A photo of paper, made to look like a scan
A phone photo of a form is a trapezoid of grey paper on a desk, darker in one corner where your hand was. A scanner would give a white rectangle. This page closes most of that gap in the browser, in four named steps you can switch on and off: it finds the edges of the sheet and proposes its four corners; it straightens the page into a rectangle by correcting the perspective; it estimates the light across the paper and divides it out, so the shadowed corner matches the rest; and it raises the contrast of the ink against the paper on a gentle curve.
A worked example from our test set: a 2400 × 1800 photo of a typed page lying at an angle on a dark desk, darker on its left side. The detector put its four corners on the paper’s edges, the page came out as a 1554 × 1398 pixel rectangle with the shadow gone and the paper reading white, a faint pencil stroke still visible, and the one-page A4 PDF at 200 DPI in grey weighed 191,368 bytes.
Propose, then confirm
Nothing is applied behind your back. Each page is shown with the proposed corners on the original photo, and the cleaned page in the document beside it. If the detector found the desk instead of the paper, drag the corners; if the paper fills the whole photo already, use the whole photo. Holding the backslash key shows every page as it was photographed, and “Looks like A4 — match its proportion” appears when a straightened page is within 4 % of A4, Letter or an ID card.
What it cannot do
It cannot recover detail the camera never recorded: a blurred photo stays blurred, and the builder flags photos that look shaken. It straightens tilt, not curl. And because every cleaned page is redrawn, a cleaned JPEG is never copied byte for byte the way an untouched one is. For how to take the photo in the first place, photograph a document properly covers light and angle; to fit the result into an upload box, try under 200 KB or under 100 KB.
Questions about scan picture to PDF
Can it flatten a curved book page?
No. Straightening corrects tilt — a page photographed at an angle becomes a rectangle — but a page bending into the spine of a bound book stays bent. Press the book flat, or photograph each page from straight above, for the best result.
What if it finds the wrong edges?
Drag the four corners onto the page; each handle is large enough for a thumb, and with a keyboard the arrow keys move a selected corner one pixel at a time. If the page edges were not distinct (a white page on a white desk), the photo is left as it is and the panel says so. “Use whole photo” always puts it back.
Are my photos uploaded?
No. Finding the edges, straightening, evening out the light and the ink contrast all run in this browser, with no model downloaded and nothing sent. The photo files themselves are never changed.
What does the PDF contain?
Your cleaned pages as images, in grey unless you switch colour on: no text layer, no camera or location data, and no title unless you type one. Cleaned pages are always redrawn, and the receipt counts them.
Will a faint signature survive?
It should. Ink contrast is a soft curve, not a hard cut to black and white: paper goes whiter and ink goes darker, and a light pencil line stays a light pencil line. Check the page before saving; each step can be switched off on its own.