Like tints and sepia tones, duotones are a popular way to add character to otherwise monochrome images. Often used for feature images in design, or to subtly enhance an image it's a simple technique that involves the overlaying of one colour onto another. The term duotone is inherited from the printing industry, where two colours are used in printing an image.
In this example, and as homage to the printing process; I have used an image of caseroom lead type taken up close with an Olloclip.
The image is then TINTED to a medium blue in this case over a MONO image with STANDARD contrast.
Other colours work equally as well, more deeper or stronger colours as opposed to lighter tones to work for the shadows; but as always it's a case of trial and error and what works for your image.
Save this image to your camera roll.
Selecting load image, bring this newly saved version into Geló and dial to a different colour. I have used a golden yellow although a pale purple or light green might work well. As we are working on the highlights; generally lighter colours work best. Apply this colour with the OVER blend mode.
Using the ALPHA slider, the intensity is reduced to give a more subtle effect. Again this depends on your image and personal tastes but this gives you an impression of the scope of image editing available.
Save this new image to your Camera Roll. The final image can be seen here... www.flickr.com/photos/filtre/8302060842/in/photostream
Next up - Screened, Pop-art Style.
You can download Geló for iPhone and iPod here... itunes.apple.com/app/id584055229?ls=1&mt=8