Grayscale & Black-and-White Image

How to convert an image to grayscale, black-and-white, sepia or duotone

1. Add your image. Drag it onto the box, click to browse, or paste it from the clipboard. PNG, JPG, WebP, GIF, BMP and AVIF are all accepted. Photos taken on a phone stay the right way up, because the decoder reads the EXIF orientation flag instead of ignoring it.
2. Pick a mode. Grayscale for a natural monochrome photo, Black & white (threshold) for a hard two-tone result, Sepia for a warm vintage cast, or Duotone to map the image onto two colours of your choosing.
3. Adjust. Threshold mode adds a 0 to 255 slider. Duotone adds a shadow colour and a highlight colour. The Invert tick box works in all four modes, and the preview redraws on every change.
4. Compare, then save. Drag the handle across the preview to wipe between the original and the result. Download PNG writes the file with a suffix that tells you which mode made it: -grayscale, -bw, -sepia or -duotone.

Grayscale and black-and-white are not the same thing

People say "black-and-white" when they usually mean grayscale: an image with no colour but a full run of grey tones, from deep shadow to bright highlight. That is what almost every classic monochrome photograph is. It is the mode you want for portraits, landscapes, product shots and anything where detail matters.

True black-and-white uses two values only, pure black and pure white, with nothing between them. The tool builds it by measuring each pixel's brightness and comparing that number to a threshold you set. Raise the threshold and more of the picture drops to black. Lower it and more turns white. This is the mode for sketches, signatures, scanned forms, logos you want to trace, and bold stencil-style graphics.

Brightness here is the Rec. 601 luma value, 0.299·R + 0.587·G + 0.114·B. Green carries the heaviest weight because the eye is most sensitive to it, so the result looks far more natural than a flat average of the three channels.

Why this grey is not the grey your browser makes

Here is something that trips up designers. If you have already previewed an image with filter: grayscale(1)in CSS, or applied an SVG <feColorMatrix>, and you now run the same file through this tool, the two results will not match.

The W3C Filter Effects Module Level 1defines those filter functions with the Rec. 709 luminance weights, 0.2126 red, 0.7152 green and 0.0722 blue. This tool uses the older Rec. 601 broadcast luma weights instead. Same input, two different maths, and the gap is easy to see with a pure colour:

So a saturated red logo comes out of this tool at about 30% grey, while a CSS grayscale filter renders the same logo at roughly 21% grey, noticeably darker. Neither is wrong. Rec. 601 is the standard-definition television convention and it is what most photo software has used for decades; Rec. 709 matches the primaries of modern displays. But if you are matching a downloaded asset to a live web page that greys images with CSS, expect a mismatch, and pick one method for the whole set.

Getting the threshold right

The slider starts at 128, the exact midpoint of the 0 to 255 range, which is a fair opening guess and rarely the final answer.

Scanned pen or pencil work usually needs the threshold pushed up, often into the 150 to 190 range, because paper is never as bright as the sensor pretends and thin strokes vanish at lower settings. A photographed whiteboard is the opposite problem: uneven lighting means one threshold cannot serve both halves of the frame, so crop first and convert each half separately. For a logo lifted from a screenshot, start low, around 90, and creep upwards until the counters inside letters like e and a open up without the strokes breaking apart. Watch the compare handle while you drag rather than the numbers.

What sepia and duotone actually do

Sepia runs the classic three-by-three colour matrix that ships with almost every image library,0.393·R + 0.769·G + 0.189·B for the red output channel and its two siblings for green and blue. Two of those three rows add up to more than 1, so bright areas overflow and clamp. Pure white comes out as#FFFFEF, a faintly warm off-white rather than a true white. That is the whole reason the effect reads as aged paper.

Duotone is a different idea. Rather than mapping brightness onto a black-to-white ramp, it maps it onto a ramp between two colours you choose. Dark pixels take the shadow colour, bright pixels take the highlight colour, and everything in between is a blend. Three presets are built in: navy and cream (#1b2a4a to #f5e6c8), teal and peach (#0f3d3e to #ffd8b1), and charcoal and gold (#232323 to#e9c46a). Touch either colour picker and the preset menu switches to Custom so your pair sticks. TickInvert and the shadows take the highlight colour instead, which is often the more striking of the two versions.

Every mode saves as a PNG. If the file needs to be lighter for email or a web page, send it on to theimage converter for a JPG or WebP, or trim the pixel count with theimage resizer first.

Frequently asked questions