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# Background

## Overview

Background estimation is performed by fitting a polynomial (Chebyshev) or filter-based curve to the diffraction pattern. The estimated background can be visualised and subtracted before peak search.

## Controls

Open Pattern → Background → Generate Background to display the Background dialog.

Parameter | Description
--- | ---
Type | Background model: Chebyshev polynomial or filter
Coefficients | Number of polynomial terms (Chebyshev mode)
Range | 2θ range to use for background fitting

It is possible to choose the background function that best fits the selected background points. The default function is the Chebyshev polynomial. The other available background functions are: polynomial, cosine Fourier series, cubic spline, Bézier spline, and a filter function based on the Brückner algorithm (Brückner, 2000).

## Manual editing

Background points selected automatically can be added or deleted using the mouse.

## Subtraction

Click Pattern → Subtract Background (or press the button in the toolbar) to subtract the estimated background from the pattern. The original pattern is preserved and can be restored by reloading the project.

Note

Background subtraction is recommended before running Peak Search, as it improves peak detection accuracy.