3.123 FAQ-698 How can I show Pseudo-Frequency axis scale in cwt image plot?

Last Update: 7/30/2018

From version 2015, Origin supports Pseudo-Frequency as the axis scale in Continuous Wavelet's output image plot. To use the Pscudo-Frequency axis scale, check the Use Pscudo-Frequency check box on the cwt dialog box. The cwt image generated will be Pseudo-Frequency scale.


If you don't like the tick labels Origin generated, you can calculate the tick locations and labels manually and then use these tick locations and labels in the cwt image. Origin provides a Pseudo-Frequency column which makes it easier to do.

  1. By checking the Use Pscudo-Frequency checkbox on the cwt dialog, you will get a Pseudo-Frequency column in the source worksheet. Add 2 more columns, Col(A) and Col(B) for example. Fill Col(A) with the major ticks you want to use as major tick labels.
  2. Calculate the corresponding scale values which are used as tick locations, and fill them in Col(B). Set Pseudo-Frequency column as X and Scale column its associated Y. Open interp1 dialog. Select Pseudo-Frequency column and Scale column as Input, and the tick labels column, col(A) as X Values to interplate, perform interpolation to get the corresponding tick locations. Output the interpolated results to Col(B).
  3. Now go to the cwt image graph, double click on the Y axis to bring up the Axis dialog. On the Scale tab, under Major Ticks branch, set Type = “By Custom Positions” and select Col(B) as Position. Go to the Tick Labels tab and then Display sub-tab, set Type = “Tick-indexed dataset” and select Col(A) as Dataset Name. Now you can get the correct ticks and labels for the image plot.