The Galaxy S6 Edge uses the feature to provide a quick way to stay in touch with select contacts, and to alert owners to important information.

It will be sold for a higher price than the standard S6, which otherwise has the same specifications.

Samsung lost market share to Apple and others after the S5 sold fewer copies than its predecessor in many countries.

Its replacements were unveiled in Barcelona, ahead of the start of Mobile World Congress. They go on sale on 10 April in 20 countries, including the UK.

Metal frame

The South Korean firm said it had set out to address past "missteps", and had codenamed the devices "project zero" to reflect the need for a rethink.

Changes include making the TouchWiz user interface simpler to use by cutting the number of pop-up messages and introducing a metal frame and glass back instead of the plastic styling of earlier models.

The redesign has, however, meant some features have had to be jettisoned: the phones are not water-resistant, they do not have a microSD slot for extra storage and their backs cannot be removed to change their batteries.

Even so, one expert praised the company's choices.

"Samsung has clearly listened to feedback - not just for the Galaxy S5, which just missed the mark last year costing the company greatly - but also the S4, which was a product that tried to cram in every piece of technology it could find," said Ben Wood, head of research at the CCS Insight tech consultancy.

"The software has been made into a much more crisp and clear experience, the design of the product has clean lines and looks very nice, and the marketing campaign is expected to only pinpoint three things - and that's certainly something that had been missing from Samsung's products for quite some time."

Others were more critical. Rob Kerr, from the price comparison site uswitch.com, declared: "The dual-curved display just seems too gimmicky, too niche, to really be a crowd pleaser."

Coloured contacts

The three topics Samsung is focusing on are:

Revamped designs, including the premium model's curved screen

Camera upgrades

In-built support for wireless charging, with support for two rival standards

The S6 Edge uses its curves to provide a couple of services.

The first is called People Edge, which provides a quick way to bring up calls, texts and other messages from five acquaintances of the owner's choosing. Each person is assigned a different colour, which the phone's edge flashes when it rings, providing a hint of the caller's identity even if the device is face down.

The second is Information Stream, which displays the time, weather and selected notifications on the curved part.

It appears Samsung has deliberately kept the functionality more basic than on its Galaxy Note Edge - a larger handset whose screen curves only around one of its sides. The older phone uses the extra space to both run apps of its its own and to add controls to other apps.

The S6 phone's front camera has been upgraded to five megapixels, while the rear one stays at 16MP.

Both gain from a wider aperture, which should improve their ability to take photos and videos in low light conditions.

Samsung has also taken steps to make the camera quicker to use, saying it now takes less than a second to double tap the home key and snap a shot.

The firm is claiming a "world first" by embedding support for both the PMA and WPC's Qi wireless charging standards.

The Android-powered handsets are also faster to recharge, and should return to 50% battery strength within half an hour of being plugged in.

Samsung said that this was half the time it would take to charge an iPhone 6.

(BBC)