Map of the artist's mind

I once tried to interview Gerhard Richter. It was the least successful meeting I have ever had with an artist. My hero (and boy, I loved his work - I still do) was in town for a show at the Tate, and he agreed to answer the carefully scripted questions of a doting young critic.

As I unfurled a stream of meaningful analysis of his work, his response to one loaded question after another was a hesitant monosyllable "Ja", punctuated by an occasional "Ach, so..." as if my questions had surprised him.

After half an hour Richter brought the agony to a close, saying that he could not disagree with my questions, but had little else to add. Crestfallen, I understood that I had missed the point. I had been trying to over-interpret the work, unaware that what makes Richter the most expensive living artist - the sale of his Three Candles set the record price at $5.4 million in 2001 - is that his work resists the extravagances of critics.

The image is the image, and Richter has little to add by way of interpretation. And while critics might wrangle with the sources, collectors read the work at face value.

Since fleeing East Germany in 1961 and settling in Dusseldorf, Richter has produced a body of work in which every image and every abstraction has an equivalent status. Richter paints not from real life, but from the photograph - an image already in circulation, as a family snap or a newspaper clipping.

Richter sorts his materials in categories, subjects and genres and is scrupulous in revealing his sources. Since 1962 he has been developing Atlas, an ongoing archive or compendium of images, typologies and taxonomies. It is the artist's intellectual, and quite public, scrapbook, mounted on framed panels. The 500-plus of these panels that go on display at the Whitechapel Gallery from Saturday reveal more or less every image that has inspired Richter's paintings.

Atlas is not itself a work of art but a work-in-progress. The collection was last shown in 1997 at Documenta, the contemporary art world's seminal, five-yearly exhibition in Kassel, Germany; the Whitechapel version is the most complete yet. Some panels - such as the leading intellectuals in 48 Portraits, completed in 1972 - are compiled over several years.

Richter's final work never lets you forget the painting process, where a small-scale image is worked up into a larger canvas. The figurative works incorporate a slight blur, achieved after an immaculate rendition has a dry brush dragged lightly across the surface of the paint.

The process produces a sense of detachment, a refusal to be seduced by the seductive image, even as the paint itself cannot help but seduce the viewer. By the time he paints a landscape, it is the image of a landscape, one stage removed, and far from field and sky. An image of an image, not casually reproduced in the manner of, say Warhol, but carefully, painstakingly remade.

With exactly the same handling, Richter raids the family album to produce images challenging and touching in equal measure. A portrait of his daughter, Betty, from 1988 is widely considered one of the great paintings of the 20th century. Her face is turned away from the camera/painter, but the intimacy of the moment cannot be disguised. In an earlier portrait on view at the Whitechapel, Betty's gaze pierces hauntingly through the image-of-the-image; it seems to me to reveal no less an ambiguous relationship between father and daughter. But there I am over-interpreting again.