Above is an updated export textures menu. It now exports the diffuse texture and normal map as an RGB image, and specular texture and bump map as a grayscale image. No more RGBA images with alpha channel, which are too complex to understand for someone. Image format can be choosen in the drop-down box. It also have an option to paint up oceans - the result is below. The bump and normal maps becomes flat on the ocean area if this option enabled, and specular map becomes a water mask.