preimage

In signal processing, the preimage ("before the fold"/recto) function of a loopstring configuration, is the sequence of pencils (ie. set of intermediate states - to include SMALL branes and yesegalo) that are framed prior to the determination of an object's image. The preimage is the inverse of an image. (see also opera)
Note (+): The preimage range is comparable to a denatured protein. Likewise, its domain could be that of subchem.