The Greenaway Legacy, which opened yesterday at Birmingham Central Library, contrasts her original illustrations with those of her contemporaries and of today’s children’s illustrators.

Under the Window, which was Greenaway’s first picture book, contains a suitably repugnant witch in addition to the expected cohorts of dear little girls. Her illustration of the Pied Piper in another book catches the menacing charm of this ambiguous figure; another picture of a fat goblin, described on the page as “a notable sinner”, glows with peasant greed.

A great draughtsman, however, she was not. Her pictures are very static, and her inability to draw realistic hands would certainly rule her out as a potential royal illustrator today. But, working closely with the renowned colour printer Edmund Evans, she was one of the first illustrators to liberate infant readers from visual overkill through the use of abundant white space.

Her borders, and the different details woven into them, are an additional delight. It was John Ruskin, with whom Greenaway was in regular correspondence, who advised her to improve her work in this way.

Ruskin had less luck in trying to persuade her to draw her children with flimsier costumes and bare feet. One letter from him about her “girlies” says of two of them: “I think they’ve both got lovers already . . . and wouldn’t be mine if I prayed them ever so.” This facetiousness papers over an admission that Greenaway’s girls regularly display their own undeniable if demure brand of sexuality. Ruskin cannot have been their only male admirer then or since whose feelings went beyond artistic appreciation.

Of the famous contemporaries whose picture books are included here, Leonie Caldecott displays all that sense of movement and energy lacking in Greenaway’s illustrations. Walter Crane, on the other hand, produces figures as frozen as Greenaway’s but without her attention to small detail, so pleasing to young eyes. All three look back to an idealised 18th-century countryside, far removed from the growing industrialism of late-Victorian Britain. But this is nothing new in books for any age; Charles Dickens and Thomas Hardy also preferred to describe a world that had largely disappeared.

The Kate Greenaway Medal has been awarded since 1956 for each year’s outstanding work of illustration. Five previous winners - Edward Ardizzone (the first medallist), Raymond Briggs, Helen Oxenbury, Michael Foreman and Janet Ahlberg - have some of their best-known works on display. These serve as a reminder of the explosion in colour that hit picture books after the introduction of new printing techniques in the 1960s and of the dramatic shift in images of childhood since Greenaway.

On show too are the seven contenders on the shortlist for this year’s Medal. A voting box allows visitors to make nominations; the winner, chosen by representatives from the Library Association’s Youth Libraries Groups, will be announced on July 17.

A visitors’ book is also on hand for recording comments. When asked to contribute in the past, older people often express their appreciation of how good modern picture books are compared with those that were around when they were young. It would be surprising if the same did not happen again during this modest but heart-warming exhibition.

The Greenaway Legacy is at the Centre for the Book, Birmingham Central Library, until August 31. Open 9am-8pm Monday to Friday, 9am-5pm Saturday.