Custom transformations can be accessed, edited, deleted, and run from the EDIT menu, but can only be created from within the standard Transformations window.   To do this, set up the transformation as you would normally (i.e., select the mathematical operation and supply the correct coefficients).   Then select ‘Add new custom transform’ from the ‘Custom transformations’ popup.   A window will open asking for a name for the new transformation; you can enter anything you like, up to a maximum of 40 characters.

After the transform name has been entered, you should select ‘Manage custom transforms’ (again, from the ‘Custom transformations’ popup) and see if the new item appears in the list.   Each new transform is appended to the end of the existing list of custom transformations.   From this window you can click buttons to delete one or more transforms (caution: this cannot be ‘undone’) or to edit the parameters of a transform. In the latter option, you can change numeric coefficients but not the basic mathematical operation.   Make sure you don’t enter coefficients that will not ‘work’ with the type of transform (e.g., don’t try to take the square root of a negative number).

• Using custom transforms:   To use a custom transformation, go to the standard ‘Transformations’ menu option, select ‘Manage custom transforms’, select the desired transform from the list in the new window, and click ‘Selection OK’.   The ‘Transformations’ window will show the name of your selection. Pick the appropriate channel(s) and then click the ‘Transform all’ button, as usual.

• NOTE:   At present, the custom transformations options do not work for ‘breakpoint’ conversions.