This dialog box is opened when you select the **Peaks...** command from the Analysis menu.
By pressing the *Find *button QtiPlot performs a search on the selected curve using the
first derivative method. This method is based on the fact that the first derivative of a function at a local
extreme point is equal to zero. The limits of the search range can be specified via the
*From Xmin * and *To Xmax * input boxes.

The *Direction* drop-down list can be used in order to specify which type of peaks
should be detected: only *Positive* peaks, only *Negative* peaks or
*Both* positive and negative peaks.

The *Filter Height* can be used to specify the minimum height of the found peaks. It is defined as follows:
if it is set to zero the standard deviation of the data is used as a threshold height else it is a percent of the maximum value of the dataset.

It is possible to specify the method to smooth the derivative of the spectrum data. The available methods are:

*None*: Do not use any smoothing method.*Savitsky-Golay*: Specifies the Savitsky-Golay method to get smooth the derivative.*FFT*: Specifies the FFT Filter method to smooth the derivative.*Moving Window Average*: Specifies the Moving Window Average method to smooth the derivative.

In the *Display* group select the *Center* check box to
mark the center of the peaks. The line style of the plotted peaks can also be specified.

Select the *Labels* check box to display labels on the data plot for each peak
found. It is possible to select the type of center labels:

*X*: Use the X coordinates of the peak centers as center labels.*Y*: Use the Y coordinates of the peak centers as center labels.*Row Indices*: Use the indices of the peaks as center labels.*(X,Y)*: Use the X and Y coordinates of the peak centers as labels.

Use the *Rotate -90* check box to specify whether or not to rotate the center labels.