Duotone image maker
Choose a photo, pick a colour for the dark parts and a colour for the light parts, and every shade of the picture is mapped between them. Start from a preset, swap the colours or blend the effect with the original. The full-size file is made in your browser.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose or drop a photo.
- Pick a preset or choose your own Shadow colour and Highlight colour.
- Lower Strength to blend some of the original colour back in.
- Press Download duotone image.
How it works
For every pixel the tool computes its brightness t between 0 (black) and 1 (white). The new colour is shadow + (highlight − shadow) × t, calculated for red, green and blue separately. At strength 100% this replaces the pixel, at lower values it is mixed with the original.
Example
With the shadow colour #000080 and the highlight colour #FFFF00, a mid-grey pixel of 128 has t = 0.502 and becomes red 128, green 128 and blue 64. A black pixel becomes #000080 and a white one #FFFF00.
Tips
- For the look of a printed poster, choose a deep shadow colour and a bright, saturated highlight colour.
- A very bright or very dark photo uses only one end of the colour line; raise its contrast first with the image filters.
Frequently asked questions
What is a duotone?
A picture printed with only two colours. Dark parts of the photo get the first colour, light parts the second, and the shades between them are a blend of the two.
How is the brightness of a pixel decided?
From its red, green and blue values with the weights 0.299, 0.587 and 0.114, which makes green count most, as the eye does. The result, from 0 to 1, is the position on the line between your two colours.
How do I get a good result?
Choose a dark shadow colour and a clearly lighter highlight colour; two colours of similar brightness give a flat, washed-out picture. A photo with good contrast works best. Swap the colours to get a negative look.
What happens to transparency and the file format?
Transparency is kept for PNG and WebP. The saved file keeps the format of the original: JPG stays JPG, PNG stays PNG and WebP stays WebP.