Field detection read only vector data: text-layer words and drawn
rectangles and lines. A scanned form is a single picture, so it found
nothing there.
A page that an image covers at least half of, and whose content draws
no lines, is now rendered at 144 dpi and its shapes are read from the
pixels (pdfcraft_forms::detect::raster): ink against a local mean,
long thin runs as lines, enclosed rectangular patches of paper as
boxes, the empty band of a box with a small printed label as its
writing area, and the open-ended horizontal lines as rules. Labels come
from the text layer, else from OCR when the models are installed;
without either the fields get default names. Detection works in the
displayed frame, so a scan stored sideways reads like any other, and
fields on a turned page get /MK /R so typing reads upright.
generated with Claude Code
