Straighten a tilted document photo
Manual four-corner perspective correction maps the selected quadrilateral into a rectangular page.
Choose four corners
1 is top left, 2 top right, 3 bottom right, and 4 bottom left in the current image. Keep them inside the page image, clockwise, with no crossed edges. Coordinates refer to the upright, possibly downsampled working page. Invalid corners show an error instead of exporting a broken page.
Refine the result
Apply preview after changes. Grayscale removes color; contrast adjusts around mid-gray; black/white applies a configurable threshold. These controls cannot restore missing or out-of-focus detail. Strong threshold settings can remove faint handwriting. Compare Original & corners with Processed preview before saving.
Pixels and limits
Source files are capped at 25 MB, 60 MP and 15,000 pixels per edge. Working pages are downsampled to at most 12 MP and 5,000 pixels per edge. Perspective dimensions use average opposing edge lengths, then percentage crop and 90° rotation. PNG is lossless; JPG and the page images inside PDF use lossy JPEG encoding.