The grandeur hits you as soon as you walk in. On the austere, slate-grey wall of the Musée d'Orsay's newly renovated impressionist gallery, Manet's Déjeuner sur l'Herbe stops visitors in their tracks.

The plump female nude at the heart of the canvas, who so scandalised 19th-century opinion in the Paris Salon, is recognisable, but there is something splendidly different about its new presentation.

After Manet, there are the other crown jewels of impressionism: the Degas ballerinas, Monet's poppies, Renoir's Moulin Rouge dancers, Cézanne's card players, and dozens more of the world's best-known 19th-century French masterpieces. The colours leap out from the long, sombre walls.

The museum's president, Guy Cogéval, had spoken before its reopening of a "renaissance" of the Musée d'Orsay and its world-renowned collection, and promised to show the impressionists as we had never seen them before. The expert judgment, ahead of the public opening of the new-look museum on 20 October, is that he has been true to his word.

It has taken almost €8m (£7m) to create this new gallery – part of a two-year renovation of the museum costing €20m – in which clever use of colour and illumination shows the works in an entirely new light.

Gone are the cramped corridors, the dead ends, the white stone walls and floors and the glaring light from the massive glass canopy that forms a central avenue over the top-floor gallery in the Pavillon Amont, the west wing of the building.

The new, subdued walls and floors, along with artificial lighting, have created what Cogéval describes as an "intimate", almost homely, atmosphere in a gallery that he says is the "beating heart of the museum".

"These paintings were, after all, intended to be hung on walls in homes, not in a museum," he says.

With his gelled hair, slightly rumpled suit and unbridled enthusiasm, Cogéval, 55, an art historian who took over as president of the Musée d'Orsay in January 2008, has the appearance and air of an over-excited schoolboy. "Everyone said I couldn't touch the museum when I arrived because it is a historic building and all that. But I have proved them wrong. I said we would do this, and we did," he says, with undisguised glee. "The whole space has been transformed. It's magnifique!"

The 19th-century painters, working in an era before the electric light bulb became widespread, would doubtless have appreciated the modern tricks of artificial light employed to show their work to extraordinary effect.

Developing artistic and scientific techniques to capture on canvas the way that light transformed landscapes and objects became an obsession among the impressionists. The focus was crucial to creating what they termed "optical realism".

Claude Monet said of impressionism, the movement he founded and led: "Light is the principal person in the picture." To that end, he strove over and over again to encapsulate the way that light danced over the Thames at Westminster, the cathedral at Rouen, the water lilies on the pond at his home in Giverny, and the nearby haystacks – all at different times and in different weathers.

Curator Xavier Rey, one of the team hanging the impressionist works in the new fifth-floor gallery, said that before the renovations the paintings had been lit solely by sunlight. "The new system of lighting has transformed everything. Now we have a combination of halogen and new-generation diode lights that reproduce the richness of sunlight, but directly light the paintings and reflect the colours and details. It really does mean the works are being seen in a new light, which was our intention."

He added: "Hanging the works on coloured walls is also closer to the way the impressionist paintings would have been displayed in their time."

As for the impressionists, the devil was in the detail and colour; Parisian architect Jean-Michel Wilmotte said his team had experimented with various shades of grey before coming up with the right one.