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# framebounds

DWT filter bank frame bounds

## Syntax

``[a,b] = framebounds(fb)``

## Description

example

````[a,b] = framebounds(fb)` returns the frame bounds for the discrete wavelet transform (DWT) filter bank `fb`. For an orthogonal wavelet filter bank, the theoretical frame bounds `a` and `b` are equal to 1.```

## Examples

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Obtain the frame bounds for the orthogonal Daubechies `db6` wavelet.

```wv = 'db6'; fb = dwtfilterbank('Wavelet',wv)```
```fb = dwtfilterbank with properties: Wavelet: 'db6' SignalLength: 1024 Level: 6 SamplingFrequency: 1 FilterType: 'Analysis' CustomWaveletFilter: [] CustomScalingFilter: [] ```
`[a,b] = framebounds(fb)`
```a = 1.0000 ```
```b = 1.0000 ```

The filter bank has the default filter type `Analysis`. Create a second filter bank using the same orthogonal wavelet but with the filter type `Synthesis`. Obtain the frame bounds of this filter bank, which are equal to the previous frame bounds.

```fbSynthesis = dwtfilterbank('Wavelet',wv,'FilterType','Synthesis'); [a2,b2] = framebounds(fbSynthesis)```
```a2 = 1.0000 ```
```b2 = 1.0000 ```

Create a filter bank for the biorthogonal `bior3.9` wavelet. Obtain the frame bounds. The frame bounds are not equal to 1.

```wv = 'bior3.9'; fbA = dwtfilterbank('Wavelet',wv); [c,d] = framebounds(fbA)```
```c = 0.6250 ```
```d = 3.2982 ```

Create a second filter bank using the same biorthogonal wavelet but with the filter type `Synthesis`. Obtain the frame bounds of this filter bank. Since the wavelet is biorthogonal, the frame bounds change.

```fbASynthesis = dwtfilterbank('Wavelet',wv,'FilterType','Synthesis'); [c2,d2] = framebounds(fbASynthesis)```
```c2 = 0.5502 ```
```d2 = 2.0015 ```

## Input Arguments

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Discrete wavelet transform (DWT) filter bank, specified as a `dwtfilterbank` object.

## Output Arguments

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Lower frame bound of the DWT filter bank `fb`, returned as a positive real number.

Upper frame bound of the DWT filter bank `fb`, returned as a positive real number.

## See Also

Introduced in R2018a

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