How to use the black and white image converter
- 1 Drop your photos on the box, or click browse to choose them. You can add many at once.
- 2 Choose grayscale, black and white or sepia, and adjust the threshold if needed.
- 3 Press Convert. One image downloads directly; several come in a ZIP file.
- 4 Check the new size and file size shown under each image.
Better black and white photos
Photos with strong light and shadow convert best. For documents and signatures, pure black and white removes paper texture and grey shadows. Then shrink the file with Compress Image, or read the text with Image to Text.
- Raise the threshold if faint lines disappear in pure black and white.
- Lower it if the background turns grey or speckled.
- Sepia works best on portraits and old family photos.
Features
Three styles
Grayscale, pure black and white and sepia.
Adjustable threshold
Control how dark a pixel must be to turn black.
Live preview
See the result before saving.
When to use it
Signatures and stamps
Pure black and white gives a clean scan of a signature for forms. Then compress it with Compress Image to 20KB.
Portraits and art
Grayscale removes distracting colours and highlights light and shadow.
Printing documents
Black and white saves colour ink and gives sharper text.
Vintage look
Sepia makes family photos look like old prints.
Related Image tasks
Frequently asked questions
What is the difference between grayscale and black and white?
Grayscale uses many shades of grey; pure black and white uses only two colours, black and white, like a photocopy.
How does the threshold work?
Each pixel's brightness is compared with the threshold. Brighter pixels turn white and darker ones turn black. Raise it to make more of the image black.
Which is best for a signature?
Pure black and white with a threshold around 128 to 160 usually gives a clean, sharp signature on a white background.
How is grayscale worked out?
It uses the standard luminance formula, which gives green the most weight because our eyes are most sensitive to it.
Can I undo it?
The original file is not changed. Colour cannot be brought back from the converted copy, so keep your original.
Does it work on transparent PNGs?
Yes. Transparent areas stay transparent in PNG files.
What is sepia?
A warm brown tone that imitates old photographs printed with sepia toning.
Does black and white make the file smaller?
Often a little, because there is less colour information. Pure black and white images saved as PNG can be very small, which helps with strict upload limits.
Can I convert a scanned document?
Yes. Pure black and white with a suitable threshold gives clean, high-contrast pages that are easy to read and print.
Is the conversion private?
Yes. The colour change is calculated in your browser on your own device, so signatures, documents and photos are never uploaded.
Can I convert a photo on my phone?
Yes. Open this page in your mobile browser, choose a photo from your gallery, pick a style and save the black and white copy.
How this tool works. These image tools run entirely in your browser using the Canvas API built into every modern browser, the open-source libheif decoder for iPhone HEIC photos and Tesseract, a widely used open-source OCR engine, for reading text. Each tool is tested with real phone photos, screenshots and scans before it goes live, and nothing you open is sent to a server.
Built and reviewed by Hamza Farooq, founder and lead developer
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