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Owning Palette: Feature Extraction VIs

Installed With: Advanced Signal Processing Toolkit

Estimates the probability density function (PDF) of 1D or 2D signals from the error-reduced statistical histogram. Wire data to the signal input to determine the polymorphic instance to use or manually select the instance.

Details  Example

Use the pull-down menu to select an instance of this VI.

Select an instance WA Probability Density Function Estimation (waveform)WA Probability Density Function Estimation (1D array)WA Probability Density Function Estimation (2D array)

WA Probability Density Function Estimation (waveform)

	signal specifies the input signal.
	num of bins specifies the number of bins to use to estimate the statistical histogram of signal.
	wavelet specifies the wavelet type to use for the discrete wavelet analysis. The default is db02. The options include two types: orthogonal (Haar, Daubechies (dbxx), Coiflets (coifx), Symmlets (symx)) and biorthogonal (FBI, Biorthogonal (biorx_x)), where x indicates the order of the wavelet. The higher the order, the smoother the wavelet. The orthogonal wavelets are not redundant and are suitable for signal or image denoising and compression. The biorthogonal wavelets usually have the linear phase property and are suitable for signal or image feature extraction. If you want to use other types of wavelets, do not wire this input. Instead, use the Wavelet Design Express VI to design the wavelet you want, bundle the resulting analysis and synthesis filters, and then wire them to the filter banks input.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	filter banks specifies the analysis filter banks and the synthesis filter banks for the wavelet you specify. If you specify a value for filter banks, the VI ignores the settings in the wavelet input. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass analysis filter, which the VI uses to compute the approximation coefficients. highpass specifies the coefficients of the highpass analysis filter, which the VI uses to compute the detail coefficients. synthesis filters specifies the coefficients of the lowpass synthesis filters and the highpass synthesis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass synthesis filter, which the VI uses to filter the interpolated approximation coefficients in the wavelet reconstruction. highpass specifies the coefficients of the highpass synthesis filter, which the VI uses to filter the interpolated detail coefficients in the wavelet reconstruction.
	PDF displays the estimated probability density function of signal on an XY graph.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

WA Probability Density Function Estimation (1D array)

	signal specifies the input signal.
	num of bins specifies the number of bins to use to estimate the statistical histogram of signal.
	wavelet specifies the wavelet type to use for the discrete wavelet analysis. The default is db02. The options include two types: orthogonal (Haar, Daubechies (dbxx), Coiflets (coifx), Symmlets (symx)) and biorthogonal (FBI, Biorthogonal (biorx_x)), where x indicates the order of the wavelet. The higher the order, the smoother the wavelet. The orthogonal wavelets are not redundant and are suitable for signal or image denoising and compression. The biorthogonal wavelets usually have the linear phase property and are suitable for signal or image feature extraction. If you want to use other types of wavelets, do not wire this input. Instead, use the Wavelet Design Express VI to design the wavelet you want, bundle the resulting analysis and synthesis filters, and then wire them to the filter banks input.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	filter banks specifies the analysis filter banks and the synthesis filter banks for the wavelet you specify. If you specify a value for filter banks, the VI ignores the settings in the wavelet input. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass analysis filter, which the VI uses to compute the approximation coefficients. highpass specifies the coefficients of the highpass analysis filter, which the VI uses to compute the detail coefficients. synthesis filters specifies the coefficients of the lowpass synthesis filters and the highpass synthesis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass synthesis filter, which the VI uses to filter the interpolated approximation coefficients in the wavelet reconstruction. highpass specifies the coefficients of the highpass synthesis filter, which the VI uses to filter the interpolated detail coefficients in the wavelet reconstruction.
	PDF displays the estimated probability density function of signal on an XY graph.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

WA Probability Density Function Estimation (2D array)

	signal is the 2D input signal.
	num of bins specifies the number of bins to use to estimate the statistical histogram of signal.
	wavelet specifies the wavelet type to use for the discrete wavelet analysis. The default is db02. The options include two types: orthogonal (Haar, Daubechies (dbxx), Coiflets (coifx), Symmlets (symx)) and biorthogonal (FBI, Biorthogonal (biorx_x)), where x indicates the order of the wavelet. The higher the order, the smoother the wavelet. The orthogonal wavelets are not redundant and are suitable for signal or image denoising and compression. The biorthogonal wavelets usually have the linear phase property and are suitable for signal or image feature extraction. If you want to use other types of wavelets, do not wire this input. Instead, use the Wavelet Design Express VI to design the wavelet you want, bundle the resulting analysis and synthesis filters, and then wire them to the filter banks input.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	filter banks specifies the analysis filter banks and the synthesis filter banks for the wavelet you specify. If you specify a value for filter banks, the VI ignores the settings in the wavelet input. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass analysis filter, which the VI uses to compute the approximation coefficients. highpass specifies the coefficients of the highpass analysis filter, which the VI uses to compute the detail coefficients. synthesis filters specifies the coefficients of the lowpass synthesis filters and the highpass synthesis filters for the wavelet you specify. lowpass specifies the coefficients of the lowpass synthesis filter, which the VI uses to filter the interpolated approximation coefficients in the wavelet reconstruction. highpass specifies the coefficients of the highpass synthesis filter, which the VI uses to filter the interpolated detail coefficients in the wavelet reconstruction.
	PDF displays the estimated probability density function of signal on an XY graph.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

WA Probability Density Function Estimation Details

The VI completes the following steps to implement the wavelet-based estimation of the probability density function.

1. Calculate the histogram of the input signal.
2. Perform the wavelet denoising on the histogram output.
3. Rescale the denoised function to return a unit integral.

You often estimate the PDF of a signal or image by computing the histogram for a large number of samples. However, when the realization number of a stochastic process is limited, such as with an image with a fixed size, the PDF estimation from the histogram might include a large variance. In this case, you can use smoothing methods to return a better estimate. The wavelet method can keep the smoothness of the estimated PDF and provide a solution for density functions with breakdown points.

Example

Refer to the Probability Density Function Estimation VI in the labview\examples\Wavelet Analysis\WAGettingStarted.llb for an example of using the WA Probability Density Function Estimation VI.