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About this tool
Recolor scanned documents into high-contrast, accessible color palettes.
The High-Contrast Document Recolor re-renders a scanned or photographed page for easier reading by applying four canvas filters — contrast from 0.5x to 4x, brightness from 0.5x to 2x, a grayscale toggle and a full inversion toggle — with a live preview and a PNG export at the image's original pixel dimensions. Grayscale is on and contrast starts at 1.8x, which is usually enough to lift faint pencil or low-toner text off the paper. It is for readers with low vision or light sensitivity, and for anyone stuck with a badly scanned handout.
Open High-Contrast Document Recolor on AltFTool — it loads instantly in your browser.
Choose a scan or photo in the Page image picker, which accepts any image file.
Drag Contrast from 0.5x up to 4x and Brightness from 0.5x to 2x, and switch Grayscale or Invert on.
Press Export PNG to save high-contrast-page.png at the image's original pixel dimensions.
The same filter string is applied to a canvas at the image's natural width and height, so the PNG you download is what you saw.
Nothing is downscaled for export — a 3000-pixel-wide scan comes back 3000 pixels wide.
Contrast and brightness are sliders over a live preview, so you tune to the specific scan rather than a fixed preset.
Turn on grayscale to remove colour cast, then raise contrast — starting around 1.8x — and lower brightness slightly if the paper is glaring. Grayscale first matters because a colour tint spreads the tonal range across three channels and makes contrast adjustment less effective.
It flips every pixel value, so black text on white paper becomes white text on black. Many people with photophobia or light sensitivity read longer on inverted pages, and it also reduces the glare of a full-page white scan on a bright screen.
No. The image is loaded as a local object URL, filtered by the browser's own rendering, and exported through an in-page canvas — no upload and no network request at any stage.
Only if the detail is still present in the pixels. Contrast stretching amplifies what was captured; if a scan clipped the light tones to pure white, no filter can bring them back. Rescanning at a higher bit depth or with the brightness lowered captures more to work with.