ntenny and Steve Smith already clarified, it is pre-exposure visualization...
The Minor White definition: "...this survey of possibilities and choice is done on location, in front of the subject, before the exposure is made. Previsualization as such survey and decision is called is to be done before the exposure is made." "...The term stands for a developed ability to look at a scene and at the same time hold in one's eye the image of the print which is still to be made."
There's talk of pre- and post-visualizing, visualizing from the print back to the original, vision communicated clockwise and counterclockwise and sometimes both directions at the same time. How this sometimes reaches an almost Zen-like state, etc.