Clip

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Amplitude clipping

Clipping is a non-linear amplitude operation commonly used to control extreme amplitudes, remove outliers, stabilize displays, and prepare data for processes that are sensitive to large values (e.g., FK filtering, deconvolution, stacking). This module performs amplitude clipping.

There are few options for clipping:

“amplitude clip” and “amplitude clip median” replace sample to percent threshold value;

“envelope clip” and “envelope clip median” cut samples smoothly.

Also, the user can set maximum amplitude value for output samples, if amplitude bigger then parameter it will cut.

Input DataItem

Input gather - connect/reference the output gather that needs to be amplitude clipping.

Clip by global maximum - Find the maximum absolute amplitude across the entire dataset i.e., all traces & samples. Then set the clip level relative to this value.

Clip by global maximum - true - check it, in case of maximum value need to be used

Maximum value - Maximum amplitude value for output sample. It can be in amplitude clip mode and in envelop clip mode. This is the maximum threshold value to clip.

Clip by global maximum - false

Clip value percent - amplitude percentage for output sample. All percent range calculated from whole input trace. Clip any amplitudes greater than the percentage value of the global maximum value.

Multichannel - Option for multichannel amplitude calculating. All input traces per loop iteration

Clip type { Amplitude clip, Envelope clip } - choose the clip type from the drop down menu.

Amplitude clip - this option applies the threshold directly on signal amplitude. This option is used when removing excess amplitude values, balancing traces and preparing the data for liner processes.

clip0013_r

In the above image, it is cutting the higher amplitudes which creates a sharp boundary and changes the wavelet shape.

Envelope clip - this option computes the instantaneous amplitude (envelope) instead of amplitudes. It preserves phase and reduces the amplitude bursts and keeps the wavelet shape intact. It is much gentler than the amplitude clip.

clip0014_r

In this image, even though there are higher amplitude values, it looks at the envelope and try to preserve the wavelet shape and then clip the amplitudes.

Auto-connection - By default, TRUE(Checked).It will automatically connects to the next module. To avoid auto-connect, the user should uncheck this option.

Bad data values option { Fix, Notify, Continue } - this is applicable whenever there is a bad value or NaN (Not a Number) in the data. By default, Notify. While testing, it is good to opt as Notify option. Once we understand the root cause of it,

the user can either choose the option Fix or Continue. In this way, the job won't stop/fail during the production.

Notify - It will notify the issue if there are any bad values or NaN. This will halt the workflow execution.

Fix - It will fix the bad values and continue executing the workflow.

Continue - This option will continue the execution of the workflow however if there are any bad values or NaN, it won't fix it.

Calculate difference - This option creates the difference display gather between input and output gathers. By default Unchecked. To create a difference, check the option.

Number of threads - One less than total no of nodes/threads to execute a job in multi-thread mode. Limit number of threads on main machine.

Skip - By default, FALSE(Unchecked). This option helps to bypass the module from the workflow.

Output DataItem

Output gather - generates the output gather after clipping the higher amplitude values.

Gather of difference - generates the difference between before and after amplitude clipping.

There is no information available for this module so the user can ignore it.

In this example workflow, we are adding some random spikes/higher amplitudes a stack section by using Expression calculator and connect/reference the Output gather from the expression calculator to Clip module as an input gather.

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