Flatten versus Merge Visible


Today’s Question: When I need to create a single-layer copy of a composite image in Photoshop, I’ve been using the Merge Visible command. I saw a reference to using Flatten Image instead, and they both seem to do the same thing. Is there a difference, and should I be using one over the other?

Tim’s Quick Answer: The only real difference between Merge Visible and Flatten Image (both found on the Layer menu in Photoshop) is that Flatten Image will always result in only a single layer, while Merge Visible will leave layers behind if the visibility is turned off for a layer.

More Detail: For all practical purposes with a photographic image in Photoshop the Merge Visible and Flatten Image commands found on the Layer menu will produce the same result: a flattened image consisting of a single layer.

However, if you have turned off the visibility of any layers, those layers will remain after you apply the Merge Visible command. This can be useful for situations where you want to merge some layers but not others. For example, if you have made a composite panorama you might reach a point where you want to merge the image layers together while still retaining the adjustment layers above.

To accomplish that you could turn off the visibility of the adjustment layers, leaving only the image layers visible. Then use the Merge Visible command and the adjustment layers will remain while the image layers have been merged into a single layer. With the Flatten Image command, the adjustment layers with visibility turned off would not be preserved.