Yes, you can mask without cutting your actual image (also known as non-destructive editing). By adding a layer mask in Photoshop before invoking ReMask, your changes will be made to your layer mask and will preserve your original image. The benefit of this, of course, is that your original image remains intact. Also, you can later remove the layer mask entirely – if desired.
You can enable the layer mask feature manually or automatically. Let’s take a look at how it’s done.
To use the manual workflow, go to your Layers palette in Photoshop and make sure that the image layer you want to mask is selected. Then look at the bottom of the Layers Palette for the “Add Layer Mask” button (it is a shaded square with a white circle in the middle). Once you click on this button, you will see a white square (represents the layer mask) added to the right of your image thumbnail in your layers palette.
Be sure that the image thumbnail (not the mask thumbnail) is selected before invoking ReMask.
Then go into ReMask and follow your normal masking workflow. Once you click “OK” to save your work back to Photoshop, it will save your cutout to the layer mask that you previously applied.
To use the automatic workflow, go to your Menu -> Preference in ReMask and click the box next to “Enable Use-Layer-Mask”. So now, whenever you go to Filter -> Topaz Labs and select ReMask, a layer mask will automatically added to your image layer before the ReMask interface opens. Then in ReMask follow your normal masking workflow, and once you click “OK” to save your work back to Photoshop, it will save your cutout to the layer mask that was automatically applied.