How to convert photos to black & white grayscale for print & publishing
- Step 1Upload your colour photo — Drop any JPG, PNG, WebP, or HEIC colour photo into the converter.
- Step 2Conversion runs instantly — Rec. 709 luminance-preserving conversion runs via Canvas API in-browser. No upload, no processing queue.
- Step 3Download your B&W image — Save the grayscale version as JPG or PNG. Resolution and pixel count are unchanged from the original.
Frequently asked questions
Why does my black and white photo look flat or dull?+
Flat greyscale usually results from simple equal-channel desaturation (averaging R/G/B). Proper greyscale uses luminance weights (Rec. 709: Red 21%, Green 72%, Blue 7%) that match how the human eye perceives brightness. Green is weighted most heavily because human vision is most sensitive to green wavelengths — this preserves tonal depth.
Can I add a sepia or duotone effect instead of pure greyscale?+
This tool outputs pure luminance-weighted greyscale. For sepia, duotone, or toned monochrome effects, convert to greyscale first then apply a colour overlay in a design tool, or use the colour palette tool to remap tones to a warm spectrum.
Does converting to black and white reduce file size?+
Slightly — JPEG files saved from greyscale images are typically 10–20% smaller than the colour original at the same quality setting, because chroma data is eliminated. For PNG, greyscale mode reduces file size more significantly (30–50%) by using 8-bit instead of 24-bit colour depth.
Privacy first
All image processing runs locally in your browser using WebAssembly and the Canvas API. No file is ever uploaded — only metadata counters are saved for signed-in dashboard stats.