Document Scan Cleaner

Start from a readable, reasonably straight document photograph. This cleanup works on tonal values rather than detecting a page outline or changing its perspective.

Grayscale mode computes luminance and stretches the darkest and lightest observed levels across the available range. A uniformly coloured image is kept stable rather than divided by zero.

Black-and-white mode compares luminance with a selected cutoff. Lower values preserve fewer dark pixels; higher values can make faint writing visible but also darken paper shadows.

Inspect small characters, seals and pencil marks before saving. A threshold can erase faint detail, and increasing contrast cannot reconstruct characters that were blurred beyond recognition.