Welcome Luca.
Perhaps you can adapt this example will help Help pls! How can I achieve this function (pick a character image, then use the image in another screen) - #6 by SteveJG
The example is similar to what I think you want to do.
Do you have a blank image place holder (blank.png)? If so, you might be able to substitute all the Image.Click event handlers in the example code for one that uses code like this
Is this what you want to do, avoid changing the image if the current image is blank?