IT COULD be one of those large French rivers — wide, placid, beige, seemingly endless, with no current and only occasional felicities visible on the bank. A gorgeous pink sky hangs above, fringed with a dark blur of trees flecked with gold. And in the centre we see the low, sensuous outline of what could be a modernist building, oozing along from right to left, smooth as a slick of oil on water.

We are looking at a recent photograph by Thomas Ruff of Mies van der Rohe’s Tugendhat House, the classic 1928 home built for Fritz and Grete Tugendhat on a commanding site overlooking the wide plains that stretch towards Vienna.

Just as the architect manipulated the building’s masses, creating shifting volumes that link interior spaces with the carefully zoned vistas of the garden, Ruff has also played with the spaces in his photograph, blurring hard edges, refining and neutralising his composition and reducing a famous building to a shape and form far removed from the iconic photographs so familiar to students of architecture.

Ruff is one of the stars, along with Andreas Gursky, of the Dusseldorf School of photography and is best known for his large-scale portraits. But in 1999, he branched out and began a series of architectural photographs of the buildings of Mies van der Rohe in Berlin, Stuttgart and Barcelona. A selection of these images are presented on a large scale as part of the Mies van der Rohe, 1905-1938 exhibition at the Whitechapel Gallery, with a small, complementary show of architectural photos and stereoscopic images at the Essor Gallery in southeast London.

Ruff’s fascination with Mies’s designs began when an exhibition of his photographs was held in one of his buildings. Commissioned by the curators Julian Heynen and Terence Riley, he was initially intimidated by the idea of photographing the much admired legacy of Mies, because, as he said, “they are so beautiful as objects, I couldn’t make a beautiful photograph of them”. But his reservations were soon surpassed by his exhilaration at the challenge of engaging with buildings that are universally known and so highly revered.

However, Ruff took up the challenge and in each case he has subjected his image to rigorous digital manipulation, adding unfamiliar features and washing his prints with patinas and hues associated with the postcards and textbooks of the early days of the Bauhaus.

His photograph of the famous Perls House in Berlin, built in 1912, has, for example, been heavily doctored, the dim yellowed tone of its shutters heightened to a bright yolk colour, its windows freshened up with white painted timbers and clear, gleaming glass. The sky has been darkened to a bruised blue and the fabric of the house has been subtly washed in a greenish putty colour. The effect is startling, presenting the apparently modern windows as eyes on the sinister lowering colours of pre-First World War Berlin.

His interpretation of Mies’s Riehl House in Potsdam-Neubabelsberg of 1907, the architect’s well-known first commission at the age of 21, is also subject to heavy distortion. The villa, built for the University of Berlin philosopher Alois Riehl and his wife Sofie, was a summer house in a secluded setting on the banks of the Griebnitzsee, less a prominent villa than an unassuming little cloister and retreat from the metropolis of Berlin. Ruff has altered the portico overlooking the lake, adding a single wall of glazed windows, not as Mies built it, nor as it was later altered, but in an in-between state that never existed.

In altering the balance of these early Mies buildings, Ruff presents a stronger, more concentrated essence of place and era while maintaining the integrity and artistic achievement of the designs.

Looking at Ruff’s photographs, which in many ways dominate the Whitechapel show, it becomes apparent that Mies was driven to his later Modernist experiments not by a yearning for a leaner form of architecture, but by an interest in architecture simply as art. Ruff’s images, with their stunning plays on light, transparency and space are surprisingly effective in their enhancement of Mies’s art, heightening the clean lines of his early classicism and the artist’s use of colour and tactile materials in his designs.

Ruff has perhaps simply followed Mies’s own personal dictum that antiquity was to be thought of not as mere frozen tradition, but rather as a living cultural idea, needing constant regeneration of the root from which it grew. His photographic language, of shifting planes and subtly altered spaces, shades and impressions, mirrors the changing architectural language of Mies. The early buildings, seen in this show, have of course been long overshadowed by the glorious modernist structures which broke with convention and made Mies famous after he moved to America in 1937. But back in the 1920s Mies’s buildings already represented a projection of the future. Ruff’s interpretations of them, using all the latest technological processing advancements of the new century, also look to the future.

Ruff’s photographs, carefully selected and well hung, comprise an exhibition within an exhibition, although the effect is almost spoilt by his pretentious and indecipherable titles (h.e.k., h.l.k., h.r.p. etc). The Essor show, while only eight works, offers a nice counterbalance in the form of two digitally distorted photographs and six stereoscopes — double images displayed at an angle and viewed in three dimensions in a mirror between.

These are just part of Ruff’s extensive experimental work which will be seen in greater detail at a Ruff retrospective at Tate Liverpool this summer.

• Thomas Ruff’s photographs are part of the Mies van der Rohe show at the Whitechapel Gallery, E1 (020-7522 7888), until March 2. Ruff is also at the Essor Gallery, 1 America Street, SE1 (020-7928 3388), until January 31 Whitechapel Gallery