102. Merge or Flatten Layers into One
Before You Begin
91 About Layers and the Layers Palette
92 Create a New Image Layer
101 Group and Organize Layers
Unfortunately, the PSD format supported by both Photoshop and Photoshop Elements is one of the only image format that supports layers (the TIFF format also supports layers, although for various reasons, it is not the prime choice for your working image). Before you can save the image as another format, all the image layers must be merged togetherin other words, the image must be flattened into a single layer. You can do this yourself or you can let the Editor do it. Typically, it's better to perform the merging process yourself, just before resaving the PSD image in another format so that you can see the result and make sure that the final merged image is what you want. When layers are merged, the Editor simplifies any vector layers (text and shape layers) by converting them to raster data (pixels), and then it blends the pixels together based on the order of the layers in the layer stack, the Opacity and blend Mode settings of each layer, and any fill/adjustment masks or clipping masks.
After resaving your merged PSD image in another, more shareable format such as JPEG or unlayered TIFF format, click Undo on the Shortcuts bar to undo the merge. Then save your unflattened PSD image with its layers intact, so that you can return to work again on it at any time.
Before completing your work and saving it in a flattened format such as JPEG or unlayered TIFF, you might decide that you want to merge just a couple of layers together because you're done working with their contents separately. Not only does this action make your image easier to work with, it also makes the file smaller. For example, if you have manipulated a giraffe on one layer so that it is positioned above the location in a jungle-scene layer where you want it to live permanently, you can merge the giraffe layer into the jungle-scene layer. The layer stack is therefore less complex to work with, and the giraffe is now treated as one with the jungle.
You can also merge only the linked layers in the image when needed. For example, if you linked layers together to resize and move them but continued to make minor adjustments to each layer separately, when each layer looks as you want it, you can merge the linked layers into a single layer you can still work with.
Open an image in the Editor in Standard Edit mode and save it in Photoshop (*.psd) format.
You can merge layers by merging neighborstwo layers that lie next to each other on the layer stack. In the Layers palette, position the two layers you want to merge so that one is directly above the other in the layer stack. Select the top layer of the two layers you want to merge, then select Layer, Merge Down. Note that the two merged layers take on the name of the lower layer.
Another way you can merge layers is to merge just the ones that are currently visible. On the Layers palette, click the Visible icon (the eye) to hide any layers you don't want to merge, or to redisplay hidden layers you do want to merge. Select one of the visible layers in the Layers palette and choose Layer, Merge Visible. This time, the merged layers take on the name of the uppermost layer.
You can't merge down if the lower layer is a fill or adjustment layer.
After an image has been flattened, saved, and closed, you cannot revert back to the separate layers. Make sure that you undo the flattening process in your PSD working image file before you save and close it.
On the Layers palette, if you select a layer, any layers it is linked to appear with the Link icon (chain). Choose Layer, Merge Linked and the linked layers are merged. The merged layers take on the name of the lowest level.
Flatten the Image
You can flatten the image when all modifications are complete. You will probably flatten the image right before you save it in any other file format (such as GIF or JPEG). Select Layer, Flatten Image to merge all the layers in the image together. The remaining layer is named Background.
In your working PSD file, you should keep the image with the layers unmerged, if possible, so that you can easily make changes to the image at a later time. After layers have been merged, it is more difficult to make changes to the individual image elements.
View the Result
When you flatten the image, all unmasked data on the merged layers is blended based on the Opacity and blend Mode settings for each layer. All layers, including adjustment, fill, type, and shape layers are merged. Any hidden layers or data are deleted. The opacity of the merged layer is 100%.