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Owning Palette: Filter Banks VIs

Installed With: Advanced Signal Processing Toolkit

Computes the single-level discrete wavelet transform using a two-channel analysis filter bank. This VI decomposes the signal into the low-frequency subband (approx coef) and the high-frequency subband (detail coef). Both subbands have half the sampling rate of signal. Wire data to the signal input to determine the polymorphic instance to use or manually select the instance.

Examples

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

Select an instance WA 1D Analysis Filter Bank (waveform)WA 1D Analysis Filter Bank (array)WA 2D Analysis Filter Bank

WA 1D Analysis Filter Bank (waveform)

	extension specifies the method to use to pad data at the borders of the input signal. The default is symmetric. The extension length is equal to the length of the wavelet filters. When you select the extension method, make the transition between the input signal and the padded data as smooth as possible because a smooth transition generates fewer large detail coefficients and enhances the efficiency of the signal representation. 0 zero padding—Uses zeroes to pad the input data. Watch for abrupt transitions between the padded zeroes and the input data, which causes large artifacts near the transition. 1 symmetric—Uses replications of the input data to pad the data, except that the VI left-flips the block at the input and right-flips the block at the end. 2 periodic—Adds a replication of the input data block before and another replication after the input data block to pad the data.
	signal specifies the input signal.
	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.
	analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters. You can use the WA Wavelet Filter VI to obtain the filters of commonly used wavelets. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. 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.
	shift specifies the index where decimation starts after the VI filters the signal. shift must be 0 or 1.
	approx coef contains the approximation coefficients, which are the output of the lowpass analysis filter followed by a decimation factor of 2.
	detail coef contains the detail coefficients, which are the output of the highpass analysis filter followed by a decimation factor of 2.
	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 1D Analysis Filter Bank (array)

	extension specifies the method to use to pad data at the borders of the input signal. The default is symmetric. The extension length is equal to the length of the wavelet filters. When you select the extension method, make the transition between the input signal and the padded data as smooth as possible because a smooth transition generates fewer large detail coefficients and enhances the efficiency of the signal representation. 0 zero padding—Uses zeroes to pad the input data. Watch for abrupt transitions between the padded zeroes and the input data, which causes large artifacts near the transition. 1 symmetric—Uses replications of the input data to pad the data, except that the VI left-flips the block at the input and right-flips the block at the end. 2 periodic—Adds a replication of the input data block before and another replication after the input data block to pad the data.
	signal specifies the input signal.
	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.
	analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters. You can use the WA Wavelet Filter VI to obtain the filters of commonly used wavelets. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. 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.
	shift specifies the index where decimation starts after the VI filters the signal. shift must be 0 or 1.
	approx coef contains the approximation coefficients, which are the output of the lowpass analysis filter followed by a decimation factor of 2.
	detail coef contains the detail coefficients, which are the output of the highpass analysis filter followed by a decimation with a factor of 2.
	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 2D Analysis Filter Bank

	extension specifies the method to use to pad data at the borders of the input signal. The default is symmetric. The extension length is equal to the length of the wavelet filters. When you select the extension method, make the transition between the input signal and the padded data as smooth as possible because a smooth transition generates fewer large detail coefficients and enhances the efficiency of the signal representation. 0 zero padding—Uses zeroes to pad the input data. Watch for abrupt transitions between the padded zeroes and the input data, which causes large artifacts near the transition. 1 symmetric—Uses replications of the input data to pad the data, except that the VI left-flips the block at the input and right-flips the block at the end. 2 periodic—Adds a replication of the input data block before and another replication after the input data block to pad the data.
	signal is the 2D input signal.
	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.
	analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters. You can use the WA Wavelet Filter VI to obtain the filters of commonly used wavelets. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters. 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.
	shift specifies the index where decimation starts after the VI filters the signal. shift must be 0 or 1.
	DWT coef contains the approximation coefficients and the detail coefficients from the 2D single-level discrete wavelet transform. low_low contains the approximation coefficients from the lowpass analysis filtering on each row and each column. The low_low coefficients are a low-resolution approximation of the original 2D signal. low_high contains the detail coefficients from the lowpass analysis filtering on each row and the highpass analysis filtering on each column. The high-frequency signal along the column direction influences the low_high coefficients. high_low contains the detail coefficients from the highpass analysis filtering on each row and the lowpass analysis filtering on each column. The high-frequency signal along the row direction influences the high_low coefficients. high_high contains the detail coefficients from the highpass analysis filtering on each row and each column. The high-frequency signal along the diagonal direction influences the high_high coefficients.
	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.

Examples

Refer to the following VIs for examples of using the WA Analysis Filter Bank VI:

• Filter Banks - 1D VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
• Filter Banks - 2D VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
• Wavelet Order Selection VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb