What is form field detection?
Definition
Form field detection is the process of automatically locating where a document's input fields belong — text lines, checkboxes, radio options, and signature areas — and classifying each so interactive fields can be placed on the page.
What it produces
Detection returns the position and type of every field it finds, usually as a structured description of the form. That description can then drive placing real interactive fields, or simply tell a downstream system where each value lives.
Why it is hard
Forms vary wildly. Underlines, boxes, grids, and tiny checkboxes all signal inputs differently, and a label can sit above, beside, or inside its field. Reliable detection has to read both the layout and the text to tell a real field from page decoration.
Where it fits
Detection is the first step in turning a flat PDF into a fillable one: find the fields, then place them. The same field description also serves as the contract a program uses to fill the form afterward.