DICOM PS3.3 2023b - Information Object Definitions

C.10.13 Waveform Filter Lookup Table Macro

This Macro contains attributes of a Waveform Filter Lookup Table.

Table C.10.13-1. Waveform Filter Lookup Table Macro Attributes

Attribute Name

Tag

Type

Attribute Description

Filter Lookup Table Description

(003A,032B)

3

A textual description of the Filter Lookup Table.

Frequency Encoding Code Sequence

(003A,032C)

1

Encoding of frequency values in the Lookup Table Data.

Magnitude Encoding Code Sequence

(003A,032D)

1

Encoding of filter response magnitude in the Lookup Table Data.

Filter Lookup Table Data

(003A,032E)

1

Lookup Table Data.

See Section C.10.13.1 for further explanation.

C.10.13.1 Lookup Table Data

Lookup Table Data consist of n triplets of double values: the first value is the input frequency. The second value is the magnitude. The third value is the phase shift of the signal resulting from filtering.

The input frequency values in the Lookup Table shall cover all frequencies from 0 to ½ of the sampling frequency. For input frequencies between two values in the Lookup Table an interpolation between the neighboring values can take place.

Frequency Encoding Code Sequence (003A,032C) defines the encoding of the first value, which could be:

• frequency given in Hz

• frequency given in radians per second

• normalized frequency, which is frequency in Hz divided by ½ of the sampling rate

• or angular frequency, which is frequency in Hz divided by ½ of the sampling rate and then multiplied by π (pi).

Magnitude Encoding Code Sequence (003A,032D) defines the encoding of the second value, which could be:

• dB microvolts, dB millivolts

• normalized magnitude

• absolute magnitude in millivolt or microvolt.

Normalized magnitude is (ω - |H(ω)|)/ ωmax, which is the input signal amplitude minus the filter output signal amplitude both divided by the maximum input signal amplitude, and has a value between 0-1; (no units, because it is the ratio of input and output amplitudes).

The phase shift is given in degrees.

DICOM PS3.3 2023b - Information Object Definitions