Fixed sheet layout

Sunbeam is not a general form reader. Its processing code assumes one canonical 800 x 1200 pixel aligned sheet and a 40-question, four-choice layout.

Alignment

The service first resizes the submitted image to 1000 pixels wide. It searches thresholded contours for approximately square corner markers, then chooses four points by smallest/largest coordinate sum and difference. When at least four qualifying markers are found, a perspective transform maps them to:

top-left      (50, 50)
top-right     (750, 50)
bottom-right  (750, 1150)
bottom-left   (50, 1150)

The result is warped to exactly 800 x 1200 pixels. If fewer than four qualifying corner contours are found, the fallback is a direct resize of the original image to 800 x 1200. Although the log message calls this a center crop, the current source does not crop in that fallback path.

Answer-grid geometry

The detector scans only y-coordinates 300 through 1000. It maps contours into four columns:

Column	x range	Questions
1	50 to 230	1-10
2	230 to 410	11-20
3	410 to 590	21-30
4	590 to 800	31-40

Each column has ten rows. Row centers are calculated from y = 380 with 51.5-pixel spacing. Option centers are calculated from column-specific starts of 93, 275, 461, and 645, with 32-pixel spacing. The four options are mapped to A, B, C, and D.

Forms with another paper size, marker design, question count, column count, spacing, or answer alphabet are unsupported unless the source is changed and revalidated.