Reduce Shadows on a Photographed Document
Reduce cast shadows (hand, phone, book binding) on a photo of a document by locally equalizing brightness, to get a more uniform background without needing photo editing software.
How It Works
The tool estimates a background brightness map by averaging the image in large blocks (the shadow appears as a darker area than the rest of the background), then compensates each pixel based on the difference between this background map and an ideal white background. The result lightens shadow-darkened areas without strongly altering areas that are already well lit.
Does the document text stay readable after correction?
Yes, the correction acts on large areas (blocks of several dozen pixels), not on fine details: text, which varies over just a few pixels, is therefore not blurred or erased by the operation; only the general brightness trend is corrected.
What if the shadow remains visible after processing?
Increase the correction strength to more strongly compensate for the brightness difference, or reduce the detection fineness (smaller value) if the shadow is thin and localized. If the shadow is very pronounced, taking a new photo with more uniform lighting will always give a better result than software correction.
100% local processing: the brightness correction is done entirely in your browser; your document is never sent to a server.