Photochromes are vibrant and nuanced prints hand-coloured from black-and-white negatives. Created using a process pioneered in the 1880s, these images offer a fascinating insight into the world when colour photography was still in its infancy. A Tour of the World in Photochromes is at the Swiss Camera Museum, Vevey, until 21 August. Here: Street food in the Strada del Porto in Naples, Italy, 1899. (Photo by Swiss Camera Museum/The Guardian)

The Bolenberg chapel sits on a rise overlooking vineyards where leaves change colors to mark a change in the season in Orschwihr in the Alsace region of France, October 12, 2015. (Photo by Jacky Naegelen/Reuters)

In Dougie Wallace’s photos of Mumbai taxis, the chatter, yelling, and constant horns of the city are almost audible. A selection of his images is on show at Gayfield Creative Spaces, Edinburgh, as part of the Retina photography festival until 30 July. For four years, the Glasgow-born Wallace focused his photos on one kind of taxi in particular: the Premier Padmini, a 1960s workhorse painted in black and yellow. Locally known as “Kaali-Peeli”, there were once more than 60,000 of them in the Indian city. But thanks to laws restricting pollution, the cars now are fast disappearing from Mumbai’s streets. (Photo by Dougie Wallace/The Guardian)

Revellers take part in the “Canto a la Tierra” parade on January 3, 2018, during the Carnival of Blacks and Whites in Pasto, Colombia, the largest festivity in the south- western region of the country. More than 10,000 people among artists, craftsmen and revellers take part in the Blacks and Whites Carnival, which has its origins in the mix of the multiple Andean, Amazonian and Pacific cultural expressions. It is celebrated every year from January 2 to 6 in the city of Pasto and is part of UNESCO's Intangible Cultural Heritage of Humanity since 2009. (Photo by Luis Robayo/AFP Photo)

Beneath the Swedish capital lies an intricate web of underground train lines. More than 90 of the 100 stations in the 110km tunnel system, sometimes referred to as “the world’s longest art gallery”, have been decorated with paintings, installations, mosaics and sculptures by 150 artists since the 1950s. After spending a couple of weeks exploring arctic Norway and Sweden, London-based travel photographer Conor MacNeill headed underground to capture images of the metro stations. Here: A rainbow arcs over a girl on the platform of Stadion station. (Photo by Conor MacNeill/The Observer)

As part of FLAIR Melbourne – a Flinders Lane art festival – Melbourne’s Lisa Minogue presents stylised photographic portraits of Australian women of colour, their faces painted vibrantly to accentuate their individuality and encourage the viewer to study each face more closely. Minogue asked each woman the same question: “What do the words “coloured girl” mean to you?”. (Photo by Lisa Minogue/The Guardian)

A college girl takes part in the Holi festival celebrations in Bhopal, India, 19 March 2019. Holi is celebrated on the full moon day and marks the beginning of the spring season. Holi will be celebrated as the Hindu spring festival of colors across the country on 21 March. (Photo by Sanjeev Gupta/EPA/EFE)