolatory subdivision schemes

❜❥, ❥ = ✶, . . . , s with scaling factors or “arity” σ❥; ❜

s ❥ ✶

❜❥ ❜

s ❥ ✶

❜❥

❥ s

Multiple multiresolution analysis

slide-58
SLIDE 58

A special construction of s-variate interpolatory schemes

1 Find s univariate interpolatory subdivision schemes

❜❥, ❥ = ✶, . . . , s with scaling factors or “arity” σ❥;

2 Consider the tensor product

❜Σ :=

s

  • ❥=✶

❜❥, ❜Σ(α) =

s

  • ❥=✶

❜❥ (α❥) , α ∈ Zs, which is an interpolatory subdivision scheme for the diagonal scaling matrix Σ, i.e. ❜Σ(Σ·) = δ

Multiple multiresolution analysis

slide-59
SLIDE 59

A special construction of s-variate interpolatory schemes

3 Set

❜▼ := ❜Σ(Θ−✶·) ❜▼ ▼ ❜▼ ③ ❜ ③

Multiple multiresolution analysis

slide-60
SLIDE 60

A special construction of s-variate interpolatory schemes

3 Set

❜▼ := ❜Σ(Θ−✶·) Then: ❜▼ defines an interpolatory scheme for the dilation matrix ▼. ❜▼ ③ ❜ ③

Multiple multiresolution analysis

slide-61
SLIDE 61

A special construction of s-variate interpolatory schemes

3 Set

❜▼ := ❜Σ(Θ−✶·) Then: ❜▼ defines an interpolatory scheme for the dilation matrix ▼. In terms of symbols: ❜♯

▼(③) = ❜♯ Σ

  • ③Θ

Multiple multiresolution analysis

slide-62
SLIDE 62

A special choice of scaling matrices

We are considering the matrices ▼✵ := ✶ ✶ ✶ −✷

  • ▼✶ := ❙✶▼✵ =

✷ −✶ ✶ −✷

  • ,

where we make use of the shear matrices ❙❥ := ✶ ❥ ✵ ✶

  • ,

❥ ∈ Z.

Multiple multiresolution analysis

slide-63
SLIDE 63

A special choice of scaling matrices

It is easily verified that ❞❡t ▼✵ = ❞❡t ▼✶ = −✸ ▼✵

✶ ✷ ✶

✶✸ ▼✶ ✸ ▼✵ ▼✶

Multiple multiresolution analysis

slide-64
SLIDE 64

A special choice of scaling matrices

It is easily verified that ❞❡t ▼✵ = ❞❡t ▼✶ = −✸ ▼✵ is anisotropic (eigenvalues:

✶ ✷

  • ✶ ±

√ ✶✸

  • ▼✶

✸ ▼✵ ▼✶

Multiple multiresolution analysis

slide-65
SLIDE 65

A special choice of scaling matrices

It is easily verified that ❞❡t ▼✵ = ❞❡t ▼✶ = −✸ ▼✵ is anisotropic (eigenvalues:

✶ ✷

  • ✶ ±

√ ✶✸

  • ▼✶ is isotropic (eigenvalues: ±

√ ✸) ▼✵ ▼✶

Multiple multiresolution analysis

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SLIDE 66

A special choice of scaling matrices

It is easily verified that ❞❡t ▼✵ = ❞❡t ▼✶ = −✸ ▼✵ is anisotropic (eigenvalues:

✶ ✷

  • ✶ ±

√ ✶✸

  • ▼✶ is isotropic (eigenvalues: ±

√ ✸) ▼✵ and ▼✶ are jointly expanding so they define a reasonable subdivision scheme.

Multiple multiresolution analysis

slide-67
SLIDE 67

Coset representation: ▼✵

Multiple multiresolution analysis

slide-68
SLIDE 68

Coset representation: ▼✶

Multiple multiresolution analysis

slide-69
SLIDE 69

The subdivision process

Initial data M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0 M0

Sequence 0 0 0 0 0 0

M0 M0 M0 M0 M0 M0

Multiple multiresolution analysis

slide-70
SLIDE 70

The subdivision process

Initial data M1 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1

Sequence 1 1 1 1 1 1

M1 M1 M1 M1 M1 M1

Multiple multiresolution analysis

slide-71
SLIDE 71

The subdivision process

Initial data M1 M0 M1 M1 M0 M1 M0 M1 M0 M1 M1 M0 M1 M0 M1

Sequence 0 1 0 1 0 1

M0 M1 M0 M1 M0 M1

Multiple multiresolution analysis

slide-72
SLIDE 72

The subdivision process

Initial data M0 M1 M0 M0 M1 M0 M1 M0 M1 M0 M0 M1 M0 M1 M0

Sequence 1 0 1 0 1 0

M1 M0 M1 M0 M1 M0

Multiple multiresolution analysis

slide-73
SLIDE 73

In ”Multiple MRA” one considers functions of the form φη(▼ǫ · −α), α ∈ Zs. ▼

Multiple multiresolution analysis

slide-74
SLIDE 74

In ”Multiple MRA” one considers functions of the form φη(▼ǫ · −α), α ∈ Zs. φη : limit function of subdivision ▼

Multiple multiresolution analysis

slide-75
SLIDE 75

In ”Multiple MRA” one considers functions of the form φη(▼ǫ · −α), α ∈ Zs. φη : limit function of subdivision Role of ▼ǫ: scale & rotate

Multiple multiresolution analysis

slide-76
SLIDE 76

In ”Multiple MRA” one considers functions of the form φη(▼ǫ · −α), α ∈ Zs. φη : limit function of subdivision Role of ▼ǫ: scale & rotate Can we get ”all rotations” by appropriate ǫ?

Multiple multiresolution analysis

slide-77
SLIDE 77

In ”Multiple MRA” one considers functions of the form φη(▼ǫ · −α), α ∈ Zs. φη : limit function of subdivision Role of ▼ǫ: scale & rotate Can we get ”all rotations” by appropriate ǫ? → Slope resolution

Multiple multiresolution analysis

slide-78
SLIDE 78

Slope resolution

Action of: ▼✶▼✶ (blue), ▼✵▼✶ (red), ▼✶▼✵ (green), ▼✵▼✵ (cyan)

  • n the unit vectors

−1 −0.8 −0.6 −0.4 −0.2 0.2 0.4 0.6 0.8 1 −1 −0.8 −0.6 −0.4 −0.2 0.2 0.4 0.6 0.8 1

−5 −4 −3 −2 −1 1 2 3 4 5 −6 −4 −2 2 4 6

Multiple multiresolution analysis

slide-79
SLIDE 79

Slope resolution

Action of:

▼✶▼✶▼✶▼✶▼✶▼✶ (blue), ▼✵▼✶▼✵▼✶▼✵▼✶ (red), ▼✶▼✵▼✶▼✵▼✶▼✵ (green), ▼✵▼✵▼✵▼✵▼✵▼✵ (cyan)

  • n the unit vectors

−1 −0.8 −0.6 −0.4 −0.2 0.2 0.4 0.6 0.8 1 −1 −0.8 −0.6 −0.4 −0.2 0.2 0.4 0.6 0.8 1

−150 −100 −50 50 100 150 −150 −100 −50 50 100 150

Multiple multiresolution analysis

slide-80
SLIDE 80

Slope resolution

Can all directions, i.e., all lines through the origin, be generated by applying an appropriate ▼ǫ to a given reference line?

Multiple multiresolution analysis

slide-81
SLIDE 81

Slope resolution

Given the reference line ▲① := R ①, ① ∈ R✷ and a target line ▲② := R ②, ② ∈ R✷ we ask whether there exists ǫ ∈ Z∗

♠ such that

▲② ∼ ▼ǫ▲①.

Multiple multiresolution analysis

slide-82
SLIDE 82

Slope resolution

We represent lines by means of slopes, setting ▲(s) := R ✶ s

  • ,

s ∈ R ∪ {±∞}, where s = ±∞ corresponds to (the same) vertical line. s ✵

✶ ✷

s ✵

s s ▲ s ▼ ▲s ▼✵✶ ▼✵▼✶ ▼✵✶ ▼✶▼✵

Multiple multiresolution analysis

slide-83
SLIDE 83

Slope resolution

We represent lines by means of slopes, setting ▲(s) := R ✶ s

  • ,

s ∈ R ∪ {±∞}, where s = ±∞ corresponds to (the same) vertical line. Theorem For each s ∈ (✵, ✶

✷), any s′ ∈ R and any δ > ✵ there exists

ǫ ∈ Z∗

♠ such that

|s′ − sǫ| < δ, ▲(sǫ) = ▼ǫ▲s. ▼✵✶ ▼✵▼✶ ▼✵✶ ▼✶▼✵

Multiple multiresolution analysis

slide-84
SLIDE 84

Slope resolution

We represent lines by means of slopes, setting ▲(s) := R ✶ s

  • ,

s ∈ R ∪ {±∞}, where s = ±∞ corresponds to (the same) vertical line. Theorem For each s ∈ (✵, ✶

✷), any s′ ∈ R and any δ > ✵ there exists

ǫ ∈ Z∗

♠ such that

|s′ − sǫ| < δ, ▲(sǫ) = ▼ǫ▲s. ▼✵✶ ▼✵▼✶ ▼✵✶ ▼✶▼✵

Multiple multiresolution analysis

slide-85
SLIDE 85

Slope resolution

We represent lines by means of slopes, setting ▲(s) := R ✶ s

  • ,

s ∈ R ∪ {±∞}, where s = ±∞ corresponds to (the same) vertical line. Theorem For each s ∈ (✵, ✶

✷), any s′ ∈ R and any δ > ✵ there exists

ǫ ∈ Z∗

♠ such that

|s′ − sǫ| < δ, ▲(sǫ) = ▼ǫ▲s. Indeed even combinations of ▼✵✶ = ▼✵▼✶ and ▼✵✶ = ▼✶▼✵ are sufficient to satisfy the claim of the theorem.

Multiple multiresolution analysis

slide-86
SLIDE 86

Bivariate interpolatory schemes associated to ▼✵ and ▼✶

Smith factorizations of ▼✵, ▼✶: ▼✵ = ✹ ✶ ✶ ✵ ✶ ✸ ✶ −✷ −✶ ✸

  • ,

▼✶ = ✺ ✶ ✶ ✵ ✶ ✸ ✶ −✷ −✶ ✸

  • .

Multiple multiresolution analysis

slide-87
SLIDE 87

Bivariate interpolatory schemes associated to ▼✵ and ▼✶

Possible choices for the ternary interpolatory schemes piecewise linear interpolant: ❜✷ = ✶ ✸ (. . . , ✵, ✶, ✷, ✸, ✷, ✶, ✵, . . . ) ❜✷ ✶ ✽✶ ✵ ✹ ✺ ✵ ✸✵ ✻✵ ✽✶ ✻✵ ✸✵ ✵ ✺ ✹ ✵

Multiple multiresolution analysis

slide-88
SLIDE 88

Bivariate interpolatory schemes associated to ▼✵ and ▼✶

Possible choices for the ternary interpolatory schemes piecewise linear interpolant: ❜✷ = ✶ ✸ (. . . , ✵, ✶, ✷, ✸, ✷, ✶, ✵, . . . ) four point scheme based on local cubic interpolation ❜✷ = ✶ ✽✶ (. . . , ✵, −✹, −✺, ✵, ✸✵, ✻✵, ✽✶, ✻✵, ✸✵, ✵, −✺, −✹, ✵, . . . )

Multiple multiresolution analysis

slide-89
SLIDE 89

Bivariate interpolatory schemes associated to ▼✵ and ▼✶

The schemes are obtained from ❜♯

▼(③) = ❜♯ Σ

  • ③Θ

which result in the following two symbols ❆♯

✶(③✶, ③✷) = ③−✷ ✶

  • ✶ + ③✶ + ③✷

✷ , ❆♯

✷(③✶, ③✷) = −③−✺ ✶

✽✶

  • ✶ + ③✶ + ③✷

✹ ✹③✷

✶ − ✶✶③✶ + ✹

  • ,

Multiple multiresolution analysis

slide-90
SLIDE 90

Theorem Suppose: ❜❥, ❥ = ✶, . . . , s define univariate subdivision schemes with scaling factors σ❥ ≥ ✶ ❙❜❥✶ = ✶. ❜▼ ▼ ❙❇ ❉

✶❙❜

❙❇ ✶ ❙❇ ❧✐♠

s✉♣

❝ ✶

❙♥

✶ ♥

❉ ❉ ❝ ❝ ❝ ❝

❝ ❥ ✶ s

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SLIDE 91

Theorem Suppose: ❜❥, ❥ = ✶, . . . , s define univariate subdivision schemes with scaling factors σ❥ ≥ ✶ ❙❜❥✶ = ✶. Then ❜▼ is a convergent subdivision scheme with dilation matrix ▼ iff the vector scheme ❙❇Σ defined by ∇❉(Θ′Θ)−✶❙❜Σ = ❙❇Σ∇ satisfies ✶ > ρ∞ (❙❇Σ | ∇) := ❧✐♠

♥→∞ s✉♣ ∇❝≤✶

  • ❙♥

❇Σ∇❝

  • ✶/♥ .

where ❉Λ is the dilation operator ❉Λ❝ = ❝(Λ·) ∇ is the forward difference operator ∇❝ = [❝(· + ǫ❥) − ❝ : ❥ = ✶, . . . , s]

slide-92
SLIDE 92

❆♯

✶(③✶, ③✷) = ③−✷

✸ (✶ + ③✶ + ③✷ ✶) ✷, ▼✵ =

✶ ✶ ✶ −✷

  • −2

2 −2 2 1

Multiple multiresolution analysis

slide-93
SLIDE 93

❆♯

✶(③✶, ③✷) = ③−✷

✸ (✶ + ③✶ + ③✷ ✶) ✷, ▼✶ =

✷ −✶ ✶ −✷

  • −2

2 −2 2 1

Multiple multiresolution analysis

slide-94
SLIDE 94

❆♯

✷(③✶, ③✷) = − ③−✺

✽✶ (✶ + ③✶ + ③✷ ✶) ✹ (✹③✷ ✶ − ✶✶③✶ + ✹),

▼✵ = ✶ ✶ ✶ −✷

  • −5

5 −5 5 1

Multiple multiresolution analysis

slide-95
SLIDE 95

❆♯

✷(③✶, ③✷) = − ③−✺

✽✶ (✶ + ③✶ + ③✷ ✶) ✹ (✹③✷ ✶ − ✶✶③✶ + ✹),

▼✶ = ✷ −✶ ✶ −✷

  • −5

5 −5 5 1

Multiple multiresolution analysis

slide-96
SLIDE 96

Filter bank associated to ▼✵

❆♯

✶(③✶, ③✷) = ③−✷

✸ (✶ + ③✶ + ③✷ ✶) ✷ and ▼✵

Analysis

❋✵ ❋✶ ❋✷   ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ − ✷

✶ ✵ − ✶

✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ − ✶

✵ ✶ − ✷

✵  

Synthesis

  ✵ ✵ ✵ ✵ ✵

✶ ✸ ✷ ✸

✷ ✸ ✶ ✸

✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵ ✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵  

Multiple multiresolution analysis

slide-97
SLIDE 97

Filter bank associated to ▼✶

❆♯

✶(③✶, ③✷) = ③−✷

✸ (✶ + ③✶ + ③✷ ✶) ✷ and ▼✶

Analysis

❋✵ ❋✶ ❋✷   ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵ ✵ ✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ − ✶

✵ ✶ − ✷

✵     ✵ ✵ ✵ ✵ ✵ ✵ − ✷

✶ ✵ − ✶

✵ ✵ ✵ ✵ ✵  

Synthesis

  ✵ ✵ ✵ ✵ ✵

✶ ✸ ✷ ✸

✷ ✸ ✶ ✸

✵ ✵ ✵ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵ ✵     ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✵ ✶ ✵ ✵ ✵ ✵ ✵ ✵  

Multiple multiresolution analysis

slide-98
SLIDE 98

c

M0

c1

M0 c2 00 d2 00 M1

c2

01

d2

01

d1

M1

c1

1 M0

c2

10

d2

10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1 c2 01 d2 01

d1

M1

c1

1 M0

c2

10

d2

10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1

c2

01

d2

01

d1

M1

c1

1 M0 c2 10 d2 10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1

c2

01

d2

01

d1

M1

c1

1 M0

c2

10

d2

10 M1 c2 11 d2 11

d1

1
slide-99
SLIDE 99

c

M0

c1

M0 c2 00 d2 00 M1

c2

01

d2

01

d1

M1

c1

1 M0

c2

10

d2

10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1 c2 01 d2 01

d1

M1

c1

1 M0

c2

10

d2

10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1

c2

01

d2

01

d1

M1

c1

1 M0 c2 10 d2 10 M1

c2

11

d2

11

d1

1

c

M0

c1

M0

c2

00

d2

00 M1

c2

01

d2

01

d1

M1

c1

1 M0

c2

10

d2

10 M1 c2 11 d2 11

d1

1
slide-100
SLIDE 100

Grazie!

Multiple multiresolution analysis