Doing the Impossible with Smart Objects

Before CS3, there were plenty of things you simply could not do in Photoshop. With CS3 and the introduction of Smart Objects, a lot has become possible.

One (almost) obvious thing is that you can apply lossless filters. Just create a layer to a Smart Object and apply the filter. You can add loads of filters and remove or activate them, and of course edit them with Layer Masks.

Smart Object layer in Adobe Photoshop CS4

But not only that - you can now mix layers of different kinds. You can have one layer as a 16 bit image in LAB colour space, while you have another in 8 bit grey scale, and blend the two layers. You can even add RAW files using File > Place, so you have a RAW file layer, which will open for adjustments in Camera RAW every time you double click on it. This means that you can have an almost endless number of different image formats - all stored in the same file.

And if that is not enough, you can have one Smart Object contain another Smart Object that contains a third one and so on.

To have several instances of the same Smart Object, highlight the layer and press command-J. You can have as many instances of the same Smart Object as you like in a file. You can apply different kinds of layer styles and rotations and transformations of them. If you then update the Smart Object, for example by changing its colour, the modification will apply to all instances of that Smart Object in the file.

To replace the content of a Smart Object: Go to Layer > Smart Objects > Replace Contents....

You cannot edit the individual pixels in a Smart Object (unless you open it). However, you can make a copy of the Smart Object, for example with merging all visible layers to a new layer above the currently selected layer with Shift-option-command-E (or alt+ Layer > Merge Visible).