Convert Photo to Grayscale Online

Grayscale conversion maps each pixel's colour to a single lightness value, producing a monochrome image. The quality of a grayscale conversion depends heavily on the algorithm: naive average treats red, green, and blue equally, while perceptual luminosity weights them according to how the human eye actually perceives brightness.

This tool offers three conversion algorithms: luminosity (perceptual, green-heavy — closest to natural vision), average (equal RGB weights — simpler), and desaturate (uses HSL lightness — different tonal character). Each produces a noticeably different result on the same photo.

All processing runs client-side in your browser using Canvas pixel manipulation. Your image is never uploaded to any server. Download the grayscale result as JPEG for photos or PNG for lossless quality.