Some issues about Texture.defaultTo4bpp

[kiffa]

What does the 4bpp mean? 4 bits per pixel? If so, what's the pixel format? 1111?

Or it means 4 bits per pixel-component?  i.e 4444.

Texture.defaultTo4bpp defined the pixel format of textures in GPU, right? 

[EgonOlsen]

Yes, it's the format used by the GPU. I either means 4444 or 5551. The engine decides which one you use based on the texture.