If ever you were looking for an example of the outward-looking nature of Scottish painting, then Samuel John Peploe is your man.

And though this is the National Gallery of Scotland's third retrospective of the oldest of the Scottish Colourists – the first having been in 1941, the second in 1985 – this one presents a timely opportunity to reassess his work for a new generation.

"I've tried to find 100 of Peploe's best paintings, and it's taken me just over a year to do so," says senior curator Alice Strang, who delivered last year's FCB Cadell retrospective and will soon begin work on JD Fergusson, which opens in 2013 and will be NGS's third and final airing of the Scottish Colourists (Edinburgh's City Art Centre had a retrospective of George Leslie Hunter, the fourth member of the group, in the summer). Two-thirds or so of the 100 Peploes on show are from private collections and they are hung chronologically.

Many of the heart-stopping still lifes, those stunning splashes of intense colour on black backgrounds for which he is so well-known, are gratifyingly evident throughout the four rooms of the show, and it's possible to witness how Peploe's style and technique in the genre developed over the years. Among the most striking are his very early works, and The Lobster (c.1901) amazes for its sheer modernity. The influence of Diego Velazquez is evident in the merging of the black background with the brown wooden table, the three-stroke bone knife handle, the stark simplicity of the brightly painted lemon on the white plate, and the brilliant orange of the shellfish and how its tones are reflected in the unusual vertical signature. When these are viewed with The Coffee Pot and The Black Bottle, from the same era, it's possible to appreciate once again why Peploe was successful right from the very beginning – one of the reasons there are more Peploes here than there were Cadells.

Even earlier than that, though, Peploe had swiftly proved himself an accomplished portraitist with figurative work such as Gipsy and Old Tom Morris – both from the late 1890s, when he had just completed his training at the RSA in Edinburgh and the Academie Julian in Paris – and had already exhibited with both the RSA and the RGI. The handling of the oils and the use of dark and light to bring his sitters to life are quite remarkable and it's a joy to view them together and to see how they contrast sharply with a later portrait of his first son, Willy Peploe (c.1930).

Old Tom Morris is the largest painting in the exhibition. "Peploe never painted on that scale again," says Strang. Neither, curiously, did he revisit his brief exploration into self-portraiture after 1900. Strang could find only four after painstaking scrutiny of books, catalogues and the archives of galleries and auction houses, and they are all from the same year. One of these, which she has named Self-Portrait (Painting And Smoking), is shown for the very first time, and has been specially framed by its private owner for the exhibition. In it, Peploe is wearing a smock and white collar and holding a smoking pipe while putting a brush to the canvas on his easel; the physical movement between each brushstroke is so palpable you can almost imagine the carpet beneath his feet being worn down.

By contrast, the others are static renditions, each charming in his distinctive bold and lively style. The artist is also playfully represented in a conte sketch that shows him outlined in bowler hat and cape, in a style that suggests a strong influence from Toulouse Lautrec.

Most of Peploe's work is on a relatively modest scale – a feature that speaks volumes about the artist's lack of competitiveness but which was also, says Strang, borne of necessity. For his many landscapes, Peploe fully embraced painting "en plein air" in both Scotland and, frequently, in France, so smaller canvases were easier to transport and to fill quickly as the paint dried more readily than in the studio. The exhibition will feature one of his pochade boxes – a device that facilitated the painting and storage of drying canvases together with artists' materials. A Windy Day At Barra (c.1903) and A Street, Comrie (c.1900), are charming examples of his Sisley-inspired style in the period before he established his reputation as a still-life artist, and Kirkcudbright (c.1918), with its flattened shapes, simplification and bold outlining in colour, shows how he applied the lessons learned in France to the Scottish landscape.

His early success – he had his first solo exhibition at the Scottish Gallery in 1903, and he was the first Scottish Colourist to have a painting acquired for a public collection – does not mean he was an "establishment" artist, however. Strang points to the fact that when the Peploes moved to Paris to enable the artist to fully embrace the latest developments in French art, the dramatic change in his work – with a bolder and more experimental technique, influenced by Matisse and the Fauves – was not instantly popular back home.

"Peploe came back from France with French work in 1910 and the Scottish Gallery refused to show him again until 1922," she says. "Before he left he'd been showing still lifes with black backgrounds and brilliant colour, and the sheer number of these works, and how quickly he painted them, shows how well received they were. Now here he was, coming back with Fauve-inspired bold and daring subjects such as Boats At Royan, where paint was applied directly from the tube, areas of primed canvas are allowed to show through, and colour was used to delineate form."

"Far from being Establishment, Peploe was very brave. His technique was always changing and developing. And remember, his bid to become an associate of the RSA was refused in 1909. It took him 10 years to be successful, and even then his election was controversial."

However, his new work was exhibited widely in London – which prompts Strang to wonder why Peploe did not move there, as his friend JD Fergusson did – and his international reputation grew during the 1920s, with the Tate acquiring Tulips of 1923 for the British national collection in 1927, the year he was elected a member of the RSA.

His paintings in this period are probably the ones for which he is best known, and there are plenty of examples here. In particular The Ginger Jar, painted in 1926, echoes the style of Paul Cezanne. "The very fact that Peploe was aware of Cezanne was exceptional at that time," says Strang. "In fact, in his obituaries the question was asked whether Peploe should be known as the Scottish Cezanne. He really was quite avant-garde. Remember, Peploe saw these French painters' work first-hand and visited the same locations. I can't over-emphasise the importance of the fact that Peploe, like all the Scottish Colourists, travelled the world and embraced these new and exciting techniques.

"Peploe's courtship with Margaret Mackay lasted 16 years before they married, so he was quite definitely living a bohemian lifestyle. The paradox is that you'd never have known to look at him that Peploe was an artist, because he looked like a businessman when he came out of his flat in India Street, Edinburgh, to walk to his studio. The Peploes lived in their relatively modest three-bedroomed flat from 1912 until he died in 1935 aged 64, and Margaret stayed there until her death in 1958. He seemed content to stay put. And he was a shy man, whereas Cadell and Fergusson where gregarious and outgoing. Margaret would go to his private views while he stayed at home, and he would go out for a walk if a dealer came to his studio. He was a serious painter who wanted to get on with painting, and he was the figurehead of the group."

The last room is dedicated to his later work, which Strang says is more sombre and serene, and with rustic subject matter such as Chops (c.1930). Boat Of Garten, painted in 1929 when the artist was quite ill, is full of light and shadow. It's possible to see the thickly layered paint and to marvel once again at his sheer mastery with oil. "I hope people will see that Peploe was a standard-bearer for the British post-Impressionist painting," says the curator, "as well as a strong contributor to Scotland's cultural identity."

SJ Peploe opens at the Scottish National Gallery of Modern Art, Edinburgh, on November 3 and runs until June 12. www.nationalgalleries.org