Today’s Question: I’ve been making a copy of the Background image layer in Photoshop when I need to use the Clone Stamp or Healing Brush tools. I think I heard somewhere that this isn’t necessary, and causes the files to get much bigger. But if I don’t want to replace my “original” pixels, how can I avoid making a Background Copy layer?
Tim’s Quick Answer: I am a big advocate of a non-destructive workflow that employs adjustment layers and additional image layers as needed, but I also am not interested in having my image files grow any larger than is necessary. Thus, instead of creating a Background Copy layer for image cleanup, I recommend creating a new empty image layer for this purpose.
More Detail: When you create a copy of the Background image layer in Photoshop, you are doubling the base file size for the image. For example, let’s assume you started with an image that didn’t have any layers beyond the Background image layer, and that the file size was 25MB. As soon as you create a Background Copy layer, the image size (assuming no compression or other factors) would now be 50MB.
When you create a new empty image layer, the file size remains virtually unchanged, at least initially. There is a slight change because there is some additional information being preserved in terms of the presence of the new layer, but that new layer doesn’t contain any pixels and so it is not adding significantly to the file size.
So, when I am going to perform image cleanup work, I will click on the Background image layer (or the top-most image layer if there are multiple image layers), and then click the “Create a New Layer” button (the blank sheet of paper icon) at the bottom of the Layers panel. This will create a new layer that is below any adjustment layers and above any image layers, and thus is ready to be used as an image cleanup layer.
You can then use any of the image cleanup tools, making sure to use the appropriate option to enable you to work across multiple image layers. For example, with the Clone Stamp tool you could choose the “All Layers” option from the Sample popup on the Options bar, and turn on the option to ignore the effect of adjustment layers. With the Spot Healing Brush tool you could simply turn on the “Sample All Layers” checkbox on the options bar. Then make sure your new empty image layer is the active layer, and then perform your image cleanup work there.
By taking this approach, the layer you created for image cleanup work will only contain the actual pixels you used to remove blemishes from the photo. That, in turn, means the image file size will not increase significantly, especially compared to creating a full copy of the Background image layer.
I also, by the way, highly recommend renaming the new layer you created for image cleanup, to help avoid confusion later. You can rename a layer by double-clicking the name of the layer on the Layers panel, typing a new name, and pressing Enter or Return on the keyboard to apply the change.