NASA's Curiosity rover has captured a "postcard" of lighting during morning and afternoon at the Martian surface, the space agency said.

The postcard is an artistic interpretation of the landscape, with colour added over two black-and-white panoramas captured by Curiosity's navigation cameras.

The views were taken on April 8 at 9.20 a.m. and 3.40 p.m. local Mars time, providing dramatically different lighting.

"Capturing two times of day provides dark shadows because the lighting is coming in from the left and the right, like you might have on a stage -- but instead of stage lights, we're relying on the Sun," said Curiosity engineer Doug Ellison of NASA's Jet Propulsion Laboratory in Southern California, who planned and processed the images, in a statement.

Blue was added to parts of the postcard captured in the morning and yellow to parts taken in the afternoon.

Curiosity is in the foothills of Mount Sharp, which stands 5 km high within Gale Crater, where the rover has been exploring since landing in 2012.

In the distance beyond its tracks is Marker Band Valley, a winding area in the "sulfate-bearing region" within which the rover discovered unexpected signs of an ancient lake.

Farther below are two hills - "Bolivar" and "Deepdale" -- that Curiosity drove between while exploring "Paraitepuy Pass."

Adding to the depth of the shadows is the fact that it was winter -- a period of lower airborne dust -- at Curiosity's location when the images were taken.

"Mars' shadows get sharper and deeper when there's low dust and softer when there's lots of dust," Ellison added.

Curiosity, which landed on Mars in 2012, was designed to assess whether Mars ever had an environment able to support small life forms called microbes.