Black and White Image Converter

Convert to black and white in two ways: grayscale, which keeps every shade of grey, or pure black and white with an adjustable threshold and optional dithering — with a live preview, in your browser.

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Runs entirely in your browser. Files stay on your device — nothing is uploaded. Verify it yourself

How do you convert an image to black and white?

For grayscale, replace each pixel with its brightness — here 0.2126 × red + 0.7152 × green + 0.0722 × blue. For pure black and white, compare that brightness with a threshold (128 by default): brighter pixels become white, darker ones black, with optional dithering to keep gradients.

Cost: Free, no limits
Upload: None — runs on your device
Sign-up: Not required
Works offline: Yes, once loaded

How to convert a photo to black and white

Choose the image
Open a JPG, PNG, WebP, AVIF, GIF or BMP. A preview up to 1200 pixels across appears straight away.
Pick grayscale or black and white
Grayscale keeps shades of grey. Black and white only gives two colours.
Adjust the threshold
In black and white mode, move the threshold slider and turn on dithering if gradients turn into flat patches.
Download
Choose PNG or JPG and download. The download is processed at the image’s full resolution.

Examples

A colour portrait, GrayscaleA black and white photo with every shade of grey
The everyday meaning of black and white.
A scanned signature, threshold 160Black ink on pure white
Raising the threshold turns pale paper texture white.
A photo, threshold 128 with ditheringA two-colour image of fine dots
Suits thermal printers and engraving.

Key features of the Black and White Image Converter

Grayscale with Rec. 709 luminance weights
Pure black and white with a threshold from 0 to 255
Optional Floyd–Steinberg dithering
Live preview as you move the slider
Full-resolution PNG or JPG download

Supported formats

Input

JPG
PNG
WebP
AVIF
GIF (first frame)
BMP

Output

PNG
JPG (92% quality)

Modes

Grayscale
Threshold
Threshold with dithering

When should you use this?

Making a black and white photo for print or a portfolio.
Cleaning up a scanned signature, stamp or drawing into black ink on white.
Preparing a two-colour image for a laser engraver, vinyl cutter or thermal printer.

Limitations

The preview is a copy of up to 1200 pixels across. Dither dots in the full-resolution download are finer than they look in the preview.
Grayscale weights are applied to the stored sRGB values, not to linear light, which is the usual practice but not a physically exact brightness.
There is no contrast, curves or colour-filter control; adjust those in a photo editor first if you need them.

Troubleshooting

The black and white image is mostly black

Lower the threshold. A dark photo has most pixels under 128, so the default sends them all to black.

Gradients turned into blotches

Turn on dithering, which turns the shades into patterns of dots.

Common mistakes to avoid

Using pure black and white for a photograph and losing all the midtones. Use grayscale, or turn on dithering.
Saving black and white line art as JPG. JPG compression adds grey fringes to hard edges; PNG keeps them clean.

Pro tips

Tips for better results

Scans
Raise the threshold until the paper texture goes
For scans of ink on paper, raise the threshold until the paper texture disappears but the strokes stay solid.
Dithering
Dither photos, not text or line art
Use dithering for photos in two colours and leave it off for text, logos and line art.
File format
Save two-colour images as PNG
Download PNG for black and white only, so the edges stay hard and the file stays small.

Concepts behind image files

The terms that decide what changes when an image is compressed, resized or converted.

Resolution: The pixel dimensions of the image or frame, such as 1920×1080. It sets the amount of real detail present. Enlarging afterwards interpolates between existing pixels and produces a softer picture — no amount of upscaling recovers detail that was never captured. Reference: CSS Values and Units Module Level 4, W3C
Colour depth: How many bits describe each pixel's colour. Most formats use 8 bits per channel, giving about 16.7 million colours. Indexed formats such as GIF store a palette of at most 256 instead, which is why photographs converted to them show visible banding. Reference: GIF89a Specification, CompuServe, hosted by W3C
Metadata: Information stored alongside the content itself — camera settings, GPS coordinates, artist and album tags, author names. Conversion frequently drops it, which is usually a privacy benefit and occasionally a loss if you relied on it.
Colour space: The rule that maps the numbers in a file to visible colours. sRGB is what browsers assume, Display P3 and Adobe RGB describe wider ranges used in photography, and CMYK describes ink rather than light. A file converted without its profile keeps its numbers and changes its colours. Reference: sRGB, the default colour space, ICC
DPI and PPI: Dots or pixels per inch: a number describing how large the picture is meant to print, stored as a tag beside the pixels. It changes nothing on a screen, which draws by pixel count alone, and nothing about the detail present — only the size a printer lays the same pixels down at. Reference: CSS Values and Units Module Level 4, W3C
EXIF data: The block cameras and phones write into a photograph: exposure, lens, orientation, the date, and on a phone usually the coordinates it was taken at. Converting writes a fresh file without it, which loses the shooting data and removes the location along with it. Reference: CIPA DC-008: Exchangeable image file format (Exif), CIPA
Pixel: One addressable square of a raster image, holding a single colour. A 1920×1080 picture is 1920 across and 1080 down, about 2.07 million in all, and that count is fixed when the file is written — which is why enlarging one later invents the pixels it does not have. Reference: PNG Specification, Third Edition, W3C

Grayscale and black and white are different

Grayscale replaces each pixel’s colour with its brightness and keeps all 256 levels of grey. That is what most people mean by a black and white photo. Pure black and white keeps only two values: every pixel becomes black or white. That suits line art, signatures, stencils, laser engraving and printing on thermal or one-colour printers.

How brightness is calculated

A simple average of red, green and blue makes greens too dark and blues too light, because the eye is far more sensitive to green. This tool uses the Rec. 709 weights: 0.2126 × red + 0.7152 × green + 0.0722 × blue, applied to the image’s stored sRGB values. A pure green becomes a light grey (182 of 255); a pure blue becomes nearly black (18).

Threshold and dithering

With a threshold, every pixel at least that bright turns white and the rest turn black. 128 is the middle; lower it to keep more white and raise it for more black. Without dithering, gradients become flat areas with hard edges. Floyd–Steinberg dithering carries each pixel’s rounding error forward to its neighbours (7/16 to the right, 3/16, 5/16 and 1/16 to the row below), so a mid grey becomes an even pattern of black and white dots that reads as grey from a distance.

Privacy and file handling

The Black and White Image Converter runs entirely in your browser. Your file is read by the page, processed on your own device, and the result is handed straight back to you — no copy is sent anywhere, because none needs to be.

You can confirm this rather than take our word for it: open your browser’s developer tools, watch the Network tab, and use the tool. No request carries your file or your input. It also keeps working with the connection off.

Details are in the privacy policy.

What next?

Another way to reduce an image to a few colours.

Turn a picture into pixel art

Black and White Image Converter — questions

How do I convert a photo to black and white?

Open the photo, keep Grayscale selected and download. For a strictly two-colour image choose Black and white only, then move the threshold until the preview looks right.

What is the difference between grayscale and black and white?

Grayscale keeps 256 shades of grey; black and white only has two values. A black and white photo in the everyday sense is grayscale.

What does dithering do?

It turns shades of grey into patterns of black and white dots, so gradients and faces keep their shape in a two-colour image. Leave it off for line art and text, which look cleaner without it.

Should I download PNG or JPG?

PNG for black and white only: it is lossless, keeps transparency and keeps edges hard. JPG suits grayscale photos; it is saved at 92% quality and fills transparent areas with white.

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