Save only edited drawings

I have a field of type Drawing with an image in its Init Value, on which the unlock pattern of a cell phone must be drawn. I want to prevent the image from being displayed when no pattern was drawn, but I see that even if it is not edited, the default image is saved.
Can I prevent the image from being saved if nothing was drawn?

If you are using a form for capturing the drawing, you could have an event action on form save something with an expression like below for the column [Dibujar Patron]

Action type" “Set the values of some columns in this row”

Column to set [Dibujar Patron] , Action Prominance: “Do not display”

Action Expression:

IF(“”= [Dibujar Patron] , " ", [Dibujar Patron])

Here is a sample initial value of the drawing column [Dibujar Patron]
Please replace with the initial value you have.

Also, I could not write the Patron word properly as a letter equivalent of “o” I could not reproduce. Please replace suitably.

Below is an example where drawing is captured when altered or else it remains blank


I had not seen that what it saved was the original path when it was not modified, I assumed that it saved copies of the image.
I just put in Show if:
[Mostrar patron],

I had to create a virtual yes / no column called [Mostrar patrón], containing the expression:

NOT([Dibujar Patrón]=[Sucursal Id].[Fondo Patrón]),

Since this did not work, although I do not understand why

          NOT([Dibujar Patrón]=[Sucursal Id].[Fondo Patrón]),

Many Thanks!!