What is the difference between flattening images and merging layers (visible & not) and which command should be used when?
When you Merge Visible all layers visible in the layer palette will be locked together and become one. Turning off a layer (clicking on the eye glasses) makes it invisible and it won’t be included in the command. Example of Merge Visible – “Interlaced Scrolls” tutorial – adding the selections for the scrolls, top and bottom and then merging before copying, mirroring etc, thereby saving time. Applying an effect like a drop shadow to more than one layer is another example. With Merge Visible the background remains transparent (checkerboard pattern showing) enabling you to apply a background colour if desired. Remember to do a save in .psp format to preserve the layers (before you merge visible) in case you need to go back and make changes. You can Undo backwards beyond a Merge Visible instruction but if you save after merging and then reload your file you will only get the merged file. When you Merge All (flatten) this groups everything together and places a background behind it. If you
