Black and White Image Converter: Grayscale, Pure B&W or Sepia

"Black and white" means two different things depending on who asks. A photographer means grayscale: a photo in shades of gray, from deep black to bright white, with all the tones in between. A crafter, a sign maker or someone preparing a logo for a stamp or a laser engraver means literally black and white: every pixel is either pure black or pure white, nothing in between. A third group wants the warm brown look of an old print, which is sepia.

This converter does all three. It shows the result live, lets you compare it with the original by dragging across the preview, and processes one photo or a whole batch in your browser. Your images are never uploaded.

How to make an image black and white

1. Drop your photos into the box above, or click it to choose them. JPG, PNG, WebP, GIF, BMP and AVIF are supported, up to 200 at once.
2. Pick an Effect: Grayscale, Black and white, or Sepia.
3. Adjust Brightness and Contrast (minus 100 to plus 100). For Black and white, move the Threshold or press Auto threshold; tick Dither for a dot pattern. For Sepia, set the Sepia strength.
4. Drag across the preview to move the gold divider: the original is on the left, the result on the right.
5. With several photos, keep Same settings for every photo ticked for a consistent look, or untick it to tune each photo separately.
6. Choose the format and click Download this photo or Download all (ZIP). Files get -grayscale, -black-white or -sepia added to their names.

The three effects compared

How the grayscale conversion works

A color photo stores red, green and blue for every pixel. The simplest way to make gray would be to average the three, but our eyes do not see them as equally bright: a pure green looks much brighter than a pure blue of the same strength. Averaging makes skies too light and foliage too dark.

This tool uses the weighting from the Rec. 709 standard used for HD video: 21.26 percent red, 71.52 percent green and 7.22 percent blue. The result keeps the brightness relationships you see in the color photo, so a red dress on a green lawn still separates instead of turning into one flat gray. Brightness and contrast are applied after that. Contrast stretches the tones away from middle gray; a value of plus 20 to plus 40 gives the punchy look common in black and white photography.

What colors turn into

Because of that weighting, colors that look very different can end up as similar grays, and colors of similar brightness merge. Some values on the 0 (black) to 255 (white) scale:

That is why a red logo on a blue background can turn into two nearly identical dark grays. If an important detail disappears, raise the contrast, or adjust brightness so the two areas separate, and check with the compare divider.

Pure black and white: threshold and dithering

For two-tone output, each pixel's gray value is compared with the threshold, from 1 to 254. Darker pixels turn black, lighter ones white. The threshold decides how much ends up black:

• Lower threshold (for example 90): only the darkest parts turn black. Lines get thinner, and light gray marks disappear. Good for cleaning up scanned pages with a gray background.
• Higher threshold (for example 170): more of the picture turns black. Faint lines get thicker. Good for pencil sketches and light signatures.
• Auto threshold picks a value with Otsu's method, a classic technique from 1979 that finds the split which best separates the dark and light groups of pixels in that photo. It is a strong starting point for logos, documents and line art.

Thresholding a photo of a face or a landscape usually looks harsh, because all the midtones vanish. Dither fixes that. It uses Floyd-Steinberg error diffusion, published in 1976, which spreads the rounding error of each pixel to its neighbors. The result is still only black and white pixels, but their density varies, so from a distance you see shades of gray. This is how newspapers, thermal receipt printers and many laser engravers show photos with a single ink.

Sepia

Sepia uses a widely used color matrix that maps each pixel to warm brown tones based on its red, green and blue values. At 100 percent strength you get the full antique look. Lower values blend the sepia with the original colors for a softer, warm vintage tint, which can flatter skin tones and wood or leather products. Brightness and contrast work on sepia too; a little extra contrast keeps it from looking washed out.

Examples with settings

A logo for a rubber stamp

Upload the logo, choose Black and white, press Auto threshold, and save as PNG. If thin parts break up, raise the threshold by 10 to 20. If black areas spread into each other, lower it. Stamp makers usually want pure black on white at a large size, so export from the biggest version of the logo you have.

A scanned contract page that looks gray

Choose Black and white, leave Dither off, set contrast to plus 20 and try a threshold around 150. The paper becomes pure white and the text sharp black. Save as PNG, which keeps two-tone images very small.

Moody product photos

Choose Grayscale, contrast plus 25, brightness minus 5. Apply the same settings to the whole batch so every photo in the set matches. Save as JPG at 85 to 90.

Coloring pages and printables

Line art for coloring pages needs clean black lines with no gray. Choose Black and white, use Auto threshold, and check the preview by dragging the divider across the drawing. Printable sellers on Etsy use the same approach for stencils, cut files and worksheets. If you sell printables, AM Jarvis's Etsy Research scores Etsy keywords and fixes your 13 tags so those listings get found.

When black and white works best

Removing color shifts attention to light, shape and texture. Photos with strong side light, clear shadows, interesting surfaces such as wood, stone, fabric or skin, and simple shapes usually convert well. Photos whose whole point is color, such as a sunset, a rainbow of products or a food spread, often look flat in gray. A quick test: drag the compare divider across the photo. If the gray side still has a clear subject and some deep blacks and bright whites, it works. If everything sits in the middle grays, add contrast or keep the photo in color.

For stores, a black and white version can set a mood on a homepage banner or an "about" section, while product photos usually stay in color so shoppers see the real shade they are buying.

Preparing artwork for cutters, stencils and engravers

• Vinyl cutters and stencils need hard edges. Use Black and white without dithering, then check that small gaps between shapes have not filled in.
• Laser engravers burn the black areas. Photos need dithering; logos and text do not. Many engraving programs dither on their own, so if yours does, give it a grayscale image instead.
• Screen printing films must be fully opaque black. Two-tone output saved as PNG prints as solid black with no gray halo.
• Size first. Thresholding a small image and then enlarging it gives jagged edges. Start from the largest original you have.

Troubleshooting

• The image turned almost all black or all white: the threshold is far from the photo's tones. Press Auto threshold, then nudge it.
• The paper background of a scan stays speckled: lower the threshold slightly and add 10 to 20 contrast, with Dither off.
• The grayscale looks dull: add contrast. Plus 20 to plus 40 is a common range for black and white photos.
• The preview divider moves when I scroll on my phone: on touch screens, start the drag near the divider to move it; touching elsewhere scrolls the page.

Format and file size

Original keeps each photo's own format, or pick JPG, PNG or WebP for the whole batch. Two things are worth knowing:

• Pure black and white compresses best as PNG. Large areas of identical pixels shrink dramatically with PNG's lossless compression, often smaller than a JPG of the same image, and with perfectly sharp edges.
• Grayscale JPGs stay similar in size. Browsers save JPGs with three color channels even when every pixel is gray, so a grayscale JPG is usually only a little smaller than the color original. Lower the quality slider, or run the file through the image compressor, if size matters.

Batch editing tips

• For a set that must match, such as a team page or a product collection, keep Same settings for every photo ticked and tune the settings on the darkest photo first.
• If one photo is much lighter or darker than the rest, untick Same settings, select it and adjust only its brightness.
• Press Reset sliders to go back to neutral settings at any time.
• Photos that cannot be opened, such as HEIC files in Chrome, are reported after the batch, and the rest are still saved. Convert HEIC first with the HEIC to JPG converter.

Why not just use a phone filter?

Phone galleries and social apps have mono filters, and for a single casual photo they are fine. They fall short in three situations. First, batches: a filter has to be applied photo by photo, while here one setting covers 200 photos and comes back as a ZIP. Second, two-tone output: phone filters give grayscale, not pure black and white, so they cannot prepare a stamp, a stencil or a cut file. Third, control and consistency: you can see the exact threshold, brightness and contrast numbers, note them down, and use the same values again next month so a product line keeps the same look. The result is also a real file in the format you choose, not an edit stored inside a gallery app.

Privacy and limits

All processing runs in your browser. The preview uses a reduced copy for speed, and downloads are made from the full resolution photo. Photos above about 60 megapixels are scaled down when opened. Dithering very large images takes a few seconds. Nothing is uploaded, and camera data such as GPS location is not copied into the new files. To hide parts of a photo rather than change its colors, use the blur image tool.

You can run as many test versions as you like: each download is a new file, and your originals stay untouched on your device.