Export textures from unreal engine 4 to own openGL app

Hello, I want to export some models from ue4. mesh are ok(export to obj file) but textures in some cases are like : so in my app it looks like : I understand that for some purpose this texture is done in this way but I can understand why and how should I render it(or I need to delete all "not correct" parts in photoshop ?). Can someone explain how I can manage this issue ?