How to export layered texture

i imported an .psd with 3 layers. and now i want to export it as .psd or .tiff to edit just a layer but there is only .tga .bmp and .pcx supported to export which not store the layer info. What is the solution?

can someone talk about this situation

Your layers are getting flattened, if you import PSD anyway. What you are trying to do is not a good workflow. Try exporting your PSD as TGA or any other format then import it to UE4. Each time you need to make changes, re-save PSD as TGA and inside UE do a reimport on the asset.