Compress Energy Spectrum

Use the RPS > Utilities > Compress Energy Spectrum option (geogxnet.dll(Geosoft.GX.Radiometrics.CompressArray;Run)*) to reduce the size of a radiometric energy spectrum by summing consecutive array elements into larger energy bins. This produces a compact spectrum, yielding a smoother result while preserving key spectral characteristics. The resulting output channel contains the compressed spectrum, with the cosmic count element retained at the end when applicable.

Compress Energy Spectrum dialog options

Input array channel	Select the radiometric array channel to compress (for example, a total count channel). Only array-type channels are listed. Script Parameter: SPECTRO.INPUT_CHANNEL
Output compressed array channel	Select a new or existing array channel to store the compressed spectrum. If the channel does not exist, it is created using the reduced array size. If the channel already exists, you will be prompted to confirm the overwrite. If you choose to overwrite, the channel is deleted and recreated with the correct array size. Script Parameter: SPECTRO.OUTPUT_CHANNEL
Compression factor	Specify the number of consecutive array elements to combine into each new energy bin. Valid values: 2, 4, 8, 16. A value of 2 halves the number of array elements (excluding any cosmic count element). Larger values further reduce the array length and increase smoothing, but also decrease spectral resolution. Script Parameter: SPECTRO.DESAMPLED
Last element cosmic count	Specify whether the final element in the array represents a cosmic count value. Yes (default): The last element is treated as a cosmic count. It is copied unchanged to the end of the output array and excluded from summations. No: All elements are treated as part of the spectrum. Script Parameter: SPECTRO.COSMIC_COUNT [0 : No; 1 : Yes]

Application Notes

How Compression Works

The tool reduces the number of elements in a radiometric energy spectrum by summing groups of n consecutive elements, where n is the selected compression factor. This produces a shorter array with fewer, broader energy bins and applies a simple smoothing effect. If the input array has defined energy increments, those increments are automatically scaled by the compression factor.

• All spectrum elements between the first and last (excluding any cosmic count element) are grouped into blocks of n.

• Each block is summed to create a single value in the output array.

• The resulting compressed spectrum contains fewer bins and exhibits reduced noise.

Handling the Cosmic Count

If Last element cosmic count = "Yes":

• The final element of the input array (the cosmic count) is not included in any summation.

• It is copied unchanged to the end of the output array. Because of this, the preceding (n−1) bins—where n is the compression factor—are dropped. These bins typically contain minimal or no counts and generally do not affect subsequent RPS processing.

  Example

  For an input array of 1024 elements and a compression factor of 4, the output array normally contains 256 elements.

  Under standard compression, groups of four input bins are summed:

  • input bins 0+1+2+3 → output bin 0

  • input bins 4+5+6+7 → output bin 1

  • …

  • input bins 1020+1021+1022+1023 → output bin 255

  However, when Last element cosmic count = “Yes”:

  • input bin 1023 (cosmic count) is copied directly → output bin 255

  • input bins 1020, 1021, and 1022 are ignored and not included in any summation

Scaling Energy Increments

If the input array has defined energy increments:

• The increment values are scaled by the compression factor.

  Example

  If the original energy increment is 3 keV and the compression factor is 2, the new increment becomes 6 keV.

When Compression Is Useful

Compression is particularly helpful when:

• The original spectrum contains a large number of channels (e.g., 2048 or 4096), and you want to reduce noise or file size before further RPS processing.

• A compressed spectrum is preferred for downstream tools such as Generate Radioelement Counts.

Choosing a Compression Factor

• Lower values (2, 4): Preserve more spectral detail.

• Higher values (8, 16): Provide a smoother outcome but reduce spectral resolution.