The meaning of low level with reference to the retinal image is exactly the same as the meaning defined in Section 1.1 on "High Level v.s. Low Level Representations", and also throughout the paper; i.e. a low level representation is more reified, specified, and uncompressed relative to a higher level abstracted, generalized, and compressed representation. In this sense the retinal image which is an edge image is more abstracted relative to the lower level surface brightness representation. This concept is counter-intuitive to conventional theorists, because the surface brightness percept is calculated from the retinal input, and is therefore assumed to be downstream of it, which they interpret as meaning at a higher level of representation. Analysis of the nature of the information encoded in the subjective percept however reveals this not to be the case.