Hi and thank you @Ron P.. Yes, I think you are right. If I create a new pixel layer as you have described and apply a filter to it, then the effect of the filter will be limited to that position in the layer stack and can therefore be deleted later (by deleting the pixel layer). I will give it a go. I did try before but some of the filters I tried did not seem to want to apply to pixel layers (some seem to make there own). I think it will be because I may not have set the parameter of the pixel layer as you have described. Anyway, that is extremely helpful, thank you and the question can be regarded as solved!