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How to fix a blurry photo of a document

Most rejected document uploads are not blurry in the way people think. They are shadowed, angled or glare-damaged — and those are all recoverable. Genuine motion blur is not. Here is how to tell which one you have.

Four problems, four different fixes

Shadow across the page

Usually your own head or the phone blocking an overhead light. The page ends up bright at one edge and grey at the other. This is the easiest to fix: estimate the lighting across the sheet and divide it out, and the page comes back to even white with the text intact. Nothing is lost, because the text was never gone — it was just sitting on a gradient.

Flash glare

A bright blown-out blob, usually on a laminated card or glossy paper. Partly recoverable. The surrounding area can be normalised so the glare does not turn into a black blob when the image is converted to black and white. But where the glare completely blew out the surface, the text underneath is gone — no software recovers it. If the glare sits on the data you need, retake the photo without flash.

Taken at an angle

Fully recoverable. Detect the four corners of the document, compute the transform that maps them back to a rectangle, and resample. The result looks like a flatbed scan. This also fixes the trapezoid distortion that makes the far edge of a document look smaller than the near edge.

Genuine soft focus

Only partly recoverable. Sharpening restores the appearance of edge definition, but detail that the sensor never captured cannot be invented. If the small print was never resolved, it stays unresolved. Anything claiming to fully restore focus is guessing at the missing detail.

How to photograph a document so you only do it once

1. Indirect daylight, no flash. Near a window, not in direct sun. Flash is the single biggest cause of unusable document photos.
2. Fill the frame. Get close enough that the document occupies most of the shot. This is what determines whether small print survives.
3. Shoot straight down. Phone parallel to the page, not tilted.
4. Watch your own shadow. Stand to the side of the light, not between it and the page.
5. Flatten folds first. A crease throws a shadow line that reads as a mark on the document.
6. Plain contrasting background. A dark desk under white paper helps edge detection find the document.

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