Following points can help you :
- http://software.metadma.com/LayerSplitter.html . Allows you to save the layers . But it is not free. It saves in directories.
2.you can have only those relevant layer(s) that you want to export visible. (So hide all the layers that you don't want to export and keep the relevant one's visible.) Then go to File - Save for web and save your image.
- Alternatively you can run this script.